Episode 397: Some Colorful Fishies

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Thanks to Cosmo, William, and Silas for their fishy suggestions this week!

You have until Sept. 13, 2024 to back the enamel pin Kickstarter!

Further reading:

The Handfish Conservation Project

Researchers Look in Tank and See Promising Cluster of Near-Extinct Babies

The unique visual systems of deep sea fish

A red handfish:

Another red handfish. This one is named Hector:

The black dragon fish:

The white-edged freshwater whipray [photo by Doni Susanto]:

Show transcript:

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

This week we return to the vertebrate world, specifically some strange and colorful fishies. Thanks to William, Cosmo, and Silas for their suggestions!

We’ll start with Silas’s suggestion, the red handfish. We talked about it before back in episode 189, but it’s definitely time to revisit it. When we last discussed it, scientists estimated there were fewer than 100 red handfish left in the wild, meaning it was in imminent danger of extinction. Let’s find out how it’s doing now, four years later.

The handfish gets its name because its pectoral fins look like big flat hands. It spends most of its time on the sea floor, and it uses its hands to walk instead of swimming. It can swim, although it’s not a very strong swimmer, and anyway if you had great big hands you might choose to walk on them too. It doesn’t have a swim bladder, which helps most fish stay buoyant.

All species of handfish are small, only growing to about 6 inches long at most, or 15 cm. This is surprising considering the handfish is closely related to anglerfish, and some anglerfish can grow over 3 feet long, or about a meter.

As for the red handfish specifically, it generally only grows about 4 inches long at most, or 10 cm, and it once lived in shallow water around much of Australia. These days, it’s only found on two reefs southeast of Tasmania. Some populations are bright red while some are pink with red spots. It has a wide downturned mouth that makes it look like a grumpy red toad with big hands.

So how is the red handfish doing? Four years ago it was almost extinct in wild, with fewer than 100 individuals alive. These days the Handfish Conservation Project estimates that the wild population is probably about the same, although because the red handfish is so small and hides so well among sea grass, algae, and rocks that make up its home, it’s hard to get a good count of how many are really alive. It’s also under even more pressure than before as an overpopulation of urchins is overgrazing the plants where it lives, which may sound familiar to you if you listened to episode 395 a few weeks ago. But there is one fantastic change that gives conservationists hope that the red handfish won’t go extinct after all.

The red handfish is so endangered, and its remaining habitat is so small, that a few years ago scientists decided they needed to start a captive breeding program. But even though the fish did just fine in captivity, they didn’t breed at first. Then, in November 2023, one of the fish laid 21 eggs and all 21 hatched safely. Hopefully it won’t be long until the babies are old enough to release into the wild.

The red handfish is one of very few fish that hatch into tiny baby fish instead of into a larval form. Newly hatched babies are only about 5 mm long. Most fish colonize new habitats after they float around aimlessly as larvae, until they grow enough to metamorphose into adults. Since the red handfish doesn’t have this larval stage, and babies just walk around on the sea floor finding tiny worms and other food, it’s hard for the fish to expand its range. Hopefully, as the captive breeding program continues and more young fish are released into the wild, scientists can start releasing red handfish into areas where they used to live.

Next, William asked about the dragon fish. We’ve talked about a few dragonfish before, in episodes 193 and 231, but there are lots of species in many genera in the family Stomiidae. Many have barbels with photophores at the end that lure prey, and most have long needle-like teeth and jaws that can open incredibly wide. They also have stretchy stomachs so they can hold whatever they manage to catch. As you may have guessed from these traits, the dragon fish lives in the deep sea where there’s little or no light from the surface.

You may wonder why deep-sea fish even have eyes if there’s no light. Fish that live in cave systems eventually evolve to be eyeless, since they don’t need their eyes to see and growing eyes is just a waste of their energy. It’s because even though there’s no sunlight in the deep sea, there is light from lots of different organisms. Many, many deep-sea animals produce bioluminescent light to attract mates or trick smaller animals into coming closer.

Any sunlight that does find its way to the depths of the ocean is blue, because blue has the shortest wavelength and can travel farther. Red wavelengths are longest so that red is the first color lost when you start descending into the water. One article that I’ve linked to in the show notes mentions that if a diver gets a cut, the blood looks brown or even black if the water is deep enough. That’s creepy.

As a result, deep-sea fish are most sensitive to the color blue. Most of them can’t perceive red at all because there just isn’t any red in their environment. And that’s where the dragon fish comes in, because some species of dragon fish can not only see red, they produce red light that illuminates everything around them. A fish or other animal swimming along has no idea that it’s lit up like it’s under a red spotlight because it can’t even see that color.

At least one species, the black dragon fish, perceives red light very differently from the way other animals do. As far as we know it’s unique among all animals. Its eyes contain a photosensitizer derived from chlorophyll, which allows it to see shorter lightwaves. Chlorophyll is found in plants and some bacteria, and it’s actually a specialized pigment that absorbs energy from light. It’s the reason why plants are green. But the black dragonfish uses the chlorophyll it digests to perceive red light.

But remember how dragon fish have giant sharp fangs and will eat pretty much anything they can swallow? Where does the black dragon fish get the chlorophyll it needs? There aren’t any plants in the deep sea anyway.

The answer seems to be that the black dragon fish eats a whole lot of copepods, tiny crustaceans that live throughout the world. The particular species of copepods that the black dragon fish prefers contain a type of chlorophyll.

Finally, Cosmo wanted to learn about the freshwater stingray. We talked about it in episode 296, but mostly we concentrated on the South American fish in that episode. There are freshwater stingrays that live in other parts of the world, such as Asia. This includes the white-edge freshwater whipray, which is extremely rare and only found in four rivers in Southeast Asia.

The white-edge freshwater whipray grows up to two feet across, or 60 cm, with a thin tail about two and a half times longer than the body itself so that technically it can grow around 6 and a half feet long, or 2 meters. Most of that length is tail, though. It’s mostly brown so it can hide in the sandy mud at the bottom of the river, with black dermal denticles down the middle of its back. The tail is mostly white, though, and has two long stinging spines that can be over 3 inches long, or 8 cm.

While the white-edged whipray lives in rivers, it can also tolerate brackish water where the ocean and the river waters mix. It eats small animals it finds on the bottom of the river, including crustaceans and mollusks. It’s endangered due to habitat loss, overfishing, and pollution.

The white-edged whipray is so rare these days that it’s unlikely that anyone would accidentally step on one in the water. But if they did, the ray would whip its long tail up and jab the spines into the person’s leg or foot. The spines can do a lot of damage on their own, but the venom they inject makes the wound incredibly painful and can even potentially kill the person.

If you plan to do some wading in a South Asian river anytime soon, make sure to shuffle your feet as you walk to scare away any potential whiprays before you step right on it.

You can find Strange Animals Podcast 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 at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

 

Episode 396: Moths!

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Thanks to Joel and an anonymous listener for their suggestions this week!

Further reading:

Dieback and recovery in poplar and attack by hornet clearwing moth

The enormous and beautiful Atlas moth:

A male hairy tentacle moth without and with coremata extended [photos from this site]:

The hornet moth looks like a hornet but can’t sting:

Show transcript:

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

Welcome to September, where we’re mere weeks away from Monster Month! Invertebrate August is over for another year, but what’s this? An episode about moths?! Hurrah for one extra invertebrate episode, because they don’t get enough attention on this podcast! Thanks to Joel and an anonymous listener for their suggestions.

First, a listener who wants to remain anonymous suggested that we talk about moths in general, and the Atlas moth in particular. I like the Atlas moth because you can catch it in Animal Crossing. It’s also beautiful and one of the largest moths in the entire world. Its wingspan can be well over 10 inches across, or about 27 cm, which is bigger than a lot of bird wingspans.

The Atlas moth’s wings are mostly cinnamon brown with darker and lighter spots. The upper wings have a curved sort of hook at the top that’s lighter in color and has an eyespot. It looks remarkably like a snake head, and in fact if a predator approaches, the moth will move its wings so that it looks like a snake is rearing its head back to strike.

Despite having such huge wings, atlas moths don’t fly very well. That’s okay because they only need to be able to fly for a few days, which they mostly do at night. They’re only looking for a mate, not food, because they don’t even have fully formed mouthparts. They don’t eat as adults. Like many moths, they mate, lay eggs, and die.

A few weeks later, the eggs hatch and the baby caterpillars emerge. The caterpillar is pale green with little spikes all over, and it eats plants until it grows to around 4 and a half inches long, or about 11 and a half cm. At that point it spins a cocoon attached to a twig, hidden from potential predators by dead leaves that the caterpillar incorporates into the cocoon’s outside.

The Atlas moth lives in forests in southern Asia, including China, India, Indonesia, and Malaysia, with a subspecies native to Japan. Its cocoons are sometimes collected to use for silk. The silk isn’t as high a quality as the domesticated silk moth’s, but it’s very strong and since the cocoons are so big, they produce lots of silk. Sometimes people will collect a cocoon after the moth has emerged and use it as a little purse.

Next, Joel suggested two interesting moths. The first is often called the hairy tentacle moth, which sounds absolutely horrifying. Its scientific name is Creatonotos gangis, and it lives in parts of Australia and southeast Asia.

The hairy tentacle moth is also called the Australian horror moth and other names that inspire fear and disgust. But why? The moth is really pretty. Its wings are pale brown and white with dark gray stripes in the middle, and it has a black spot on its head. The abdomen is usually red with black spots in a row. The wingspan is about 40 mm.

The issue comes with the way the male attracts a female. Inside his abdomen the male has four coremata, which are glands that emit pheromones. Pheromones are chemicals that other moths can detect, much like smells. When a male is ready to advertise for a mate, he perches on the edge of a leaf or somewhere similar and inflates the coremata so that they unfurl from inside the abdomen, like blowing up a balloon. Sometimes he only extends two of the coremata, sometimes all of them. Either way, the coremata are surprisingly large, sometimes longer than the entire abdomen. They’re dark gray with feathery hairs and they do actually look like hairy tentacles. They’re sometimes called hair pencils, but the term coremata is actually Greek for feather dusters.

If you don’t know what they are, the coremata really do look weird and unpleasant. But the moth is just doing his best to get his pheromones picked up on the breeze so a female will find him. The pheromone also repels other males.

The hairy tentacle moth can only develop his coremata and the pheromones he needs if he eats enough of plants that contain pyrrolizidine alkaloids. These are intensely bitter compounds that are also toxic to many animals. When he’s a caterpillar, the male eats plants that contain these alkaloids and retains them in his body, chemically modifying them later into pheromones, but if he doesn’t eat enough of them, he’s not able to grow coremata either.

