Category Archives: invertebrates

Episode 487: Animals and the Sense of Taste

Posted on by

Podcast: Play in new window | Download (Duration: 8:53 — 10.0MB)

Subscribe: RSS | More

Further reading:

What gives bees their sweet tooth?

Show transcript:

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

Right before I left on my trip to Belize a few months ago, my aunt Janice gave me a magazine to read on the plane, the Autumn 2021 copy of LivingBird. It’s about birds and birdwatching. I actually forgot to take it with me and it was in my car the whole time I was gone, but when I got home I took it in to read.

One article caught my eye, titled “Investigating the Sweet Tooth of Songbirds.” Literally the same day that I read that article, I stumbled across another article on ScienceDaily titled “What gives bees their sweet tooth?” And a podcast episode idea was born!

You may have heard that domestic cats can’t taste sweetness, and that’s true. When your pet cat wants to drink the milk in a bowl of sugary cereal, it’s not the sugar they care about because they can’t taste it. Also, milk isn’t good for cats and even if they can’t taste the sugar, it can end up giving them cavities.

The question is, why don’t cats taste sweetness? And what other animals can’t taste it either?

Carnivores like cats don’t need to taste sweet flavors because it’s just not present in meat, which is what carnivores eat. You can test this easily if you put two saucers on the floor for your cat, one with a small amount of unseasoned chicken and a sugar cube in the other. I guarantee you the cat will eat the chicken and play with the sugar cube, which will get sugar all over the floor so maybe don’t do that after all. This is where I share with you, for no reason, that when I was in elementary school I used to eat sugar cubes while pretending I was a horse.

Horses can taste sweet flavors like sugar because they’re herbivores. Herbivores eat plants, and in fact herbivores have a whole lot of taste buds so that they can easily tell what kind of plants they’re eating. Bitter tasting plants might be toxic while sweet ones provide lots of energy. Herbivores are also keenly attuned to the taste of salt since their diet is typically low in salt and they need to seek it out.

Humans are omnivores, and omnivores eat pretty much anything. Like our great ape cousins, we also evolved to eat a lot of fruit. Ripe fruit tastes sweet so we really like our sweet foods. Omnivores like dogs, pigs, and bears also like sweet foods because they’re high in calories and therefore provide a lot of energy.

But how does an animal lose an entire sense of taste? It’s not like all tigers woke up one day and boom, the ability to taste sweetness was gone. It happens gradually as the genes responsible for an animal’s sense of taste mutate over many generations.

Let’s take as our example the bottlenose dolphin. The ancestors of the dolphin and other cetaceans were terrestrial animals related to the ancestors of modern even-toed ungulates like hippos, camels, deer, and pigs, and were probably either herbivores or omnivores. But as the dolphin’s ancestors evolved over millions of years, they shifted to a fully marine lifestyle and a fully carnivorous diet. Over the thousands and thousands of generations, the genes that control the ability to taste sweetness mutated so much that they’re now useless, but since the dolphin doesn’t need to taste sweetness the mutations don’t matter.

In the case of the bottlenose dolphin and other cetaceans, in fact, they also can’t taste bitterness or umami. Umami is what helps you taste the difference between chicken and turkey, steak and pork, tuna and trout. Basically it’s the flavor of meat or savory foods, including cheeses. You can taste the difference between cheddar and Swiss because of the umami receptors in your taste buds, which are determined by genes.

But the dolphin eats nothing but meat! Why would it lose the ability to taste meat? Researchers think it’s because the dolphin swallows fish and other animals whole, without chewing. Cetaceans and other marine carnivores like sea lions that swallow their food whole actually have almost no taste buds at all.

If you’re wondering what happens when an animal that can’t taste sweetness has to adapt to a diet where tasting sweet foods is important, that’s exactly what happened with songbirds. The ancestors of birds lost the ability to taste sweetness millions of years ago when they were dinosaurs. Then, well, you know what happened to the non-avian dinosaurs. Suddenly the ancestors of modern birds had a lot of available ecological niches to take advantage of and they evolved rapidly to fill them. This included small birds who eat berries and nectar.

Genetic studies suggest that the ancestors of songbirds regained the ability to taste sweetness around 30 million years ago in Australia. The same thing happened in hummingbirds at about the same time. In both cases, the genes that control the ability to taste umami evolved to taste sweetness instead—but songbirds and hummingbirds adapted different umami genes. That’s what you call a subtle case of convergent evolution.

Songbirds and hummingbirds adapted to a diet high in sugar because it’s a good source of energy and easily found in flowers. In turn, flowers needed to be pollinated and have their seeds spread around, so they evolved to provide even more sugars in nectar and berries. But birds aren’t the only animals that pollinate flowers and are attracted to nectar. Insects can all detect sweetness. However, bees are exceptionally attuned to sweetness and have two taste neurons instead of one per taste bud.

Insects don’t have taste buds the same way we do, of course. In mammals, reptiles, and birds, taste buds are located on the tongue, in a few parts of the mouth, and at the top of the throat. In insects, taste receptors can be in any number of places. They’re on an insect’s mouthparts but often also on their feet, legs, and antennae.

Some amphibians have taste receptors on the body as well as concentrated in the mouth, and many fish have taste receptors all over their body. Catfish in particular have the most taste buds known, up to 175,000. Humans have about 10,000. Cats only have about 500.

Before you start feeling sorry for your cat for not being able to taste sweet foods and not having a great sense of taste in general, cats have a taste receptor we don’t. It’s the water sense. To us, a nice cold glass of water tastes refreshing but doesn’t really have a flavor. A cat or dog, and many other animals whose diet is mostly meat even if they aren’t specifically carnivores, have the ability to taste water in a way we can’t even imagine. Because meat is high in salt content, having taste buds attuned to water helps the animal drink enough water to process all that salt.

If you gave me the choice, I’d choose sweetness over the ability to taste water. But my cats would probably disagree.

Thanks for your support, and thanks for listening!

Episode 484: The Sewellel and the Superflea

Posted on by

Podcast: Play in new window | Download (Duration: 7:54 — 8.0MB)

Subscribe: RSS | More

The sewellel is a little rodent:

The superflea is a big flea (left, compared to a regular flea, right):

Show transcript:

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

Let’s learn about a rodent you may never have heard of, unless you live where it does, and a parasite that makes that rodent its host. It’s not an ordinary parasite, but don’t worry, it’s not icky. You can continue to snack.

The rodent is called the sewellel, Aplodontia rufa. It’s also called the mountain beaver even though it doesn’t always live in the mountains and it isn’t a beaver. It doesn’t even look like a beaver. For one thing, it only has a little nub of a tail and it only grows around 20 inches long, or 50 cm. It has small eyes and ears, short legs, a chunky body, and long claws. This body shape should give you a hint about its lifestyle: the sewellel is a digger, although it can also swim just fine and can even climb small trees to eat young twigs and leaves.

The sewellel is an aplodont, a large group of rodents that have been common in Europe, Asia, and North America for 40 million years. But it’s the only one left. All the other aplodonts went extinct several million years ago at least. We’ve actually talked before about one of the sewellel’s extinct relations, the horned gopher (which was not a gopher), in the Patreon episode about animals with nose horns.

The sewellel itself hasn’t been around all that long, only appearing in the fossil record a few million years ago. It lives in a small area of northwestern North America, in parts of British Columbia, Washington state, Oregon, and a few parts of California. It lives in forests where it doesn’t get too cold in the winter, since it doesn’t hibernate and isn’t as good at keeping itself warm as other rodents are. It also needs to drink more water than other rodents and prefers to live in wet climates as a result.

In fact, the sewellel is sometimes referred to as a living fossil since it lacks many features that all other living rodents have. Its teeth resemble a simpler version of squirrel teeth, so some researchers think it may be most closely related to squirrels, but even if that’s the case, it isn’t very closely related. The sewellel’s ancestors were more adapted to live in trees and a study published in 2018 determined that it had a larger brain than the sewellel. Since the sewellel is nocturnal and spends most of its life underground, it doesn’t need to see very well, and the part of the brain that processes vision is much smaller than in its ancestors.

The sewellel mostly eats ferns, although it also eats other plants, and some of its favorite plants are toxic to other animals. It’s a solitary, mostly nocturnal animal that digs deep, complex burrows, and it stays as close as possible to the burrow entrance so it can hide easily if it needs to. Everything eats the sewellel, from owls to coyotes to bobcats to eagles.

And that brings us to the parasite associated with the sewellel. Many animals have parasites that are specific to that particular species. The Patreon episode about whale lice has some information about how specific this can get. The male sperm whale has a different species of louse than the species that lives on female sperm whales, for instance. Also, the whale louse isn’t a louse, it’s a type of crustacean.

The sewellel’s parasite is a type of flea. Big deal, you say, fleas are all about the same.

Are they, though? Because the sewellel’s flea is actually kind of a big deal. It is, in fact, the largest flea known, called the superflea. It can grow up to 8 mm long (and possibly longer, reports vary). I just measured, and that’s the length of my little fingernail, from the base to the quick. Most species of flea are 3 mm long at most.

The superflea is only found on the sewellel. It looks like an ordinary flea except for its size, meaning it’s laterally flattened with legs that allow it to jump long distances. So why is it so big compared to other fleas, especially considering that it lives on an animal that’s about the size of a chonky cat? No one knows. No one has even the slightest idea why this flea is so big.

There used to be even bigger fleas, some up to two cm long. That’s 20 mm, or just a little more than twice the length of the superflea. Of course, those 20 mm fleas lived 165 million years ago and probably lived on dinosaurs. Also, they couldn’t jump and instead of being flattened laterally, or side to side, like modern fleas, they were flattened dorsoventrally, or top to bottom. So they weren’t very much like modern fleas.

That’s all we know about the superflea, but let’s have one last sewellel fact before we go. With all this talk of the sewellel being a primitive rodent whose closest relations are all extinct, you might think there’s nothing really special about it beyond its giant fleas. You would be wrong, though, because the sewellel’s front paws have opposable thumbs. It’s not as mobile as our opposable thumbs, but it allows the sewellel to manipulate food more easily. It will sometimes sit up on its big round bottom to eat, just like a really weird squirrel.

