Category Archives: invertebrates

Episode 147: Snails and the Gooseneck Barnacle

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Thanks to Kim and Richard E. this week for two awesome suggestions! We’re going to learn about land snails and about the gooseneck barnacle!

Some baby snails and a mama snail, or at least an adult snail that is probably ignoring all those babies:

A giant African snail:

Unlocked Patreon episode about giant African snails (and other stuff)

A rare Polynesian tree snail, white-shelled variety:

A grove snail:

Gooseneck barnacles:

A barnacle goose. Not actually related to the gooseneck barnacle:

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

We’re getting to some more excellent listener suggestions this week, this time about some interesting invertebrates. Thanks to Kim who suggested snails, and to Richard E for suggesting the gooseneck barnacle.

We’ve talked about various snails before, in episodes 27, 57, 81, and 136, but let’s dig in and really learn about them.

Snails are in the class gastropoda, which includes slugs, whether terrestrial, freshwater, or saltwater. Gastropods appear in the fossil record way back in the late Cambrian, almost 500 million years ago. Snails and slugs are so common that no matter where you live, you can probably find one within seconds, if you know where to look.

Snails have shells while slugs don’t, but there’s a third type of gastropod called a semi-slug. It has a shell, but one that’s too small for it to live inside. It’s more of a little armor plate than a snail shell. Slugs also have shells, but they’re vestigial and are actually inside the slug so you can’t see them.

Scientists have long tried to figure out if mollusks developed shells early or if they started out as a wormlike creature that later evolved a shell. A discovery of a 400 million year old mollusk fossil in Wales shows a wormlike body but also a shell—actually seven plate-like shells—which suggests that the shells developed early and that shell-less mollusks later lost them.

The snail has a spiraled shell that it can retract its body into, although not all snails can retract all the way into their shells. Snails that live on land are called terrestrial snails, or just land snails, and those are the ones we’ll talk about today. Land snails have lungs, or rather a single lung, although some land snails have gills instead and live in wet areas, although they’re not technically water snails.

Most land snails eat plant material, which they scrape up using a radula. You may remember from other episodes that the radula is a tongue-like structure studded with tiny chitinous teeth, microscopic ones in this case. Snails are sometimes so numerous that they can cause damage to gardens, so often people buy poison to kill the snails in their yard. But a 2014 study shows that killing snails isn’t very effective. The best way to get rid of snails, or at least minimize the damage they do to gardens, is to pick the snails up and transport them at least 30 yards away, or about 20 meters. Snails have a homing instinct, but distances more than about 20 meters are hard for them to navigate. The snails will probably just make a home where they end up. Also, no throwing them into your neighbor’s garden. That’s cheating.

Most land snails are hermaphrodites, which means the snail fertilizes the eggs of other snails and also produces eggs for other snails to fertilize. Some snails bury their eggs in soil while some hide them in damp leaf litter. The eggs hatch into teeny snails with teeny shells, and as the snail grows, its shell grows too by adding layers at the opening.

Snails need moisture to survive, so a snail secretes mucous that helps it retain moisture. The mucus is also thick enough to protect the snail from sharp objects as it travels around on the flat underside of its body, called a foot. Until recently researchers thought that the mucous also helped the snail move, but it turns out that gastropods move entirely due to muscular motions of the body, which start at the tail and travel in a sort of wave motion to the head. This isn’t the most rapid way to move—a typical snail can only advance about one millimeter per second—but it works for the snail. It can also climb walls and other vertical surfaces since the mucous helps it stick, even if it’s upside-down. The mucus a snail leaves behind in its track is visible until it dries after a few hours, usually called a snail trail or a slime trail.

If a snail’s environment becomes too dry, it will retract itself into its shell and secrete a layer of mucous that hardens, protecting its body from drying out. Later, when the environment is wetter, it softens the mucous and goes about its normal snail activities.

Scientists of all kinds study snails. One recently published study investigated the properties of snail mucous to try to develop an adhesive that can be turned from sticky to non-sticky and back to sticky. Another study from 2011 examined the way snails move to see if that can be adapted to various technologies.

Because snail shells are so common in the fossil record, scientists can measure the oxygen isotopes in shells to learn how dry or wet the environment was during the snail’s life. A recent study of snail shells from the Canary Islands indicates that 50,000 years ago the islands were much wetter than they are now. Also, there were more snails then than now.

The largest living snail known is the giant African snail, which can grow almost a foot long, or 30 cm. It’s native to East Africa but it’s an invasive species in many parts of the world. I actually covered this species of snail in a Patreon episode a few months ago, so I’ll unlock that episode and put a link to it in the show notes if you want to learn more about it. It’s kind of a weird episode and I spend entirely too much time at the end talking about my recent eye surgery, but you’ll learn about the giant African snail and a marine snail called the periwinkle.

New species of snail are discovered all the time, since snails are usually small, often hard to find, and many snails look sort of alike except to the trained eye. In 2012, two species of tiny snails were discovered in a cave in northern Spain. They’re called thorn snails and are less than 2 mm in size. Since they live in caves, like many cave animals they’ve lost pigment and are essentially transparent. More thorn snails new to science were discovered in Panama a few years ago. A snail specimen collected in South America in the 19th century was finally examined a few years ago and described as a new species in 2015. Those are just a few examples; so many snails have been described in the last few decades that it would get boring if I talked about all of them.

Not all snails are brown, of course. Some have lovely shells in different colors, patterns, and shapes. A colorful snail called the Polynesian tree snail, found in Tahiti and a few nearby islands, has been a puzzle to researchers for over a century, since they couldn’t figure out how the snail came to be on the islands. Not only that, but a few of the islands have a variety of the snail with a white shell, which isn’t found on Tahiti. It turns out that the people of the area just liked the white shells, which they used to make jewelry, so they introduced the snails to their islands for a better supply of the shells. The Polynesian tree snail is critically endangered now, but some zoos have started a captive breeding program.

People have eaten snails for thousands of years, and certain species of snail are considered delicacies today. A type of grove snail that lives in Ireland and southern France but not anywhere in between may be evidence that humans brought the snails with them when they first colonized Ireland. Researchers suggest humans arrived in Ireland by boat from southern Europe around 8,000 years ago and brought the snails with them, possibly to farm. They’re actually really pretty snails with a yellow or yellowy-white shell striped with brown.

Another invertebrate humans like to eat is the gooseneck barnacle, also called the goose barnacle. It’s actually a crustacean, and I’m glad I checked because I was honestly certain that it was another mollusk. I think I had it mixed up with certain types of clams with long siphons. But the gooseneck barnacle is a crustacean like last week’s roly poly, but unlike the roly poly, it actually tastes really good—if you can get it.

The gooseneck barnacle attaches itself to rocks and other hard objects in intertidal areas of the Atlantic and Pacific, and it prefers rough water. It can be dangerous to gather. Richard E., who suggested the topic, specifically mentioned the variety known as percebes, which is a delicacy popular around the Iberian peninsula, especially in Portugal and Spain. He mentions that people have died trying to get them, and that his own grandparents have a saying about them, “If you want to get, you have to get your backside wet.”

The gooseneck barnacle attaches itself to an object by its stalk, called a peduncle, which is strong and tough enough to withstand rough waves. At the end of the stalk is the capitulum, which contains the body and is protected with five plates. It extends its legs, which are called cirri and resemble feathers, from an opening in the capitulum, and uses them to filter tiny organisms out of the water that it eats.

Like the land snail and many other invertebrates, the gooseneck barnacle is a hermaphrodite. It mates with the nearest other gooseneck barnacle, and since it literally cements itself to its rock and can’t move afterwards, it’s a good thing that barnacles live in clusters or there wouldn’t be any new ones, since the gooseneck barnacle can’t fertilize its own eggs. The barnacle keeps its fertilized eggs inside its body until they hatch into tiny larvae, which it releases into the water. The larvae live in the sea as plankton for a few months, moulting six times before they metamorphose into cyprid larvae. You may remember that term from the horrifying zombie animals episode last month, but these cyprid larvae are just looking for a nice rock to cement themselves to.

The gooseneck barnacle gets its name from its long stalk, which resembles a goose’s neck, and the protective plates on the capitulum do kinda-sorta look like a goose’s beak from the right angle. Now, back in the olden days people didn’t know that birds migrate. People knew that some birds lived in their area in the winter or summer, but they didn’t know what happened to the birds the rest of the year. Some people believed some birds hibernated, others actually believed they flew to the moon during the winter. In the case of a goose called the barnacle goose, which mostly breeds on remote Arctic islands and then spends the rest of the year in various parts of Europe, in the early medieval days people actually thought it didn’t actually lay eggs or have babies. They thought it and the gooseneck barnacle were the SAME ANIMAL, but that the gooseneck barnacle was a young barnacle goose that was still developing. Therefore, people rationalized, they weren’t actually geese but some sort of fish so could be eaten during Christian fast days when meat wasn’t allowed. This lasted until 1215 when the pope said no, actually, wherever they come from, those things are birds and you can’t eat them on fast days.

The gooseneck barnacle is still causing consternation these days. In 2016, some pieces of driftwood washed up on a few New Zealand beaches, covered with gooseneck barnacles. No one knew what in the heck those things were. A species of gooseneck barnacle is native to the area, but they aren’t usually seen on sandy beaches where people like to swim. A picture of the barnacles caused a lot of speculation as to what they were until scientists and naturalists identified them. Fortunately, though, no one suggested they were baby geese.

You can find Strange Animals Podcast online at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. You can also support the show and get two bonus episodes a month by signing up as a patron at Patreon.com/strangeanimalspodcast.

Thanks for listening!

Episode 146: Three strange animals

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The next few weeks will be all listener suggestions! This week, Dylan and Genevieve of What Are You? Podcast request a strange fish, Kim suggests a strange invertebrate, and Callum suggests a strange bird. Thanks for the great suggestions!

An archerfish, pew pew pew:

A regular roly poly and a spiky yellow woodlouse. Can you spot which is which??

A nightjar. Turn out light pls, is too bright:

A white-winged nightjar showing off his wings:

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

I’m really, really behind in getting to suggestions, as you will probably know if you have sent in a suggestion and you think I’ve forgotten all about it. So before the end of the year, which is coming up frighteningly fast, I’m going to try to get to a lot of the older suggestions. So this week we’re going to learn about a fish, an invertebrate, and a bird.

We’ll start with the archerfish, suggested by Dylan and Genevieve, who are part of the What Are You? Podcast. If you don’t already listen to What Are You?, I really recommend it. It’s a new animal podcast that’s especially for younger kids. If you like Cool Facts About Animals, you’ll like What Are You? Anyway, Dylan and Genevieve both really like the archerfish, so let’s find out why it’s such a weird and interesting fish.

The archerfish isn’t one fish, it’s a family of fish who all catch insects in an unusual way. Most archerfish species are small, maybe 7 inches at the most, or 18 cm, but the largescale archerfish can sometimes grow up to 16 inches long, or 40 cm. All archerfish live in Asia or Australia, especially southeast Asia. They like rivers and streams, sometimes ponds, and a few species live in mangrove swamps and the mouths of rivers where the water is brackish. That means it’s saltier than ordinary fresh water but not as salty as the ocean.

The reason the archerfish is so weird is the way it catches insects. Think about its name for a minute. Archer-fish. Hmm. An archer is someone who uses a bow and arrow, but obviously the archerfish doesn’t have arms and hands so it can’t shoot tiny arrows at insects. But it can shoot water at insects, and that’s exactly what it does.

The archerfish has really good eyesight, and it learns to compensate for the way light refracts when it passes from air to water. When it sees an insect or other small animal, maybe a spider sitting on a branch above its stream, it rises to the surface but only far enough so that its mouth is above water. Then it forms its tongue and mouth to make a sort of channel for the water to pass through. Then it contracts its gill covers, which shoots a stream of water out of its mouth. But because it shapes it mouth in a really specific way, the stream of water turns into a blob as it flies through the air, like a tiny water bullet. The water hits the spider, which falls from its branch and into the stream, where the archerfish slurps it up.

But the archerfish has to learn how to aim. Young archerfish aren’t very good at it, and they have to practice to shoot accurately and far. They can even learn by watching other archerfish shooting water, which is rare among all animals but practically unheard-of in fish.

Sometimes the archerfish will shoot underwater, sending out a jet of water instead of a bullet. It does this mostly to expose small animals hidden in the silt at the bottom of a pond or stream. And sometimes, of course, if the insect is close enough to the surface of the water, the archerfish will just jump up and grab it.

The archerfish shoots water with a force that’s actually six times stronger than its muscles would allow, and it does this by taking advantage of natural water dynamics. This means it uses a lot less energy to shoot water than if it was only using its muscles, and it gets a better result. It can shoot water up to ten feet away, or three meters, to bring down an insect or other small animal, although of course it prefers closer targets.

Archerfish do well in aquariums, so they’ve been studied by scientists to find out how smart they are. It turns out, they’re pretty darn clever. The archerfish takes into account the size of its target to adjust how strong a blob of water it needs to shoot. It also recognizes individual humans by their facial features. So it’s probably a good thing that they don’t have little arms and hands.

Next, Kim sent me some great suggestions way back in August, and I feel terrible that I’ve taken so long to get to any of them. We’ll look at one of those today, an invertebrate officially called a terrestrial isopod, although you may know it by one of a lot of different names. My preferred name for it is roly poly, but it’s also called a sowbug, a wood louse, a pillbug, a doodlebug, and many others.

You have probably seen roly polies, because they’re really common. The most well-known family are the various species that can actually roll up into a ball when threatened, Armadillidiidae, and someone with a sense of humor came up with that name. They’re native to Europe, but they’ve been introduced all over the world. They’re gray or brown-gray in color, armored on the back with overlapping segments, with seven pairs of little legs underneath and a pair of little antennae.

Roly polies eat decaying plant material and sometimes living plants, especially if the plant is wet. In a pinch, they will also eat dead insects and other decaying matter, but mostly they just want that yummy rotting leaf. As a result, they’re valuable decomposers in the food web. They also need moisture to breathe, so they’re often found in soil, under rocks and leaf litter, and in moss.

But Armadillidiidae isn’t the only family of roly polies. Most roly polies actually can’t roll up at all, so I should start using one of their other names, woodlouse. Technically, woodlice are crustaceans. You know, related to crabs and lobsters. But they are infinitely cuter than other crustaceans. And if you’re curious about whether they taste like lobster, apparently they taste awful, like urine. I don’t even want to think about how anyone knows what a woodlouse tastes like, or how anyone knows what urine tastes like. Yuck. Anyway, they’re descended from marine isopods that ventured out on land over 300 million years ago, but a few species have returned to the water and are aquatic.

All woodlice have segmented, flattened bodies with seven pairs of legs. When a woodlouse molts its exoskeleton, it does it in two stages. It molts the back half first, then the front half a few days later. This means that it’s not as unprotected as other arthropods that shed the whole exoskeleton at once.

There’s another arthropod called a pill millipede that looks a lot like a woodlouse, including being able to roll into a ball. But it’s actually not very closely related to the woodlouse. Pill millipedes have 18 pairs of legs and a smoother appearance.