Finally, Joel also suggested the hornet moth, which lives in Europe and the Middle East. It’s a moth, but it genuinely looks exactly like a yellow and black striped hornet. It even has clear wings like a hornet or wasp and flies like one too, and it’s about the size of a hornet. Even though it’s harmless, it looks like it would give you a bad sting, which protects it from potential predators who know better than to mess with a hornet. It’s a great example of what’s called Batesian mimicry, but it has one big drawback. The moth lives in some areas where there aren’t any hornets, and in those areas birds and other animals soon learn that those brightly striped insects are yummy and easy to catch.

The female hornet moth lays her eggs in the plants around the base of a tree or on its bark, especially the poplar tree. When the eggs hatch, the larvae spend the next two or three years in and around the tree, mostly around its roots. It eats the wood of the roots, and when it’s ready to pupate it burrows into the tree trunk and spins its cocoon in the burrow. The problem is that it needs the cocoon to be protected inside the tree, not near the entrance of the burrow, but when it emerges from the cocoon it needs to be near the entrance or its newly metamorphosed body will be too large for it to crawl out. To solve the problem, when it’s getting close to emerging, the moth will wriggle around in its cocoon so energetically that it manages to push the pupa up the burrow to the entrance. You can imitate this action by zipping yourself into a sleeping bag and trying to crawl across a room.

For a long time people thought the hornet moth was damaging poplar trees by this behavior, causing them to die. It turns out that the moths aren’t hurting the trees, they’re just more noticeable when poplars are already injured by drought.

There’s also an American hornet moth that lives in some parts of the Midwest and western areas of North America. It’s closely related to the hornet moth of Europe and adults look an awful lot like hornets, but they don’t sting. So the next time you’re about to run from a hornet, take a moment to determine if the hornet is actually a harmless moth. Or at least don’t run, just walk away quickly and safely. Just in case.

You can find Strange Animals Podcast 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 at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Episode 395: Crinoids and Urchins

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Thanks to Sy and Finn for their suggestions this week!

Further reading:

Creeping Crinoids! Sea Lilies Crawl to Escape Predators, New Video Shows

New and Unusual Crinoid Discovered

Sea otters maintain remnants of healthy kelp forest amid sea urchin barrens

Sea urchins see with their feet

A sea lily [photo from this page]:

A feather star [still from a video posted on this page]:

Purple urchins [photo by James Maughn]:

Show transcript:

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

This week as we bring invertebrate August to a close, we’re going to cover some animals suggested by Finn and Sy.

We’ll start with Sy’s suggestion, crinoids, also called feather stars or sea lilies depending on what body plan a particular species has. We talked about them in episode 79 but it’s definitely time to revisit them.

Crinoids are echinoderms, a really old phylum of animals. Fossils of ancient echinoderms date back to the Cambrian half a billion years ago and they’re still incredibly common throughout the world’s oceans.

Ancient crinoids had five arms the way many starfish do, which makes sense because crinoids are related to starfish. At some point each arm developed into two, so many crinoids have ten arms or even more, and many have arms that branch. The arms are used for feeding and have feathery appendages lined with sticky mucus that traps tiny bits of food floating in the water.

There are two big divisions of crinoids today, the feather stars and the sea lilies. Feather stars are more common and can swim around as adults if they want to, although most stick to crawling along the sea floor. They swim by waving their feathery arms. Sea lilies look like flowers as adults, with a slender stem-like structure with the small body and long feathery arms at the top. I specify that sea lilies have stems as adults because a lot of feather stars also have stems as juveniles, but when they reach maturity they become free-swimming.

Even though the sea lily looks like a plant, and some species even have root-like filaments that help it anchor itself to the sea floor or to rocks, it’s still an animal. For one thing, it can uproot itself and move to a better location if it wants to, crawling with its arms and pulling its stem behind it, which is not something a plant can do except in cartoons. If a predator attacks it, the sea lily will even shed its stem completely so it can crawl away much faster. Since echinoderms in general are really good at regenerating parts of the body, losing its stem isn’t a big deal.

The biggest sea lilies today are deep-sea species, but even they only grow a stem up to about three feet long at most, or about a meter. This wasn’t the case in the ancient past, though. The longest crinoid stem fossil ever discovered was 130 feet long, or 40 meters.

Crinoids filter food particles from the water that flows through the feathery arms. Even though they look like feathers or petals, a crinoid’s arms are actually arms. They have tiny tube feet on them that act sort of like fingers to help the crinoid hold onto pieces of food, and to do a better job of holding the food, the tube feet are covered with a sticky mucus. The mouth is in the middle of the arms on the top of the body.

Crinoids absorb oxygen directly from the water. Its body contains a system of chambers and pores that are full of water, and by contracting special muscles, the crinoid moves water around in its body to transport nutrients and oxygen and to collect waste material.

Crinoids are closely related to starfish, sea cucumbers, sand dollars, and sea urchins, which brings us to Finn’s suggestion. Finn suggested urchins, which are also echinoderms. In fact, at the end of episode 79 I mentioned that one day I’d do an episode about urchins, and it only took me six years to get here!

Many urchins look like living pincushions because they’re covered in spines. That’s where the name urchin comes from, in fact. Hedgehogs, which are little round mammals with spiny backs that we talked about in episode 126, were called urchins in the olden days. Some people call the echinoderm type of urchin the sea urchin to distinguish it from the mammal type of urchin, and some people call the echinoderm urchin the sea hedgehog.

Urchins live throughout the world’s oceans, in shallow water or deep water, warm water and cold water, and there are almost a thousand species known to science. There are undoubtedly many more species yet to be discovered.

The typical urchin has a body shaped sort of like a little ball, but unlike most balls it has spines growing all over it. Depending on the species, the spines may be thin and sharp or thick and blunt. Some species even have venomous spines. Underneath, the urchin has a small area of its body that isn’t protected by spines. This is where its mouth is and its little tube feet that allow it to move around. Like crinoids and other echinoderms, it pumps water in and out of its tube feet to move them. It can also push itself off of surfaces with its spines to help it maneuver.

You may be wondering if, under its spines, an urchin has a soft body like a bouncy ball or a hard body like a baseball. Its body is actually hard, but not due to an exoskeleton. Echinoderms have an endoskeleton, meaning the hard parts of its body are on the inside like our bones are, not on the outside like a lobster’s armor. Instead of bones, echinoderms have tiny plates called ossicles that fit together like puzzle pieces and are covered with tough skin. The ossicles fit together to make the stem of a sea lily or a spiky ball in urchins, called a test.

If you look at an urchin, it’s pretty obvious it has no head or face. It’s just a little spiky ball with feet and a mouth underneath. But urchins can not only sense light and dark, at least some species can see images to some degree, and they see without eyes. Instead they have light-sensitive cells in their tube feet. Since the tube feet aren’t just for walking, and most urchins have tube feet in between spines as well as underneath, it can keep a lookout for danger with some of its feet while it’s walking around or eating with its other feet.

Unlike its crinoid cousins, the urchin isn’t a filter feeder. It mainly it eats algae and kelp but it will also eat lots of small animals, including crinoids. Its spines help keep it safe from being eaten by larger predators, but lobsters, crabs, and some kinds of starfish aren’t very worried about the spines and will eat urchins without any trouble.

One animal that specializes in eating urchins is the sea otter. The sea otter loves to eat urchins, and is good at flipping them over and biting them on their unprotected underside, or just hitting them with a rock to break off the spines. It cracks the poor urchin open like a nut and gobbles up the insides.

Because urchins like to eat kelp, and otters like to eat urchins, the kelp forests off the coast of California have always had a lot of both animals. But about a decade ago now, starting in about 2013, several things happened to alter the balance of kelp and urchin and otter. First, a disease caused the sunflower sea star to die off in great numbers, and in fact it’s still critically endangered as a result. Since that’s a type of starfish that eats a whole lot of urchins, the urchin population exploded. The next year, 2014, a heatwave over the west coast of North America caused a lot of kelp to stop growing. Kelp needs cold water to thrive. The hordes of urchins started chomping down on as much kelp as they could find, decimating more than 80% of the kelp forests in northern California before scientists even realized what was happening.

The urchin in question is the purple urchin, which lives along the eastern coast of North America. Its spines are purple and it can grow up to 4 inches across, or 10 cm. Sea otters love purple urchins so much that sometimes their teeth turn purplish in color from eating so many.

The sea otters responded to the population explosion by turning into urchin-eating maniacs, eating up to four times as many urchins as usual. The problem is that the sea otter population is still rebounding from being hunted nearly to extinction in the early 20th century, and they’re still an endangered species. There just weren’t enough otters to eat all the urchins.

Scientists studying the situation noticed something strange. The otters were only eating urchins where the kelp forests were still healthy. They ignored all the millions of urchins where the kelp forests had been eaten down to the ground, even though the urchins didn’t have anywhere to hide from hungry otters. The scientists discovered that the urchins in what they called urchin barrens were basically starving to death. There were far too many urchins and no food left for them to eat. That meant they weren’t as nutritious, so the otters didn’t bother to eat them.

The result was actually positive. The balance of urchins and sea otters and healthy kelp was maintained, so the urchin barrens didn’t get any worse. The kelp forests will rebound, although it will take a long time. Everybody say hello to the otters, and goodbye to all the extra urchins.

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. If you like the podcast and want to help us out, leave us a rating and review on Apple Podcasts or whatever platform you listen on. We also have a Patreon if you’d like to support us that way.

Thanks for listening!

Episode 394: Mantis Shrimp!

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Thanks to Anbo and Siya for suggesting the mantis shrimp this week!

The Kickstarter for some animal-themed enamel pins is still going on!

Further reading:

Rolling with the punches: How mantis shrimp defend against high-speed strikes

The magnificent peacock mantis shrimp [picture by Cédric Péneau, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=117431670]:

Show transcript:

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

As invertebrate August continues, this week we have a topic suggested by Anbo and Siya. They both wanted to learn about the mantis shrimp!

The mantis shrimp, which is properly called a stomatopod, is a crustacean that looks sort of like a lobster without the bulky front end, or a really big crayfish. Despite its name, it’s not a shrimp although it is related to shrimps, but it’s more closely related to lobsters and crabs. It can grow as much as 18 inches long, or 46 cm, but most are about half that size. Most are brown but there are hundreds of different species and some are various brighter colors like pink, blue, orange, red, or bright green, or a rainbow of colors and patterns.