Thanks for your support, and thanks for listening!

Episode 482: Smoky Mountain Mystery Animals

Posted on by

Podcast: Play in new window | Download (Duration: 18:13 — 18.8MB)

Subscribe: RSS | More

I took this episode from an article I wrote for Flying Snake magazine, which was published in December 2020 (Vol. 6, #18).

Show transcript:

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

The Great Smoky Mountains is a subrange of the Appalachian Mountains, which stretches from the middle of Alabama in the United States north into southeastern Canada. The Appalachians formed when the world’s continents crunched together to form the supercontinent Pangaea. The southern Appalachians formed separately and later than the northern Appalachians, around 270 million years ago.

The Appalachians were once as high as the Rockies or Himalayas, but by the time the dinosaurs went extinct, they had eroded down to the mountain cores. Sediment weathered from the peaks and filled in valleys. But during the Pleistocene, when massive glaciers covered the northern parts of North America, the weight of the ice pushed the North American plate down, causing the southern part of the plate to rise. Eventually the ancient mountains’ roots were a thousand feet (300 m) above sea level again. Rivers that once flowed east into the Atlantic Ocean or west into the remains of the shallow Western Interior Seaway shifted their courses to flow northward. Streams that once meandered across the land now plunged down steep slopes and dug gorges into the rock. And over thousands of years, animals and plants retreating from the ice migrated southward along the mountain range.

When the climate warmed some 11,000 years ago and the ice age glaciers melted, many cold-adapted species were trapped in the peaks of the southern Appalachians. One of the highest peaks is Mount LeConte, with its highest point, High Top, measured at 6,593 ft, or 2,010 meters. I hiked Mount LeConte on 7 May, 2016 when the weather in nearby Knoxville, Tennessee was a warm 82 Fahrenheit, or 27.8 Celcius, but there was snow on the mountain that morning. I wrote my name in it. A spruce-fir forest grows on the upper slopes, a remnant of forest that grew throughout the mountains during the last ice age. The climate at the peak of Mount LeConte is more like that of southern Canada than the warm, humid southeastern United States.

The Great Smoky Mountains National Park was established in 1934 to protect the mountains along the Tennessee/North Carolina border. No one lives in the park’s 800 square miles (2,072 square km), which receives up to 90 inches [2.29 m] of rain a year, some of it from hurricanes that sweep up from the southern Atlantic or the Gulf of Mexico. Large tracts of old-growth forest still remain in the park too.

So as you can see, the Smokies are a biodiversity hotspot. In 2018, the park announced its 1,000th species discovered that is new to science, which by July 2020 had grown to 1,025. Overall, 20,000 known species live in the park as of 2019 and scientists estimate that up to 100,000 more are yet to be discovered.

The Smokies are heavily forested, of course, but some mountain summits and crests have no trees. Instead, native grasses and shrubs grow. They’re called grassy balds and no one is sure why they exist. The prevailing theory is that Pleistocene megaherbivores opened the forests for grazing, and after their extinction, the balds remained open due to bison, elk (wapiti), and deer. When white settlers moved into the area, they used the balds to graze cattle and other livestock. Remains of mammoth and mastodon, musk ox, ground sloth, and other megaherbivores have been excavated from various balds throughout the park.

Amphibian enthusiasts call the Smokies the Salamander Capital of the World, with 30 known species. Largest of these is the hellbender, which we talked about in episode 14, a giant salamander that can grow nearly 2 ½ feet long, or 74 cm, and which lives in swift-moving mountain streams. It’s most closely related to the Chinese and Japanese giant salamanders, which can grow over twice as long as the hellbender. Twenty-seven of the salamanders found in the Smokies are lungless, in the family Plethodontidae. Instead of breathing with lungs or gills, the lungless salamanders absorb oxygen through their skin. Of these, the red-cheeked salamander is endemic to the Smokies—that is, it’s found nowhere else in the world.

The red-cheeked salamander lives in forests in high elevations. It can grow up to seven inches long, or 18 cm, and is gray or black with bright red patches on its face. It spends the day in a burrow, then comes out at night to find insects in the leaf litter. But it’s hard to tell apart from the imitator salamander, although the imitator only grows a little over four inches long, or 11 cm. The imitator has red cheeks but its body is patterned black and brown instead of solid gray or black. Sometimes its cheeks are yellow, too, while the red-cheeked salamander only ever has red cheeks.

Another animal found only in the Smoky Mountains, although it may also be present in mountains outside of the park, is a species of jeweled spider fly called Mary-Alice’s emerald (Eulonchus marialiciae). Mary-Alice’s emerald has a metallic-green body and yellow legs, and the adults eat nectar. But the larvae eat spiders. Specifically, they parasitize spiders. After hatching, the larva goes in search of a spider, especially trapdoor spiders that live in burrows. When it finds one, it works its way into the spider’s body and eats it from the inside out, eventually killing it. Then it pupates in the burrow and emerges as an adult spider fly. It prefers high elevations that are cool and moist.

A less horrific animal found in the Smokies is the Carolina northern flying squirrel. It was one of the species whose ancestors migrated south along the Appalachians during the Pleistocene. Then, after temperatures started to warm, the cold-adapted flying squirrel migrated north again. Some populations remained on mountaintops in the Smoky Mountains and have been isolated for thousands of years, evolving into a subspecies of flying squirrel found only in high elevations of the Smokies. It’s much rarer than the southern flying squirrel that lives throughout the southeastern United States, and prefers spruce forests instead of the hardwood forests that southern flying squirrels like. But the spruce forests are threatened by climate change, the introduced woolly adelgid insect that kills fir trees, and pollution in the form of acid rain and pesticides that travel to the mountains from other states and even other countries.

The Carolina northern flying squirrel has a patagium of furry skin that connects its front and back legs. When it jumps from a branch, it stretches its legs out and uses the patagia to glide to a new perch. It’s clumsy on the ground, though, and spends most of its time in trees. It mostly eats fungi, mushrooms, and lichens, but will also eat nuts, insects, bird eggs and even baby birds, and other plant material like tree sap and buds.

Bobcats still live in the Smokies, but the cougar, or mountain lion, was supposedly killed off in the area by the end of the 19th century. The U.S. Fish and Wildlife Service removed the eastern cougar subspecies from the endangered species list in 2018, since it is supposed to be extinct. The last cougar in what is now the park was supposedly killed in 1920. But sightings continue in the Smokies, close to a dozen a year, and some sightings are compelling, like the 2002 report of a cougar crossing a road in the park, spotted by a veterinarian who treated captive cougars in his practice. Considering how seldom seen the bobcat is despite it being relatively abundant, it’s possible that a small number of cougars still live in the park—either animals that have moved back into the mountains from elsewhere, or a relict population.

The red wolf is native to the eastern United States and was once common in the Smoky Mountains, but was killed off by white settlers throughout most of its range. Where it remained in the wild, it interbred with closely related coyotes, until it was declared extinct in the wild in 1980. Fortunately, by then a captive breeding program was in place. Starting in 1991, 37 red wolves were released in the Great Smoky Mountains National Park in Tennessee, following the release of 63 red wolves into the Alligator River Natural Area in North Carolina a few years earlier. But the release didn’t go well in the Smokies. Wolves are shy and need enormous territories with lots of game. Before long some wolves were leaving the park and attacking livestock. Others died of parvo virus, especially wolf pups.

Worse, this was about the same time that coyotes moved into the area from the west. The wolves started interbreeding with the coyotes, and the coyotes also competed with the wolves for food. In 1998, the Fish and Wildlife Service ended the program and recaptured all but one of the wolves originally released into the park.

The North Carolina release went better, with a population peak in 2006 estimated at nearly 130 wolves. But that program was suspended in 2015, and without management of the wild population, the number has dwindled. As of 2019, only 14 wolves remain in North Carolina—and that’s the entire population of red wolves in the wild.

But sightings of red wolves continue in the Smokies. The trouble is that the red wolf looks very similar to the coyote. It’s taller and larger, with a more pronounced reddish shade to its coat, but even experts can have trouble telling the two species apart if they can’t get a good look at the animal. Most likely people are seeing coyotes, possibly ones descended from red wolf/coyote hybrids born during the reintroduction program.

The biggest mystery in the park is the occasional sighting of a Bigfoot-type creature. Most sightings are probably bears, though. An estimated 1,500 American black bears live in the Smokies, and while some bears get used to hikers and tourists, most are shy and seldom seen. A black bear keeping an eye on hikers or cars will sometimes stand on its hind legs for a better view, and would naturally look like a hulking humanoid if glimpsed. But other sightings aren’t so easy to explain.

In February of 2009, a photographer named Deb Campbell was hiking the Middle Prong Trail in the snow. The Middle Prong Trail passes three major waterfalls and many smaller ones as it follows along a tributary of the Little River. She had the trail almost completely to herself—she says she only saw one person the whole time. Later she reported, “[A]t some point I am photographing along the stream and I start to smell a gawd awful stench. Not really like anything I had ever smelled before. I look around, see nothing, listen intently…nothing. So I finish up at that spot and go further up the trail.” The smell receded behind her but the snow increased, so finally she turned around to hike out. Around the area where she smelled the stink earlier, she started feeling watched. She stopped long enough to secure her camera gear for much faster hiking in slick conditions, when she heard a deep growl that she described as “very low, not like a cat, almost guttural.” Needless to say, she got off the mountain as quickly as possible.

The black bear doesn’t truly hibernate since its body temperature remains normal instead of dropping, but it does find a den in cold weather and will sleep for long stretches. It may emerge from its den occasionally during the winter during warm spells, but for the most part it’s asleep in its den from around November through March in the Smoky Mountains. But Campbell was hiking in February during a snowfall, with snow already on the ground. A bear would most likely not be out of its den in that weather unless it had been disturbed.

And bears don’t actually smell bad. During the winter hibernation most bears don’t defecate at all. Any feces left in a bear’s digestive tract harden to form a fecal plug. If it does feel the need to defecate near the end of the winter, it will do so just outside its den, but the fecal plug has very little odor. Even under ordinary conditions, unless a bear has been eating carrion, it will smell no worse than a dog that needs a bath.

