Thanks to Tim and Mia who suggested one of this week’s animals!

Further reading:

Genomic insights into the evolutionary origin of Myxozoa within Cnidaria

A tardigrade, photo taken with an electron microscope because these little guys are incredibly tiny:

Show transcript:

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

This week we’re going to talk about two microscopic or almost microscopic animals, one suggested by Mia and Tim, the other one I just learned about myself.

We’ll start with Mia and Tim’s suggestion, the water bear, also known as the tardigrade. We’ve talked about it before but there’s always more to learn about an animal.

The water bear isn’t a bear at all 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. It looks for all the world like a plump eight-legged stuffed animal made out of couch upholstery. 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. It has a tubular mouth that looks a little like a pig’s snout.

An extremophile is an organism adapted to live in a particular environment that’s considered extreme, like undersea volcanic vents or inside rocks deep below the ocean floor. Tardigrades aren’t technically extremophiles, but they are incredibly tough. Researchers have found tardigrades in environments such as the gloppy ooze at the bottom of the ocean and the icy peaks of the Himalayas. It can survive massive amounts of radiation, dehydration for up to five years, pressures even more intense than at the bottom of the Mariana Trench, temperatures as low as -450 Fahrenheit, or -270 Celsius, heat up to 300 degrees Fahrenheit, or 150 Celsius, and even outer space. It’s survived on Earth for at least half a billion years. Mostly, though, it just lives in moss.

Not every tardigrade is able to do everything we just talked about. They’re tough, but they’re not invulnerable, and different species of tardigrade are good at withstanding different extreme environments. Many species can withstand incredible heat, but only for half an hour or less. Long-term temperature increases, even if only a little warmer than what it’s used to, can cause the tardigrade to die.

Most species of tardigrade eat plant material or bacteria, but a few eat smaller species of tardigrade. It has no lungs since it just absorbs air directly into its body by gas exchange. It has a teeny brain, teeny eyes, and teeny sensory bristles on its body. Its legs have no joints. Its tubular mouth contains tube-like structures called stylets that are secreted from glands on either side of the mouth. Every time the tardigrade molts its cuticle, or body covering, it loses the stylets too and has to regrow them. In some species, the only time the tardigrade poops is when it molts. The poop is left behind in the molted cuticle.

The tardigrade’s success is largely 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.

Tests in 2007 and 2011 that exposed tardigrades to outer space led to some speculation that tardigrades might actually be from outer space, and that they, or organisms that gave rise to them, might have hitched a ride on a comet or some other heavenly body and ended up on earth. But this isn’t actually the case, since genetic studies show that tardigrades fit neatly into what we know of animal development and evolution. In other words, tardigrades are weird, but they’re Earth weird.

Our other tiny animal today is one that lacks pretty much everything animals usually have. Myxozoa are parasites that can’t live outside of the host’s body, a condition called obligate parasitism. They’re found in both freshwater and ocean water animals but evolved from an animal similar to a jellyfish that would have just swum around happily in the ocean. Now they’re microscopic parasites with the smallest genomes of any animals studied. Most only measure 300 micrometers at most, or 1/3 of a millimeter, although the largest known grows a humongous 2 mm long.

Different myxozoa have different life cycles, some of them complex. Because they’re so small, we naturally don’t know that much about them, and there are undoubtedly a whole lot of species that haven’t been discovered by science. They’re so numerous, and so different from other animals, that they’ve been placed into their own subphylum, classified in the Phylum Cnidaria. Cnidarians include jellyfish, corals, sea anemones, and many other aquatic invertebrates that show radial symmetry–but not comb jellies which have their own phylum.

In general, this is how a myxozoan spreads to a new host. A myxozoan secretes tiny capsules called myxospores that contain polar filaments. The myxopores are eaten by worms, at which point the capsule opens and the polar filaments uncoil and attach to the worm’s gut, where it develops into a sporoplasm and eventually detaches from the worm. The sporoplasm floats around in the water until it touches a fish, especially a fish’s gills, at which point it digs into the fish’s body and continues to develop.

When scientists identified the first myxozoans, they were classified as protozoans, single-celled animals. Many protozoans are parasitic. But as genetic testing became more refined and easier to do, and some myxozoans had their DNA sequenced, it became obvious that they were something else. Scientists just weren’t sure what. Finally scientists realized that they were similar genetically to jellyfish and their close relations, although they estimate it’s been about 600 million years since they shared a common ancestor.