There are two things almost everyone knows about the mantis shrimp. One, it can punch so hard with its claws that it breaks aquarium glass, and two, it has 12 to 16 types of photoreceptor cells compared to 3 that humans have, and therefore it must be able to see colors humans can’t possibly imagine.

One of those things is right, but one is wrong, or at least partially wrong. We’ll discuss both in a minute, but first let’s learn the basics about these fascinating animals.

The mantis shrimp lives in shallow water and spends most of its time in a burrow that it digs either in the sea floor or in crevices in rocks or coral, which it enlarges if necessary. Some species will dig elaborate tunnel systems while others just wedge themselves into any old crack that will hide them. It molts its exoskeleton periodically as it grows, like other crustaceans, and after that it either has to expand its burrow or move to a larger one. Most species live in tropical or subtropical areas, but some prefer more temperate waters.

It has eight pairs of legs, which includes three pairs of walking legs, four pairs with claws that help it grasp items, and its front pair, which are hinged and look a little like the front legs of a praying mantis. That’s where the “mantis” in mantis shrimp comes from, although of course it has lots of other names worldwide. In some places it’s called the thumb splitter.

The mantis shrimp has two eyes on stalks that move independently. Its brain extends into the eye stalks, and the section of the brain in the eye stalks, called the reniform body, is what processes vision. This allows it to process a lot of visual information very quickly. Reniform bodies have also been identified in the brains of some other crustaceans, including shrimp, crayfish, and some crabs. Scientists also think that the eyes themselves do a lot of visual processing before that information gets to the reniform body or the brain at all. In other words, part of the reason the mantis shrimp’s eyes are so complicated and so unusual compared to other animals’ eyes is because each eye is sort of a tiny additional brain that mainly processes color.

The typical human eye can only sense three wavelengths of light, which correspond to red, green, and blue. The mantis shrimp has twelve different photoreceptors instead of three, meaning it can sense twelve wavelengths of light, and some species have even more photoreceptors. But while our brains are really good at synthesizing the three wavelengths of light we can see, combining them so that we see incredibly fine gradations of color in between red, green, and blue, the mantis shrimp doesn’t process color the same way we do. So while its eyes can sense colors we can’t, its brain doesn’t seem to do anything with the color information. The eyes themselves process the colors to determine if an object is important or dangerous or food or whatever, and the determination of the object is the part that’s important to the brain, not what the actual color is.

Maybe by the year 2124, you can go into an eye clinic and have those extra sensors added to your eyes so you can see more colors, because a human brain knows exactly what to do with extra color information. We use it to make art.

Mantis shrimp can see ultraviolet light, which we talked about in episode 369. To be clear, we didn’t specifically talk about mantis shrimp in that episode, just UV light. At least six species of mantis shrimp can also see polarized light, with at least one species, the purple spot mantis shrimp, capable of dynamic polarization vision. (I don’t know what that means.) When sunlight reaches our earth’s atmosphere, the light waves are affected by earth’s magnetic field and the atmosphere itself. This scatters the light, causing it to travel in a sort of spiral. A lot of animals can sense light polarization, like bees and octopuses, which allows them to navigate more accurately. Mantis shrimp have patterns on their bodies that reflect polarized light in certain ways, so scientists think that’s one way mantis shrimp identify each other while staying hidden from most animals, which either can’t sense polarized light at all or can only sense it faintly.

So we must ask ourselves: If the mantis shrimp doesn’t use its multiple photoreceptors to see color, what does it use them for? We’re not fully sure yet, but scientists have some suggestions. The fertility of a female mantis shrimp depends on the tidal cycle, which is dependent on the phase of the moon, but if you live underwater and spend most of the time in a burrow, you can’t exactly look up at the moon easily or check how big the waves are. The female fluoresces when she’s fertile, though, and she fluoresces at a wavelength that the male can see but other animals can’t.

So it’s not completely accurate to say that the mantis shrimp can see colors we can’t even imagine, because there’s a difference in the eye seeing something and the brain processing it. But that means that the other mantis shrimp fact is completely true, that its claws are so strong that it can crack aquarium glass. But it’s more complicated than it sounds, because different mantis shrimp species have different abilities.

Mantis shrimp that hunt fish are called spearers, because the ends of their front pair of legs have a barbed spike that the mantis shrimp uses to spear the fish. Mantis shrimp that eat clams and other animals with hard shells are called smashers, and instead of spikes, the ends of their front pair of legs have a hammer-like club that the mantis shrimp uses to punch its prey. Both spearers and smashers can move their front legs incredibly fast, literally at the speed that a bullet leaves the barrel of a gun, with a correspondingly strong amount of force when the leg connects with something.

Moving the legs so fast also causes a small shock wave in the water, which can kill a small animal even if the mantis shrimp misses hitting it. The shock wave is actually what the mantis shrimp uses to smash the shells of clams and other hard-shelled prey, and it also uses the shock wave to smash pieces of coral or rock when it wants to enlarge its burrow. Its body has multiple layers of tissue that absorb the shock wave so it won’t damage the mantis shrimp itself.

Smashing or spearing so fast costs the mantis shrimp a lot of energy, so if it feels threatened by a potential predator it will spread its arms wide to look intimidating before it actually resorts to striking. That’s when it earns the name thumb splitter. That’s also the main reason why it isn’t very common for people to eat mantis shrimp even though they’re perfectly edible to humans and reportedly taste like lobster. They’re just too hard to catch and kill safely.

Some species of mantis shrimp mate for life, with some bonded pairs staying together for decades. Depending on the species, both parents take care of the eggs, or the female takes care of the eggs and the male brings her food. In one species, the female lays two bunches of eggs. She takes care of one bunch, while the male takes care of the other.

Many species of mantis shrimp are territorial, and if one enters another’s territory, the two may end up fighting. When you can punch as hard as a mantis shrimp, you need a good defense. During fights, the mantis shrimp coils its tail in front of its body to act as a shield. The tail is well armored, but the armor is layered to absorb and dissipate energy from punches.

The peacock mantis shrimp is the one that most people have heard about. It’s even one of the creatures you can catch in Animal Crossing by diving. It’s metallic green and blue with orange legs, purple eyes, and white spots, so some aquarium keepers love having one on display. The problem is that they will kill and eat pretty much anything else kept in the same tank, will smash up any rocks or coral in the tank too, and yes, they will even smash the aquarium glass—which is exceptionally strong in big aquariums, more like a car window than a window in your house. Sometimes an aquarium keeper will use a rock from the ocean to decorate the aquarium, and only find out too late that there’s a peacock mantis shrimp already living in a crevice in the rock. Then all they can do is take the rock back to the ocean, because getting a mantis shrimp out of its rock safely is pretty much impossible.

You can find Strange Animals Podcast 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 at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Episode 393: Little Spiders

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Thanks to Siya, Zachary, Khalil, and Eilee for their suggestions this week!

The enamel pin Kickstarter goes live on Wednesday, August 14, 2024!!

Further reading:

How spiders breathe under water: Spider’s diving bell performs like gill extracting oxygen from water

Aggressive spiders are quick at making accurate decisions, better at hunting unpredictable preys

Into the Spider-Verse: A young biologist shares her love for eight-legged creatures

A New Genus of Prodidominae Cave Spider from a Paleoburrow and Ferruginous Caves in Brazil

The diving bell spider [photo from this paper]:

Jumping spiders are incredibly cute, even the ones that eat other spiders [photo taken from this excellent site]:

The spoor spider’s web looks like a cloven hoofprint in the sand [photo by JMK – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=39988887]:

Show transcript:

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

I’m excited this week, because on Wednesday my little Kickstarter to fund getting more enamel pins made goes live, and also we’re talking about some weird and fascinating spiders! Thanks to Siya, Zachary, Khalil, and Eilee for their spider suggestions!

A lot of people are afraid of spiders, but don’t worry. All the spiders in this episode are small and completely harmless unless you are a bug. Also, they probably live very far away from you. Personally, I think most spiders are cute.

Let’s start with a spider suggested by Siya, who pointed out that we don’t actually have very many episodes about spiders. Siya suggested we learn about the diving bell spider, a tiny, remarkable animal that lives in parts of Europe and Asia.

The diving bell spider gets its name because it mostly lives underwater but still needs to breathe air, so it brings air with it into the water. A diving bell made by humans is a structure shaped sort of like a big bell that can be lowered straight down into the water on a cable. If the diving bell doesn’t tip to one side or another, the air inside it stays inside and allows a human diver to take breaths without coming to the surface. A diving bell made by spiders is made of silk but is shaped sort of the same, with an entrance at the bottom. The spider builds its bell among water plants to anchor it and keep it hidden. The spider brings air from the surface to replenish the supply of air inside the bell.

The spider does this by surfacing briefly. Its belly and legs are covered with tiny water-repellent hairs, and after surfacing the hairs trap air, so that when it dives back into the water it’s covered with little silvery bubbles. It swims down to its diving bell and rubs the bubbles off its body, which rise into the bell and are trapped there by the closely woven silk. Then it goes back to the surface for more air.

Once the bell is full of air, the spider only needs to replenish the air supply about once a day under normal circumstances. That’s because the bell itself acts as a sort of external gill. It’s able to absorb oxygen from the water quite efficiently, but it still loses volume slowly because nitrogen from the air diffuses into the water. If not for that, the spider probably wouldn’t need to come to the surface at all.

The diving bell is the spider’s home, especially for the female. Unlike most spiders, the female diving bell spider is much smaller than the male and she hunts differently. The male is an active hunter, swimming quickly to catch tiny animals like mosquito larvae, so he’s large and strong but only has a small diving bell. The female spends most of her time in her diving bell and only swims out to catch animals that come too close, or occasionally to replenish the air in her bell.

When the spider leaves its diving bell to hunt, air bubbles remain trapped on its abdomen, which allows it to breathe while it’s hunting too. Then it can dart back to its bell to get more air or hide if it needs to.

When a male finds a female, he will build his diving bell near hers. If she doesn’t object, he’ll build a little tunnel between the two bells so he can visit her more easily. The pair will mate in the female’s bell and she either attaches her egg sac to the inside wall of her bell or will build a little addition onto her bell that acts as a nursery.

The diving bell spider is gray or black in color and even a big male only grows about 15 mm long, head and body size together. His legs are longer. In the water the spiders appear silver because of the bubbles attached to their bodies.