Not only that, black bears don’t actually growl. They make grunty, huffing noises when warning people away or when males fight in the summer, and a frightened bear will moan, but they don’t growl like a dog.

It’s possible that Campbell hiked past a bear that had emerged from its den early and had found and eaten carrion, possibly roadkill, and that she was so close to the bear without seeing it that she smelled its breath. That’s almost more frightening than the thought of passing near a Bigfoot. The growl might have come from a different animal, a coyote or who knows, maybe even a red wolf. Or Campbell might have encountered a creature sometimes called a skunk ape due to its foul odor.

The skunk ape is most commonly reported in Florida swamps, but sightings—or smellings—have come from many other states. The smell is sometimes described as that of rotting food and roadkill on a hot day. A bear or other animal that has been rooting around in garbage bins can pick up this odor, especially in hot weather, but it’s hard to believe that a bear would be actively foraging so much in winter that it would smell like trash. January and February are the depths of winter in East Tennessee. The bears are hibernating, not foraging.

Thanks for your support, and thanks for listening! This is what a couple of fighting bears sound like:

[bear sounds]

Episode 480: Old, Old Life

Posted on by

Podcast: Play in new window | Download (Duration: 7:36 — 8.3MB)

Subscribe: RSS | More

Let’s learn about some of the oldest life ever discovered!

Further reading:

Microbiologists Find Living Microbes in 2-Billion-Year-Old Rock

Chart of life extended by nearly 1.5 billion years

Show transcript:

Back in episode 168 we talked about the longest-lived organisms known, and finished the episode by discussing endoliths. I’ll quote from that episode as a refresher.

An endolith isn’t a particular animal or even a group of related animals. An endolith is an organism that lives inside a rock or other rock-like substance, such as coral. Some are fungi, some lichens, some amoebas, some bacteria, and various other organisms, many of them single-celled and all of them very small if not microscopic. Some live in tiny cracks in a rock, some live in porous rocks that have space between grains of mineral, some bore into the rock. Many are considered extremophiles, living in rocks inside Antarctic permafrost, at the tops of the highest mountains, in the abyssal depths of the oceans, and at least two miles, or 3 km, below the earth’s surface.

Various endoliths eat different minerals, including potassium, sulfur, and iron. Some endoliths even eat other endoliths. We don’t know a whole lot about them, but studies of endoliths found in soil deep beneath the ocean’s floor suggest that they grow extremely slowly. Like, from one generation to the next could be as long as 10,000 years, with the oldest endoliths potentially being millions of years old—even as old as the sediment itself, which dates to 100 million years old.

That episode was almost five years ago, and in October of 2024 some new information was published. The study mentions the 100-million-year-old limit known so far, where living microorganisms were indeed discovered in geological layers below the ocean floor. But what they found was even older.

The scientific team analyzed rock samples from northeastern South Africa, specifically rock that formed when magma cooled below the surface of the earth. It’s called the Bushveld Igneous Complex and is very large, very old, and very stable.

The team drilled core samples of the rock from 50 feet down, or 15 meters, and cut it into thin slices to examine. To their surprise, they discovered microbial life in the rock’s cracks, which were sealed tightly with clay so that nothing should be able to get in or out of the rocks. To be sure the microbes hadn’t been introduced during the drilling or preparing process, they used infrared spectroscopy to compare the proteins in the microbes with the proteins caught in the clay. They matched, meaning the microbes had been there as long as the clay had been there, which was basically almost as long as the rocks had been in place. They were also able to verify that yes, the microbes were definitely alive.

So, how old are the rocks? TWO BILLION YEARS OLD. Billion with a B! While the individual microbes probably aren’t actually that old, the population of microbes has been living in those cracks far within the rock for two billion years. Scientists are excited to learn more about them, because by studying organisms that have been separated from all other life for that long, they can learn about how early life on earth evolved.

Even more exciting, at least if you’re me, NASA’s Perseverance rover on Mars is going to be bringing some rocks back to earth that are about 2 billion years old. Scientists are really excited to see if there is any evidence for microbial life inside the Martian rocks!

I know I won’t live long enough to see the first macrobial life from another planet, but I really hope I’m alive when we discover the first microbial life. I don’t think life is rare on other planets, it’s just that the distances are so enormous that getting to another planet and sending information back home is an almost insurmountable problem right now. The closest planets to us are Mars and Venus, and these days Mars just doesn’t seem like it would be very habitable for anything but microbes. But microbes can live just about anywhere!

Also in 2024, a team from Virginia Tech has put together a chart marking when various life forms started appearing in the fossil record and when they also stopped appearing in the fossil record. Versions of this chart of life have been made before, but they typically only go back to about half a billion years ago, around the time of the Cambrian. Before that, life was much less likely to fossilize, or the rocks containing the fossils have been worn away.

The team gathered fossil data from scientists and institutions around the world and compiled it into a chart of life that extends back two billion years. The farther back you look, the less changes there are among the type and differences in species. There’s even a huge stretch of time called the boring billion where things really weren’t changing much at all, at least not according to the fossil record we have available. It wasn’t until the earth’s climate became much cooler and then warmed again, between 720 and 635 million years ago, that things really began to change.

The team is considering factors that contributed to the stability of the boring billion, and why it all changed so radically. It’s a good thing it did from our perspective, since if the boring billion had continued over the next billion years until today, we’d all be single-celled organisms. I wonder if the microbes in those two billion year old rocks even noticed the changes. Probably not. They were in rocks.

Thanks for your support, and thanks for listening!

Episode 479: Metal Animals

Posted on by

Podcast: Play in new window | Download (Duration: 7:50 — 7.9MB)

Subscribe: RSS | More

Further reading:

Beavers Have Metal Teeth

Show transcript:

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

Let’s find out about some animals that incorporate metal into their bodies in more than just trace amounts.

We’ll start with the scaly-foot gastropod, a deep-sea snail. It lives around hydrothermal vents in the Indian Ocean, about 1 and ¾ miles below the surface, or about 2800 meters. The water around these vents, referred to as black smokers, can be more than 350 degrees Celsius. That’s 660 degrees F, if you even need to know that that’s too hot to live.

The scaly-foot gastropod was discovered in 2001 but not formally described until 2015. The color of its shell varies from almost black to golden, depending on which population it’s from, and it grows to almost 2 inches long, or nearly 5 cm. It doesn’t have eyes, and while it does have a small mouth, it doesn’t use it for eating. Instead, the snail contains symbiotic bacteria in a gland in its esophagus. The bacteria convert toxic hydrogen sulfide from the water around the hydrothermal vents into energy the snail uses to live. It’s a process called chemosynthesis.

In return, the bacteria get a safe place to live.

The snail’s shell contains an outer layer made of iron sulfides. Not only that, the bottom of the snail’s foot is covered with sclerites, or spiky scales, that are also mineralized with iron sulfides. While the snail can’t pull itself entirely into its shell, if something attacks it, the bottom of its foot is heavily armored and its shell is similarly tough.

Researchers are studying the scaly-foot gastropod’s shell to possibly make a similar composite material for protective gear and other items. The inner layer of the shell is made of a type of calcium carbonate, common in mollusk shells and some corals. The middle layer of the shell is regular snail shell material, organic periostracum, which helps dissipate heat as well as pressure from squeezing attacks, like from crab claws. And the outer layer, of course, is iron sulfides like pyrite and greigite. Oh, and since greigite is magnetic, the snails stick to magnets.

The scaly-foot gastropod is the only animal known that incorporates iron sulfide into its skeleton, but other animals use metals in their teeth. Some spiders have tiny amounts of zinc in the tips of their fangs. Some mollusks have small amounts of iron in the teeth of their radulas—you know, the tongue-like structure used to scrape food off rocks. The teeth of the limpet, a type of mollusk, may be one of the strongest structures in the world. It contains goethite nanofibers, and goethite is a type of iron.

The teeth of beavers and some other rodents contain iron in the enamel coating. This makes the teeth much harder, although the amount of iron is quite small and unstructured. Most other mammals, including humans, have magnesium in tooth enamel instead of iron. The iron content makes the teeth look orange because of rust.

Bloodworms are disgusting horrible worms that my uncle used to fish with when we visited the beach when I was a kid. I was scared of the bloodworms, which irritated my uncle, because I was very vocal about hating the worms and he wasn’t catching any fish with them. Bloodworms live in the sand or silt of shallow water, usually in the ocean but since they can tolerate low salt levels, they may also live farther inland in canals and inlets. Some species can grow nearly 15 inches long, or 37 cm. They’re usually pink or reddish in color with bristles along the body and four little antennae on the head. But the reason I’m talking about them here is that their teeth are reinforced with copper that makes them nearly as hard as teeth coated with enamel. Its jaw also contains copper ions.

Copper is toxic to most animals, which may be the source of the bloodworm’s venom. That’s right: horrible worms are also venomous.

Another invertebrate that incorporates metal in its body is the parasitic fig wasp. Fig wasps are interesting and there are a lot of them. Figs are pollinated by fig wasps that are not parasitic. The fig flower has a bulb at its base containing a tiny hole. The pollinating fig wasp crawls into the hole, pollinating the flower at the same time, and lays her eggs inside the bulb. She then dies. As the fig developes, the wasp eggs hatch into larvae and then develop into adult wasps. Males mate with females, then chew a hole out of the fig, but only the female wasps have wings, so the males remain and die. As the fig ripens, it actually digests the dead wasps, and—and this is important to those of us who really like figs—leaves no bits of dead wasp inside the fig. So that’s how the pollinating fig wasps work. It’s a symbiotic relationship between the fig tree and the wasp.

But the parasitic fig wasp is different. The female has a long ovipositor, which it uses to drill into developing figs and into the pollinating fig wasp larvae. When its eggs hatch, they eat the larva alive. This is yet another reminder that nature is disgusting! But the really interesting thing is that at least one parasitic fig wasp species, Apocrypta westwoodi, has an ovipositor that resembles a drill bit, and it’s hardened with zinc. The ovipositor is basically a syringe with a drill bit, but since it’s so strong while being much thinner than a human hair, researchers are studying its structure to help develop minimally invasive medical syringes.