Almost all woodlice are gray or brown, although a few may have small yellow spots. But one is actually yellow and looks very different from other woodlice. It’s called the spiky yellow woodlouse, which is a perfect description. It’s critically endangered, because it only lives in one part of the world, a volcanic tropical island in the South Atlantic, Saint Helena. It lives in trees, but it’s so threatened by habitat loss and introduced rats and other non-native species of woodlice that a captive breeding program is underway to save it. There may be as few as 100 individuals left in the wild, but fortunately it’s a lot easier to keep in captivity than, say, 100 rhinoceroses.

Let’s finish with a bird. Callum suggested caprimulgiformes, which includes nightjars, potoos, oilbirds, and whippoorwills. We’ve talked about a few of them before in previous episodes, including the oilbird in episode 121 and the Nechisar nightjar in episode 70. I know we’ve talked about the tawny frogmouth somewhere, but I can’t remember which episode. Maybe it was a Patreon episode. But we’ve never looked at most caprimulgiformes, so let’s do that now, because they are weird birds. We’ll focus on the nightjars, which are also sometimes called goatsuckers, not to be confused with the chupacabra, which also means goatsucker. In the olden days people used to think nightjars snuck into barns at night and suckled milk from dairy goats. They don’t, though. Birds can’t digest milk.

Nightjars and their close relatives are nocturnal, although some species are mostly crepuscular, which means they’re most active at dawn and dusk. Like the owl, the nightjar’s feathers are very soft so that it can fly silently. It eats insects, especially moths.

There are three subfamilies of nightjars: the typical nightjars, the eared nightjars, and the nighthawks, with lots of species in each group. They live throughout most of the world and they all look similar. We’ll take one typical nightjar as an example, the European nightjar. It lives throughout most of Europe and part of Asia, although it migrates to Africa for the winter. It’s brown and gray mottled with lighter and darker speckles, which makes it really hard to see when it’s sitting on a branch or on the ground in dead leaves. Its head appears flattened and it has a short, broad bill. Its feet are small. It has large eyes and sees well even in darkness. It grows to about 11 inches long, or 28 cm, with a wingspan of about two feet, or 60 cm.

The female nightjar lays her eggs directly on the ground instead of building a nest. Usually she’ll pick a spot where long grass or other vegetation hangs over to form a little hidden alcove. Since the nightjar is so well camouflaged, it can incubate its eggs on the ground in plain sight and probably won’t be seen. If a predator does approach the nest, the parents will pretend to be injured, so that the predator follows the supposedly injured bird hoping for an easy meal. Once the nightjar has drawn the predator far enough away from the nest, it flies away. Some nightjars can even pretend to be injured while flying.

Some nightjars have beautiful, haunting songs while some are nearly silent. The male chuck will’s widow, which lives in the southeastern United States and much of Mexico, sings at night and also claps his wings to show off for females. His song sounds like this.

[chuck will’s widow song]

Because nightjars are so well camouflaged and mostly nocturnal, they’re hard for birdwatchers and scientists to spot. As a result, there are undoubtedly nightjar species still unknown to science. This is the case with the Nechisar nightjar, which we talked about in episode 70. It’s only known from a single wing found on an otherwise squashed dead bird that was hit by a car. And until 1997, the white-winged nightjar from South America was only known from two museum specimens.

Since the first white-winged nightjar nest was discovered in 1997, researchers have learned a lot about it. It’s only been found in a few places in Brazil, Bolivia, and Paraguay, and it likes open lowlands and savannas. The male has white markings on his wings, and during breeding season he finds a termite mound to stand on, spreads his wings to show them off, and then flies up. As he does, his wings make a distinctive sound. Since most nightjars fly silently like owls, the beating of the male’s wings is intended to attract a female. This is what it sounds like:

[white-winged nightjar wings beating]

Like other nightjars, the white-winged nightjar female lays her eggs directly on the ground. Some researchers think she times the eggs to hatch around the full moon so the parent birds have more light to forage for insects. In years where there’s lots of food, the female may lay eggs in a second nest near the first one and incubate them while the male feeds the babies of the first nest.

Many nightjar species are endangered due to habitat loss, but it’s also killed by cars more often than other birds because of its habit of sitting in the road. That does not strike me as being very smart. Maybe it needs to talk to the archerfish for some advice.

You can find Strange Animals Podcast online at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. We also have a Patreon if you’d like to support us that way.

Thanks for listening!

This is what the little nightjar sounds like. It lives in South America:

[little nightjar calls]

Episode 142: Gigantic and Otherwise Octopuses

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Happy birthday to me! For my birthday, we’re all going to learn about octopuses, including a mysterious gigantic octopus (maybe)! Thanks to Wyatt for his question about skeletons and movement that is a SURPRISE SPOOKY SKELETON SEGMENT of the episode, or maybe not that much of a surprise if you read this first.

Further reading:

How octopus arms make decisions

Octopus shows unique hunting, social and sexual behavior

Kraken Rises: New Fossil Evidence Revives Sea Monster Debate

The larger Pacific striped octopus is not especially large, but it is interesting and pretty:

The giant Pacific octopus is the largest species known. It even eats sharks, like this one:

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

Today happens to be my birthday, and not just any birthday. It’s a significant birthday that ends with a zero. That’s right, I’m TWENTY! Or maybe a little bit older than that. So for my birthday celebration, and one week closer to Halloween, let’s learn about the octopus. The episode was going to be about possible giant octopuses, but as I researched, octopuses in general turned out to be so interesting and weird that that’s what the episode is about. But we will talk about some mystery gigantic octopuses at the very end.

The first thing to know about the octopus is what the correct plural is. Sometimes people say octopi but that’s actually technically incorrect, although it’s not like you’ll be arrested if you say octopi. The correct plural of octopus is octopuses, although octopodes is also correct. No one says octopodes because that sounds weird.

But who cares about that, because we’re talking about awesome creepy weird cephalopods! The octopus lives in the ocean but it can come out of the water and walk around on land if it wants to, although it usually only does so for a matter of minutes. The octopus breathes through gills but it can also absorb a certain amount of oxygen through its skin, as long as its skin stays moist. Generally people don’t see octopuses come out of the water because most octopuses are nocturnal.

Most octopuses spend their time on the ocean floor, crawling around looking for food. When it’s threatened or frightened, though, it swims by sucking water into its body cavity and shooting it back out through a tube called a siphon, which allows it to jet propel itself quickly through the water headfirst with its arms trailing, so that it looks like a squid. But most of the time the octopus doesn’t swim like this, because when it does, the heart that pumps blood through most of the body stops. The octopus has three hearts, but two of them are only auxiliary hearts that move blood to the gills to make sure the blood stays oxygenated.

Octopus blood is blue because it’s copper-based instead of iron-based like the blood of mammals and other vertebrates. This allows it to absorb more oxygen than iron-based blood can. Since many octopuses live in cold water that doesn’t contain very much oxygen, they need all the help they can get.

The octopus also uses its siphon to release ink into the water when it’s threatened. Of course it’s not ink, but it is black and resembles ink. Also, people have used octopus ink to write with so, you know, I guess maybe it is sort of ink. Anyway, when the octopus releases ink, it can choose to mix it with mucus. Without the mucus, the ink makes a cloud of dark water that hides the octopus while it jets away, and it may also interfere with the predator’s sense of smell. With the mucus, the ink forms a blob that looks solid and in fact looks a lot like a dark-colored octopus. This is called a pseudomorph or false body, and the octopus uses it to confuse predators into thinking it’s still right there, when in fact the octopus is jetting away while the predator attacks the false body. Researchers have found that young sea turtles who attack the false body thinking it’s the real octopus later ignore real octopuses instead of trying to eat them.

In addition to their ninja-like ability to disappear behind a smoke screen, or ink screen, the octopus can also change its color and even its texture to blend in with its background. Its skin contains cells with different-colored pigments, and tiny muscles can change both the color and the texture of the cells. Think of it like being able to shiver to give yourself goosebumps whenever you want, but at the same time you can change the color and shape of the goosebumps. An octopus species that lives in shallow water and is active during the day generally can camouflage itself better than a species that lives in deeper water and is nocturnal, and small species are typically better at camouflage than large ones. Some species mimic rocks or algae with six arms and use the other two arms to creep along the ocean floor, inching away from a potential predator without it noticing.

But the octopus doesn’t just use its ability to change colors to hide from predators. It also communicates with other octopuses by changing colors. And some species have a special threat display of bright colors that warns predators away. This is especially true of the blue-ringed octopus that lives in the Pacific and Indian Oceans, which will display bright blue spots if it feels threatened. Since the blue-ringed octopus has the strongest venom of any octopus, if you see this particular threat display, swim away quickly. I don’t know why I’m assuming my listeners include sharks and whales. Actually, the place you’re most likely to encounter a blue-ringed octopus is in a shallow tide pool on the beach, so watch where you step.

You probably already know what an octopus looks like, but I haven’t actually mentioned it yet. The octopus has a bulbous body with two large eyes, eight arms lined on the bottom with suckers, and in the middle of the arms, a mouth with a beak. The beak looks sort of like a parrot’s beak and is made of chitin, a tough material that’s similar to keratin. Inside the mouth, the octopus has a radula, a tongue-like structure studded with tiny tooth-like bumps.

Until about ten years ago, researchers thought that only the blue-ringed octopus was venomous. The blue-ringed octopus is tiny but super venomous. Its venom can kill humans, although that’s extremely rare. But now we’ve learned that all octopuses appear to have venomous saliva, most of it relatively weak, but enough to kill mollusks and other small animals. The octopus eats anything it can catch, for the most part, including crabs, shrimp, small fish, mollusks, and so forth. Its suckers can attach so firmly to a bivalve’s shells that it can pull the shells apart. If it can’t manage this, though, it will cover the shells with its toxic saliva. The toxin dissolves tiny holes in the shell and kills the mollusk, allowing the octopus to open the shells easily and eat the animal inside. It can also inject the toxins into crabs to paralyze them, then uses its beak to bite the shells open without the crab being able to fight back.

The octopus can regrow an arm if it’s bitten off or otherwise lost. Some species will even drop an arm like some lizards can drop their tails in order to distract a predator. In the case of the lizard, its tail thrashes around after it’s detached, while in the case of an octopus arm, the arm continues to crawl away and tries to escape from being hurt. This is creepy to the extreme, especially when you realize the arm acts this way because it contains a sort of brain of its own.

An octopus’s brain doesn’t fully control its arms. In fact, the arms contain about twice the number of neurons that the brain contains, which means they can act autonomously in a lot of ways. Basically, each octopus arm processes information the same way that a brain does, without involving the actual brain. The arms have an excellent sense of touch, naturally, and the suckers have chemical receptors that act as a sense of taste as well. When an arm touches something, the arm decides whether it’s food, or if it’s dangerous, or if it’s in the way, or so forth. Then it decides what it should do about it. The arms use the peripheral nervous system, again not the brain, to make decisions that require arms to work together. The result is that the arms can all work at different tasks, together or separately, while the central brain is processing other information, primarily from its eyes. But also as a result, the octopus doesn’t have a good sense of where its body is in space at all times. You don’t have to see your arms to figure out where they are in relation to your body, but the octopus does.

This is all very different from the way our brains work. Researchers study the octopus to determine how its brain works with the arms to help the octopus navigate its environment. Some researchers point out that the octopus’s intelligence is so different from the intelligence of other animals we’ve studied that it’s as close as we can come to studying intelligent life from another planet.

The main reason why the octopus has such a different nervous system is that it’s an invertebrate. Humans and other mammals, birds, reptiles, and fish are all vertebrates, meaning they have a backbone of some kind. The backbone contains a spinal cord that is the main pathway for the nervous system, connecting the brain with the rest of the body. The brain processes everything that the body does. But invertebrates and vertebrates started evolving separately over half a billion years ago, and while most invertebrates don’t demonstrate a lot of what we would consider intelligence, the octopus does. Instead of a central spinal cord of nerves, the octopus, like other invertebrates, has concentrations of neurons throughout its body, called ganglia. The ganglia form a sort of neural net. This actually means the octopus can process information much more quickly than a human or other vertebrate can.

And the octopus is intelligent, probably as intelligent as parrots, crows, and primates. An octopus can learn to recognize individual humans and solve complex puzzles, can learn from watching another octopus solve a problem, and many species use tools in the wild. Some species of octopus spend the day in dens that they make out of rocks, including a rock door that they close after they go inside. The veined octopus will collect pieces of coconut shells, stack them up, and carry them around. If it’s threatened, or if it just wants to take a nap or rest, it uses the coconut shells as a hiding place.

Octopuses in captivity can cause a lot of trouble because they’re so intelligent. They will dismantle their tanks out of curiosity or just escape. An octopus in an aquarium in Bermuda escaped repeatedly in order to eat the fish and other animals displayed in nearby tanks. A common New Zealand octopus named Inky, kept at the National Aquarium, was famous for causing mischief, and one day in 2016 he managed to move the lid to his enclosure just enough to squeeze out. Then he walked around until he found a small pipe. He squeezed into the pipe, and fortunately for him it was a pipe that led directly outside and into the ocean.

The reason that octopuses can squeeze through such tiny openings is that they have NO BONES. There is not a single bone in the octopus’s body. The only hard part of the body is its beak. As long as the octopus can get its beak through an opening, the rest of the body can squish through too.

And that brings us to a surprise spooky SKELETON SECTION, thanks to a suggestion by Wyatt!

[spooky scary skeletons song!]

Wyatt wants to know how bones work and move, which is a good question and will help us learn about octopuses too. Bones have many purposes, including making blood cells and protecting the brain—that would be the skull part of the skeleton, of course—but mainly bones help your body move. Muscles are attached to bones, and when you contract a muscle, it moves the bone and therefore the rest of that part of your body. Without muscles, your bones couldn’t move; but without bones, your muscles wouldn’t do much. Also, you’d look sort of like a blob because bones provide structure for your body.

But if you need bones to move, how does an octopus move? An octopus has no bones! Do I even know what I’m talking about?

The octopus’s muscles are structured differently than muscles in animals with bones. Our muscles are made up of fibers that contract in one direction. Let’s say you pick up something heavy. To do so, you contract the fibers in some muscles to shorten them, which makes the bone they’re attached to move. Then, when you push a heavy door closed, you contract other muscles and at the same time you relax the muscles you used to pick up something heavy. This pulls the arm bone in the other direction.

But in the octopus, the fibers in its muscles run in three directions. When one set of fibers contracts, the other two tighten against each other and form a hard surface for the contracted fibers to move. So they’re muscles that also sort of act like bones. It’s called a muscular hydrostat, and it actually can result in muscle movements much more precise than muscle movements where a bone is involved.

There are exceptions to the “bones and muscles work together” rule, of course. Your tongue is a muscle. So is an elephant’s trunk, or at least it’s made up of lots and lots of muscles that aren’t attached to bones. Tongues and elephant trunks and worms and things like that all use muscular hydrostatic functioning to move.