The spider used to be common throughout much of Asia and Europe, but its numbers are in decline due to pollution and habitat loss, since it needs slow-moving streams, ponds, marshes, and other clean freshwater with aquatic plants to survive. It will bite if it feels threatened and some people claim that its bite is painful and leads to symptoms like fever, but there’s not a lot of evidence for the bite being dangerous or even all that painful to humans.

Next, Zachary suggested the Portia spider, and pointed out that it demonstrates “uniquely intelligent hunting.” If it weren’t such a tiny spider, it might be scary because it’s so smart. Fortunately for humans, not only is it even smaller than the diving bell spider, with even a big female no more than 10 mm long counting her head and body together, it’s a spider that eats other spiders.

There are 17 species of portia spider currently known, living in parts of Africa, Asia, Australia, and a lot of islands in southeast Asia. It’s a type of jumping spider and can jump as much as 6 inches, or 15 cm, from a complete standstill. It’s mostly brown with mottled darker and lighter markings that make it look like a bit of dead leaf when it’s standing still. It also has flaps on its legs that help it look less like a spider too.

Looking like a bit of dead leaf helps the Portia spider keep from being eaten by birds and frogs, but it also helps it when hunting prey spiders. Unlike almost all other spiders, the portia spider can travel on the webs of pretty much any species of spider without getting stuck. It will creep into another spider’s web and sneak up on it very slowly, or pretend to be a stuck insect to lure it closer. Most spiders don’t see very well, so they don’t identify the portia as a predatory spider. They either think it’s just a leaf stuck in its web or an insect, until it’s too late.

The portia spider will try many different ways to catch a spider. If one doesn’t work it will use another method, and will continue to try new methods and combinations of methods until it outsmarts the prey spider and can jump on it. The methods it uses can be incredibly complex and often require the portia spider to move away from the prey spider or even out of view of it, but it can remember exactly where the prey spider is and what it wants to do to approach it. Remember, this is an animal about the size of one of your fingernails. It has a teeny brain!

In captive studies, portia spiders are observed to be more or less aggressive depending on the individual. The more aggressive spiders tend to do a better job hunting prey with unpredictable behaviors, while the less aggressive spiders are more patient.

When the portia spider walks, it does so arrhythmically, which helps it imitate a dead leaf being moved by the wind. Some spiders are so nervous of portia spiders that if they sense an arrhythmic movement on their web, even if it’s not a portia spider, they’ll run and hide. For that matter, the portia spider will take advantage of wind and other natural occurrences to get closer to their prey.

In addition to active hunting, female portia spiders will also build funnel webs to catch insects. You know, kind of a side hustle. Any portia spider will spin a simple web to hide behind to rest. Portia spiders are also social, sharing food and even living together.

When the male portia spider wants to find a mate, he spins a little web near a female’s web and shakes his legs to attract the female. If she likes him, she’ll drum on his web to let him know. However, in most species, mating is a death sentence for the male. Remember how last week we talked about the praying mantis and how sometimes the female will actually eat the male after or even during mating? Well, that’s true for most species of portia spider too. In some species the female almost always eats the male. He gets to pass his genes along to the next generation, and she gets a good meal to help her grow healthy eggs.

Next, Leo’s friend Khalil suggested the wandering spider. This is the name given to a big family of spiders that live throughout much of the world. Most of them are quite large and look like tarantulas, especially the Brazilian wandering spider, also called the banana spider. It can have a head and body length of two inches, or about 5 cm, but a legspan of up to 7 inches, or 18 cm. That’s a lot of spider, and this week we’re talking about small spiders, but let’s take a quick detour and find out if the banana spider really is sometimes found in bunches of bananas sold in stores.

The banana spider lives in Brazil and other parts of northern South America and Central America, and that’s where a lot of the world’s bananas are grown. I couldn’t find any good estimates of how many bananas are exported every year, but the United States is the biggest importer of bananas. I’m going to switch completely to imperial measurements for a moment because the amounts I’m about to talk about make no logical sense anyway. About four bananas add up to one pound of weight, and 2000 pounds make up one ton. That means one ton of bananas is approximately 8,000 bananas. In 2023, over 5 million tons of bananas were imported to the United States. That is at least 40 billion bananas!

In comparison, no one seems to be tracking how many spiders are found hiding in banana bunches, but one paper from 2014 documented that of 135 spiders submitted to the scientists for study as having been found in all international shipments, of bananas and everything else, only seven were actually banana spiders. The rest were other kinds of spider, most of them completely harmless. When one is found it gets into the news because it’s so rare.

Spiders don’t live inside the banana peel anyway, and they don’t eat bananas. It’s just that bunches of bananas make good hiding places, and the spiders don’t know that people are going to chop the whole bunch down without even noticing a hidden spider. By the time the bananas get to the store, the big bunches have been cut up into little bunches of a few bananas each, which isn’t a great hiding space for a big spider. So your bananas are safe.

Anyway, the smallest wandering spider is probably in the genus Acanthonoctenus, which are native to Central and South America. A big female only grows about 15 mm long, head and body measured together, although her legspan is much larger. There are other wandering spiders with about the same body size in various genera. The problem is, there are hundreds of known species of wandering spider and probably a lot more that haven’t been discovered yet, but not a lot of people are studying them. We don’t know a whole lot about the smallest species because they’re harder to find and therefore harder to study. Many species have only ever had a single specimen collected. So if you want to become an arachnologist, you might look into wandering spiders for your specialization. Many of them are absolutely gorgeous, with striped legs and bright colors.

Like some other spiders, many Acanthonoctenus spiders will hide on a leaf or tree trunk by lying flat and stretching four of its legs out in front of it and the other four legs behind it. This makes it less spider shaped when a bird or lizard is looking around trying to find a snack.

Next, Eilee suggested the spoor spider, the name for Seothyra, a genus of spiders that live in sandy areas in southern Africa. Females grow up to 15 mm long, head and body together, while males grow up to 12 mm long and are usually considerably smaller than the females. The female can be brown, gray, or tan and may have stripes on her abdomen, while the male is more brightly colored. He can be yellow and black with a rusty-red head, sometimes with white spots on his abdomen.

The male spends most of his time running around finding food, and since he looks a lot like a type of wasp called the velvet ant, he’s in less danger than you’d think considering he’s active during the day. The female spends almost all of her life in an elaborate web that she builds into the sand.

The female excavates a burrow in the sand that can be as much as 6 inches deep, or 15 cm, lined with silk to keep it from collapsing. She gets sand out of the burrow as she constructs it by spinning little silk bags around the sand to carry it out. She leaves the bags of sand around the entrance, and once the burrow is finished, she incorporates the sandbags into the web itself. She spins web sheets and mixes them with sand to make mats around the burrow’s opening, which is hidden, and the spider can lift the web sheets to go in and out. Ideally she stays in the same burrow her whole life, repairing it as needed, because while it’s not an especially big web, it takes her a lot of energy to make.

The female puts sticky strands of silk around the edges of the web, then retreats to the underside of the web sheet or into the burrow if it’s too hot. When an insect gets stuck on the silk, she darts out and kills it, then takes it into her burrow to eat. Mostly she eats ants.

The name spoor spider, also called buck spoor spider, comes from the shape of the female’s web. In most species, the web sheet has two sides in a shallow depression in the sand. Since the web is also covered with and incorporates sand to hide it, the little depression with a rounded double shape at the bottom looks an awful lot like the footprint of an animal with a cloven hoof. The word “spoor” is a term indicating an animal’s track.

The spoor spider female only produces one egg sac in her life, and takes care of it in her burrow until the babies hatch. Then she takes care of the babies by gradually liquefying her own internal organs and regurgitating the liquid so the babies can eat it. When all her organs are gone she dies, naturally, and the babies eat the remainder of her body before venturing out into the world on their own.

Fossilized web sheets very similar to the modern spoor spider’s web have been found dating back 16 million years. Most spiderwebs can’t fossilize, but most spiderwebs aren’t built partly out of sand.

Finally, let’s finish up with a newly discovered spider from South America. I learned about it from Zeke Darwin, a science teacher who makes really interesting videos on TikTok. The spider has been described as a new species, named Paleotoca, and was discovered in Brazil. We know very little about it so far so I don’t have much information to share, but it’s so interesting that I just had to include it.

Paleotoca is pale yellow, although its abdomen has very little pigmentation, and its head and body together measure barely 2 mm. It doesn’t have eyes. You might be able to guess where it lives from its lack of eyes and lack of pigment in its body, but I bet I’m going to surprise you anyway. Paleotoca does live in caves, but technically these caves are burrows. It’s just that the burrows where it lives are extremely large, dug into the sides of hills thousands of years ago by giant ground sloths before they went extinct.

Luckily for the spider, there are also some natural caves in the area and at least one of the spiders has been found living in one. So little Paleotoca isn’t in danger of going extinct just because the burrow-builders are gone.

You can find Strange Animals Podcast 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 at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

 

Episode 392: Moon Jellyfish, Kung Fu Mantis, and Octocorals

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Thanks to Kari and Joel for their suggestions this week! You can find Kari Lavelle’s excellent book Butt or Face? Volume 2: Revenge of the Butts at any bookstore.

Our Kickstarter for some enamel pins goes live in just over a week if you’re interested!

Further reading:

Jellyfish size might influence their nutritional value

History of Taiji Mantis

Glowing octocorals have been around for at least 540 million years

The moon jellyfish [photo by Alexander Vasenin – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=32753304]:

A Chinese mantis [photo by Ashley Bradford, taken from this site]:

Also a Chinese mantis:

A type of octocoral:

Show transcript:

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

It’s finally Invertebrate August! We have some great episodes coming up this month, so let’s get started. Thanks to Kari and Joel for their suggestions this week!

First, we’ll start with an invertebrate from Kari Lavelle’s latest book, Butt or Face? Volume 2: Revenge of the Butts! It’s a sequel to the hilarious and really interesting book we talked about last summer. Kari kindly sent me a copy of the book and it’s just as good as the first one. Don’t worry, I won’t spoil the answer of whether the picture in the book is of an animal’s butt or face, but let’s talk about the moon jellyfish.

We’ve talked about jellyfish in several previous episodes, most recently in episode 343. Moon jellyfish is the term for jellies in the genus Aurelia, all of which look so identical that it takes close study by an expert, or a genetic test, to determine which species is which. We’re going to talk about a specific species in this episode, Aurelia aurita, but most of what we’ll learn about it also applies to the other moon jelly species.