One interesting note. You’d think that iron and other metals would be more common in animal bodies as armor. Animals use some metals for various purposes as it is, like the iron containing hemoglobin in our blood. But incorporating iron and other metals into the body has a high metabolic cost and frequently biological materials are stronger than metal in the ways that count. Plus, they don’t rust.

Thanks for your support, and thanks for listening!

Episode 478: Life in Ice

Posted on by

Podcast: Play in new window | Download (Duration: 13:12 — 14.6MB)

Subscribe: RSS | More

Is there life on Europa? We take a look at Greenland and Antarctica to find out more about life on Jupiter’s icy moon.

Further reading:

Life on Venus claim faces strongest challenge yet

Stanford researchers’ explanation for formation of abundant features on Europa bodes well for search for extraterrestrial life 

Show transcript:

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

Today we’re going to learn about the potential of life on Europa, a moon of Jupiter! To do that we’ll need to look at some extreme life on Earth too.

Back in September 2020, we talked about potential signs of life in the atmosphere of Venus, which excited me a whole lot. As a follow-up to that episode, further studies suggest that signs of phosphine detected in Venus’s atmosphere, which might be produced by life, may actually just be sulfur dioxide (not a sign of life). But while it’s not looking likely that phosphine is actually found in Venus’s atmosphere, so far no studies can completely rule it out. So, maybe.

Venus isn’t the only part of our solar system where life might exist outside of Earth, though. Astronomers have been speculating about Europa for a long time. The planet Jupiter is a gas giant that has at least 80 moons, but Europa is the one that’s closest to the planet. It’s only a little bit smaller than our own moon.

Europa has an atmosphere, mostly made up of oxygen but so thin that if you could magically appear on the moon, you wouldn’t be able to breathe. Also, you would freeze to death almost immediately. It’s a dense moon, so astronomers think it’s probably mostly made up of silicate rock, which is what Earth is mostly made up of, along with Mars, Venus, Mercury, and a lot of moons.

If you’ve ever looked at our moon through a telescope or binoculars, you know it has lots of impact craters on its surface caused by asteroid strikes in the past. Europa doesn’t have very many craters—in fact, its surface is incredibly smooth except for what look like cracks all over it. It’s mostly pale in color, but the cracks are reddish-orange or brown.

The cause of the cracks has been a mystery ever since astronomers got the first good look at Europa. Many astronomers think these cracks are where warm material from below the surface erupted through the crust, sort of like what happens where lava oozes up on Earth and forms oceanic ridges. But on Europa, the material breaking through the crust isn’t lava, it’s ice—but ice that isn’t as cold as the surface ice. You know you’re on a cold, cold moon when ice that’s close to freezing instead of way below freezing can act like lava. The surface of Europa is about 110 kelvin at the equator and even colder at the poles. That’s -260 F or -160 C.

The exciting thing is that researchers are pretty sure the surface of Europa is icy but that the crust lies over a deep saltwater ocean that covers the entire moon. Yes, an ocean! As Europa orbits Jupiter, the planet’s gravity pulls at the moon, while the smaller gravity fields of the other nearest moons also pull on Europa in other directions. This push and pull causes tides that help warm the ocean and keep it from freezing solid. The brown coloration in the moon’s cracks may be due to mineral salts from the water that get leached up through the cracks after warm ice breaks through, assuming that’s what is actually happening to cause the cracks. Astronomers even have images of Europa taken by space probes that show what look like water plumes erupting through the surface and shooting up an estimated 120 miles high, or 200 km.

But new studies suggest that the water plumes might not be from the ocean. They might be from pockets of water that form within the crust itself, which grow larger until they burst out through the crust. This is even more exciting when it comes to potential life on the moon, because it suggests that the crust isn’t just a big block of ice. It’s a dynamic system that might harbor life instead of all potential life on Europa being restricted to the ocean. But to learn more about Europa, we have to come back to Earth and examine the island of Greenland.

Most of Greenland is covered with a permanent ice sheet like the ones found in Antarctica, but it’s a lot easier to study than Antarctica. One feature seen in the ice sheet is something called a double ridge, shaped sort of like a capital letter M. It’s caused when the ice fractures around pressurized water that forms inside the ice sheet and refreezes. This is caused when water from streams and lakes on the surface finds its way into the ice. The double ridge can look like a crack. New pictures of the cracks on Europa’s surface look just like Greenland’s double ridges, but much bigger.

My explanation of all this is extremely clumsy, because this is a really complex mechanism. Researchers only figured it out because some of the team had been studying Greenland’s double ridges for a completely different project, and noticed the similarities. There’s a link in the show notes to an article about this phenomenon if you want to learn more.

The Greenland ice sheet is over a mile thick. In 1966, the U.S. Army drilled into the ice to see what was under it, and the answer is dirt, as you might have expected. They took a 15-foot, or 4.5 meter, core sample and stuck it in a freezer, where everyone promptly forgot about it for 51 years. At some point it ended up in Denmark, where someone noticed it in 2017.

In 2019, the frozen core sample was finally studied by scientists. They expected to find mostly sand and rock. Instead, it was full of beautifully fossilized leaves and other plant material.

The main reason scientists were so surprised to find leaves and soil instead of just rock is that ice is really heavy, and it moves—slowly, but a mile-thick sheet of ice cannot be stopped. If you listened to the recent episode in the main feed about the rewilding of Scotland, you may remember that Scotland doesn’t have a lot of fossils from the Pleistocene because it was covered in glaciers that scoured the soil and everything in it down to bedrock, destroying everything in its path. But this hasn’t happened in Greenland, even though the sample was taken from an area only about 800 miles, or 1,290 km, from the North Pole.

Where the ice sheet now is, there used to be a forest. Obviously, the ice sheet hasn’t always covered Greenland. Research is ongoing, but a study of the sediment published in 2021 indicates that Greenland was ice free within the last million years, and possibly as recently as a few hundred thousand years.

All this is interesting, but it’s very different from Europa, whose ice sheets have probably been in place almost from the moon’s formation. What kind of life can live on, in, or under ice sheets?

On Earth, at least, a lot of organisms live on glaciers. Most are tiny or microscopic, including a type of algae that grows on top of ice, bacteria that live pretty much everywhere, including inside ice crystals, and microbes of various kinds. But there are some larger organisms, including glacial copepods, snow fleas, glacial midges, and the ice worms we talked about in episode 185 that live on glaciers in the Pacific Northwest.

Most likely, life on Europa will be tiny too. Researchers hypothesize that there could be microbial life living deep within the ice or in the pockets of melted water that develop inside it. There might be microbial mats or algae-type organisms that live on the underside of the ice, anchored there but able to extract nutrients from the ocean water.

But obviously, Europa’s ocean is where most life will probably be found, assuming it’s there. While there’s no environment quite like Europa’s to be found on Earth, since Earth is so close to the sun and nice and warm in comparison, parts of the deep sea are somewhat similar. Lots of animals live around hydrothermal vents, where volcanic activity breaks through the ocean floor and superheats water in small areas. Invertebrates of all kinds have adapted to live between boiling hot water and frigid deep-sea water, where absolutely no sunlight has ever reached. Animals like giant tube worms can grow nearly 10 feet long, or 3 meters, and don’t actually eat anything. Instead, they have symbiotic bacteria that provide them with all the nutrients they need while in turn, the bacteria get a safe place to live.

When the intensely heated, mineral-rich water of a hydrothermal vent comes in contact with cold water, it causes all sorts of chemical reactions. That’s what fuels most of the life around the vents. There are even some fish that live around hydrothermal vents, including the cutthroat eel that can grow over 5 feet long, or 1.6 meters. They’re bottom-dwelling deep-sea eels that live worldwide, but they spend time around hydrothermal vents to eat some of the other animals that live there exclusively. There’s even a type of bacteria found at one vent off the coast of Mexico that uses the faint light emitted by lava deep within the vent for photosynthesis. All other known photosynthesizing organisms use the sun as a light source.

Scientists think that Europa has hydrothermal vents similar to the ones on Earth. Since at least some researchers think life on Earth got its start around hydrothermal vents, it wouldn’t be surprising if life forms also live around Europa’s vents. But that doesn’t mean that life could only live around the vents.

In 2018, a team of scientists in Antarctica bored through the ice sheet and took a sample from the sea floor far below the ice to see if anything lived there. Since this was in the middle of the ice sheet with absolutely no sunlight or open ocean within a million square kilometers, they didn’t expect to find much. When they gave the sample to marine biologist David Barnes to examine, and he got a first look at it, initially he actually thought they’d pulled a practical joke on him. There was no way this one small sample could contain evidence of so much life in such an extreme environment.

He counted 77 different species of organism in the sample. There were worms, bryozoans, sponges, even fragments of jellyfish, and of course there were lots and lots of microorganisms. All the animals were small, which isn’t surprising. That they were there at all was the truly surprising thing.

We don’t know yet if life exists anywhere outside of Earth. Odds are good that it does, just because there are so many planets and moons around so many stars throughout our galaxy and all the other galaxies in the universe. Whether we’ll ever find it is another thing. Until we do, though, we will just have to appreciate all the amazing diversity of life on our own planet, and keep watching the night skies and wondering.

Thanks for your support, and thanks for listening!

Episode 475 Superweb

Posted on by

Podcast: Play in new window | Download (Duration: 6:48 — 7.5MB)

Subscribe: RSS | More

This week let’s look at the work of a really astonishing number of spiders!

Further reading:

Megaweb!

Some of the webs:

Show transcript:

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

Baltimore, Maryland is a city in the northeastern United States, in North America, with a population of 2.8 million people. In 1993 a new wastewater treatment plant was built called the Back River Wastewater Treatment Plant, which filters water through big sand beds to trap any particles remaining in it after it’s been filtered and treated in other facilities. The plant consists of 48 big sand beds with a corridor down the middle, and in order to keep the sand beds as clean as possible, the whole area has a big metal roof over it held up with steel columns. It doesn’t have walls, though, just a roof. The whole thing covers four acres, or 1.6 hectares, which I think is a metric term. It’s just over 16,000 square meters. It’s big, in other words, and the roof is pretty tall, up to 24 feet high over the walkway, or 7.5 meters.