The octopus has a lifespan that seems abbreviated compared to other intelligent animals. It typically only lives a year or two and dies soon after it has babies. After the female lays her eggs, she stops eating and instead just takes care of the eggs, which she attaches to a rock or other hard surface. It usually takes several months for the eggs to hatch, and all that time the female protects them and makes sure they have plenty of well-oxygenated water circulating around them. She dies about the time the babies hatch. As for the male, he doesn’t take care of the eggs but after he mates with a female he starts showing signs of old age and usually dies within a few weeks. That’s if the female doesn’t just decide to eat him after mating. Most male octopuses stay as far away as they can from a female while mating, and uses one of his arms to transfer a packet of sperm into her mantle, which she uses to fertilize her eggs.

At least one octopus species has been observed to brood its eggs for four and a half years, guarding them from predators and keeping them clean. Researchers studying life in an area of Monterey Bay called Monterey Canyon, off the coast of western North America, regularly survey animals in the area. In May of 2007 they saw a female octopus on a rocky ledge about 4,600 feet, or 1,400 meters, below the surface. She had distinctive scars so the researchers could identify her, and she didn’t leave her eggs once during the next four and a half years. She also didn’t appear to eat or even be interested in the small crabs and other delicious octopus food within easy reach of her. As the years went by she became thinner and paler. She and her eggs were still there in September of 2011 but when the researchers returned in October, she was gone and her eggs had hatched.

Babies are teensy when they’re first hatched, typically only a few millimeters long. The babies drift with the currents and eat tiny animals like zooplankton as they grow. One exception is the same deep-sea octopus species that spends so long protecting its eggs, Graneledone boreopacifica. Because they develop in the egg for so long, babies of this species are much larger than most baby octopuses and can even hunt for small prey immediately.

Another exception to the usual octopus habit of only reproducing once before dying is the larger Pacific striped octopus, which lives in the eastern Pacific Ocean in warm, shallow water. Not only is it gregarious, instead of mostly solitary like other octopus species, it can reproduce repeatedly without dying. Mated pairs sometimes live and hunt together and even share food. Despite the word “larger” in its name, the larger Pacific striped octopus only grows to about three inches across, or 7 cm. It is striped, though. It’s quite attractive, in fact. And its many differences from other octopus species show just how little we know about octopuses.

So how big can an octopus grow? We don’t actually know. The species that grows the largest is called the giant Pacific octopus, and the biggest one ever measured had an armspan of about 30 feet, or 9 meters.

But there are always rumors and sightings of octopuses of colossal sizes, often referred to as the gigantic octopus or the colossal octopus. In 2002 a fishing trawler brought up the incomplete carcass of a dead octopus near New Zealand, and estimates of its armspan when it was alive are around 32 feet, or 10 meters. In 1928 a man named Robert Todd Aiken reported seeing six octopuses off the coast of Oahu, Hawaii with armspans of nearly 40 feet, or 12.5 meters. In 1950, also off the coast of Oahu, a diver named Madison Rigdon reported seeing an octopus with each arm alone measuring almost 30 feet, or over 9 meters.

But because octopuses are soft-bodied animals that are eaten by so many predators, and because the biggest ones typically live in deeper water, we just don’t know that much about how big they can get. When we do find a big dead octopus, its size is difficult to estimate since cephalopods actually shrink quite quickly after they die.

We only have a few remains of ancient octopuses, mostly body impressions and fossilized beaks. In 2009, paleontologists working in Lebanon reported finding five specimens of fossilized octopus that date to 95 million years ago. The specimens are remarkably well preserved, too, which allows researchers to determine that the octopuses belong to three different species that appear to be unchanged from their modern counterparts. In 2014 the impressions of cephalopod beaks dated to around 80 million years ago were found in Hokkaido, Japan. The impressions were well preserved and paleontologists have determined that all but one belonged to an extinct species related to the vampire squid, that we talked about in episode 11. They estimate its body to have been about two feet across, or 60 cm, without the arms. The other beak impression was from a different species, one related to modern squid.

If you listened to episode 86 about ammonoids and nautiloids, which are related to octopuses, you may remember that some extinct species grew enormous, probably over 19 feet long, or 6 meters. Since those species have shells, we have a lot more fossilized remains.

But we have almost no remains of ancient octopuses, so we have no way of knowing how big some species once grew. The colossal squid was only determined to be a real animal a matter of years ago (and we talked about it and giant squid in episode 74). I wouldn’t be one bit surprised if the colossal octopus was one day found to be a real animal too.

Let’s finish with an ancient cephalopod mystery. The octopus is a messy eater, so sometimes researchers can identify an octopus’s territory by the way it leaves shells lying around. Some species of octopus arrange shells and other items in heaped-up patterns around its den. In 2011 a pair of paleontologists named Mark McMenamin and Dianna Schulte McMenamin examined an unusual pattern of ichthyosaur remains in Nevada and suggested that they might have been arranged by an octopus after eating them. But since the nine ichthyosaurs are 45 feet long, or 14 meters, the octopus would have had to be equally enormous. Dr. McMenamin and other Dr. McMenamin think the octopus might have killed the ichthyosaurs by either breaking their necks or drowning them, or both. In 2013 the team investigating the site found what may be part of a fossilized cephalopod beak, further backing up the theory. Then again, that species of ichthyosaur, Shonisaurus, ate squid and other cephalopods, so it’s possible the beak was actually inside an ichthyosaur stomach when it died and that a giant octopus or other cephalopod had nothing to do with the deaths. Still, it’s fun to think about, and it might be true!

You can find Strange Animals Podcast online at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. We also have a Patreon if you’d like to support us that way.

Thanks for listening!

Episode 141: Zombie Animals

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We’re inching closer to Halloween and it’s getting spookier out there! This week let’s learn about some animals that get zombified for various reasons. This is an icky episode, so you might not want to snack while you’re listening. Thanks to Sylvan for the suggestion about the loxo and mud crabs!

Further reading:

Zombie Crabs!

Ladybird made into ‘zombie’ bodyguard by parasitic wasp

A mud crab held by a dangerous wizard:

A paralyzed ladybug sitting on a parasitic wasp cocoon:

A cat and a rodent:

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

It’s another week closer to Halloween, so watch out for ghosts and goblins and zombie animals! Zombie animals?! Yes, that’s this week’s topic! Thanks to Sylvan for suggesting the loxo parasite, which we’ll talk about first. Brace yourself, everyone, because it’s about to get icky!

Before we learn about loxo, let’s learn about the mud crab, for reasons that will shortly become clear. Mud crab is the term for a whole lot of small crabs that live in shallow water, mostly in the Atlantic or eastern Pacific Oceans but sometimes in lakes and other fresh water near the ocean, depending on the species. Most are less than an inch long, or under about 30 mm. The largest is called the black-fingered mud crab, which grows to as much as an inch and a half long, or 4 cm. Most mud crabs are scavengers, eating anything they come across, but the black-fingered mud crab will hunt hermit crabs, grabbing their little legs and yanking them right out of their shells. It also uses its strong claws to crack the shells of oysters.

Loxothylacus panopaei is actually a type of barnacle. You know, the little arthropods that fasten themselves to ships and whales and things. But loxo, as it’s called, doesn’t look a bit like those barnacles except in its larval stages. After it hatches, it passes through two larval stages; during the first stage, it molts four times in only two days as it grows rapidly.

Then, during the cyprid larval stage, the microscopic loxo searches for a place to live. The male remains free-swimming but the female cyprid larva is looking for a mud crab. She enters the crab’s body through its gills and waits for it to molt its exoskeleton, during which time she metamorphoses into what’s called a kentrogon, basically a larva with a pointy end. As soon as the crab molts its exoskeleton, the female loxo uses her pointy end, called a stylet, to stab a hole in the crab’s unprotected body. Then she injects parasitic material that actually seems to be the important part of herself, which enters the crab’s blood—called hemolymph in arthropods like crabs. Like most invertebrates, crabs don’t have blood vessels. The hemolymph circulates throughout the inside of the body, coming into direct contact with tissues and organs. This means that once the loxo has infiltrated the hemolymph, she has access to all parts of the crab’s body.

At this stage, the loxo matures into something that isn’t anything like a barnacle, but is an awful lot like something from a horror movie. She grows throughout the crab, forming rootlets that merge with the crab’s body and changes them. Basically, the female loxo becomes part of her crab host. Eventually she controls its nervous system and molds it to her own needs. She even molds the body to her own needs, since if she’s parasitized a male crab she has to widen its body cavity so it can hold her eggs.

The crab stops being able to reproduce and doesn’t want to. It only wants to care for the eggs that the female loxo produces. She extrudes an egg sac so that it hangs beneath the crab’s abdomen, where a male loxo can fertilize it when he swims by. The crab then treats the egg sac as if it contains its own eggs, protecting them and making sure they get plenty of oxygenated water. This is true even for male crabs, which ordinarily don’t take part in protecting their own eggs. The loxo eggs hatch in about a week, and as soon as they do, the female loxo inhabiting the crab starts the process over again. While a mud crab in the wild can live for a few years, once it’s taken over by the loxo parasite it only lives around 45 days.

Most mud crab populations are reasonably resistant to the parasite, but where the loxo has been introduced to areas where it didn’t live before, it can decimate the local mud crab population. This happened in Chesapeake Bay in the 1960s in North America. The local oysters had been so over-fished that they were nearly completely gone, also nearly destroying the local oyster industry. They imported oysters from the Gulf of Mexico to replenish local stocks, but no one realized they were bringing the loxo with those oysters. These days, up to 90% of the Chesapeake Bay mud crabs are infected with the loxo parasite, while only up to 5% of the Gulf of Mexico mud crabs are infected. Researchers at the Chesapeake Bay Parasite Project are working to figure out more about how the loxo infiltrates its host and changes it genetically, and are monitoring infection rates in the wild.

If you think that’s gross, it’s not going to get any better the rest of this episode.

Next let’s learn about another zombie animal, this one a spider. A number of spiders are parasitized by a tiny wasp called Zatypota percontatoria. It lives throughout much of the northern hemisphere and prefers forested areas with plenty of web-building spiders in the family Theridiidae, also known as cobweb spiders.

Cobweb spiders are really common with around 3,000 species that live throughout the world, including the black widow, which by the way is not nearly as dangerous as people think. Some cobweb spiders are kleptoparasites, which means they steal food and other resources from another animal, in this case larger spiders. A kleptoparasite cobweb spider actually lives in the web of a larger spider, and when a small bug gets caught in the web, it steals it. Sometimes the cobweb spider will kill and eat the spider that built the web in the first place too.

But most cobweb spiders are ordinary spiders, and most are quite small, usually only a few millimeters long. Many are marked with pretty patterns in brown, white, black, and other colors. Different species build different kinds of webs, but they all eat small insects.

As for the wasp, it’s about the same size as the spider it’s trying to parasitize, and sometimes smaller. It has long wings, long antennae, and a long abdomen that in the female ends in a sharp ovipositor. The female finds a spider, usually a young spider that’s less able to defend itself, and stabs it in the abdomen with her ovipositor. Then she lays a single egg inside the spider and flies away.

The egg doesn’t bother the spider, although once the egg hatches into a larva it starts to feed on the spider’s hemolymph. Remember, that’s the equivalent of blood in the invertebrate world. At the same time, it’s releasing hormones into the spider that change its habits. Basically the wasp larva controls the spider so that it acts to the benefit of the larva, not itself.

All this takes about a month. When the larva is ready to pupate and metamorphose into an adult wasp, it secretes a final hormone that influences the spider’s behavior. This one causes the spider to spin a strong, cocoon-like web. When the web is finished, the larva bursts out of the spider’s body, killing it, and eats the spider. Then it enters the cocoon and develops into an adult wasp.

Because spiders are good at defending themselves, only about 1% of spiders end up parasitized. I’m sure the spiders think that’s 1% too many. There are other parasitic wasp species in other places, but they all act about the same as Zatypota.

Another wasp, Dinocampus coccinellae, parasitizes ladybugs. Like Zatypota, the female wasp lays one egg in the ladybug’s body. When it hatches, the larva eats the ladybug’s insides while the ladybug continues to go about its ordinary activities. But after several weeks, the larva is ready to pupate. It paralyzes the ladybug, bursts out of its body, and spins a cocoon that the ladybug sits on.

But the ladybug isn’t dead. It protects the cocoon from other insects by twitching and making grasping motions with its legs.

After about a week, the adult wasp emerges from its cocoon and flies away. The ladybug usually dies, but not always. About a quarter of infected ladybugs recover and are fine. Researchers aren’t sure how the wasp larva causes the paralysis. It may release a virus that infects the ladybug or it may have something to do with venom released by the larva.

This wouldn’t be a proper zombie episode if I didn’t talk about that disgusting parasitic fungus that affects certain carpenter ants in the rainforests in Brazil and Thailand. It completely squicks me out so I’m going to explain it very, very quickly.

Fungal spores float through the air and land on an ant, where they stick. They release enzymes that eventually break down the ant’s exoskeleton, allowing the fungus to spread inside the ant’s body. Finally it’s able to control the ant and makes it crawl up the stem of a plant and bite into a leaf vein. The ant is unable to move at this point and eventually dies. The fungus sprouts from inside the ant and grows into stalks, especially from the ant’s head. About a week later it releases spores that go on to infect other ants. Ugh. So glad I’m not an ant.

Ants can sense when one of the colony has contracted the fungus, and will carry the infected ant far away from the colony so it’s less likely to infect others. The ants also groom each other to remove any spores that may have attached. The fungus can completely destroy ant colonies, but it has a parasite of its own, another fungus that stops the first fungus from releasing spores. A related parasitic fungus also infects certain caterpillars.

Look, I’m totally over talking about fungus, so let’s move on.

So is there any chance that a parasite will turn you into a zombie? There’s not, but a behavior-changing parasite does sometimes infect humans. It’s called Toxoplasma gondii, and while its effects on human behavior has been studied extensively, the effects are so minor as to be nearly nonexistent in most cases.

Toxoplasmosis is a disease caused by a single-celled parasite, and it’s one that not only infects humans, it’s really common. I probably have it but I’m not going to think too hard about that. For most people, it never bothers them and never causes any symptoms, or only mild short-term symptoms like a lowgrade cold that takes a few weeks to clear up. But it can be more serious in people with a suppressed or weak immune system, and can cause problems for the baby if its mother gets infected while she’s pregnant.

There are estimates that up to half the people in the world are infected with toxoplasmosis but never know. The reason it’s so common is that the parasite targets cats, and can be spread in cat feces. And, you know, if you scoop out the cat’s litter box you might be exposed. That’s why pregnant women shouldn’t clean up after a cat. Infection can also result from eating undercooked meat from an infected animal, eating unwashed fruit or vegetables, drinking unpasteurized milk, and drinking untreated water.

Any mammal or bird can contract the parasite, but it can only reproduce in a cat’s digestive system. It doesn’t hurt the cat, it just wants to get inside the cat so it can reproduce. And the best way to get inside a cat is to be part of a rodent that a cat eats.

When a rat or other rodent is infected with Toxoplasma gondii, its behavior changes. Suddenly, it starts to like cats. You can probably see where this is going. Not only does it stop avoiding cats, it actually seeks them out. The cat, naturally, can’t believe its luck, kills and eats the rodent, and may become infected.