Aurelia aurita lives in temperate, shallow water and is often found in harbors and close to shore. It’s mostly transparent and can grow up to 16 inches across, or 40 cm, although most are smaller. It’s sometimes called the saucer jelly because when its bell is open, it’s shaped sort of like a saucer or shallow bowl, if the bowl was upside down in the water with pinkish-white internal organs inside and short stinging tentacles. That’s most bowls, I think.

Unlike a lot of jellyfish, the moon jelly doesn’t have long tentacles that hang down from the middle of the bell. Instead, its tentacles are short and thin and line the edges of the bell. There are hundreds of them, but while the tentacles do have stinging cells, they’re not very strong. If you were to pet a moon jelly, you probably wouldn’t even feel the stings but you’d probably get sticky digestive mucus on your hands from the tentacles. The mucus is sticky to trap tiny pieces of food, which can include everything from fish eggs and various types of larvae to microscopic animals called diatoms and rotifers.

The moon jellyfish can survive in water with low oxygen, and in fact it prefers low oxygen water. Since most larger marine animals that live near the surface need a lot of oxygen to survive, the moon jelly can safely find its tiny food in low-oxygen areas without worrying too much about predators. Actually the moon jellyfish doesn’t worry about much of anything, because like other jellies, technically it doesn’t have a brain, just a nerve net.

Speaking of predators, for a long time scientists have wondered why anything bothers to eat jellies. They’re mostly water, which makes them easy for other animals to digest, but they contain almost no nutritional value. A study published in March 2023 determined that the bigger the jellyfish is, the more fatty acids its body contains, and fatty acids are an important nutrient. The main difference between a little jelly and a big jelly (besides size) is what they eat, so scientists think the bigger jellies are eating prey that contain more fatty acids, which slowly accumulate in the jelly’s body too.

Next, Joel sent a bunch of excellent suggestions for invertebrates, so many good ones I had trouble choosing which one to put in this episode. I chose the kung fu mantis because I love the Kung Fu Panda movies and think Mantis is an awesome character who is not appreciated enough.

Everyone loves praying mantises and we’ve talked about various species in different episodes, most recently episode 375. The one we’re talking about today is specifically called the Chinese mantis, Tenodera sinensis, which is native to Asia but which is invasive in parts of North America. It grows over 4 inches long, or about 11 cm, and is brown and green in color. It has a yellow spot between its raptorial arms, which as you can guess from the “raptor” part of that word are the arms with the big spikes that help it catch and kill its prey.

The reason this mantis is also called the kung fu mantis is because its ferocity and grace when hunting inspired a style of martial arts in China hundreds of years ago. The story goes that a great hero called Wang Lang was defeated in a duel, and afterwards set himself to study and train harder. One day he noticed a bird trying to catch a praying mantis, but the mantis was so skilled in defending itself against a much larger opponent that the bird eventually gave up and flew away. Wang Lang was inspired to incorporate the mantis’s movements into kung fu, and afterwards he never lost a duel.

Like other mantises, the Chinese mantis will eat pretty much anything it can catch. That’s mostly insects and spiders, but occasionally it will eat frogs and other amphibians, lizards and other reptiles, and occasionally even small birds. It’s a good insect to have around the garden because it eats so many garden pests, but it also eats bees and butterflies, which isn’t so good for the gardener. The Chinese mantis also eats other mantises, which is a problem in North America where it will kill and eat the native mantis species. But because the Chinese mantis is easy to keep in captivity, if you order mantises to release in your garden in the United States, as a natural pest control, there’s a good chance that the species is actually the Chinese mantis. The native Carolina mantis looks very similar but is smaller, only about 2.5 inches long, or 6 cm.

The Chinese mantis also eats other Chinese mantises. You may have heard about how the praying mantis female will bite the male’s head right off after or even while they’re in the process of mating, and then she’ll just eat him up for a nice big meal to help her develop her eggs. This is actually something that happens, although not always. In the case of the Chinese mantis, scientific observations have found that the female eats the male about half the time.

Let’s finish with a type of coral you may not have heard of, octocoral, also called soft coral. We’ve mentioned corals lots of times in various episodes but we haven’t really discussed them in detail. When most people think of coral they think of stony corals that make up coral reefs. Most corals are colonial animals, meaning each individual polyp grows together in a group, and stony coral polyps form a type of exoskeleton or shell made of calcium carbonate to protect its soft body. The polyps have small tentacles that they extend into the water to catch plankton and other particles of food, although some species are larger and can even grab little fish. The tentacles contain stinging cells called nematocysts that can stun or even kill small animals. As the colony grows, with old polyps dying and young polyps attaching to the hard skeletons left behind, the reef gets larger and larger as the years pass.

Not all stony corals live in shallow warm water and build reefs. Some live in cold water and deeper water, and there are even deep-sea corals, and these types of coral don’t build reefs. Octocorals don’t build reefs and are found in both shallow and deep water, and they don’t form hard skeletons.

Instead, the polyps of octocoral form a soft tissue full of tiny channels that allow water through. Octocorals are colonial, so the tissue of each polyp blurps together with those of all the other polyps around it. Some species of octocoral secrete little pieces of harder material to help the tissue keep its shape, but most species are still overall quite soft. It’s strong, though, and the tiny channels through it allow water to carry nutrients to all the polyps.

The octocoral gets its name because it has exactly eight tentacles, although the tentacles are feathery in appearance with lots of little branches growing off the main tentacle. This allows it to catch more tiny food. Some octocorals have long, elaborate tentacles, which has earned them the names sea fans and sea pens, from the old-timey days when pens were made from big feathers.

Corals in general appear in the fossil record for about half a billion years, with stony corals more likely to preserve for obvious reasons. Many species of octocoral exhibit bioluminescence, and that leads us to a recent study, published in April 2024.

Until this new study, scientists estimated that the first bioluminescent creatures lived around 250 million years ago. Bioluminescence has evolved separately over 100 times, though, and is found today in animals as different as fungus and fish. For the new study, scientists analyzed the genetics of 185 octocoral species to see how they were related, and then compared their findings with fossil corals to learn more about when the species split from their common ancestors. That gave them a good idea of when octocorals might have evolved originally and hinted at which ancestors were bioluminescent. They estimated that the first octocoral evolved around 540 million years ago and was already bioluminescent!

The scientists who worked on the study suggest that bioluminescence may have developed originally as a byproduct of other chemical reactions, but it was useful to the animal by possibly attracting food or other octocorals. Bioluminescence is common in marine animals these days, especially in deep-sea animals, so it’s possible that the ocean half a billion years ago was filled with lights from octocorals and many other organisms.

You can find Strange Animals Podcast 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 at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Episode 391: Welcome to Snake Island

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Follow the enamel pin Kickstarter here!

Let’s learn about some snakes this week! Thanks to Eilee, BlueTheChickenWing, and Richard from NC for their suggestions.

Further Reading:

Snake Island’s Venomous Vipers Find a New Home in Sao Paulo

‘Rarest Snake’ in the U.S. Hatches at Tennessee Zoo

The golden lancehead [picture from first article linked above]:

The Martinique lancehead/fer-de-lance:

The Louisiana pine snake, and a pine cone:

Show Transcript:

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

After today, the next four weeks will be all about invertebrates, or animals without a backbone, because it’s almost Invertebrate August! But this week let’s learn about some animals that are basically nothing but backbones, snakes! Thanks to Eilee, BlueTheChickenWing, and Richard from NC for their suggestions!

Also, if you like enamel pins even slightly as much as I do, I’m starting a Kickstarter in a few weeks to make some more. These will be bigger than the ones I made a few years ago and will include an aye-aye. Where else are you going to get an aye-aye enamel pin? There’s a link in the show notes if you want to sign up for an email reminder when the campaign goes live in mid-August. https://www.kickstarter.com/projects/kateshaw/familiar-friends-enamel-pins

Anyway, let’s start with Snake Island, suggested by Eilee. Snake Island is off the coast of Brazil in South America, and it’s quite small, only about 106 acres total, or 43 hectares. It’s hilly and a little over half of it is covered with a temperate rainforest, while the rest is grassy or just bare rocks. No one lives there these days and it’s a protected area that only scientists are allowed to visit, with the exception of members of the Brazilian navy who occasionally stop by to maintain the lighthouse that keeps ships from smashing into the rocky coast. Lots of birds live on the island or visit there, but other than that it’s mostly just snakes.

Specifically, the critically endangered golden lancehead pit viper lives on Snake Island and nowhere else in the world. It can grow nearly four feet long, or 118 cm, and is pale gold or golden-brown in color with darker splotches. It’s also incredibly venomous—but no one has ever been bitten by one as far as we know. If somehow you were bitten by one, it probably wouldn’t be a pleasant situation but you also probably wouldn’t die. That’s mainly because the golden lancehead’s venom is adapted to kill birds and reptiles, not mammals. And that’s because there are no mammals living on Snake Island.

The golden lancehead spends most of its time in trees or bushes, hunting for birds. It mainly eats two particular species of small bird that live on the island, although it will also eat other birds, lizards, and invertebrates like insects. Some reports say it will even eat smaller golden lanceheads. There’s another snake that lives on the island, Sauvage’s snail-eater, and the golden lancehead might occasionally snack on one of those. The snail-eater is also present on mainland Brazil and isn’t venomous. You can probably guess that it mainly eats snails. It’s small and thin, lives in trees, and is brownish-yellow with darker stripes and splotches.

The issue with Snake Island and its snakes is that there isn’t that much land available for the snakes to live on, and the forest has been damaged by human activity. Big chunks of forest were cleared by fire when people decided to try growing bananas on the island, which didn’t work very well. No one lives there now, but poachers do occasionally visit the island to catch snakes for the illegal wildlife trade. The golden lancehead is starting to show signs of inbreeding and disease as a result. As if that wasn’t bad enough, because the island is so close to the coast of Brazil, and mainland Brazil has its own problems with deforestation, fewer birds are migrating through the area every year. That means fewer birds stop at Snake Island and the snakes have less to eat.

Some reports claim that the island is so overrun by snakes that you’d encounter one with every step if you visited, but that’s not actually true. The snakes don’t live everywhere, and they spend almost all their time in trees. Recent studies estimate that around 2,000 to 4,000 snakes live on the island, which sounds like a lot until you remember that these are the only golden lanceheads in the whole world! Fortunately, rumors that anyone who sets foot on the island is at risk of being bitten and dying horribly from the golden lancehead’s venom keep a lot of people away. A captive breeding program in São Paulo, Brazil is also working to help the snakes.