Obviously, I’m telling you about this place in detail because of an animal that got into the water treatment plant and caused a lot of alarm. It wasn’t a big animal like a bear, though. It wasn’t even a dangerous animal. It was, in fact, a really small animal that’s mostly harmless to humans, various species of orbweaver spider. The problem wasn’t the spider itself but just how many spiders were in the water treatment plant.

The plant had always had problems with lots of orbweavers, but in 2009 there were so many spiders that the workers were worried for their safety. In late October 2009, the managers called for help about “an extreme spider situation.” The problem was way beyond anything that an ordinary pest control business could deal with, so the city put together a team of arachnologists, entomologists, and experts in urban pest control to figure out the best course of action.

The team didn’t just charge in, say, “Wow, that’s a lot of spiders, let’s hose the whole place down.” They were scientists and studied the situation methodically. They consulted the architectural plans of the plant to determine just how much volume was available under the roof, they took samples of the webs and stored them for study, they took over 300 photos, and basically they got as much data as they could.

There were so many spiders that their webs blended together into thick mats that filled almost every space the spiders could reach. These cobweb mats were attached to the rafters, the walkways, everywhere, with the older mats starting to detach and fray. Light fixtures hung down from the tallest point of the roof that were 8 feet long, or 2.44 meters, and there were so many webs attached to them that they were pulled out of alignment. And all the webs were filled with spiders.

The spiders in the web samples were removed and preserved, then examined to see what species they belonged to. The team identified specimens from nine genera in six families, but most of the spiders caught were the species Tetragnatha guatemalensis. This is a type of long-jawed orbweaver native to North and Central America. Females are much larger than males, with a legspan up to 2 inches across, or about 5 cm. Long-jawed orbweavers have long, thin bodies, and one of the ways it hides is by stretching out on a blade of grass or a twig with its legs out straight. It especially likes marshy areas, such as in the rafters above 48 giant sand beds full of water.

A conservative estimate of the number of spiders in the Back River Wastewater Treatment Plant in the first week of November, 2009 was 107 million. 107 million spiders! Since a big percentage of the spiders were newly hatched, there were probably a lot more in the facility than the scientists estimated from the samples they took, so there might easily have been several hundred million spiders total. The sheets of webbing in the ceiling covered an estimated 2 acres total, or about 8,000 square meters, while the cloud-like masses of webbing in other areas was about half that size and would have filled 23 railroad boxcars.

The really interesting thing is that orbweaver spiders are usually solitary. Spiders may build webs near each other, but not usually like this. But these orbweavers lived in a place protected from wind and weather, and close to water, which attracted lots of midges and other small insects, and the presence of humans probably kept a lot of potential spider predators away, like birds. Life was good for these spiders and the scientists observed that they weren’t acting aggressively to each other, even when they were of different species.

After studying the water treatment plant and its spiders, the team came to several conclusions. Since the spiders are harmless to humans, and are doing a really good job controlling the midge population, the scientists decided that pest control was not necessary and would even be a bad idea since the pesticides would inevitably get into the water. Instead, they recommended that web removal be implemented as a normal course of action when the webs started building up too much. They even suggested that the workers should be proud of their record-breaking webs, and that the plant was an ideal site for scientists to study the spiders in detail.

Thanks for your support, and thanks for listening!

Episode 471: Mystery Larvae

Posted on by

Podcast: Play in new window | Download ()

Subscribe: RSS | More

Further reading:

I Can Has Mutant Larvae?

200-Year-Old ‘Monster Larva’ Mystery Solved

‘Snakeworm’ mystery yields species new to science

Hearkening back to the hazelworm

Show transcript:

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

A few weeks ago when I was researching big eels, I remembered the mystery eel larva we talked about back in episode 49, and that led me down a fun rabbit hole about other mystery larvae.

Let’s start with that eel larva. Eel larvae can be extremely hard to tell apart, so as a catchall term every eel larva is called a leptocephalus. They’re flattened side to side, which is properly referred to as laterally compressed, and transparent, shaped roughly like a slender leaf, with a tiny head at the front. Depending on the species, an eel may remain in its larval form for more than a year, much longer than most other fish, and when it does metamorphose into its next life stage, it usually grows much longer than its larval form. For instance, the larvae of conger eels are only about 4 inches long, or 10 cm, while an adult conger can grow up to 10 feet long, or 3 meters.

On January 31, 1930, a Danish research ship caught an eel larva 900 feet deep, or about 275 meters, off the coast of South Africa. But the larva was over 6 feet long, or 1.85 meters!

Scientists boggled at the thought that this larva might grow into an eel more than 50 feet long, or 15 meters, raising the possibility that this unknown eel might be the basis of many sea serpent sightings.

The larva was preserved and has been studied extensively. In 1958, a similar eel larva was caught off of New Zealand. It and the 1930 specimen were determined to belong to the same species, which was named Leptocephalus giganteus.

In 1966, two more of the larvae were discovered in the stomach of a western Atlantic lancet fish. They were much smaller than the others, though—only four inches and eleven inches long, or 10 cm and 28 cm respectively. Other than size, they were pretty much identical to Leptocephalus giganteus.

The ichthyologist who examined them determined that the larvae were probably not true eels at all, but larvae of a fish called the spiny eel. Deep-sea spiny eels look superficially like eels but aren’t closely related, and while they do have a larval form that resembles that of a true eel, they’re much different in one important way. Spiny eel larvae grow larger than the adults, then shrink a little when they develop into their mature form. The six-foot eel larva was actually a spiny eel larva that was close to metamorphosing into its adult form.

Not everyone agrees that Leptocephalus giganteus is a spiny eel. Some think it belongs to the genus Coloconger, also called worm eels, which are true eels but which have large larvae that only grow to the same size as adults. But worm eels don’t grow much bigger than about two feet long, or 61 cm. If the mystery larvae does belong to the genus Coloconger, it’s probably a new species. Until scientists identify an adult Leptocephalus giganteus, we can’t know for sure.

Another mystery larva is Planctosphaera pelagica, which sits all alone in its own class because the only thing it resembles are acorn worms, but scientists are pretty sure it isn’t the larva of an acorn worm. It’s not much to look at, since the larva is just a little barrel-shaped blob that grows about 25 mm across. This sounds small compared to the eel larva we just discussed, but it’s actually quite large compared to similar larvae. Acorn worm larvae are usually only about a millimeter long.

Planctosphaera has been classified as a hemichordate, which are related to echinoderms but which show bilateral symmetry instead of radial symmetry. Hemichordates are also closely related to chordates, which include all vertebrates. They’re marine animals that resemble worms but aren’t worms, so it’s likely that Planctosphaera is also wormlike as an adult.

Planctosphaera isn’t encountered very often by scientists. It has limited swimming abilities and mostly floats around near the surface of the open ocean, eating tiny food particles. One suggestion is that it might actually be the larva of a known species, but one where an occasional larva just never metamorphoses into an adult. It just grows and grows until something eats it. So far, attempts to sequence DNA from a Planctosphaera hasn’t succeeded and attempts to raise one to maturity in captivity hasn’t worked either.

Some people have estimated that an adult Planctosphaera might be a type of acorn worm that can grow nine feet long, or 2.75 meters, which isn’t out of the realm of possibility. The largest species of acorn worm known is Balanoglossus gigas, which can grow almost six feet long, or 1.8 meters, and not only is it bioluminescent, its body contains a lot of iodine, so it smells like medicine. It lives in mucus-lined burrows on the sea floor.

Another mystery larva is Facetotecta, which have been found in shallow areas in many oceans around the world. Unlike the other larvae we’ve talked about, they’re genuinely tiny, measured in micrometers, and eleven species have been described. They all have a cephalic shield, meaning a little dome over the head, and scientists have been able to observe several phases of their development but not the adult form. The juvenile form was observed and it looked kind of like a tiny slug with nonfunctioning eyes and weak muscles.

Scientists speculate that facetotecta may actually be the larva of an endoparasite that infests some marine animals. That would explain why no adult form has been identified. Genetic testing has confirmed that Facetotecta is related to a group of parasitic crustaceans.

DNA has solved some mysteries of what larvae belong to which adults. For instance, Cerataspis monstrosa, a larval crustacean that was first described in 1828. It’s over a cm long, pinkish-purple in color with stalked eyes, little swimming leg-like appendages, and neon blue horn-like structures on its head and back which act as armor. The armor doesn’t help too much against big animals like dolphins and tuna, which love to eat it, and in fact that’s where it was initially discovered, in the digestive tract of a dolphin. But scientists had no idea what the monstrous larva eventually grew up to be.

In 2012 the mystery was solved when a team of scientists compared the monster larva’s DNA to that of lots of various types of shrimp, since the larva had long been suspected to be a type of shrimp. It turns out that it’s the larval form of a rare deep-sea aristeid shrimp that can grow up to 9 inches long, or 23 cm.

Let’s finish with another solved mystery, this one from larvae found on land. In 2007, someone sent photos and a bag of little dead worms to Derek Sikes at the University of Alaska Museum. Usually when someone sends you a bag of dead worms, they’re giving you an obscure but distressing message, but Sikes was curator of the insect collection and he was happy to get a bag of mystery worms.

The worms had been collected from an entire column of the creatures that had been crawling over each other so that the group looked like a garden hose on the ground. Sikes thought they were probably fly larvae but he had never heard of larvae traveling in a column. If you’ve listened to the hazelworm episode from August 2018, you might have an idea. The hazelworm was supposed to be a snake or even a dragon that was only seen in times of unrest. It turns out that it the larvae of some species of fungus gnat travel together in long, narrow columns that really do look like a moving snake. But that’s in Europe, not Alaska.