If you have a pet cat, the best way to reduce the risk of contracting toxoplasmosis is to scoop the litter box daily, then wash your hands. It takes about a day for the parasite to become active after being shed in cat poop, so if you scoop the litter box right away the risk is lower. Researchers are working on vaccines, and they’ve actually already developed a vaccine that’s now used in sheep. If you keep your cat inside, where it’s safer anyway, it’s much less likely to be exposed to the parasite in the first place.

So, take ordinary precautions but don’t worry too much about toxoplasmosis. Unless, of course, you are a rodent.

You can find Strange Animals Podcast online at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. We also have a Patreon if you’d like to support us that way.

Thanks for listening!

Episode 136: Smallest of the Small

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Last week we learned about the smallest species of animals not typically thought of as small, like snakes and cetaceans. This week let’s look at some of the tiniest animals in the world, the smallest of the small!

Further watching:

A short video about jerboas. Really interesting and well-made!

A button quail:

Baby button quails are the size of BEES:

Kinglets are teeny birds even when grown up. Left, the golden-crowned kinglet. Right, the goldcrest. These birds MAY BE RELATED, you think?

The pale-billed flowerpecker, also teeny and with a cute name:

Moving on from birds, the pygmy jerboa is one of the smallest rodents in the world:

The Etruscan pygmy shrew is even tinier, probably the smallest known mammal alive today. Shown here with friend/lunch:

The Western pygmy blue butterfly is probably the smallest butterfly known:

But the pygmy sorrel moth is even smaller. Right: red marks left behind on a sorrel leaf eaten by its larvae:

One of the world’s teeniest frogs:

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

Last week we learned about the smallest species of animals that aren’t typically thought of as small. But this week let’s learn about the smallest of the small animals. It’s like saying they’re the cutest of the cute animals. We’ll start with the bigger ones and get smaller and smaller as we go.

Let’s start with a bird. The smallest bird is the bee hummingbird, which we’ve talked about before. But there’s another bird that’s really small, the button quail. It’s about the size of a sparrow.

The button quail isn’t actually a quail, but it looks like one due to convergent evolution. There are a number of species in parts of Asia and Africa and throughout Australia. It generally lives in grasslands and is actually more closely related to shore and ocean birds like sandpipers and gulls than to actual quails, but it’s not very closely related to any other living birds. It can fly but it mostly doesn’t. Instead it depends on its coloring to hide it in the grass where it lives. It’s mostly brown with darker and lighter speckled markings, relatively large feet, and a little stubby nothing of a tail. It mostly eats seeds and other plant parts as well as insects and other invertebrates.

The button quail is especially interesting because the female is more brightly colored than the male, although not by much. In some species the female may have bright white markings, in some their speckled markings are crisper than the males. The female is the one who calls to attract a male and who defends her territory from other females. The female even has a special bulb in her throat that she can inflate with air to make a loud booming call.

The male incubates the eggs and takes care of the chicks when they hatch. Baby button quails are fuzzy and active like domestic chicken babies but they’re only about the size of a bumblebee. In many species, as soon as the female has laid her eggs, she leaves them and the male and goes on to attract another male for her next clutch of eggs.

People sometimes keep button quails as pets, specifically a species called the painted buttonquail or the Chinese painted quail. It’s about five inches long, or 12 cm. The female has black and white stripes on her face and throat. The birds can become quite tame and can live several years.

Button quails make a lot of different noises. This is what a button quail sounds like:

[button quail calls]

One of the smallest birds in the world that isn’t a hummingbird is the kinglet, with several species that live in North America and Eurasia. The goldcrest is a type of kinglet and the smallest European bird. It’s only 3.3 inches long, or 8.5 cm, although some individuals are larger. It looks a lot like the North American bird the golden-crowned kinglet, which is just a shade smaller at 3.1 inches, or 8 cm. Both species have a golden patch on the top of the head. The male also has an orangey spot in the middle of the golden patch. Both live in coniferous forests and eat insects and spiders.

Because kinglets are so small and active, they can starve to death quickly—in only an hour in some cases. Females lay up to 12 eggs at a time. TWELVE EGGS. That is a lot of eggs. The nest is too small to hold a dozen eggs in one layer so they end up in a pile. The female keeps all of them warm by pushing her legs down into the pile of eggs. Since her legs have a lot of blood vessels near the surface, they’re much warmer than most birds’ legs.

When the babies hatch, they stay in a pile. The ones on the top of the pile get fed first, naturally, but then they burrow down into the pile and push their siblings up toward the top. They’re not just being nice, though, since birds in the bottom of the pile stay warmer.

This is what a golden-crowned kinglet sounds like:

[bird call]

The pale-billed flowerpecker is even smaller than the kinglets and are among the smallest birds in Asia. It lives in parts of India and nearby areas and mostly eats berries, although it also eats flower nectar. It grows to only 3 inches long, or 8 cm, and is plain brownish-green in color with a short tail and shiny black eyes. It lives in forests but often visits gardens. It doesn’t lay a dozen eggs at a time, just an ordinary two or three.

This is what a pale-billed flowerpecker sounds like. These are some teeny sounds from teeny birds:

[bird call]

There are several rodents that are considered the smallest rodent, but we’re only going to learn about one of them today, the pygmy jerboa. On average it’s only 1.7 inches long, or 4.4 cm, not counting its extremely long tail.

The pygmy jerboa lives in the deserts of Pakistan and possibly in nearby areas too. It has very long hind legs and very short front legs so it hops like a tiny kangaroo, using its long tail as a way to balance and maneuver at high speeds. Its tail is twice as long as its body. Its large hind feet and the end of its tail are very furry to give it more surface area so it can easily maneuver through loose sand.

It mostly eats seeds and leaves, and it gets all the moisture it needs from the food it eats. It’s nocturnal and spends its days in the burrow it usually digs under bushes. Like many other tiny animals, when it rests it slows its metabolism drastically so it won’t starve to death while it’s asleep. Life is rough for tiny animals.

We don’t know a whole lot about the pygmy jerboa except that it’s endangered due to habitat loss, so let’s move on to an even smaller mammal.

The Etruscan shrew grows to about 1.6 inches long, or 4 cm, on average, not counting its short tail. The tail is about a third of the length of its body. It lives in southern Europe, parts of Asia, parts of the Arabian Peninsula, and northern Africa and prefers warm, moist climates. It’s the same size and weight as the bumblebee bat we talked about last week, so it’s one of the smallest mammals known.

The Etruscan pygmy shrew is pale brown with a lighter colored belly, a long nose, and short whiskers around its mouth that it uses to help it find its prey. It’s incredibly active and makes clicking noises almost constantly, as a way to alert other shrews that it’s there and is willing to defend its territory. It makes its nest among rocks and in the abandoned burrows of other animals.

Like the kinglets and other highly active, tiny animals, it has to eat a lot to keep its metabolism going—up to twice its own weight in food every day. It can also enter a torpid state where it reduces its body temperature and metabolism the same way the pygmy jerboa does, in order to not starve while it sleeps. But the Etruscan shrew doesn’t rest very often.

It mostly eats insects and other invertebrates like earthworms, but it will eat anything it can kill. This includes lizards, small rodents, and frogs. It especially likes grasshoppers and crickets, which are often as large as it is. In order to kill prey its own size, the shrew is incredibly fast. If you remember episode 82 where we talked about the star-nosed mole, the Etruscan shrew primarily hunts by touch and can react in barely 25 milliseconds when it touches something it wants to eat. It takes something like 300 milliseconds for a human to blink their eyes, if that gives you an idea of how fast the shrew is. It can touch a cricket and kill it in less time than it takes to blink.

So that’s as small as mammals get, as far as we know. What’s the smallest amphibian?

Well, it’s really, really small. The smallest known frog is only 7.7 mm long. Paedophryne amauensis isn’t just the smallest frog, it’s the smallest vertebrate known. It was only discovered in 2009 in Papua New Guinea.

It sounds like an insect and lives in the damp leaf litter on the forest floor, and it’s dark brown and black in color to blend in with dead leaves, so it was hard to find. Researchers only found it by using sensitive microphones to triangulate on its call, then quickly scooping up lots of leaf litter and stuffing it into plastic bags so anything living in the leaves couldn’t escape. Its eggs hatch into tiny froglets instead of tadpoles.

The tiniest frog is just about the same length as the tiniest fish, the stout infantfish that lives in a few coral reefs near Australia, including the Great Barrier Reef. It also grows 7.7 mm long on average, although females are typically longer and it can grow as much as 10 mm long. But the smallest known fish is the male of an anglerfish species that only grow 6.2 mm long. This doesn’t really count, though, since females grow up to two inches long, or 50 mm. Like other deep-sea anglerfish species, when a male of Photocorynus spiniceps finds a female, he bites her and stays there. Eventually his mouth actually fuses to her body and he lives the rest of his life as a sort of parasitic extension of the female. He supplies her with sperm to fertilize her eggs before she lays them, and she supplies him with nutrition and oxygen since he’s basically part of her body at that point. A female can have more than one male fused to her.

So, we seem to have reached the smallest vertebrates. What about the smallest insects and other invertebrates?

Butterflies are generally pretty small, but the smallest butterfly known is really, really small. The Western pygmy blue butterfly only has a wingspan of 20 mm at most but usually more like 12 mm across. That’s less than an inch. It lives in western North America and parts of the middle east, and has even been found on Hawaii. Its wings are a pretty coppery brown color with rows of black and white spots. It likes deserts and waste places where you wouldn’t expect to find anything as delicate as a tiny butterfly. Its caterpillars eat various types of weed plants.

That is pretty much it. There’s not much to this tiny butterfly. The real mystery is why it’s called the western pygmy blue when it’s not actually blue.

Compared to the smallest moth known, the western pygmy blue butterfly is a giant. The smallest moth is the pygmy sorrel moth and its wingspan is barely four millimeters. Its wings shade from silvery with a metallic bronze tint to purply with a white stripe, and gray along the ends. It’s really pretty but so tiny that it’s hard to spot. It lives in much of Europe and its larvae leave distinctive spiral shapes on sorrel leaves as it eats.

We’ll come back to insects in a minute or two, but let’s look at a few snails first. The smallest land snail is the Borneo snail. Its shell is only .7 of a mm high. It was only discovered in 2015. We don’t know a lot of about it yet, but it probably eats bacterial film growing on limestone in caves. So far researchers haven’t even found a living Borneo snail, though, just its shells.

The smallest water snail is even smaller than the Borneo snail. It’s from North America and its shell is only half a millimeter across at the most. Some individuals are only .3 mm across. Ammonicera minortalis lives in shallow water off the coast of southern Florida and around Cuba and other islands in that area. And that’s pretty much all we know about it. It’s a lot easier to study bigger animals just because they’re easier to find.

Small as that is, on average the smallest beetle is smaller than the smallest snail. It’s a type of featherwing beetle only described in 1999, and on average it’s .338 mm long. So far it’s only been found in Central America and it eats fungus. It’s yellowish-brown in color but that doesn’t really matter because it’s so small that you need a magnifying glass to really see it.

Once you start dividing millimeters, you’re getting into ridiculously tiny territory. But the smallest insect is a type of wasp known as a fairyfly. Kikiki huna is so small it’s measured in micrometers, sometimes called microns, and is smaller than some single-celled organisms. It’s only 150 micrometers long, which is shorter than an ordinary piece of printer paper is thick. It’s been found on Hawaii, Costa Rica, and Trinidad but it probably lives in other places but just hasn’t been found yet. Some researchers suspect that it’s as small as a flying animal can become without losing the ability to fly under its own power instead of just floating on the wind.

At this point anything smaller than Kikiki huna and its close relatives are made up largely of bacteria, which are frankly not as cute or as interesting as, say, button quail. So let’s finish with what may be the very smallest living organism ever found. Or it may not be. Because researchers are literally not even sure if the nanobe is even alive.

In 1996 researchers found what looked like filiments growing among rock samples collected from wells off the Australian coast. Some of them were only 20 nanometers in diameter. To put that into perspective, a nanometer is one billionth of a meter. That’s billion with a B. It’s one thousandth of a micrometer. A nanobe is a tenth of the size of the smallest known bacteria.

The researchers weren’t sure what they’d found so they did a lot of tests. They thought they might have discovered a new kind of crystal, but when they stained the nanobes with a type of dye that binds to DNA, the results indicated the nanobes might be living organisms. But no DNA has been successfully recovered from nanobes.

There’s still a lot of research to be done to determine what they are and if they’re actually alive, though. The main problem is that nanobes appear to be too small to contain all the things that living organisms need. But they do resemble fungi in some ways, just much, much smaller. If nanobes are alive, they’re extremely different from any living animal ever known and presumably live and reproduce in ways completely unlike all other life.

But here’s an interesting note. In 1996 researchers found structures inside a meteorite from Mars that look a lot like nanobes.

You can find Strange Animals Podcast online at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. We also have a Patreon if you’d like to support us that way.

Thanks for listening!

Episode 135: Smallest of the Large

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This week we’re looking at some very small animals–but not animals that we think of as small. Join us for a horrendously cute episode!

Further reading:

The Echinoblog

Further listening:

Animals to the Max episode #75: The Sea Panda (vaquita)

Varmints! episode #49: Hippos

Further watching:

An adorable baby pygmy hippo

The Barbados threadsnake will protecc your fingertip:

Parvulastra will decorate your thumbnail:

Berthe’s mouse lemur will defend this twig:

The bumblebee bat will eat any bugs that come near your finger:

The vaquita, tiny critically endangered porpoise:

The long-tailed planigale is going to steal this ring and wear it as a belt:

He höwl:

A pygmy hippo and its mother will sample this grass:

This Virgin Islands dwarf gecko will spend this dime if it can just pick it up:

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

I talk a lot about biggest animals on this podcast, so maybe it’s time to look at the very smallest animals. I don’t mean algae or bacteria or things like that, I mean the smallest species of animals that aren’t usually considered especially small.

We’ll start with the smolest snek, the Barbados threadsnake. It only lives on a few islands in the Caribbean, notably Barbados. The very largest individual ever measured was only 4.09 inches long, or 10.4 cm, but most are under four inches long. But it’s an extremely thin snake, not much thicker than a spaghetti noodle.

The Barbados threadsnake mostly eats termites and ant larvae. It spends most of its time in leaf litter or under rocks, hunting for food. The female only lays one single egg, but the baby is relatively large, about half the mother’s length when it hatches.

That’s so cute. Why are small things so cute?

Remember the starfish episode where we talked about the largest starfish? Well, what’s the smallest starfish? That would be Parvulastra parvivipara, which is smaller than a fingernail decoration sticker. It grows to about ten millimeters across and is orangey-yellow in color. It lives on the coast of Tasmania in rock pools between low and high tide, called intertidal rock pools.

If you remember the Mangrove killifish from a few episodes ago, you’ll remember how killifish females are hermaphrodites that produce both eggs and sperm, and usually self-fertilize their eggs to produce tiny clones of themselves. Well, Parvulastra does that too, although like the killifish it probably doesn’t always self-fertilize its eggs. But then it does something interesting for a starfish. Instead of releasing its eggs into the water to develop by themselves, Parvulastra keeps the eggs inside its body. And instead of the eggs hatching into larvae, they hatch into impossibly tiny miniature baby starfish, which the parent keeps inside its body until the baby is big enough to survive safely on its own.