The golden lancehead is a type of pit viper, closely related to other pit vipers found in Brazil. Its ancestors were trapped on the island when ocean levels rose at the end of the Pleistocene, around 11,000 years ago, and it’s been evolving separately ever since. Species in the genus Bothrops are also called fer-de-lance snakes, and that brings us to our next suggestion from BlueTheChickenWing.

BlueThe ChickenWing left us a nice review a while back and made two suggestions, one of which is the fer-de-lance. Fer-de-lance is a French term meaning spearhead, or lancehead, as in golden lancehead. The golden lancehead belongs to the genus Bothrops, pit vipers that are found throughout much of Central and South America as well as some Caribbean islands. We’re only going to talk about one other species of fer-de-lance this week, though, Bothrops lanceolatus, also called the Martinique lancehead. It too lives on an island, in this case the Caribbean island of Martinique.

The Martinique lancehead can grow up to 5 feet long, or 1.5 meters, with unverified reports of individuals twice that length. It’s light brown with darker speckles and a paler belly. It lives in forested areas and spends most of its time hidden, waiting for an animal to happen by. Then it strikes! It eats pretty much anything it can catch, including frogs and rats, bats and birds, rabbits, lizards, other snakes, and even large insects. Its venom isn’t as potent as the golden lancehead’s but it’s still dangerous to humans, and unlike the golden lancehead, it can and does occasionally bite people.

The Martinique lancehead is endangered due to habitat loss and poaching. People are naturally afraid of the snake and will kill it when they can, when all it wants is to be left alone to eat animals like rats and other snakes that people don’t want around either. Hospitals in Martinique keep antivenin in stock to treat the 20 or 30 people who are bitten by a fer-de-lance every year. Most people are fine after receiving treatment, but those who can’t get to the hospital in time or who try to treat the bite at home sometimes die.

The Martinique lancehead gives birth to live young, as is the case for other fer-de-lance snakes. The eggs remain inside the mother until the babies hatch, at which point the mother delivers them and they slither away to live on their own.

Speaking of snakes having babies, let’s finish with a suggestion by Richard from NC, who sent me an article that was only published literally two days ago as this episode goes live. This is not about a snake that lives on an island, but it’s so interesting I wanted to include it. It’s about the Louisiana pine snake, which is not venomous, but which is one of the rarest snakes in North America.

The pine snake is a type of constrictor, and like other constrictors it can grow quite large. The largest individual ever reliably measured was over 5 and a half feet long, or 1.8 meters. It’s tan or yellowish in color with a darker brown pattern.

It lives in open pine forests and grasslands in parts of western Louisiana and east Texas, but even when it wasn’t so rare, hardly anyone ever saw one because it spends most of its time underground. It’s specialized to eat a little rodent called Baird’s pocket gopher, and when it’s not actually hunting the gopher, it hangs out in the gopher’s old burrows to stay cool and safe. In winter it hibernates in a gopher burrow, and there’s nothing the gopher can do about that.

Baird’s pocket gopher looks a little bit like a small guinea pig because of its large head, tiny ears and eyes, chunky body, and short legs. It has long claws that help it dig rapidly in the sandy ground it prefers. While the Louisiana pine snake mostly eats the gophers, it will also eat other small animals like frogs, rabbits, and bird eggs when it finds them. The snake is threatened by habitat loss, especially the problem of roads being built through its habitat. A lot of snakes are killed by cars while trying to cross the road. Since the snake usually only lays a few eggs a year, rarely more than five, it’s hard for populations to grow.

Fortunately, the Memphis Zoo in Tennessee is headquarters for a careful captive breeding program of the pine snake. And a few days ago, a baby snake hatched and is doing great! Hopefully more will hatch soon. The babies will be cared for until they’re big enough to be safe from most predators, and then they’ll be released into the wild. So far around 300 captive-born snakes have been released into the wild, increasing the Louisiana pine snake’s chance for long-term survival.

You can find Strange Animals Podcast 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 at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Episode 390: The Wallaby and Wiwaxia

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Thanks to Jaxon and Lorenzo for their suggestions this week!

Further reading:

Rock-wallaby bite size ‘packs a punch’

Tiny Australian wallaby the last living link to extinct giant kangaroos

Extraordinary Fossil of Giant Short-Faced Kangaroo Found in Australia

Wiwaxia corrugata – The Burgess Shale

The nabarlek:

The banded hare-wallaby:

Wiwaxia was a little less cute than wallabies are:

An artist’s rendition of what Wiwaxia might have looked like when alive [picture from last page linked above]:

Show transcript:

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

Every so often I get an animal suggestion that I’m positive we’ve already covered, but then I’m flabbergasted when it turns out we haven’t. That’s the case for the animals we’ll learn about this episode, with thanks to Jaxon and Lorenzo!

A while ago, Jaxon left us a nice review and suggested we talk about wallabies. I was CONVINCED we’d talked about the wallaby repeatedly, but I think I was thinking about the wombat. We’ve hardly ever mentioned the wallaby, and it’s such a great animal!

The wallaby is a marsupial that basically looks like a miniature kangaroo, although some species grow pretty large. The resemblance makes sense because kangaroos and wallabies are closely related, but everything else about the wallaby family tree is confusing. That’s because there are a lot of animals called wallabies that aren’t actually the same type of animal. “Wallaby” is just a catchall term used by people to describe any animal that looks kind of like a miniature kangaroo.

Wallabies are native to Australia and New Guinea, but various species have been introduced to other places where they’re invasive, including New Zealand, France, England, Scotland, and Hawaii. Most of these non-native populations happened by accident when pets or zoo animals escaped into the wild, but some were introduced on purpose by people who didn’t know they were causing damage to the local ecosystems.

One thing everyone knows about kangaroos, which is also true for wallabies, is that they hop instead of running. Their hind legs are extremely strong with big feet, and in fact the name of the family they share, Macropodidae, means big feet. So, you know, Bigfoot exists but maybe doesn’t look like most people think. The animal hops by leaning forward and jumping, with its big hind feet leaving the ground at about the same time, and landing at the same time too before it bounces again. Its big tail helps it balance. But there’s a lot more to this hopping than you might think.

While the wallaby or kangaroo has strong leg muscles, what’s even more important is that it has very strong, very elastic tendons in its legs. These basically act like massively strong rubber bands. When you stretch a rubber band, it stores energy that it releases when you let go of it and it snaps back and whips you in the thumb and you wonder why you did that because it hurt. The tendons in the wallaby’s legs store energy when it hops, and when it lands, the energy releases and helps bounce the animal right back into the next hop. Once it gets going, its muscles are only doing a fraction of the work to keep it hopping at high speed. Even better for the animal, a lot of its breathing is regulated by its movements when it’s hopping, so it always has plenty of oxygen to power its body while moving fast. When it lands after a bounce, the impact pushes its breath out of its lungs, but the action of bringing its legs forward helps suck fresh air in. It’s an incredibly efficient way to move, and allows the animal to travel long distances to find food and water without spending a lot of energy.

Wallabies eat plants, and naturally the bigger species can eat bigger, tougher plants than smaller species. The exception is the dwarf rock-wallaby, according to a study published in March of 2024. There are over a dozen species of rock-wallaby, but in general they live in small groups in rocky areas. They’re nocturnal and spend the day sleeping in shady areas among the rocks, under rock overhangs, or in small caves in cliffs. At night they come out to find plants, but because they live in such harsh environments, most of the plants are pretty tough. Two species of dwarf rock-wallaby in particular turn out to have incredibly strong jaws for their size, as strong as the jaws of much larger species. Their teeth are also larger to help them grind up tough plants, and one species, called the nabarlek wallaby, even grows new molars throughout its life as the old ones wear down. That’s the only marsupial known to grow new molars throughout its life.

The nabarlek is reddish-gray in color and only weighs about 3 ½ pounds at most, or 1.6 kilograms, and is barely more than a foot long, or 30 cm, with its fluffy tail almost doubling that length. When it hops, it curls its tail up over its back. It eats grass, ferns, and other tough plants. Like most species of wallaby, it’s endangered due to habitat loss and introduced predators like foxes.

Another very small wallaby is the banded hare-wallaby, which only has a few small populations remaining on a few islands. It’s almost exactly the same size and weight as the nabarlek and is gray with lighter speckles and darker stripes on its back. It’s also nocturnal and lives in brushy areas where it can hide easily.

Even though these wallabies are smaller than domestic cats, some 45,000 years ago there used to be a type of kangaroo that was extremely large. The short-faced kangaroo stood as tall as a big grey or red kangaroo, about five feet tall, or 1.5 meters, but was much bulkier—as much as twice the weight of a modern kangaroo. It was so heavy that some researchers think it couldn’t hop but actually walked on its hind legs instead like a person. (Bigfoot.)

A few years ago, scientists comparing the genetic sequence of the short-faced kangaroo to other macropods discovered that this big strong kangaroo’s closest living relative was the tiny banded hare-wallaby.

Our next animal is a suggestion from Lorenzo, who sent a bunch of requests a while back. Before we talk about the animal, I should probably explain the situation with the List. This is the list of topics that I want to cover, a lot of them suggestions from listeners and a lot of them animals I’ve added myself. It started out as a simple Word document, but after a few years I moved it over to a spreadsheet and divided it into categories. There’s a page for mammals, a page for birds, and so on. I copied and pasted Lorenzo’s suggestions into the reptiles page because I recognized the first few as reptiles, or at least therapsids.

Well, at some point I took a closer look at the list of Lorenzo’s suggestions and added a note, “these may not all be reptiles.” Then later I took an even closer look and added another note, “these down here are basal arthropods, why did you put them under reptiles?” But next to today’s animal, at some point I added the note “I think this is a bird.”

Dear listener, Wiwaxia is not a bird. Scientists aren’t actually sure what it is, but 100% it is not a bird. It lived just over half a billion years ago in the early to middle Cambrian period, which we talked about in episode 69 about the Cambrian explosion. That’s when life on earth evolved from relatively simple, tiny organisms to much larger and more complex ones. Many of the Cambrian animals look bizarre and confusing to us today because they’re so different from the animals we’re familiar with, and that’s the case for Wiwaxia.