Sikes examined the larvae, but since they were dead he couldn’t guess what type of insect they would grow up to be. Luckily, a few months later he got a call from a forester who had spotted a column of the same worms crossing a road. Sikes got there in time to witness the phenomenon himself.

The larvae were only a few millimeters long each, but there were so many of them that the column stretched right across the road into the forest. He collected some of them carefully and took them back to the museum, where he tended them in hopes that they would pupate successfully.

This they did, and the insects that emerged were a little larger than fruit flies and were black in color. Sikes identified them as fungus gnats, but when he consulted fungus gnat experts in Germany and Japan, they were excited to report that they didn’t recognize the Alaskan gnats. It was a new species, which Sikes described in late 2023. His summer students helped name the species, Sciara serpens, which are better known now as snakeworm gnats. He and his co-authors think the larvae form columns when they cross surfaces like roads and rocks, to help minimize contacting the dry ground. Fungus gnats live in moist areas with lots of organic matter, like forest leaf litter and the edges of ponds.

So the next time you see a huge long snake crossing the road, don’t panic. It might just be a whole lot of tiny, tiny larvae looking for a new home.

Thanks for your support, and thanks for listening!

BONUS: here’s the Hazelworm episode too!

The hazelworm today is a type of reptile, although called the slow worm, blind worm, or deaf adder. It lives in Eurasia, and while it looks like a snake, it’s actually a legless lizard. It can even drop and regrow its tail like a lizard if threatened. It spends most of its time underground in burrows or underneath leaf litter or under logs. It grows almost 2 feet long, or 50 cm, and is brown. Females sometimes have blue racing stripes while males may have blue spots. It eats slugs, worms, and other small animals, so is good for the garden.

But that kind of hazelworm isn’t what we’re talking about here. Back in the middle ages in central Europe, especially in parts of the Alps, there were stories of a big dragonlike serpent that lived in areas where hazel bushes were common. Like its slow-worm namesake, it lived most of its life underground, especially twined around the roots of the hazel. Instead of scales, it had a hairy skin and was frequently white in color. It was supposed to be the same type of snake that had tempted Adam and Eve in the Garden of Eden.

It had a lot of names besides hazelworm, including white worm for its color, paradise worm for its supposed history in the Garden of Eden, and even war worm. That one was because it was only supposed to show itself just before a war broke out.

People really believed it existed, although stories about it sound more like folklore. For instance, anyone who ate hazelworm flesh was supposed to become immortal. It was also supposed to suck milk from dairy cows and spread poison.

Some accounts said it was enormous, as big around as a man’s thigh and some 18 feet long, or 5.5 meters. Sometimes it was even supposed to have feet, or have various bright colors. Sometimes drawings showed wings.

There does seem to be some confusion about stories of the hazelworm and of the tatzelwurm, especially in older accounts. But unlike the tatzelwurm, the mystery of the hazelworm has been solved for a long time—long enough that knowledge of the animal has dropped out of folklore.

Back in the 1770s, a physician named August C. Kuehn pointed out that hazelworm sightings matched up with a real animal…but not a snake. Not even any kind of reptile. Not a fish or a bird or a mammal. Nope, he pointed at the fungus gnat.

The fungus gnat is about 8 mm long and eats decaying plant matter and fungus. You know, sort of exactly not like an 18-foot hairy white snake.

But the larvae of some species of fungus gnat are called army worms. The larvae have white, gray, or brown bodies and black heads, and travel in long, wide columns that do look like a moving snake, especially if seen in poor light or in the distance. I’ve watched videos online of these processions and they are horrifying! They’re also rare, so it’s certainly possible that even people who have lived in one rural area their whole life had never seen an armyworm procession. Naturally, they’d assume they were seeing a monstrous hairy snake of some kind, because that’s what it looks like.

Sightings of smaller hazelworms may be due to the caterpillar of the pine processionary moth, which also travels in a line nose to tail, which looks remarkably like a long, thin, hairy snake. Don’t touch those caterpillars, by the way. They look fuzzy and cute but their hairs can cause painful reactions when touched.

The adult moths lay their eggs in pine trees and when the eggs hatch the larvae eat pine needles and can cause considerable damage to the trees. They overwinter in silk tents, then leave the trees in spring and travel in a snaky conga line to eat pine needles. Eventually they burrow underground to pupate. They emerge from their cocoons as adult moths, mate, lay eggs, and die, all within one day.

Episode 470: Animals Discovered in 2025

Posted on by

Podcast: Play in new window | Download (Duration: 16:44 — 18.9MB)

Subscribe: RSS | More

It’s the annual discoveries episode! Thanks to Stephen and Aryeh for their corrections and suggestions this week!

Further reading:

Salinella Salve: The Vanishing Creature That Defied Science for Over a Century

Three new species of the genus Scutiger

Baeticoniscus carmonaensis sp. nov. a new Isopod found in an underground aqueduct from the Roman period located in Southwest Spain (Crustacea, Isopoda, Trichoniscidae)

A new species of supergiant Bathynomus

Giant ‘Darth Vader’ sea bug discovered off the coast of Vietnam

A New Species of easter egg weevil

Bizarre ‘bone collector’ caterpillar discovered by UH scientists

Researchers Discover ‘Death Ball’ Sponge and Dozens of Other Bizarre Deep-Sea Creatures in the Southern Ocean

1,500th Bat Species Discovered in Africa’s Equatorial Guinea

Show transcript:

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

This week we’re going to learn about some animals discovered in 2025! We’ll also make this our corrections episode. This is the last new episode we’ll have until the end of August when we reach our 500th episode, but don’t worry, until then there will be rescheduled Patreon episodes every single week as usual.

We’ll start with some corrections. Shortly after episode 452 was published in September, where we talked about the swamp wallaby and some other animals, Stephen emailed to point out that I’d made a major mistake! In that episode I said that not all animals called wallabies were actually members of the family Macropodidae, but that’s actually not the case. All wallabies are macropodids, but they aren’t all members of the same genus in that family. I corrected the episode but I wanted to mention it here too so no one is confused.

Stephen also caught another mistake in episode 458, which is embarrassing. I mentioned that marsupials didn’t just live in Australia, they were found all over the world. That’s not actually the case! Marsupials are found in North and South America, Australia, New Guinea and nearby areas, and that’s it. They were once also found in what is now Asia, but that was millions of years ago. So I apologize to everyone in Africa, Asia, and Europe who were excited about finding out what their local marsupials are. You don’t have any, sorry.

One update that Aryeh asked about specifically is an animal we talked about in episode 445, salinella. Aryeh emailed asking for more information if I could find any, because it’s such a fascinating mystery! I looked for some more recent findings, unfortunately without luck. I do have an article linked in the show notes that goes into detail about everything we covered in that episode, though, dated to mid-January 2026, and it’s a nice clear account.

Now, let’s get into the 2025 discoveries! There are lots more animals that were discovered last year, but I just chose some that I thought were especially interesting. Mostly I chose ones that I thought had funny names.

Let’s start with three new species of frog in the genus Scutiger. Species in this genus are called lazy toads and I couldn’t find out why. Maybe they don’t like to move around too much. Lazy toads live in mountains in some parts of Asia, and we don’t know very much about most of the 31 species described so far. Probably the most common lazy toad is the Sikkim lazy toad that lives along high altitude streams in the Himalaya Mountains. It’s mottled greenish-brown and yellowish in color with lots of warts, and while its feet have webbed toes, it doesn’t have webbed fingers on its little froggy hands. This is your reminder that every toad is a frog but not every frog is a toad. The Sikkim lazy toad grows about two and a half inches long, or about 65 mm, from nose to butt. It seems to be pretty average for a lazy toad.

The three new species of lazy toad are found in Yunnan Province in China, in a mountainous region where several species of lazy toad were already known. Between 2021 and 2024, a team of scientists collected 27 lazy toads from various places, then carefully examined them to see if they were species already known to science. This included genetic analysis. The team compared their findings with other lazy toad species and discovered that not all of the specimens matched any known species. Further comparison with each other revealed that the team had discovered three new species, which they described in December of 2025.

Next, isopods are common crustaceans that live throughout the world. You have undoubtedly seen at least one species of isopod, because an animal with lots of common names, including woodlouse, pill bug, roly-poly, and sowbug, is a terrestrial isopod. That’s right, the roly-poly is not a bug or a centipede but a crustacean. The order Isopoda contains more than 10,000 species, and there are undoubtedly thousands more that haven’t been discovered by scientists yet. About half the species discovered so far live on land and the other half live in water, most in the ocean but some in fresh water. They don’t all look like roly-polies, of course. Many look like their distant crustacean cousins, shrimps and crayfish, while others look more like weird centipedes or fleas or worms. There’s a lot of variation in an animal that’s extremely common throughout the world, so it’s no surprise that more species are discovered almost every year.

In 2021 and 2022, a team of Spanish scientists took a biological survey of an ancient Roman tunnel system beneath Carmona, Spain. The tunnels were built around 2,000 years ago as a water source, since they capture groundwater, but it hasn’t been used in so long that it’s more or less a natural environment these days.

The scientists quickly discovered plenty of life in the tunnels, including an isopod living in cracks in some ancient timbers. It grows about two and a half millimeters long and actually does look a lot like a tiny roly-poly. It has long antennae and its body mostly lacks pigment, but it does have dark eyes. Most animals that live in total darkness eventually evolve to no longer have functioning eyes, since they don’t need them, but that isn’t the case for this new isopod. Scientists think it might take advantage of small amounts of light available near the tunnel entrances.

As far as the scientists can tell, the Carmona isopod only lives in this one tunnel system, so it’s vulnerable to pollutants and human activity that might disrupt its underground home.

Another new isopod species that’s vulnerable to human activity, in this case overfishing, lives off the coast of Vietnam. It’s another isopod that looks a lot like a roly-poly, which I swear is not what every isopod looks like. It’s a deep-sea animal that hunts for food on the ocean floor, and it’s a popular delicacy in Vietnam. Remember, it’s a crustacean, and people say it tastes like another crustacean, lobster. In fact, scientists discovered their specimens in a fish market.