But what do the baby starfish eat while they’re still inside the mother? Well, they eat their SIBLINGS. The larger babies eat the smaller ones, and eventually leave through one of the openings in the parent’s body wall, called gonopores. Researchers theorize that one of the reasons the babies leave the parent is to escape being eaten by its siblings. And yes, occasionally a baby grows so big that it won’t fit through the gonopores. So it just goes on living inside the parent.

Next, let’s look at the smallest primate. The primate order includes humans, apes, monkeys, and a lot of other animals, including lemurs. And the very smallest one is Berthe’s mouse lemur. Its body is only 3.6 inches long on average, or 9.2 cm, with a tail that more than doubles its length. Its fur is yellowish and brownish-red.

Berthe’s mouse lemur was only discovered in 1992. It lives in one tiny area of western Madagascar, where it lives in trees, which means it’s vulnerable to the deforestation going on all over Madagascar and is considered endangered.

It mostly eats insects, but also fruit, flowers, and small animals of various kinds. Its habitat overlaps with another small primate, the gray mouse lemur, but they avoid each other. Madagascar has 24 known mouse lemur species and they all seem to get along well by avoiding each other and eating slightly different diets. Researchers discover new species all the time, including three in 2016.

Last October we had an episode about bats, specifically macrobats that have wingspans as broad as eagles’. But the smallest bat is called the bumblebee bat. It’s also called Kitti’s hog-nosed bat, but bumblebee bat is way cuter. It’s a microbat that lives in western Thailand and southeast Myanmar, and like other microbats it uses echolocation to find and catch flying insects. Its body is only about an inch long, or maybe 30 millimeters, although it has a respectable wingspan of about 6 ½ inches, or 17 cm. It’s reddish-brown in color with a little pig-like snoot, and it only weighs two grams. That’s just a tad more than a single Pringle chip weighs.

Because the bumblebee bat is so rare and lives in such remote areas, we don’t know a whole lot about it. It was only discovered in 1974 and is increasingly endangered due to habitat loss, since it’s only been found in 35 caves in Thailand and 8 in Myanmar, and those are often disturbed by people entering them. The land around the caves is burned every year to clear brush for farming, which affects the bats too.

The bumblebee bat roosts in caves during the day and most of the night, only flying out at dawn and dusk to catch insects. It rarely flies more than about a kilometer from its cave, or a little over half a mile, but it does migrate from one cave to another seasonally. Females give birth to one tiny baby a year. Oh my gosh, tiny baby bats.

So what about whales and dolphins? You know, some of the biggest animals in Earth’s history? Well, the vaquita is a species of porpoise that lives in the Gulf of California, and it only grows about four and a half feet long, or 1.4 meters. Like other porpoises, it uses echolocation to navigate and catch its prey. It eats small fish, squid, crustaceans, and other small animals.

The vaquita is usually solitary and spends very little time at the surface of the water, so it’s hard to spot and not a lot is known about it. It mostly lives in shallow water and it especially likes lagoons with murky water, properly called turbid water, since it attracts more small animals.

Unfortunately, the vaquita is critically endangered, mostly because it often gets trapped in illegal gillnets and drowns. The gillnets are set to catch a different critically endangered animal, a fish called the totoaba. The totoaba is larger than the vaquita and is caught for its swim bladder, which is considered a delicacy in China and is exported on the black market. The vaquita’s total population may be no more than ten animals at this point, fifteen at the most, and the illegal gillnets are still drowning them, so it may be extinct within a few years. A captive breeding plan was tried in 2017, but porpoises don’t do well in captivity and the individuals the group caught all died. Hope isn’t lost, though, because vaquita females are still having healthy babies, and there are conservation groups patrolling the part of the Gulf of California where they live to remove gill nets and chase off fishing boats trying to set more of the nets.

If you want to learn a little more about the vaquita and how to help it, episode 75 of Corbin Maxey’s excellent podcast Animals to the Max is an interview with a vaquita expert. I’ll put a link in the show notes.

Next, let’s talk about an animal that is not in danger of extinction. Please! The long-tailed planigale is doing just fine, a common marsupial from Australia. So, if it’s a marsupial, it must be pretty big—like kangaroos and wallabies. Right? Nope, the long-tailed planigale is the size of a mouse, which it somewhat resembles. It even has a long tail that’s bare of fur. It grows to 2 ½ inches long not counting its tail, or 6.5 cm. It’s brown with longer hind legs than forelegs so it often sits up like a tiny squirrel. Its nose is pointed and it has little round mouse-like ears. But it has a weird skull.

The long-tailed planigale’s skull is flattened—in fact, it’s no more than 4 mm top to bottom. This helps it squeeze into cracks in the dry ground, where it hunts insects and other small animals, and hides from predators.

The pygmy hippopotamus is a real animal, which I did not know until recently. It grows about half the height of the common hippo and only weighs about a quarter as much. It’s just over three feet tall at the shoulder, or 100 cm. It’s black or brown in color and spends most of its time in shallow water, usually rivers. It’s sometimes seen resting in burrows along river banks, but no one’s sure if it digs these burrows or makes use of burrows dug by other animals. It comes out of the water at night to find food. Its nostrils and eyes are smaller than the common hippo’s.

Unlike the common hippo, the pygmy hippo lives in deep forests and as a result, mostly eats ferns, fruit, and various leaves. Common hippos eat more grass and water plants. The pygmy hippo seems to be less aggressive than the common hippo, but it also shares some behaviors with its larger cousins. For instance, the pooping thing. If you haven’t listened to the Varmints! Episode about hippos, you owe it to yourself to do so because it’s hilarious. I’ll put a link in the show notes to that one too. While the hippo poops, it wags its little tail really fast to spread the poop out across a larger distance.

Also like the common hippo, the pygmy hippo secretes a reddish substance that looks like blood. It’s actually called hipposudoric acid, which researchers thinks acts as a sunscreen and an antiseptic. Hippos have delicate skin with almost no hair, so its skin dries out and cracks when it’s out of water too long.

The pygmy hippo is endangered in the wild due to habitat loss and poaching, but fortunately it breeds successfully in zoos and lives a long time, up to about 55 years in captivity. For some reason females are much more likely to be born in captivity, so when a male baby is born it’s a big deal for the captive breeding program. I’ll put a link in the show notes to a video where you can watch a baby pygmy hippo named Sapo and his mother. He’s adorable.

Finally, let’s finish where we started, with another reptile. The smallest lizard is a gecko, although there are a lot of small geckos out there and it’s a toss-up which one is actually smallest on average. Let’s go with the Virgin Islands dwarf gecko, which lives on three of the British Virgin Islands. It’s closely related to the other contender for smallest reptile, the dwarf sphaero from Puerto Rico, which is a nearby island, but while that gecko is just a shade shorter on average, it’s much heavier.

The Virgin Islands dwarf gecko is only 18 mm long not counting its tail, and it weighs .15 grams. A paperclip weighs more than this gecko. It’s brown with darker speckles and a yellow stripe behind the eyes. Females are usually slightly larger than males. Like other geckos, it can lose its tail once and regrow a little stump of a tail.

The Virgin Islands dwarf gecko lives in dry forests and especially likes rocky hills, where it spends a lot of its time hunting for tiny animals under rocks. We don’t know a whole lot about it, but it does seem to be rare and only lives in a few places, so it’s considered endangered. In 2011 some rich guy decided he was going to release a bunch of lemurs from Madagascar onto Moskito Island, one of the islands where the dwarf gecko lives. Every conservationist ever told him oh NO you don’t, rich man, what is your problem? Those lemurs will destroy the island’s delicate ecosystem, drive the dwarf gecko and many other species to extinction, and then die because the habitat is all wrong for lemurs. So Mr. Rich Man said fine, whatever, I’ll take my lemurs and go home. And he did, and the dwarf gecko was saved.

Look, if you have so much money that you’re making plans to move lemurs halfway across the world because you think it’s a good idea, I can help take some of that money off your hands.

You can find Strange Animals Podcast online at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. We also have a Patreon if you’d like to support us that way.

Thanks for listening!

Episode 129: The blurry line between animals and plants

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This week we’re looking at some really strange animals…or are they plants? Or both? We’ll start with the sea anemone, then learn about a sea slug that photosynthesizes like a plant (sort of), then learn a little about whether algae is a plant or an animal…and then we’re off and running through the wild world of carnivorous plants–including some carnivorous plants of mystery!

Thanks to Joshua Hobbs of A Degree in Nonsense for the suggestion, and to Simon for the article link I’ve already managed to lose!

A sea anemone and some actual anemones. Usually pretty easy to tell apart:

The sea onion looks so much like an onion I can’t even stand it. This is an ANIMAL, y’all!

Venus flytrap sea anemone and actual Venus flytrap. It’s usually pretty easy to tell these two apart too.

 

The eastern emerald elysia, a sea slug that looks and acts like a leaf:

Giant kelp. Not a plant. Actually gigantic algae. Algae is neither a plant nor an animal:

The corpse flower (left) and the corpse lily (right). Both smell like UGH and both are extremely BIG:

The pitcher plant can grow very big:

Maybe don’t go near trees with a lot of skulls around them:

Puya chilensis (the clumps in the foreground are its leaves; the spikes in the background are its flower spikes):

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

This week we’re going to explore the sometimes blurry line between animals and plants. Joshua Hobbs of a great new podcast A Degree in Nonsense suggested a type of carrion flower that smells like rotting flesh to attract insects, and friend of the pod Simon sent me an article about carnivorous plants. Our very first Patreon bonus episode was actually about carnivorous plants, so I’ve expanded on that episode and added lots of interesting new content. Buckle up, folks, because we’re going to cover a whole lot of ground today!

Oh, and Joshua also says, quote, “I never had a pet growing up, but recently gained an interest in animals. Now after getting into your podcast and animal YouTube channels, I’ve got my first pet, a little corn snake named Arnold!” So welcome to podcasting, Joshua and Arnold!

Let’s start by looking at an animal that resembles a plant. The sea anemone looks so much like a plant that it was named after an actual flower, the anemone, but the sea anemone is related to jellyfish. Most sea anemones attach to a rock or other hard surface most of their lives and don’t move much, although they can creep along very slowly—so slowly that snails are racecar drivers in comparison. Many species have a body shaped like a plant stem and colorful tentacles that resemble flower petals. But those tentacles aren’t just to look pretty. The sea anemone uses them to catch prey. The tentacles are lined with stinging cells that contain venom, just like many jellyfish have. The venom contains neurotoxins that paralyzes a fish or other small animal so that the sea anemone can eat it.

So how does something that looks like a plant eat a fish?

The sea anemone has an interesting body plan. What looks like the stem of a plant is called the column, and in some species it’s thin and delicate while in other species it’s thick like a tree trunk. It sticks to its rock or whatever with an adhesive foot called a basal disc, and on the other end of the column is what’s called the oral disc. Oral means mouth. The actual mouth is in the middle of the oral disc, surrounded by tentacles. The mouth is usually shaped like a slit, which if you think about it is sort of how people’s mouths are too. The digestive system is inside the column. But there is no other opening into the body. The mouth is it. So like jellyfish, the mouth takes in food but it also expels waste, so, you know, not precisely a mouth like ours. When the sea anemone wants to eat, it uses its tentacles to push the food into its mouth.

You know the movie Finding Nemo? Nemo and his dad are clownfish, which aren’t affected by sea anemone venom. Clownfish hide among sea anemone tentacles so predators won’t bother them. In return, the sea anemone eats the clownfish’s poops. I wish I were making that up.

If a sea anemone feels threatened, many species can not only suck its tentacles into its mouth, it can retract the whole mouth inside its body. Basically, it can swallow its own mouth. A sea anemone called the sea onion retracts its tentacles and inflates its column so that it looks like an actual onion. The sea onion lives in a burrow it digs very slowly into the sediment at the bottom of the ocean, with just its tentacles sticking out.

Most sea anemones live in relatively shallow water, but there are some deep-sea species. The Venus flytrap sea anemone has been found at 5,000 feet deep, or over 1,500 meters. At first glance looks like a Venus flytrap plant, thus the name. Its body is a long, usually slender column that widens into a big oral disc on top that’s fringed with short tentacles. It mostly eats detritus that drifts down from above, which it filters from the water with its tentacles, although if a living creature strays into its tentacles it’ll eat it too.

That brings us to the actual Venus flytrap. It’s a plant that eats insects and spiders, especially crawling insects like ants and beetles. The ends of its leaves are modified into lobes that look a little like flowers because the insides of the lobes are a cheerful red while the edges and the hair-like cilia are yellow. When a bug touches the receptors inside the lobes it closes tightly. If the insect continues to move around inside, stimulating the receptors even more, the lobes seal and form a sort of stomach. Digestive enzymes are secreted and about ten days later the lobes reopen and there’s nothing left of the insect but its empty exoskeleton.

If bugs made movies, this would be the subject of every single bug horror film.

The Venus flyptrap is only found in one small part of the world, the boggy areas surrounding Wilmington, North Carolina in the United States. They’re so in demand that the plant is almost extinct in the wild due to idiots digging them up to sell. But Venus flytraps really aren’t that difficult to grow, you just have to make sure the soil you use is deficient in nitrogen and phosphorus. So you can buy Venus flytraps that were grown ethically instead of dug up from the wild. As of 2014 digging up a Venus flytrap is a felony in North Carolina.

Before we go on to talk about some other carnivorous plants, let’s discuss an animal that acts like a plant. It’s a sea slug called the eastern emerald elysia and it lives along the east coast of North America in shallow water. Even though it’s a sea slug, it will also live in fresh water. It grows to about an inch long, or 3 cm, and is green. It’s green because it photosynthesizes like a plant…sort of.

The sea slug eats algae, but it doesn’t fully digest the algae it eats. Its digestive system retains the algae’s chloroplasts, which are the parts of a plant cell that convert sunlight into energy, which is what photosynthesis is. The sea slug keeps the chloroplasts in its digestive system and keeps them alive for months, living off the energy the chloroplasts produce. Researchers aren’t sure how the sea slugs keep the chloroplasts alive.

This is pretty amazing, but it’s not the only sea slug that photosynthesizes in this way. The blue dragon sea slug, that lives along coasts around the Indo-Pacific Ocean, doesn’t just keep chloroplasts alive to produce chlorophyll energy. It gets even more complicated about it. The blue dragon eats tiny animals called hydrozoa, which are related to jellyfish and include the freshwater hydra, although since the blue dragon only lives in the ocean it doesn’t actually eat the hydra. The blue dragon eats hydrozoa that themselves contain a type of microscopic algae that live in a lot of animals, like giant clams, some jellyfish, even some sea anemones, and exchange energy from photosynthesis for protection from predators by living in or on its host. So when the blue dragon eats the hydrozoa containing these algae, it retains the algae and keep them alive. So basically it gets to eat its prey and steals its prey’s symbiotic algae.

Speaking of algae, most algae photosynthesize, and in fact many seaweeds, like kelp, aren’t plants but are giant plant-like algae. But algae, technically, aren’t plants. They’re not animals either. Researchers and taxonomists are still working out the ways various algae are related to each other and to other organisms, but most algae are considered more closely related to plants than to animals without actually being plants. They’re usually grouped with plants above the kingdom level of taxonomy, but since at that level animals like humans and fish and worms and mosquitoes are grouped with fungi, this is a really broad category.