Many myxozoans no longer have genes that allow communication between cells, multicellular development, body coordination, or even respiration in some species. Most are only a few cells in size and the most complex cell is the one that contains what’s called a polar capsule. This probably developed from its ancestor’s nematocysts, which are the cells that sting you if you touch a jellyfish, which is why you should never touch a jellyfish no matter how pretty it is.

Most myxozoa infect fish, but they’ve also been discovered in other animals. This includes a few frogs, turtles, aquatic birds, and octopuses. But they’ve also been discovered in two mammals, both of them shrews. Even though we already know about more than 2,000 species of myxozoa, scientists think there are probably hundreds, if not thousands more, but no one’s noticed them yet because they’re so small.

If you remember the Dr. Seuss book Horton Hears a Who, consider that the Whos might have actually been tardigrades. But probably not myxozoa, which wouldn’t have been able to build a Who city.

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at [email protected]. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Thanks to Nora, Holly, Stephen, and Aila for their suggestions this week!

Further reading:

How ‘bin chickens’ learnt to wash poisonous cane toads

Monkeys in Australia? Revisiting a Forgotten Furry Mystery Down Under

The Australian white ibis:

The greater glider looks like a toy:

The thorny devil is very pointy:

Show transcript:

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

This week we’re going to talk about some animals native to Australia, which is Nora’s suggestion. We’ll learn about animals suggested by Holly, Stephen, and Aila, along with a mystery animal reported in the 1930s in northern Australia.

Australia isn’t currently connected to any other landmass and hasn’t been for about 50 million years. That means that most animals on the continent have been evolving separately for a very long time. While in other parts of the world placental mammals took over many ecological niches, marsupials are still the dominant mammal type in Australia. Most marsupial females give birth to tiny, helpless babies that then continue their development outside of her body, usually in a pouch.

But let’s start the episode not with a marsupial but with a bird. Stephen suggested the Australian white ibis, a beautiful bird that doesn’t deserve its nickname of bin chicken.

The white ibis is related to ibises from other parts of the world, but it’s native to Australia, and is especially common in eastern, northern, and southwestern Australia. It’s a large, social bird that likes to gather in flocks. Its body is mostly white with a short tail, long black legs, and a black head. Like other ibises, the adult bird’s head is bare of feathers. It also has a long, down-curved black bill that it uses to dig in the mud for crayfish and other small animals. When the bird spreads its magnificent black-tipped wings, it displays a stripe of featherless skin that’s bright red.

The Australian white ibis prefers marshy areas where it can eat as many frogs, crayfish, mussels, and other animals as it can catch. But at some point around 50 years ago, the birds started moving into more urban areas. They discovered that humans throw out a lot of perfectly good food, and before long they started to become a nuisance to people who had never encountered raccoons and didn’t know they should clamp those trash barrels closed really securely.

But no matter how annoying the Australian white ibis can be to people, it’s been really helpful in another way. In the 1930s, sugarcane plantation owners wanted to control beetles and other pests that eat sugarcane plants, so they released a bunch of cane toads in some of their fields in Queensland. But the cane toads didn’t do any good eating the beetles. Instead, they ate native animals and spread like wildfire. Since the toads are toxic, nothing could stop them, and there are now an estimated two billion cane toads living in Australia. But the Australian white ibis eventually figured out how to deal with cane toads.

The ibis will grab a cane toad, then whip it around and throw it into the air so that the toad secretes its toxins in hopes that the bird will leave it alone. Then the ibis will wash the toad in water or wipe it in wet grass, which washes away the toxins. Then the ibis eats the toad. Goodbye, toad!

Our next Australian animal is one suggested by Holly, the greater glider. When I saw the picture Holly sent, I was convinced it wasn’t a real animal but a toy plushie, but that’s just what the greater glider looks like. It’s incredibly cute!

The greater glider lives in eastern Australia, and as you might guess from its name, it is the largest of the three glider species found in Australia, and it can glide from tree to tree on flaps of skin between its front and back legs. Until 2020 scientists thought there was only one species of glider with local variations in size and coat color, but it turns out those differences are significant enough that it’s been split into three separate but closely related species.