Deep-sea animals sometimes feature what’s called deep-sea gigantism. Most isopods are quite small, no more than a few cm at most, but the new species grows almost 13 inches long, or over 32 cm. It’s almost the largest isopod known. Its head covering made the scientists think of Darth Vader’s helmet, so it’s been named Bathynomus vaderi.

Next we have a new species of Easter egg weevil, a flightless beetle found on many islands in Southeast Asia. Easter egg weevils are beautiful, with every species having a different pattern of spots and stripes. Many are brightly colored and iridescent. The new species shows a lot of variability, but it’s basically a black beetle with a diamond-shaped pattern that can be yellow, gold, or blue. Some individuals have pink spots in the middle of some of the diamonds. It’s really pretty and that is just about all I could find out about it.

Another new insect is a type of Hawaiian fancy case caterpillar, which metamorphose into moths. They’re only found on the Hawaiian islands, and there are over 350 species known. The new species has been named the bone collector, because of what the caterpillar does.

Fancy case caterpillars spin a sort of shell out of silk, which is called a case, and the caterpillar carries its case around with it as protection. Some of the cases are unadorned but resemble tree bark, while many species will decorate the case with lichens, sand, or other items that help it blend in with its background. Some fancy case caterpillars can live in water as well as on land, and while most caterpillars eat plant material, some fancy case caterpillars eat insects.

That’s the situation with the bone collector caterpillar. It lives in spider webs, which right there is astonishing, and decorates its case with bits and pieces of dead insect it finds in the web. This can include wings, heads, legs, and other body parts.

The bone collector caterpillar eats insects, and it will chew through strands of the spider’s web to get to a trapped insect before the spider does. Sometimes it will eat what’s left of a spider’s meal once the spider is finished.

The bone collector caterpillar has only been found in one tiny part of O’ahu, a 15-square-km area of forest, although researchers think it was probably much more widespread before invasive plants and animals were introduced to the island.

Next, the Antarctic Ocean is one of the least explored parts of the world, and a whole batch of new species was announced in 2025 after two recent expeditions. One of the expeditions explored ocean that was newly revealed after a huge iceberg split off the ice shelf off West Antarctica in early 2025. That’s not where the expedition had planned to go, but it happened to be nearby when the iceberg broke off, and of course the team immediately went to take a look.

Back in episode 199 we talked about some carnivorous sponges. Sponges have been around for more than half a billion years, and early on they evolved a simple but effective body plan that they mostly still retain. Most sponges have a skeleton made of calcium carbonate that forms a sort of dense net that’s covered with soft body tissues. The sponge has lots of open pores in the outside of its body, which generally just resembles a sack or sometimes a tube, with one end attached to something hard like a rock, or just the bottom of the ocean. Water flows into the sponge’s tissues through the pores, and special cells filter out particles of food from the water, much of it microscopic, and release any waste material. The sponge doesn’t have a stomach or any kind of digestive tract. The cells process the food individually and pass on any extra nutrients to adjoining cells.

In 1995, scientists discovered a tiny sponge that wasn’t a regular filter feeder. It had little hooks all over it, and it turns out that when a small animal gets caught on the hooks, the sponge grows a membrane that envelops the animal within a few hours. The cells of the membrane contain bacteria that help digest the animal so the cells can absorb the nutrients.

Since then, other carnivorous sponges have been discovered, or scientists have found that some sponges already known to science are actually carnivorous. That’s the case with the ping-pong tree sponge. It looks kind of like a bunch of grapes on a central stem that grows up from the bottom of the ocean, and it can be more than 20 inches tall, or 50 cm. The little balls are actually balloon-like structures that inflate with water and are covered with little hooks. It was discovered off the coast of South America near Easter Island, in deep water where the sea floor is mostly made of hardened lava. It was classified in the genus Chondrocladia, and so far there are more than 30 other species known.

The reason we’re talking about the ping-pong tree sponge is that a new species of Chondrocladia has been discovered in the Antarctic Ocean, and it looks a lot like the ping-pong tree sponge. It’s been dubbed the death-ball sponge, which is hilarious. It was found two and a quarter miles deep on the ocean floor, or 3.6 km, and while scientists have determined it’s a new species of sponge, it hasn’t been described yet. It’s one of 30 new species found so far, and the team says that there are many other specimens collected that haven’t been studied yet.

We haven’t talked about any new mammal discoveries yet, so let’s finish with one of my favorites, a new bat! It was discovered on Bioko Island in Equatorial Guinea, which is part of Africa. During a 2024 biodiversity assessment on the island, a PhD student named Laura Torrent captured a bat that turned out to be not only a brand new species, it is the 1,500th species of bat known to science!

Pipistrellus etula gets its name from the local language, Bantu, since “etula” means both “island” and “god of the island” in that language. The bat was found in forests at elevations over 1,000 meters, on the slopes of a volcano. Back in 1989, a different researcher captured a few of the bats on another volcano, but never got a chance to examine them to determine if they were a new species. When Torrent’s team were studying their bats, one of the things they did was compare them to the preserved specimens from 1989, and they discovered the bats were indeed a match.

P. etula is a type of vesper bat, which is mostly active at dusk and eats insects. It’s brown with black wings and ears. Just like all the other species we’ve talked about today, now that we know it exists, it can be protected and studied in the wild.

That’s what science is really for, after all. It’s not just to satisfy our human curiosity and desire for knowledge, although that’s important too. It’s so we can make this world a better place for everyone to live—humans, animals, plants, isopods, weird caterpillars, and everything else on Earth and beyond.

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. Thanks for listening! I’ll see you in August.

Episode 466: Lots of Invertebrates!

Posted on by

Podcast: Play in new window | Download (Duration: 20:41 — 22.9MB)

Subscribe: RSS | More

Here’s the big invertebrate episode I’ve been promising people! Thanks to Sam, warbrlwatchr, Jayson, Richard from NC, Holly, Kabir, Stewie, Thaddeus, and Trech for their suggestions this week!

Further reading:

Does the Spiral Siphonophore Reign as the Longest Animal in the World?

The common nawab butterfly:

The common nawab caterpillar:

A velvet worm:

A giant siphonophore [photo by Catriona Munro, Stefan Siebert, Felipe Zapata, Mark Howison, Alejandro Damian-Serrano, Samuel H. Church, Freya E.Goetz, Philip R. Pugh, Steven H.D.Haddock, Casey W.Dunn – https://www.sciencedirect.com/science/article/pii/S1055790318300460#f0030]:

Show transcript:

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

Hello to 2026! This is usually where I announce that I’m going to do a series of themed episodes throughout the coming year, and usually I forget all about it after a few months. This year I have a different announcement. After our nine-year anniversary next month, which is episode 470, instead of new episodes I’m going to be switching to old Patreon episodes. I closed the Patreon permanently at the end of December but all the best episodes will now run in the main feed until our ten-year anniversary in February 2027. That’s episode 523, when we’ll have a big new episode that will also be the very last one ever.

I thought this was the best way to close out the podcast instead of just stopping one day. The only problem is the big list of suggestions. During January I’m going to cover as many suggestions as I possibly can. This week’s episode is about invertebrates, and in the next few weeks we’ll have an episode about mammals, one about reptiles and birds, and one about amphibians and fish, although I don’t know what order they’ll be in yet. Episode 470 will be about animals discovered in 2025, along with some corrections and updates.

I hope no one is sad about the podcast ending! You have a whole year to get used to it, and the old episodes will remain forever on the website so you can listen whenever you like.

All that out of the way, let’s start 2026 right with a whole lot of invertebrates! Thanks to Sam, warbrlwatchr, Jayson, Richard from NC, Holly, Kabir, Stewie, Thaddeus, and Trech for their suggestions this week!

Let’s start with Trech’s suggestion, a humble ant called the weaver ant. It’s also called the green ant even though not all species are green, because a species found in Australia is partially green. Most species are red, brown, or yellowish, and they’re found in parts of northern and western Australia, southern Asia, and on most islands in between the two areas, and in parts of central Africa. The weaver ant lives in trees in tropical areas, and gets the name weaver ant because of the way it makes its nest.

The nests are made out of leaves, but the leaves are still growing on the tree. Worker ants grab the edge of a leaf in their mandibles, then pull the leaf toward another leaf or sometimes double the leaf over. Sometimes ants have to make a chain to reach another leaf, with each ant grabbing the next ant around the middle until the ant at the end of the chain can grab the edge of a leaf. While the leaf is being pulled into place alongside the edge of another leaf, or the opposite edge of the same leaf, other workers bring larvae from an established part of the nest. The larvae secrete silk to make cocoons, but a worker ant holds a larva at the edge of the leaf, taps its little head, and the larva secretes silk that the workers use to bind the leaf edges together. A single colony has multiple nests, often in more than one tree, and are constantly constructing new ones as the old leaves are damaged by weather or just die off naturally.

The weaver ant mainly eats insects, which is good for the trees because many of the insects the ants kill and eat are ones that can damage trees. This is one reason why farmers in some places like seeing weaver ants, especially fruit farmers, and sometimes farmers will even buy a weaver ant colony starter pack to place in their trees deliberately. The farmer doesn’t have to use pesticides, and the weaver ants even cause some fruit- and leaf-eating animals to stay away, because the ants can give a painful bite. People in many areas also eat the weaver ant larvae, which is considered a delicacy.

Our next suggestion is by Holly, the zombie snail. I actually covered this in a Patreon episode, but I didn’t schedule it for next year because I thought I’d used the information already in a regular episode, but now I can’t find it. So let’s talk about it now!

In August of 2019, hikers in Taiwan came across a snail that looked like it was on its way to a rave. It had what looked like flashing neon decorations in its head, pulsing in green and orange. Strobing colors are just not something you’d expect to find on an animal, or if you did it would be a deep-sea animal. The situation is not good for the snail, let me tell you. It’s due to a parasitic flatworm called the green-banded broodsac.

The flatworm infects birds, but to get into the bird, first it has to get into a snail. To get into a snail, it has to be in a bird, though, because it lives in the cloaca of a bird and attaches its eggs to the bird’s droppings. When a snail eats a yummy bird dropping, it also eats the eggs. The eggs hatch in the snail’s body instead of being digested, where eventually they develop into sporocysts. That’s a branched structure that spreads throughout the snail’s body, including into its head and eyestalks.