And that brings us, in a roundabout way, to the rotten meat smelling plant suggested by Joshua. There are several plants that attract flies and other insects to pollinate their flowers by smelling of rotten meat. Some of these have freakishly large flowers, like the corpse flower. It lives in rainforests in parts of Sumatra and Java and is actually related to the calla lily. It’s a weird-shaped plant and hard to describe. You know how a calla lily has a pretty white petal that wraps around a yellow spike thing? The corpse flower is like that, only it can be ten feet high, or 3 meters. The thing that looks like a petal is actually a specialized leaf and the yellow spike is called the spadix. The yellow part is made up of tiny flowers, so a calla lily isn’t a single flower, it’s lots of flowers that look like one. Well, the corpse flower is like that, although its flowers are actually only at the bottom of the spadix. The petal-like leaf is dark red inside. The top of the spadix is where the rotten smell comes from, and it’s incredibly stinky—something like rotting meat and rotting fish with some extra smell like dung on top of it. It releases this stink mostly in the evenings and the top of the spadix actually grows hot to better disperse the smell.

The largest single flower in the world is sometimes called the corpse lily and it can grow over three feet across, or about a meter. It’s dark reddish-brown with white speckles and five fleshy petals, which look like meat. It smells like rotting meat too. Flies are attracted to the flower, which pollinate it. The flower can take an entire year to develop but only blooms for a few days. If it’s successfully pollinated, the flower produces a round fruit full of seeds that are eaten by tree shrews, which later poop the seeds out and spread them.

But the corpse lily isn’t any ordinary plant. It doesn’t even have roots or a stem or leaves. All it has is the flower, which grows directly from the roots of the corpse lily’s host plant. That’s right, the corpse lily is a parasitic plant, but it’s no ordinary parasite. It grows not on or around its host plant, but inside it. The host plant is a type of vine called Tetrastigma, related to the grape vine. When a tree shrew poops out a seed, the seed germinates and if it happens to germinate on a Tetrastigma vine, it develops tiny threadlike filaments that penetrate the vine and grow inside it.

The corpse lily lives only in the rainforests of Borneo and Sumatra, and it’s rare and getting rarer since so much of the rainforests in those areas are being destroyed. Fortunately, the corpse lily is actually a tourist attraction since it’s so rare, so spectacular, and so stinky. People who have corpse lilies growing in their yard sometimes protect the flower buds from harm and charge tourists to come look at them, which helps the people of the area and the plants.

There are literally hundreds of carnivorous plant species, with carnivorous habits evolving probably nine different times among plants that aren’t related. Different species use different methods to catch insects. For instance, the pitcher plant has modified leaf that forms a slippery-sided pitcher filled with nectar-like liquid. When an insect crawls down to drink the liquid, it falls in. The insect drowns and is dissolved and digested.

Some carnivorous plants have leaves lined with sticky mucilage, which traps small insects. The sundew has tentacles lined with hair-like structures beaded with mucilage. When an insect becomes trapped in the mucilage, the tentacles bend toward the insect and stick onto it, sometimes quite quickly—in seconds, or in at least one species, a fraction of a second. Generally you don’t think of plants as moving that fast.

Almost all known carnivorous plants are pretty small. The largest are pitcher plants. Two species of big pitcher plants grow in the mountains of the Philippines. Attenborough’s pitcher plant was discovered in 2007 and described in 2009, and is a shrub with pitchers that can hold nearly two liters of fluid. An even bigger pitcher plant was discovered in 2010. But the biggest pitcher plant known is from a couple of mountains in Malaysian Borneo called Nepenthes rajah. It’s been known to science since 1858 and its pitchers can hold over 2 ½ liters of digestive fluid. The biggest pitcher ever measured was over 16 inches tall, or about 41 cm, and the plant itself is a messy sort of vine that can grow nearly 20 feet long, or 6 meters. Mostly pitcher plants just attract insects, but these giant ones also trap frogs, lizards, rats and other small mammals, and even birds.

There’s always the chance that even bigger pitcher plants have yet to be discovered by science, although probably not much bigger than the ones we do know about. The larger an animal, the more likely it is to damage the pitcher while trying to escape. Insects and the occasional small animal are fine, anything bigger than that could just bust through the leaf.

But there have long been rumors about plants that eat much larger animals, even humans. In the 1870s, a German explorer named Karl Liche claimed he’d witnessed a tribe in Madagascar sacrifice a woman to a carnivorous tree. His account is not very believable. He describes the tree as about eight feet high with a thick trunk. A coat of leaves hang down from the top of the tree, leaves about twelve feet long with thorns. At their base is a flower-like receptacle with sweet liquid inside, with six ever-moving tendrils stretching up from it. When the sacrificial woman was made to drink the liquid, the tendrils wrapped around her and the tree’s long leaves folded up and over her. After ten days, the leaves relaxed, leaving nothing but a bleached skull at the base of the tree.

Later expeditions to Madagascar never found any plant that resembled Liche’s. In fact, everyone who’s researched Liche, the tribe he mentioned, and the tree in question haven’t found any evidence that any of them ever existed. It turns out that the account was a hoax from start to finish, written by a reporter named Edmund Spencer for a newspaper called the New York World in 1874.

A 1924 book called Madagascar: Land of the Man-Eating Tree describes a more realistic-sounding carnivorous plant that was supposed to be from India. Its blossoms have a pungent smell that attracts mice and sometimes large insects, which crawl into a hole in the blossom that turns out to be a bristly trap. This sounds a little like the corkscrew plant that lives in wet areas of Africa and Central and South America. It has ordinary leaves aboveground but modified leaves that grow underground. The modified leaves are traps with a stalk lined with hairs pointing in one direction. Tiny water animals, especially single-celled protozoans, stray into the leaves but can’t get out because of the hairs. They’re digested and absorbed by the leaves. But there are no known corkscrew plants or anything like them that trap larger animals or animals that live aboveground.

An 1892 article describes a friend of a friend of a friend’s encounter with a tangle of thin, willow-branch-like vines covered with an incredibly sticky gum. This was supposed to have happened in Nicaragua in Central America. A Mr. Dunstan’s dog was ensnared by the plant but was rescued by Dunstan, who managed to cut the vines with his knife. In the process, both man and dog suffered blistered injuries from the plant, as though it had been trying to suck their blood. The article also says that natives of the area say the plant will reduce a lump of meat to a dried husk in only five minutes.

From these sorts of factual-seeming accounts, it’s a short step to plants of folklore like the Japanese Jubokko tree that grows on battlefields and drinks human blood. It captures people who pass too close to it, sticks its branches into them, and sucks out their blood. If someone cuts into the tree’s bark, blood comes out instead of sap.

Another carnivorous plant was supposedly encountered by a French explorer in 1933 in the jungles of southern Mexico. He doesn’t describe the plant in his 1934 magazine article, just says it’s enormous, but he does say that when a bird alighted on one of its leaves, the leaf closed and pierced the bird with long thorns. The expedition’s guide called it a vampire plant.

A similar story supposedly of a plant found in South America and Central Africa is of a short tree with barbed leaves that grow along the ground, and if an animal or bird steps on the leaves they twine around it and stab it to death, then squeeze the blood out to absorb.

There may actually be a real plant that these stories are based on. It’s called the Puya chilensis and it lives in Chile in South America, on dry hillsides of the Andes Mountains near the ocean. It’s an evergreen plant that only flowers after it’s some 20 years old, with a flower spike that can grow over 6 ½ feet high, or up to 2 meters. The flowers are pollinated by birds. But its leaves are long, edged with hooked spines, and grow in clumps that can be up to six feet wide, or nearly two meters.

Those hooks along the leaves give the plant its other name, the sheep-killer. Sheep and other animals can become entangled in the leaves, which are so tough that locals use the leaf’s fibers to make rope. If the animal can’t escape, it dies and its body decomposes, adding nutrients to the soil around the plant. Yum.

You can find Strange Animals Podcast online at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. We’re on Twitter at strangebeasties and have a facebook page at facebook.com/strangeanimalspodcast. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. We also have a Patreon if you’d like to support us that way.

Thanks for listening!

Episode 123: Linnaeus’s mystery animals

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Carolus Linnaeus was a botanist who worked out modern taxonomy and binomial nomenclature, but there are two mystery animals associated with his work. Let’s find out about them!

Rembrandt sketched this elephant whose skeleton is now the type specimen of the Asian elephant:

Linnaeus’s original entry about Furia infernalis:

Further reading:

Ewen Callaway, “Linnaeus’s Asian elephant was wrong species”

Karl Shuker, “Linnaeus’s Hellish Fury Worm – The History (and Mystery) of a Non-Existent Micro-Assassin”

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

This week let’s learn a little something about binomial nomenclature, which is the system for giving organisms scientific names. Then we’ll learn about a couple of mystery animals associated with the guy who invented binomial nomenclature.

That guy was Carlolus Linnaeus, a Swedish botanist who lived in the 18th century. Botany is the study of plants. If you’ve ever tried to figure out what a particular plant is called, you can understand how frustrating it must have been for botanists back then. The same plant can have dozens of common names depending on who you ask.

When I was a kid, the local name for a common plant with edible leaves that tasted deliciously tart was rabbit grass. I’ve never heard anyone anywhere else call it rabbit grass. Maybe you know it as sourgrass or false shamrock or wood sorrel.

There are over a hundred species of that plant throughout the world in the genus Oxalis, so it’s also sometimes just called oxalis. The species that’s most common in East Tennessee where I grew up is Oxalis dellenii, but all species look pretty much the same unless you get down on your stomach and really study the leaves and the flower petals and the stems. So if you were a botanist wanting to talk to another botanist about Oxalis dellenii back in the early 18th century, you couldn’t call it Oxalis dellennii. Not yet. You’d have to say, hey, do you know what rabbit grass is? And the other botanist would say, why no, I have never heard of this no doubt rare and astounding plant; and you’d produce a pot full of this pretty little weed that will grow just about anywhere, and the other botanist would look at it and say, “Oh. You mean sourgrass.” But imagine if you weren’t right by the other botanist and didn’t have the plant to show them. You’d have to draw it and label the drawing and write a paragraph describing it, just so the other botanist would have a clue about which plant you were discussing. Nowadays, all you have to do is say, “Hey, are you familiar with Oxalis dellenii?” and the other botanist will say, “Ah yes, although I myself believe it is the same as Oxalis stricta and that the differences some botanists insist on are not significant.” And then you’d fight. But at least you’d know what plant you were both fighting about.

Before Linnaeus worked out his system, botanists and other scientists tried various different ways of describing plants and animals so that other scientists knew what was being discussed. They gave each plant or animal a name, usually in Latin, that described it as closely as possible. But because the descriptions sometimes had to be really elaborate to indicate differences between closely related species, the names got unwieldy—sometimes nine or ten words long.

Carl Linnaeus sorted this out first by sorting out taxonomy, or how living creatures are related to each other. It seems pretty obvious to us now that a cat and a lion are related in some way, but back in the olden days no one was certain if that was the case and if so, how closely related they were. It’s taken hundreds of years of intensive study by thousands upon thousands of scientists and dedicated amateurs to get where we are today, not to mention lots of technological advances. But Linnaeus was the first to really attempt to codify different types of animals and other organisms depending on how closely they appeared to be related, a practice called taxonomy.

Linnaeus’s system is beautifully simple. Each organism receives a generic name, which indicates what genus it’s in, and a specific name, which indicates the species. This conveys a whole lot of information in just two words. A zoologist who hears the name Stenella longirostris will know that it belongs to the genus Stenella, which means it’s a type of dolphin, which means it’s in the family delphinidae. If they’re familiar with dolphins they’ll also know they’re talking about the spinner dolphin, and in this case they can even get an idea of what it looks like, since the specific name longirostris means ‘long beak.’ To make things even clearer, a subspecies name can be tagged on the end, so Stenella longirostris centroamericana is a subspecies of spinner dolphin that—you guessed it—lives in the ocean around Central America.

Carl Linnaeus was a young man when he started working out his classification system. He was only 25 when he traveled to Lapland on a scientific expedition to find new plants and describe them for science. This was in 1732 so travel was quite difficult. Linnaeus traveled on horseback and on foot, which as you can imagine took a long time and gave him lots of time to think. Within three years he had worked out the system we still use today.

You know what else Linnaeus invented? The index card. He needed index cards to keep track of all the animals and plants he and other scientists named using his binomial nomenclature system.

Linnaeus named a whole lot of plants and animals himself—something like ten thousand of them during his lifetime. And naturally enough, some mistakes crept in that have since been corrected. But a couple of his mistakes have led to mysteries, and those are the ones we’re going to look at today.

In 1753 Linnaeus got to examine a fetal elephant preserved in a jar of alcohol. Back then hardly anyone outside of Asia and Africa had seen an elephant, so Linnaeus was enormously excited about it and wrote to a friend that the specimen was as rare as a diamond.

Linnaeus described the species and named it Elephas maximus, also known as the Asian elephant today. But from records that still survive, the specimen was marked as having come from Africa. A Dutch pharmacist and collector had acquired the specimen around 1736, and after he died it was sold to King Adolf Frederick of Sweden, who let Linnaeus examine it. The auction catalog where it was listed for sale indicates that it was from Africa, but in his official description of the elephant Linnaeus wrote that it was from Ceylon, which is now called Sri Lanka, which is in Asia.

So ever since there’s been a mystery as to whether the elephant specimen was actually an Asian elephant or an African elephant, and if Linnaeus even knew that there were elephants in Africa. Because the specimen is of a fetal elephant—that is, a baby that died before it was fully developed, probably when its mother was killed while she was pregnant—it’s hard to tell just by looking if the specimen is an African or Asian elephant. We do still have the specimen, fortunately, which is held in the Swedish Natural History Museum’s collection.

A mammal expert at the London Natural History Museum, named Anthea Gentry, got curious about the specimen in 1999, when she saw it on a trip to Sweden. Gentry’s husband was a paleontologist who specialized in mammals, and later she showed him a photograph of the specimen and asked what he thought. He said he was pretty sure it was an African elephant, not an Asian elephant. Gentry got permission to do DNA testing on the specimen, but since it had been in alcohol for so long, not even the most advanced technology and the world’s most experienced expert in ancient DNA could get a usable genetic sequence from the tissue.

The world’s most experienced expert in ancient DNA was Tom Gilbert of the University of Copenhagen in Denmark. He did his best and failed, but he couldn’t forget about the little mystery elephant. In 2009 he got an idea for extracting genetic material from the specimen in a new way that might yield results. It took years, but he and his team got it to work. In 2012 the mystery was finally solved. Linnaeus’s little elephant was actually an African elephant.

But that’s not the end of the story. When a scientist describes a new species and gives it its scientific name, the first specimen described is known as the type specimen. Linnaeus’s elephant was the type specimen of the Asian elephant—but since it was proven to be an African elephant, it couldn’t continue to be the type specimen of the Asian elephant. But that meant that there was no official type specimen of the Asian elephant. They needed a specimen that was still available and that had been described by someone who had examined it scientifically.