Wiwaxia grew about 2 inches long at most, or 5 cm, and slightly less wide. It was flat underneath like a slug, and it probably moved sort of like a slug too. The upper part of its body was covered in overlapping plates called sclerites, which acted as armor. As the animal grew older, it also developed spines that grew between the sclerites in two rows, with the longest spines growing 2 inches long, or 5 cm. Modern marine invertebrates have mineralized spines and scales that make them harder, but this hadn’t evolved yet and wiwaxia’s were basically the same material as the rest of the body, but tougher. Both the scales and the spines were shed and regrown every so often.

Like all the other animals in the Cambrian, wiwaxia lived in warm, shallow ocean water. It had a feeding apparatus at its front that had tiny conical teeth, and scientists think it used this feeding apparatus to scrape bacteria off the microbial mats that lived on the sea floor in most places, or it might have lived directly on the sea floor or on rocks. Either way, its feeding apparatus is enough like the radula found in modern mollusks that it’s been tentatively placed in the phylum Mollusca. This means it may be a very distant ancestor of slugs, snails, clams, mussels, oysters, squid, octopuses, and lots of other animals.

Wiwaxia was originally classified as an ancestor or at least a relation of modern polychaete worms, and a lot of scientists still think that’s correct. Since the original description of wiwaxia in 1899, a lot of specimens have been discovered in the Burgess shale in Canada, along with lots more found in China, Russia, the Czech Republic, and Australia, with more fossils found in other places that might be wiwaxia spines.

Because all the Cambrian fossils discovered are flattened, there’s a limit to how much we know about its anatomy when alive. The best fossils are reexamined frequently as new and more powerful methods of study are invented. Wiwaxia was apparently very common throughout the world between about 520 and 505 million years ago, so as more and more fossils are discovered, we’ll definitely learn more about it.

You can find Strange Animals Podcast 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 at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Episode 389: Updates 7 and the Lava Bear

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It’s our annual updates episode! Thanks to Kelsey and Torin for the extra information about ultraviolet light, and thanks to Caleb for suggesting we learn more about the dingo!

Further reading:

At Least 125 Species of Mammals Glow under Ultraviolet Light, New Study Reveals

DNA has revealed the origin of this giant ‘mystery’ gecko

Bootlace Worm: Earth’s Longest Animal Produces Powerful Toxin

Non-stop flight: 4,200 km transatlantic flight of the Painted Lady butterfly mapped

Gigantopithecus Went Extinct between 295,000 and 215,000 Years Ago, New Study Says

First-Ever Terror Bird Footprints Discovered

Last surviving woolly mammoths were inbred but not doomed to extinction

Australian Dingoes Are Early Offshoot of Modern Breed Dogs, Study Shows

A (badly) stuffed lava bear:

Show transcript:

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

This week we have our annual updates episode, and we’ll also learn about a mystery animal called the lava bear! As usual, a reminder that I don’t try to update everything we’ve ever talked about. That would be impossible. I just pick new information that is especially interesting.

After our episode about animals and ultraviolet light, I got a great email from Kelsey and Torin with some information I didn’t know. I got permission to quote the email, which I think you’ll find really interesting too:

“You said humans can’t see UV light, which is true, however humans can detect UV light via neuropsin (a non-visual photoreceptor in the retina). These detectors allow the body to be signaled that it’s time to do things like make sex-steroid hormones, neurotransmitters, etc. (Spending too much time indoors results in non-optimal hormone levels, lowered neurotransmitter production, etc.)

“Humans also have melanopsin detectors in the retina and skin. Melanopsin detectors respond to blue light. Artificial light (LEDs, flourescents, etc) after dark entering the eye or shining on the skin is sensed by these proteins as mid-day daylight. This results in an immediate drop in melatonin production when it should be increasing getting closer to bedtime.”

And that’s why you shouldn’t look at your phone at night, which I am super bad about doing.

Our first update is related to ultraviolet light. A study published in October of 2023 examined hundreds of mammals to see if any part of their bodies glowed in ultraviolet light, called fluorescence. More than 125 of them did! It was more common in nocturnal animals that lived on land or in trees, and light-colored fur and skin was more likely to fluoresce than darker fur or skin. The white stripes of a mountain zebra, for example, fluoresce while the black stripes don’t.

The study was only carried out on animals that were already dead, many of them taxidermied. To rule out that the fluorescence had something to do with chemicals used in taxidermy, they also tested specimens that had been flash-frozen after dying, and the results were the same. The study concluded that ultraviolet fluorescence is actually really common in mammals, we just didn’t know because we can’t see it. The glow is typically faint and may appear pink, green, or blue. Some other animals that fluoresce include bats, cats, flying squirrels, wombats, koalas, Tasmanian devils, polar bears, armadillos, red foxes, and even the dwarf spinner dolphin.

In episode 20 we talked about Delcourt’s giant gecko, which is only known from a single museum specimen donated in the 19th century. In 1979 a herpetologist named Alain Delcourt, working in the Marseilles Natural History Museum in France, noticed a big taxidermied lizard in storage and wondered what it was. It wasn’t labeled and he didn’t recognize it, surprising since it was the biggest gecko he’d ever seen—two feet long, or about 60 cm. He sent photos to several reptile experts and they didn’t know what it was either. Finally the specimen was examined and in 1986 it was described as a new species.

No one knew anything about the stuffed specimen, including where it was caught. At first researchers thought it might be from New Caledonia since a lot of the museum’s other specimens were collected from the Pacific Islands. None of the specimens donated between 1833 and 1869 had any documentation, so it seemed probable the giant gecko was donated during that time and probably collected not long before. More recently there was speculation that it was actually from New Zealand, since it matched Maori lore about a big lizard called the kawekaweau.

In June of 2023, Delcourt’s gecko was finally genetically tested and determined to belong to a group of geckos from New Caledonia, an archipelago of islands east of Australia. Many of its close relations are large, although not as large as it is. It’s now been placed into its own genus.

Of course, this means that Delcourt’s gecko isn’t the identity of the kawekaweau, since it isn’t very closely related to the geckos of New Zealand, but it might mean the gecko still survives in remote parts of New Caledonia. It was probably nocturnal and lived in trees, hunting birds, lizards, and other small animals.

We talked about some really big worms in episode 289, but somehow I missed the longest worm of all. It’s called the bootlace worm and is a type of ribbon worm that lives off the coast of Norway, Denmark, Sweden, and Britain, and it’s one of the longest animals alive. The longest worm we talked about in episode 289 was an African giant earthworm, and one was measured in 1967 as 21 feet long, or 6.7 meters. The bootlace worm is only 5 to 10 mm wide, but it routinely grows between 15 and 50 feet long, or 5 to 15 meters, with one dead specimen that washed ashore in Scotland in 1864 measured as over 180 feet long, or 55 meters.

When it feels threatened, the bootlace worm releases thick mucus. The mucus smells bad to humans but it’s not toxic to us or other mammals, but a recent study revealed that it contains toxins that can kill crustaceans and even some insects.

We talked about the painted lady butterfly in episode 203, which was about insect migrations. The painted lady is a small, pretty butterfly that lives throughout much of the world, even the Arctic, but not South America for some reason. Some populations stay put year-round, but some migrate long distances. One population winters in tropical Africa and travels as far as the Arctic Circle during summer, a distance of 4,500 miles, or 7,200 km, which takes six generations. The butterflies who travel back to Africa fly at high altitude, unlike monarch butterflies that fly quite low to the ground most of the time. Unlike the monarch, painted ladies don’t always migrate every year.

In October of 2013, a researcher in a small country in South America called French Guiana found some painted lady butterflies on the beach. Gerard Talavera was visiting from Spain when he noticed the butterflies, and while he recognized them immediately, he knew they weren’t found in South America. But here they were! There were maybe a few dozen of them and he noticed that they all looked pretty raggedy, as though they’d flown a long way. He captured several to examine more closely.

A genetic study determined that the butterflies weren’t from North America but belonged to the groups found in Africa and Europe. The question was how did they get to South America? Talavera teamed up with scientists from lots of different disciplines to figure out the mystery. Their findings were only published last month, in June 2024.

The butterflies most likely rode a well-known wind current called the Saharan air layer, which blows enough dust from the Sahara to South America that it has an impact on the Amazon River basin. The trip from Africa to South America would have taken the butterflies 5 to 8 days, and they would have been able to glide most of the time, thus conserving energy. Until this study, no one realized the Saharan air layer could transport insects.

We talked about the giant great ape relation Gigantopithecus in episode 348, and only a few months later a new study found that it went extinct 100,000 years earlier than scientists had thought. The study tested the age of the cave soils where Gigantopithecus teeth have been discovered, to see how old it was, and tested the teeth again too. As we talked about in episode 348, Gigantopithecus ate fruit and other plant material, and because it was so big it would have needed a lot of it. It lived in thick forests, but as the overall climate changed around 700,000 years ago, the forest environment changed too. Other great apes living in Asia at the time were able to adapt to these changes, but Gigantopithecus couldn’t find enough food to sustain its population. It went extinct between 295,000 and 215,000 years ago according to the new study, which is actually later than I had in episode 348, where I wrote that it went extinct 350,000 years ago. Where did I get my information? I do not know.

The first footprints of a terror bird were discovered recently in Argentina, dating to 8 million years ago. We talked about terror birds in episode 202. The footprints were made by a medium-sized bird that was walking across a mudflat, and the track is beautifully preserved, which allows scientists to determine lots of new information, such as how fast the bird could run, how its toes would have helped it run or catch prey, and how heavy the bird was. We don’t know what species of terror bird made the tracks, but we know it was a terror bird.

We talked about the extinction of the mammoth in episode 256, especially the last population of mammoths to survive. They lived on Wrangel Island, a mountainous island in the Arctic Ocean off the coast of western Siberia, which was cut off from the mainland about 10,000 years ago when ocean levels rose. Mammoths survived on the island until about 4,000 years ago, which is several hundred years after the Great Pyramid of Giza was built. It’s kind of weird to imagine ancient Egyptians building pyramids, and at the same time, mammoths were quietly living on Wrangel Island, and the Egyptians had no idea what mammoths were. And vice versa.

A 2017 genetic study stated that the last surviving mammoths were highly inbred and prone to multiple genetic issues as a result. But a study released in June of 2024 reevaluated the population’s genetic diversity and made a much different determination. The population did show inbreeding and low genetic diversity, but not to an extent that it would have affected the individuals’ health. The population was stable and healthy right to the end.

In that case, why did the last mammoths go extinct? Humans arrived on the island for the first time around 1700 BCE, but we don’t know if they encountered mammoths or, if they did, if they killed any. There’s no evidence either way. All we know is that whatever happened, it must have been widespread and cataclysmic to kill all several hundred of the mammoths on Wrangel Island.