The sporocyst branches that are in the snail’s eyestalks further develop into broodsacs, which look like little worms or caterpillars banded with green and orange or green and yellow, sometimes with black or brown bands too—it depends on the species. About the time the broodsacs are ready for the next stage of life, the parasite takes control of the snail’s brain. The snail goes out in daylight and sits somewhere conspicuous, and its body, or sometimes just its head or eyestalks, becomes semi-translucent so that the broodsacs show through it. Then the broodsacs swell up and start to pulse.

The colors and movement resemble a caterpillar enough that it attracts birds that eat caterpillars. A bird will fly up, grab what it thinks is a caterpillar, and eat it up. The broodsac develops into a mature flatworm in the bird’s digestive system, and sticks itself to the walls of the cloaca with two suckers, and the whole process starts again.

The snail gets the worst part of this bargain, naturally, but it doesn’t necessarily die. It can survive for a year or more even with the parasite living in it, and it can still use its eyes. When it’s bird time, the bird isn’t interested in the snail itself. It just wants what it thinks is a caterpillar, and a lot of times it just snips the broodsac out of the snail’s eyestalk without doing a lot of damage to the snail.

If a bird doesn’t show up right away, sometimes the broodsac will burst out of the eyestalk anyway. It can survive for up to an hour outside the snail and continues to pulsate, so it will sometimes still get eaten by a bird.

Okay, that was disgusting. Let’s move on quickly to the tiger beetle, suggested by both Sam and warblrwatchr.

There are thousands of tiger beetle species known and they live all over the world, except for Antarctica. Because there are so many different species in so many different habitats, they don’t all look the same, but many common species are reddish-orange with black stripes, which is where the name tiger beetle comes from. Others are plain black or gray, shiny blue, dark or pale brown, spotted, mottled, iridescent, bumpy, plain, bulky, or lightly built. They vary a lot, but one thing they all share are long legs.

That’s because the tiger beetle is famous for its running speed. Not all species can fly, but even in the ones that can, its wings are small and it can’t fly far. But it can run so fast that scientists have discovered that its simple eyes can’t gather enough photons for the brain to process an image of its surroundings while it runs. That’s why the beetle will run extremely fast, then stop for a moment before running again. Its brain needs a moment to catch up.

The tiger beetle eats insects and other small animals, which it runs after to catch. The fastest species known lives around the shores of Lake Eyre in South Australia, Rivacindela hudsoni. It grows around 20 mm long, and can run as much as 5.6 mph, or 9 km/hour, not that it’s going to be running for an entire hour at a time. Still, that’s incredibly fast for something with little teeny legs.

Another insect that is really fast is called the common nawab, suggested by Jayson. It’s a butterfly that lives in tropical forests and rainforests in South Asia and many islands. Its wings are mainly brown or black with a big yellow or greenish spot in the middle and some little white spots along the edges, and the hind wings have two little tails that look like spikes. It’s really pretty and has a wingspan more than three inches across, or about 8.5 cm.

The common nawab spends most of its time in the forest canopy, flying quickly from flower to flower. Females will travel long distances, but when a female is ready to lay her eggs, she returns to where she hatched. The male stays in his territory, and will chase away other common nawab males if they approach.

The common nawab caterpillar is green with pale yellow stripes, and it has four horn-like projections on its head, which is why it’s called the dragon-headed caterpillar. It’s really awesome-looking and I put it on the list to cover years ago, then forgot it until Jayson recommended it. But it turns out there’s not a lot known about the common nawab, so there’s not a lot to say about it.

Next, Richard from NC suggested the velvet worm. It’s not a worm and it’s not made of velvet, although its body is soft and velvety to the touch. It’s long and fairly thin, sort of like a caterpillar in shape but with lots of stubby little legs. There are hundreds of species known in two families. Most species of velvet worm are found in South America and Australia.

Some species of velvet worm can grow up to 8 and a half inches long, or 22 cm, but most are much smaller. The smallest lives in New Zealand on the South Island, and only grows up to 10 mm long, with 13 pairs of legs. The largest lives in Costa Rica in Central America and was only discovered in 2010. It has up to 41 pairs of legs, although males only have 34 pairs.

Various species of velvet worm are different colors, although a lot of them are reddish, brown, or orangey-brown. Most species have simple eyes, although some have no eyes at all. Its legs are stubby, hollow, and very simple, with a pair of tiny chitin claws at the ends. The claws are retractable and help it climb around. It likes humid, dark places like mossy rocks, leaf litter, fallen logs, caves, and similar habitats. Some species are solitary but others live in social groups of closely related individuals.

The velvet worm is an ambush predator, and it hunts in a really weird way. It’s nocturnal and its eyes are not only very simple, but the velvet worm can’t even see ahead of it because its eyes are behind a pair of fleshy antennae that it uses to feel its way delicately forward. It walks so softly on its little legs that the small insects and other invertebrates that it preys on often don’t even notice it. When it comes across an animal, it uses its antennae to very carefully touch it and decide whether it’s worth attacking.

When it decides to attack, it squirts slime that acts like glue. It has a gland on either side of its head that squirts slime quite accurately. Once the prey is immobilized, the velvet worm may give smaller squirts of slime at dangerous parts, like the fangs of spiders. Then it punctures the body of its prey with its jaws and injects saliva, which kills the animal and starts to liquefy its insides. While the velvet worm is waiting for this to happen, it eats up its slime to reuse it, then sucks the liquid out of the prey. This can take a long time depending on the size of the animal—more than an hour.

A huge number of invertebrates, including all insects and crustaceans, are arthropods, and velvet worms look like they should belong to the phylum Arthropoda. But arthropods always have jointed legs. Velvet worm legs don’t have joints.

Velvet worms aren’t arthropods, although they’re closely related. A modern-day velvet worm looks surprisingly like an animal that lived half a billion years ago, Antennacanthopodia, although it lived in the ocean and all velvet worms live on land. Scientists think that the velvet worm’s closest living relative is a very small invertebrate called the tardigrade, or water bear, which is Stewie’s suggestion.

The water bear isn’t a bear but a tiny eight-legged animal that barely ever grows larger than 1.5 millimeters. Some species are microscopic. There are about 1,300 known species of water bear and they all look pretty similar, like a plump eight-legged stuffed animal with a tubular mouth that looks a little like a pig’s snout. It uses six of its fat little legs for walking and the hind two to cling to the moss and other plant material where it lives. Each leg has four to eight long hooked claws. Like the velvet worm, the tardigrade’s legs don’t have joints. They can bend wherever they want.

Tardigrades have the reputation of being extremophiles, able to withstand incredible heat, cold, radiation, space, and anything else scientists can think of. In reality, it’s just a little guy that mostly lives in moss and eats tiny animals or plant material. It is tough, and some species can indeed withstand extreme heat, cold, and so forth, but only for short amounts of time.

The tardigrade’s success is mainly due to its ability to suspend its metabolism, during which time the water in its body is replaced with a type of protein that protects its cells from damage. It retracts its legs and rearranges its internal organs so it can curl up into a teeny barrel shape, at which point it’s called a tun. It needs a moist environment, and if its environment dries out too much, the water bear will automatically go into this suspended state, called cryptobiosis. When conditions improve, the tardigrade returns to normal.

Another animal has a similar ability, and it’s a suggestion by Thaddeus, the immortal jellyfish. It’s barely more than 4 mm across as an adult, and lives throughout much of the world’s oceans, especially where it’s warm. It eats tiny food, including plankton and fish eggs, which it grabs with its tiny tentacles. Small as it is, the immortal jellyfish has stinging cells in its tentacles. It’s mostly transparent, although its stomach is red and an adult jelly has up to 90 white tentacles.

The immortal jellyfish starts life as a larva called a planula, which can swim, but when it finds a place it likes, it sticks itself to a rock or shell, or just onto the sea floor. There it develops into a polyp colony, and this colony buds new polyps that are clones of the original. These polyps swim away and grow into jellyfish, which spawn and develop eggs, and those eggs hatch into new planulae.

Polyps can live for years, while adult jellies, called medusae, usually only live a few months. But if an adult immortal jellyfish is injured, starving, sick, or otherwise under stress, it can transform back into a polyp. It forms a new polyp colony and buds clones of itself that then grow into adult jellies.

It’s the only organism known that can revert to an earlier stage of life after reaching sexual maturity–but only an individual at the adult stage, called the medusa stage, can revert to an earlier stage of development, and an individual can only achieve the medusa stage once after it buds from the polyp colony. If it reverts to the polyp stage, it will remain a polyp until it eventually dies, so it’s not really immortal but it’s still very cool.

All the animals we’ve talked about today have been quite small. Let’s finish with a suggestion from Kabir, a deep-sea animal that’s really big! It’s the giant siphonophore, Praya dubia, which lives in cold ocean water around many parts of the world. It’s one of the longest creatures known to exist, but it’s not a single animal. Each siphonophore is a colony of tiny animals called zooids, all clones although they perform different functions so the whole colony can thrive. Some zooids help the colony swim, while others have tiny tentacles that grab prey, and others digest the food and disperse the nutrients to the zooids around it.

Some siphonophores are small but some can grow quite large. The Portuguese man o’ war, which looks like a floating jellyfish, is actually a type of siphonophore. Its stinging tentacles can be 100 feet long, or 30 m. Other siphonophores are long, transparent, gelatinous strings that float through the depths of the sea, and that’s the kind the giant siphonophore is.

The giant siphonophore can definitely grow longer than 160 feet, or 50 meters, and may grow considerably longer. Siphonophores are delicate, and if they get washed too close to shore or the surface, waves and currents can tear them into pieces. Other than that, and maybe the occasional whale or big fish swimming right through them and breaking them up, there’s really no reason why a siphonophore can’t just keep on growing and growing and growing…

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, corrections, or suggestions, email us at strangeanimalspodcast@gmail.com.

Thanks for listening!