When an animal is described officially, it’s a formal process. The International Commission on Zoological Nomenclature decides whether a suggested name is acceptable and makes decisions on type specimens and taxonomy. So researchers connected with the Commission started digging around for a new type specimen, preferably one from Linnaeus’s time or earlier.

A type specimen isn’t always a whole animal. A lot of times it’s just a little piece of a skeleton or a partial fossil, although the more complete a specimen is, the better. Linnaeus had described a partial elephant tooth at some point which was still available in a Swedish museum, and taxonomists were considering using that as a type specimen when they got an email from a paleontologist who specialized in elephants. He sent a copy of a travel journal from an amateur naturalist named John Ray, who had visited Florence in 1664 and wrote his observations of an elephant skeleton and skin on display in the duke’s palace.

And, it turned out, the elephant skeleton John Ray had described was in the collection of a museum in Florence. And it was definitely the skeleton of an Asian elephant—in fact, we even have what amounts to a photograph of the elephant when it was alive, because none other than the artist Rembrandt sketched it. So that skeleton was designated as the type specimen of the Asian elephant and all is well.

That brings us to the other mystery associated with Linnaeus, and this one is a lot less cute than a misidentified baby elephant. But before I tell you what the mystery animal is, let me tell you something that happened to Linnaeus before he’d even come up with his system of nomenclature. This happened in 1728, when Linnaeus was a broke college student staying with a professor and spending all his free time collecting botanical specimens in the marshes.

One day Linnaeus was searching for plants he didn’t already have specimens of when something stung him on the neck. Since he was wading around in a marsh, this was not really that unusual. But this wasn’t the usual insect sting or midge bite. Before long Linnaeus’s neck was painfully swollen, and soon one of his arms had swollen up too.

These days we’d recognize this as an allergic reaction, but back in 1728 they didn’t know what allergies were. By the time Linnaeus got home, he was in such bad shape that the doctor they called worried he wouldn’t survive.

Fortunately for Linnaeus and for science and humanity in general, he survived and went on to invent his naming system only eight years later. Some thirty years after he almost died, he published the tenth edition of his book, Systema Naturae, and included a formal description of the animal that had almost killed him. He named it the fury worm, Furia infernalis.

But there was no type specimen of a fury worm. Linnaeus hadn’t seen the one he believed had bitten him, and the only one anyone had shown him was a tiny worm so dried up and old that he couldn’t see any details. But he knew the fury worm existed because it had bitten him, and anyway everyone knew it was a real animal.

The fury worm was supposed to be tiny and slender, so small that it could be picked up by the wind and blown to other places. If it landed on a person or an animal it would immediately bite them with its sharp mouthparts, breaking the skin, then burrow into the flesh through the wound. It would dig in so quickly and so deeply that it was impossible to find, and even if you did find it, it was impossible to get out because of the backward-pointing bristles on its tail that kept it anchored in place. A person or animal bitten by the worm was likely to die within a day, sometimes within half an hour, unless a poultice of cheese or curds was applied to the bite.

Fortunately for most of the world, this horrible worm only lived in swampy areas in northern Sweden and Finland, Russia, and a few other nearby areas. In one year, 1823, some 5,000 reindeer died from fury worm attacks, and the export of reindeer furs was banned so the worm wouldn’t spread.

But. Where. Are. The. Worms??? And why would a parasitic worm kill its host so quickly? A parasite depends on its host staying alive for enough time that the parasite can benefit from whatever it’s getting from the host, whether that’s nutrients or a protected place to develop into its next life stage. This isn’t going to happen in half an hour.

So we have all this anecdotal evidence of the fury worm’s existence, even from such noted a scientist as Linnaeus himself, but no worms. And the symptoms reported from fury worm attacks varied quite a lot from patient to patient.

Doubts about the fury worm’s existence were already common in the 19th century, and even back in the late 18th century Linnaeus started to have doubts. And as technology and scientific knowledge improved, the fury worm started to look less and less like a real animal and more and more like an explanation for things people had once not understood—like allergies, infection, and bacteria. The death of 5,000 reindeer in 1823 was finally traced to a disease called neurocysticercosis [neuro-cyst-iser-kosis], which is actually caused by a parasite, but not a fury worm. It’s caused by tapeworm larvae that only kill its host after the larvae have matured and are ready to infect a new animal, which happens when something eats the meat of the animal that has died.

So was the fury worm ever a real animal? Almost certainly not. I tried to find out if people are still reporting fury worm bites in northern Sweden and Finland, but I didn’t come up with anything. On the other hand, I did check and it doesn’t look like there’s a band named Furia infernalis, so if you were trying to think of a really cool name for your band, I got you.

You can find Strange Animals Podcast online at strangeanimalspodcast.com. We’re on Twitter at strangebeasties and have a facebook page at facebook.com/strangeanimalspodcast. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. We also have a Patreon if you’d like to support us that way.

Thanks for listening!

 

Episode 121: Cave Dwelling Animals

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This week let’s learn about some animals that live in caves!

The dipluran Haplocampa:

Oilbirds and their big black eyes:

A swiftlet:

The angel cave fish that can walk on its fins like a salamander walks on its feet:

Leptodirus, carrying around some air in its abdomen in case it needs some air:

The cave robber spider and its teeny hooked feet:

The devils hole pupfish:

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

Way back in episode 27 we learned about some animals that live deep in caves. Cave dwelling animals are always interesting because of the way they’ve adapted to an unusual environment, so let’s learn about some of them!

We’ll start with an invertebrate. Diplurans are common animals that are related to insects but aren’t insects. They live all over the world, with hundreds of species known to science, but most people have never seen one because of where they live. They like moist, dark areas like soil, dead leaves, and caves. They’re also small, usually only a few millimeters long, although a few species grow larger, up to two inches long, or five cm.

Diplurans have long bodies with a number of segments, six legs, long antennae, and a pair of tail appendages called cerci. Depending on the species, the cerci may just be a pair of straight filaments like an extra pair of antennae, or they may look like pincers. Diplurans with pincer-like cerci use them to help capture prey, while ones with antennae-like cerci eat fungi and plant material.

Diplurans also don’t have eyes. They don’t need eyes because they live underground where there’s little or no light. A lot of species are pale in color or lack pigment completely.

Diplurans have been around for something like 350 million years, although we don’t have very many fossil diplurans. But recently, a new species of dipluran was discovered in North America that has raised some interesting questions.

Vancouver Island is a large island on the west coast of Canada, near the city of Vancouver. It’s prone to earthquakes and contains a lot of caves, and last summer, in June of 2018, a party of cavers and scientists explored two of the caves and found a new dipluran, which has been named Haplocampa wagnelli. This dipluran is chunkier than most other known diplurans, with shorter antennae, which researchers think points to a more primitive body plan. Since the dipluran is so different from most other diplurans known, and because the caves where it was found were under a thick ice sheet until around 18,000 years ago, researchers are trying to figure out if it found its way into the caves after the ice sheet melted or if it survived in the caves while they were buried under ice.

Haplocampa seems to be most closely related to a few diplurans found in Asia. Asia was connected to western North America during the Pleistocene when sea levels were much lower, since so much of the world’s water was frozen, so it’s possible the ancestors of Haplocampa migrated from Asia after the ice sheets started to melt but before the Bering Land Bridge was completely submerged. Possibly its eggs were accidentally transported by birds who foraged in leaf litter where its ancestor lived.

A lot of animals that live in caves are only found in one particular cave system. This happens when a species of animal that lives near a cave moves into the cave, either full-time or part-time. As its descendants grow up, they become more and more adapted to cave life, until eventually they couldn’t live outside of the cave. Since there’s no way for them to travel from one cave system to another, they are confined to that single cave. And since caves are largely difficult for humans to explore, that means there are lots and lots and lots of animals unknown to science living out their quiet lives deep within caves where humans have never visited. Every so often a group of adventurous and brave scientists explore a cave and discover new animals, usually with the help of experienced cavers.

Animals that are endemic to a specific cave system are rare to start with and vulnerable to any changes in the cave environment. The Tumbling Creek cave snail is only found in a single stream in Tumbling Creek Cave in Missouri, in the United States. It lives its whole life in the water and is only about 2 millimeters in size, with a pale yellowish shell. When it was first discovered in 1971 it was common. Thirty years later, researchers could only find about forty of the snails due to water pollution.

Caves aren’t very friendly environments. Most of the animals that live in caves are very small as a result. Lots of insects and spiders live in caves, some snails, lots of fish, lots of crustaceans that live in fresh water, like crawdads and amphipods, and some salamanders. But the only mammals and birds that live in caves leave the cave to hunt or forage outside of it, like bats. There just isn’t enough food inside a typical cave to sustain a population of larger animals.

So what do cave animals eat? Obviously they eat each other, but without plants a cave system is definitely lacking in organic matter that can sustain populations of animals. Nutrients enter a cave primarily in two ways. Water flowing into a cave brings nutrients from outside, and animals that mainly live outside but sleep in caves also bring nutrients in. In the case of animals, their poop is a major source of organic material, with dead animals also contributing to the cave’s ecosystem. Bats in particular support a lot of cave animals with their poop, which is called guano, but bears, hyenas, and various other animals, birds, and insects also spend time in caves, either to sleep or to hibernate, and bring nutrients in from outside in one way or another.

There are two birds that spend time in caves, and I’m going to talk about both of them briefly even though technically they don’t live in caves, because they’re so interesting. Both birds are nocturnal and can echolocate like bats. The oilbird lives in parts of northern South America and is related to nightjars. I have a whole episode planned about nightjars and their relatives, but the oilbird is the only one that echolocates (as far as we know). The other bird that echolocates is the swiftlet.

The oilbird nests in caves and also roosts in caves during the day, then flies out at night and eats fruit. Some oilbirds roost in trees during the day instead. Its wings have evolved to allow it to hover and to navigate through tight areas, which helps it fly through caves. It sees well in darkness, with eyes that are arranged more like those of deep-sea fish rather than typical bird eyes.

Several species of swiflet echolocate. These are the birds that make their nests from saliva, and which humans gather to make bird’s nest soup from. They mostly live in Asia. They nest in caves and roost in caves at night, then fly out during the day to catch insects.

Researchers don’t know a lot yet about either bird’s echolocation. It’s audible to human ears, unlike most bat echolocating, and some researchers think it’s less sophisticated than bats’. It’s always possible there are other birds that echolocate, but we don’t know about them yet because maybe we can’t hear their echolocating.

This is what oilbirds sound like. The clicking noises are the echolocation calls.

[oilbird calls]

Cave fish are especially interesting. There isn’t one kind of cave fish but hundreds, mostly evolved from ordinary fish species that ended up in a cave’s water system and stayed. Sometimes the species of fish that gave rise to cave fish are still around, living outside the cave, but most cave fish species have evolved so much that they’re no longer very closely related to their outside ancestors.

Cave fish are considered extremophiles and they tend to have similar characteristics. They usually have no pigment, no scales, and often have no eyes at all, or tiny eyes that no longer function. They’re usually only a few inches long, or maybe 10 cm, and have low metabolic rates. They typically eat anything they can find.

Some cave fish have evolved in unusual ways to better fit their specific habitats. The cave angel fish lives in a single large cave system in Thailand, in fast-moving water. It’s about an inch long, or not quite 3 cm, and gets its name from its four broad fins, which look feathery like angel wings.

It was discovered in 1985 but it wasn’t until 2016 that researchers verified a persistent rumor about the fish, which is that it can WALK on its fins. It has a robust pelvis and vertebral column, and strong fin muscles that allow it to climb rocks to navigate waterfalls.

Other fish navigate waterfalls and other obstacles by squirming and wriggling, using their fins to push them along. But the cave angel fish walks like a salamander. Scientists are studying the way it walks to learn more about how the ancestors of four-legged animals evolved.

The largest cave dwelling animal is the blind cave eel, which grows up to 16 inches long, or 40 cm, although it’s very slender. Since it appears pink due to a lack of pigment in its skin and it has no eyes or fins, it looks a lot like a really long worm. But it’s actually a fish. Not much is known about it, but it’s widespread throughout western Australia and is sometimes found in wells. It lives in caves or underground waterways that are connected to the ocean.

The first insect that was recognized as living only in caves is a beetle called Leptodirus hochenwartii. It was discovered in 1831 deep in a cave in Slovenia, and researchers of the time found it so intriguing that they invented a whole new discipline to study it and other cave animals, known as biospeleology.

Leptodirus has some interesting adaptations to cave living. It has no wings and no eyes, its antennae and legs are long, but the real surprise is its body. Its head is small and the thorax, the middle section of an insect, is slender. But the abdomen is relatively large and round, and the insect uses it to store moist air. Caves tend to be humid environments and Leptodirus has evolved to need plenty of moisture in the air it breathes. But some parts of a cave can be dry, so not only does Leptodirus keep a supply of breathable air in its abdomen, its antennae can sense humidity levels with a receptor called the Hamann organ.

Some spiders live in caves and like other cave dwellers, they’ve evolved to look strange compared to ordinary spiders. The cave robber spider was only discovered in 2010 in a few caves in Oregon. Researchers suspect there are more species of cave robber spider in other cave systems that haven’t been explored yet by scientists.

The cave robber spider is so different from other spiders that it’s been placed in its own family, Trogloraptoridae, which means cave robber. It has hook-like claws on the ends of its legs which it probably uses to capture prey. It spins small, simple webs on the roofs of caves and researchers think it probably hangs upside down from its web and grabs its prey as it passes by. But since no one knows what the cave robber spider eats, it’s anyone’s guess. Researchers have even tried raising the spider in captivity to learn more about it, but it wouldn’t eat any of the insects or other small invertebrates it was offered as food. It starved to death without ever eating anything, so it’s possible it only eats specific prey. It’s a yellowish-brown spider with two rows of teeth, called serrula in spiders, which researchers say is unique among spiders.

It’s also pretty big for a cave dweller. Its body is up to 10 millimeters long, or about a third of an inch, and it has a legspan of about 3 inches, or 7.6 cm. But it’s very shy and rare, and of course it’s not going to hurt you. It literally wouldn’t even hurt a fly to keep itself from starving.

One of the scientists who discovered the spider and is studying it, Charles Griswold, points out that there are stories in the area of giant spiders living in caves. He suggests the cave robber spider might be the source of the stories, since a three inch spider looks much bigger when it’s hanging down from the roof of a cave right in your face, with hooked claws.

Let’s finish with a remarkable cave fish known as the devil’s hole pupfish. Devil’s hole is a geothermal pool inside a cavern in the Amargosa Desert in Nevada, which is in the southwestern United States. It’s not far from Death Valley. The cavern is more than 500 feet deep, or 150 meters, with water that stays at about 92 degrees Fahrenheit, or 33 degrees Celsius. There’s a single small opening into the cavern at the surface, which geologists estimate opened about 60,000 years ago. The cavern and cave system are more than half a million years old.

The geothermal pool is home to the devils hole pupfish, which is barely an inch long, or 25 millimeters, and looks pretty ordinary. It mostly stays around the opening to the surface, where there’s a limestone shelf just below the water’s surface that measures about 6 ½ by 13 feet, or 2 by 4 meters. While the pupfish does swim deeper into the cavern at times, it mostly eats algae that live on and around the shelf, and tiny animals that live within the algae. It also depends on the shelf for laying eggs and spawning.