We talked about the dingo in episode 232, about animals that are only semi-domesticated. That episode came out in 2021, and last year Caleb suggested we learn more about the dingo. I found a really interesting 2022 study that re-evaluated the dingo’s genome and made some interesting discoveries.

The dingo was probably brought to Australia by humans somewhere between 3,500 and 8,500 years ago, and after the thylacine was driven to extinction in the early 20th century, it became the continent’s apex predator. Genetic studies in the past have shown that it’s most closely related to the New Guinea singing dog, but the 2022 study compared the dingo’s genome to that of five modern dog breeds, the oldest known dog breed, the basenji, and the Greenland wolf.

The results show that the dingo is genetically in between wolves and dogs, an intermediary that shows us what the dog’s journey to domestication may have looked like. The study also discovered something else interesting. Domestic dogs have multiple copies of a gene that controls digestion, which allows them to eat a wide variety of foods. The dingo only has one copy of that gene, which means it can’t digest a lot of foods that other dogs can. Remember, the dingo has spent thousands of years adapting to eat the native animals of Australia. When white settlers arrived, they would kill dingoes because they thought their livestock was in danger from them. The study shows that the dingo has little to no interest in livestock because it would have trouble digesting, for instance, a lamb or calf. The animals most likely to be hurting livestock are domestic dogs that are allowed to run wild.

We’ll finish with a mystery animal called the lava bear. In the early 20th century, starting in 1917, a strange type of bear kept being seen in Oregon in the United States. Its fur was light brown like a grizzly bear’s, but otherwise it looked like a black bear—except for its size, which was very small. The largest was only about 18 inches tall at the back, or 46 cm, and it only weighed about 35 pounds, or 16 kg. That’s the size of an ordinary dog, not even a big dog. Ordinarily, a black bear can stand 3 feet tall at the back, or about 91 cm, and weighs around 175 pounds, or 79 kg, and a big male can be twice that weight and much taller.

The small bear was seen in desert, especially around old lava beds, which is where it gets its name. A shepherd shot one in 1917, thinking it was a bear cub, and when he retrieved the body he was surprised to find it was an adult. He had it taxidermied and photographs of it were published in the newspapers and a hunting magazine, which brought more hunters to the area.

People speculated that the animal might be an unknown species of bear, possibly related to the grizzly or black bear, and maybe even a new species of sun bear, a small bear native to Asia.

Over the next 17 years, many lava bears were killed by hunters and several were captured for exhibition. When scientists finally got a chance to examine one, they discovered that it was just a black bear. Its small size was due to malnutrition, since it lived in a harsh environment without a lot of food, and its light-colored fur was well within the range of fur color for an American black bear. Lava bears are still occasionally sited in the area around Fossil Lake.

You can find Strange Animals Podcast 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 at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Episode 388: Washington’s Eagle

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Further reading:

Audubon’s Bird of Washington: Unraveling the fraud that launched The Birds of America

The Mystery of the Missing John James Audubon Self-Portrait

Washington’s eagle, as painted by Audubon:

The tiny detail in Audubon’s golden eagle painting that is supposed to be a self-portrait:

The golden eagle painting as it was published. Note that there’s no tiny figure in the lower left-hand corner:

Show transcript:

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

This past weekend I was out of town, or to be completely honest I will have been out of town, because I’m getting this episode ready well in advance. Since July 4 was only a few days ago, or will have been only a few days ago, and July 4 is Independence Day in the United States of America, I thought it might be fun to talk about a very American bird, Washington’s eagle.

We talked about it before way back in episode 17, and I updated that information for the Beyond Bigfoot & Nessie book for its own chapter. When I was researching birds for episode 381 I revisited the topic briefly and realized it’s so interesting that I should just turn it into a full episode.

We only have two known species of eagle in North America, the bald eagle and the North American golden eagle. Both have wingspans that can reach more than 8 feet, or 2.4 meters, and both are relatively common throughout most of North America. But we might have a third eagle, or had one only a few hundred years ago. We might even have a depiction of one by the most famous bird artist in the world, James Audubon.

In February 1814, Audubon was traveling on a boat on the upper Mississippi River when he spotted a big eagle he didn’t recognize. A Canadian fur dealer who was with him said it was a rare eagle that he’d only ever seen around the Great Lakes before, called the great eagle. Audubon was familiar with bald eagles and golden eagles, but he was convinced the “great eagle” was something else.

Audubon made four more sightings over the next few years, including at close range in Kentucky where he was able to watch a pair with a nest and two babies. Two years after that he spotted an adult eagle at a farm near Henderson, Kentucky. Some pigs had just been slaughtered and the eagle was looking for scraps. Audubon shot the bird and took it to a friend who lived nearby, an experienced hunter, and both men examined the body carefully.

According to the notes Audubon made at the time, the bird was a male with a wingspan of 10.2 feet, or just over 3 meters. Since female eagles are generally larger than males, that means this 10-foot wingspan was likely on the smaller side of average for the species. It was dark brown on its upper body, a lighter cinnamon brown underneath, and had a dark bill and yellow legs.

Audubon named the bird Washington’s eagle and used the specimen as a model for a life-sized painting. Audubon was meticulous about details and size, using a double-grid method to make sure his bird paintings were exact. This was long before photography.

So we have a detailed painting and first-hand notes from James Audubon himself about an eagle that…doesn’t appear to exist.

Audubon painted a few birds that went extinct afterwards, including the ivory-billed woodpecker and the passenger pigeon, along with less well-known birds like Bachman’s warbler and the Carolina parakeet. He also made some mistakes. Many people think Washington’s eagle is another mistake and was just an immature bald eagle, which it resembles.

But here’s the problem. Audubon wasn’t always truthful. He painted some birds that he never saw but claimed he did, because another bird illustrator had painted them first. Once he claimed he went hunting with Daniel Boone in Kentucky in 1810, but at that time Boone would have been in his 70s and was living several states away.

Audubon also claimed that he discovered a little bird called Lincoln’s sparrow, but this wasn’t the case. His wife’s transcript of his diary doesn’t match up with the account that Audubon published about the discovery, but magically, when his granddaughter published her version of the diary later, Audubon’s discovery of the sparrow was in it. Historians think his granddaughter changed the diary entry to match up with Audubon’s published claim, and then she burned the original diaries. Further research into Audubon’s published writings have revealed plagiarism, false data, outright lies, and even completely fake species.

Audubon was also patriotic, as evidenced by his naming the eagle after George Washington. His journals and letters are full of praise for Washington, who died in 1799, only fifteen years before Audubon first saw the “great eagle.” There’s always a chance that Audubon wanted to name a bird after his idol, but not just any bird. It had to be majestic and bold, the largest eagle in the world! Maybe he decided to invent one.

Audubon also needed money to continue his work of painting birds, and most of the money came from English nobility. His painting and notes about a gigantic eagle made a real splash, bringing him money and fame for the rest of his life. But no evidence of the eagle’s existence has been discovered in the last 200 years. All we have are one man’s notes, a painting, and some stories of other specimens here and there. What we don’t have are the specimens, not even any feathers.

While we’re talking about one Audubon eagle mystery, let’s learn about another mystery. While Audubon was an incredible painter of birds, he wasn’t all that great at painting people. Only two of his famous bird paintings contain human figures, and one of them is his painting of the golden eagle. The other is a hunter painted in the background of the snowy egret, but Audubon didn’t paint that figure himself. He painted the bird, but hired another artist to paint the background. But this isn’t the case for the golden eagle painting, and that’s where the mystery lies. Even though it’s not technically anything to do with the bird, I know we’re all here for a good mystery too, so let’s talk about this painting.

Most of the time Audubon shot the birds he painted, which isn’t a great thing to do but which was common back then for scientists and collectors to shoot even very rare animals. Few people really understood conservation at the time. In the case of the golden eagle, though, the bird was already so rare in the early 19th century that Audubon couldn’t find one to shoot. He eventually bought one from a museum in 1833—but the bird wasn’t dead. It was injured, and Audubon was so impressed by its beauty that he almost set it free. But he needed to paint the bird, and in order to do that to his own meticulous standard, the bird had to be dead so he could really examine it in detail. So, after wrestling with his conscience, he killed the bird.

He spent the next two weeks drawing, studying, and eventually painting the bird. As soon as he finished, he reportedly had a mental breakdown. Not only had he been painting almost nonstop for years at that point, he really didn’t like killing birds. Plus, in the case of the golden eagle, instead of shooting it from a distance, he had killed it up close in person—as humanely as possible, but he still ended its life, and that bothered him.

The mystery comes from a detail in the painting’s background. The golden eagle is shown in front of a dramatic background of snowy mountains, with a dead snowshoe hare in its talons. But in a tiny detail in the lower left-hand corner, a man is shown crossing a gorge on a fallen tree trunk. Strapped onto the man’s back is a dead golden eagle.

The man is awkwardly rendered, but experts believe it’s a self-portrait of Audubon himself. Some experts believe Audubon included himself with a dead eagle, navigating a perilous climb, to indicate his emotional struggle in killing the bird. But when the painting was eventually included in Audubon’s famous book of bird illustrations, the figure was gone. The gorge with the fallen tree remains, but the little man carrying the dead bird has been painted out.

The question is why. Who made that decision, Audubon himself or the publisher? If Audubon did it, was it because he was embarrassed that he’d included a self-portrait, or was he embarrassed at the poor rendering of his figure, or did he just think it detracted from the painting, or some other reason? If the publisher did it, did he dislike the badly painted little man, or did Audubon ask him to remove the figure, or some other reason? We don’t know, and very likely we’ll never know.

While Audubon reportedly loved birds, it turns out he wasn’t a great human. Besides shooting a whole lot of birds and other animals, sometimes hundreds in a single day, and lying in published scientific papers, he “owned” enslaved people and reportedly made money selling them. (Just saying that sentence makes me so mad. You cannot own people.) In 2023, members of the National Audubon Society called for the group to change its name and drop any mention of Audubon, and when the board of directors said no, a lot of members resigned.

I came into this topic really hoping Washington’s eagle was a real bird, and believing that James Audubon was an artist who loved birds and was an honest man who made some mistakes. Now I’ve discovered that Audubon was a liar and a bad person, and that Washington’s eagle was probably just the result of one of his lies. At least we still have golden eagles, bald eagles, and lots of other amazing birds to admire!

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