So the shelf is really important. But it’s also really small and close to the surface. It can only support so many pupfish, so the average devil’s hole pupfish population is about 200 or 300 fish, although this fluctuates naturally depending on many factors. In the 1960s, a farming corporation drilled wells in the area and pumped water out for irrigation, and the water in devil’s hole started to drop and drop. Devil’s hole is part of Death Valley National Monument, and conservationists were well aware of how fragile the pupfish’s environment was. As the water level dropped, threatening to expose the limestone shelf that the pupfish depended on for their entire lives, conservation groups sued to stop the pumping of groundwater in the area. After a series of court cases that went all the way up to the Supreme Court, the water rights were acknowledged to be part of the national monument status. Pumping of groundwater was limited and the pupfish was saved.

The water level in devil’s hole is monitored daily, which has led to a lot of information about how the water is affected by seismic events. Earthquakes as far away as Alaska, Japan, and South America have all affected the water level.

Researchers aren’t sure how long the pupfish have lived in devil’s hole. Some researchers think they’ve been there for 20,000 years, others think it’s more like a few hundred. Researchers aren’t sure how such a small population of fish has stayed healthy for so long, since such a restricted number of individuals should be so inbred they’re no longer viable. The most recent genetic analysis of the pupfish suggests they became isolated from other pupfish species in the area less than a thousand years ago. But if that’s the case, no one’s sure how they got into devil’s hole in the first place. Flooding of the area hasn’t happened in the last thousand years.

Because the pupfish’s habitat is so fragile, the U.S. Fish and Wildlife Service has moved some of the fish into captive populations that mimic the fish’s original habitat. It’s nice to think that these tiny silvery-blue fish with big eyes have so many people working to keep them safe.

You can find Strange Animals Podcast online at strangeanimalspodcast.com. We’re on Twitter at strangebeasties and have a facebook page at facebook.com/strangeanimalspodcast. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. We also have a Patreon if you’d like to support us that way.

Thanks for listening!

Episode 111: Poisonous moths, venomous bugs

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Let’s get gross and horrible this week! Are there any bugs with so much venom they could kill you? What would happen if you ate 5,000 moth digestive tracts? Why am I even talking about this stuff? Listen and find out! Thanks to Grady and Tania for today’s topic suggestions!

The giant silkworm moth caterpillar. Do not touch. No seriously, don’t! You might d i e

The southern flannel moth and its larva, a puss caterpillar. Fuzzy, yes, but don’t pet the caterpillar:

A luna moth and its caterpillar. It will not kill you:

A bullet ant. Look at those chompers!

The white-spotted assassin bug. At least you can see it coming:

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

This week’s episode is a suggestion from Grady, who also sent several other really good suggestions we’ll hopefully get to soon. The one we’re looking at this week is poisonous bugs! And because another listener, Tania, suggested we cover moths, we’ll also make sure to talk about a lot of poisonous or venomous moths too.

Technically, if an insect is poisonous that means it will make you sick if you eat it. If an insect bites or stings you and it injects poison into the wound, it’s referred to as venomous. But you can call both poisonous because everyone will know what you mean. Also, you would probably get sick if you ate a venomous bug too, now that I think about it.

You might think I’m joking when I talk about eating bugs, but in many parts of the world people do. If you think about it, it’s no weirder than eating shrimp, lobster, oysters, or eggs. Remember that humans are omnivores, and that means we will eat just about anything. Those things don’t all have to be cookies and peanut butter sandwiches, although I haven’t had my lunch yet and if I had to choose between a PB&J with maybe a couple of Thin Mints afterwards, I’d choose that over a big bowl of deep-fried crickets. But lots of people would choose the crickets. It all depends on what you’re used to and what’s considered acceptable in your culture.

But even in areas where people eat lots of insects, they don’t eat every kind of insect. Some really are poisonous because they eat plants that contain toxins and store those toxins in the body. The monarch butterfly caterpillar eats milkweed, which contains poisons that can harm the heart, so don’t eat monarch butterflies. But because insects are generally quite small, the toxins one insect can hold aren’t usually enough to make you really sick unless you eat a whole bunch of them. That’s why children in some parts of Italy can eat a particular moth without dying even though it contains the deadly poison cyanide.

You know what? Let’s start with this moth, because what the heck, Italian children. Why are you eating these moths anyway, and why are you not dying of cyanide poisoning?

There are a number of closely related moth species that children in the Carnia region of Italy traditionally eat. The moth’s wingspan is only about an inch wide, or 30 millimeters. It’s most common in the Italian Alps and it flies around during the day, which makes it easy to find and catch. Its body is grayish, and one pair of its wings are greenish or gray with red spots, while the other pair of wings is mostly red. There’s also a variety with yellow wing markings instead of red. The reason it has such bright colors is because it stores a liquid containing cyanide in its digestive system, and the bright colors tell potential predators to leave it alone, it’s poisonous.

The problem is, the moth’s digestive system also contains sugars called glucosides, which makes it taste sweet. And before you laugh at little Italian children catching moths to eat because they’re sweet-tasting, think about how much effort you may have put into extracting a tiny bead of nectar from honeysuckle blossoms.

But honeysuckle doesn’t contain cyanide. Why don’t those little moth-eating kids get sick?

Researchers have studied this, mostly because they were worried about the children. It turns out that there’s so little cyanide in each moth that even a small child would have to eat at least 170 moths whole in a short period of time to die. Since most of the time the kids pull the moths apart and only eat the tiny piece of the digestive tract that contains sugar, that reduces the amount of cyanide they ingest. A kid would have to eat 5,000 moth digestive tracts to die, and frankly if a kid was that determined to have that much sugar, they’d probably be more likely to spend their time doing odd jobs for money to buy candy instead of catching thousands of moths.

Well, that was gross. I feel like we’re off to a really good start in this episode.

So, eating 5,000 moth digestive tracts aside, are there any bugs out there that are so venomous that they could kill you?

Yes there are. But you’re probably not going to run across them, and even if you do, you’re probably going to be just fine. It’s rare that someone dies after touching Lonomia moth caterpillars, although it does happen. But if you do touch one of the caterpillars, even if you don’t die, you’re not going to feel very good.

There are a number of Lonomia species. The adult moths are brown or grayish, with the males sometimes yellow. It has delicate darker brown markings to help it mimic small dead leaves. The species that is most venomous is sometimes called the giant silkworm moth, Lonomia obliqua, and it lives in South America. It’s especially well known in southern Brazil. The caterpillar grows to about two inches long, or 5.5 cm, and is either green or brown with lots of hair-like spines growing from the back and sides.

A lot of caterpillars have these hair-like spines, and most of them aren’t venomous. They can cause a rash, though, since the spines are very thin, detach easily, and can irritate the skin. But the caterpillar of the giant silkworm moth has spines with powerful venom. The venom contains an anti-clotting agent that causes internal bleeding that can eventually lead to death. But one little caterpillar doesn’t contain enough venom to kill a person all by itself. The trouble comes when the caterpillars are gathered in groups on leaves or tree trunks, because then it’s easier for someone to accidentally touch a bunch of caterpillars at once, receiving hundreds or even thousands of tiny stings from the venomous hairs. Fortunately, the mortality rate for people who are stung by these caterpillars is only a little over 2%. That means almost 98% of people stung by one survive.

Another moth with a venomous caterpillar lives in the United States, especially the southeastern states. It’s called the southern flannel moth and it’s really pretty and fuzzy, yellow and white with some brown markings. The caterpillar is often called the puss caterpillar because it’s also fuzzy and somewhat resembles the end of a cat’s tail or a cat’s paw. But don’t touch it! The puss caterpillar has spines with venom sacs at the base just like the giant silkworm moth caterpillar has. If someone brushes against the spines, they inject venom into the skin. The puss caterpillar isn’t deadly, and most people who touch it only end up with a painful swelling at the injection site that feels like an extra bad bee sting. But some people have a more severe reaction, including fever, vomiting, and heart trouble.

Incidentally, in case you were wondering if caterpillars poop, of course they do. Some caterpillars, though, including the puss caterpillar, actually eject fecal pellets so that they fly away like tiny bullets of poop. This is partly so the caterpillar doesn’t make a mess on the leaf it’s eating, but mainly so that predators aren’t able to find the caterpillar after seeing or smelling its poop. But sometimes the puss caterpillar will fire fecal pellets at predators, so that’s yet another reason not to touch one.

Puss caterpillars build really tough cocoons, so tough that they can stay on a tree or bush for years after the moth is long gone. Some ant species actually move into puss caterpillar cocoons to raise their eggs. Spiders also sometimes live inside empty puss caterpillar cocoons.

There are other venomous moth caterpillars, but they’re all pretty similar to the ones we’ve discussed already. But while we’re on the subject of moths, let’s talk about just how amazing and weird they are. This goes for butterflies too, of course, which are very similar.

As an example, let’s discuss a type of moth that isn’t venomous or poisonous or dangerous in any way, the luna moth.

The luna moth is one of the largest moths in North America, and it’s fairly common in the eastern part of the continent. It’s beautiful, with pale green wings and a white body. Its wingspan can be as much as seven inches across, or 18 cm. The wings have yellow eyespots and long swallowtails that confuse bats’ echolocation by fluttering as the moth flies, scattering the reflections of the bat’s echolocation calls. The bat attacks the swallowtail instead of the moth’s body, allowing the moth to fly away.

This is the life cycle of the luna moth, which is similar to most moths’ life cycles. A female moth will lay several hundred eggs on the undersides of leaves the caterpillars will eat, usually only one or a few eggs per leaf spread across many trees. The luna moth caterpillar especially likes persimmon, sweet gum, wild cherry, hickory, willow, black walnut, and white birch trees. The eggs hatch into little green caterpillars after about a week. The caterpillars eat leaves, grow big enough to molt, eat and grow some more, molt again, and so on. The period between molts is called an instar, which in the luna moth is about a week, give or take. After five instars, the caterpillar is as big as it will get, generally around 3 ½ inches long, or 9 cm. It’s not dangerous, but if a predator approaches, it will rear up, clack its mandibles, and puke up the contents of its digestive system, which stinks.

Finally, the caterpillar leaves the tree where it’s lived its whole life and crawls around in the leaf litter underneath the tree. There it spins a cocoon out of silk, wrapped inside leaves to hide it, expels any water or food still in its intestines, and transforms within the cocoon into a pupa. The pupal stage takes about two or three weeks, and let’s find out what’s going on inside the cocoon during that time.

First, the pupa is encased in a sort of exoskeleton called a chrysalis, which is inside the cocoon. Within the chrysalis, the caterpillar’s body starts to digest itself using its own digestive juices. This breaks its body down into cells in a sort of soup inside the chrysalis, and the cells then reform into the adult moth or butterfly.

Clearly, if you go through a metamorphosis like this that requires all your cells to turn into cell soup, you aren’t going to retain any memories from before you ensouped. Right? Well, according to a 2008 study with a moth called the tobacco hornworm, caterpillars that learned to avoid a particular odor retained those memories as full-grown moths. The moths would also avoid that odor. Researchers aren’t sure how this happens and I wasn’t able to find any follow-up studies, but it’s pretty mind-blowing. My brother sent this article to me ages ago, so thanks, Richard!

So, the luna moth has developed from a caterpillar into caterpillar soup and then into a newly-formed luna moth. The moth has serrated spurs made of chitin at the base of the front wings, which it uses to tear its way out of the cocoon. Its new wings are soft and wet, so it will spend a couple of hours waiting for the wings to harden before it can fly.

Male luna moths usually hatch first and fly away to find females. When a female luna moth hatches, she flies around until she finds a tree she likes, and then she stays in the tree and releases pheromones once it grows dark. Pheromones are chemicals that attract males, which is why the male moth has wider antennae than the female. He detects pheromones with his antennae, and can sense them up to six miles away from the female, or about 11 km. After he finds her, the pair mate, and within a day or so she starts laying eggs.

Like many moth species, adult luna moths don’t eat. They only have vestigial mouths and no digestive system at all. They mate, lay eggs, and die within about a week of hatching.

The luna moth is harmless even if you eat it or pet it—please don’t do either—but it is related to the deadly giant silkworm moth of South America. Fortunately, they look totally different and live in different places.

One last note before we leave moths behind and look at some other venomous insects. Back in episode 93 where we talked about some of the biggest insects in the world, I mentioned the queen alexandra’s birdwing butterfly. I put a picture of it in the show notes, or so I thought. Listener Judith caught my mistake and pointed out that the picture I’d posted was actually of an atlas moth. The atlas moth is in fact bigger than the queen alexandra’s birdwing butterfly, with a wingspan just shy of a foot across, or 30 cm. I swapped out the picture so it’s correct, so thank you to Judith for letting me know!

Now let’s take a look at some venomous insects that aren’t moths. Let’s just skip right over the ones you know about, like bees, and talk about a few interesting ones you might not have heard of. Like the bullet ant. It gets its name because its bite is so painful it feels like you’ve been shot with a gun.

The bullet ant lives in the rainforests of Central and South America. Worker ants are about an inch long, or 3 cm, which is pretty darn big for an ant. The queen ant is about the same size as the worker ants. It’s not closely related to any other ants alive today, but an ant discovered in amber dated to at least 15 million years old was determined to be the bullet ant’s closest relative. The bullet ant looks more like a wasp without wings than an ant, in fact. It’s black in color with massive jaws.

The bullet ant’s bite is considered the most painful of any insect. The ant injects venom with the bite that causes a burning pain throughout the body that lasts for a solid 24 hours without fading. It won’t kill you, but you may wish you were dead. The venom is a neurotoxin that can cause temporary paralysis of the part of the body that was bitten too.

An indigenous people of Brazil, the Sateré-Mawé, use the bullet ant bite in an initiation rite for warriors. That’s how much the ant’s bite hurts.

Finally, let’s learn about an insect with a terrifying name, the assassin bug. There are a lot of assassin bug species throughout the world, and while they sound scary, they can’t actually kill you. Their bite might hurt, but compared to a bullet ant bite, pffft. Easy peasy. But the white-spotted assassin bug of Africa does something the bullet ant only wishes it could do. If something disturbs a white-spotted assassin bug, it can spit venom. And if any of the venom gets into your eyes, it can temporarily blind you.

Assassin bugs mostly eat other insects. Some specialize in hunting spiders, some in hunting bedbugs or cockroaches. The assassin bug has a strong proboscis, or rostrum, that it uses to stab its prey and inject venom containing digestive enzymes. The venom paralyzes the insect and the digestive enzymes liquefy its insides. The assassin bug slurps up the liquefied insect insides. But if a predator attacks the assassin bug, it will inject a different kind of venom that causes intense localized pain and kills off the tissue around the injection site. No other insects are known to produce two different types of venom.

Some people keep assassin bugs as pets. What is wrong with those people?

You can find Strange Animals Podcast online at strangeanimalspodcast.com. We’re on Twitter at strangebeasties and have a facebook page at facebook.com/strangeanimalspodcast. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. We also have a Patreon if you’d like to support us that way.

Thanks for listening!