The greater glider is nocturnal and only eats plant material, mostly from eucalyptus trees. It has a long fluffy tail, longer than the rest of its body is. Its tail can be as much as 21 inches long, or 53 cm, while its body and head together can measure as much as 17 inches long, or 43 cm. It has dense, plush fur, a small head with big round ears, black eyes, and a little pinkish nose, and it superficially looks like a big flying squirrel. But the greater glider isn’t a rodent. It’s a marsupial, closely related to the ringtail possum. Some individuals have dark gray or black fur and some have lighter gray or brown fur, but all greater gliders have cream-colored fur on their tummies.

The greater glider’s gliding membranes, also called patagia, are connected at what we can refer to as their elbows and ankles. It uses its long tail as a rudder and it’s very good at gliding from tree to tree. It almost never comes down to the ground if it can avoid it. When it glides, it folds its front legs so its little fists are under its chin and its elbows are stuck out, which stretches the membranes taut.

Aila suggested we learn more about the thorny devil, an Australian reptile we talked about way back in episode 97. It’s a spiky lizard that grows to around 8 inches long, or 20 cm. In warm weather its blotchy brown and yellow coloring is paler than in colder weather, when it turns darker. It can also turn orangey, reddish, or gray to blend in to the background soil. Its color changes slowly over the course of the day as the temperature changes. It also tends to turn darker if something threatens it.

It has a thick spiny tail that it usually holds curved upward, which makes it look kind of like a stick. It moves slowly and jerkily, rocking back and forth on its legs, then surging forward a couple of steps. Researchers think this may confuse predators. It certainly looks confusing.

As if that wasn’t enough, the thorny devil has a false head on the back of its neck. It’s basically a big bump with two spikes sticking out of its sides. When something threatens the lizard, it ducks its head between its forelegs, which makes the bump on its neck look like a little head. But all its spines make it a painful mouthful for a predator. If something does try to swallow it, the thorny devil can puff itself up to make it even harder to swallow, like many toads do. It does this by inflating its chest with air.

The thorny devil eats ants, specifically various species of tiny black ants found only in Australia. It has a sticky tongue to lick them up. This is very similar to the horned lizard of North America, also called the horny toad even though it’s not a toad, which we talked about most recently in episode 376. But despite their similarities in looks, behavior, and diet, the horned lizard and the thorny devil aren’t closely related. It’s just yet another example of convergent evolution.

Now, let’s finish with a strange report from the 1930s about a colony of hundreds, if not thousands, of monkeys in Australia. Australia doesn’t have very many native placental mammals, and no monkeys. But several Australian newspapers reported in 1932 that a party of gold prospectors encountered the monkeys in northern Australia, specifically Cape York Peninsula. The monkeys were reportedly gathered in one area to eat a huge crop of red nuts, and they appeared to be large monkeys that weighed up to 30 lbs, or 13 kg. Another gold prospector said in follow-up articles that he too had seen the monkeys and even shot a few of them, although he hadn’t saved any part of the bodies.

Newspaper hoaxes were pretty common back in the day, but by the 1930s things had mostly settled down and papers were more interested in imparting actual news instead of making it up. Cape York Peninsula was quite remote at the time, with rivers, rainforests, and savannas where a lot of animals unknown to science probably still live. But not monkeys!

One thing to remember is that at the end of the 19th century, it was a fad to release animals from one area into another. That’s how the European starling was introduced to North America, where it has become incredibly invasive. In the early 1890s, a group of people released a hundred starlings into New York City’s Central Park, because they wanted all the birds mentioned in Shakespeare’s writings to be present in the United States. This fad included Australia, where colonizers tried to release all sorts of animals. Most of the animals didn’t survive long, and we don’t have any records of monkeys being released, but it’s possible that someone just did it for fun and didn’t tell anyone.

Another suggestion is that the prospectors saw tree kangaroos and thought they were monkeys, even though tree kangaroos don’t actually look like monkeys. They look like little kangaroos that live in trees, not to mention they’re mostly nocturnal. Besides, the local Aboriginal people reportedly told the prospectors about the monkeys, and they would have identified tree kangaroos easily if that’s what they were. No other native Australian animal known to live in the area resembles a monkey either.

Zoologist Karl Shuker suggests the monkeys might have been macaques native to New Guinea. New Guinea isn’t all that far away from Australia, and macaques were often kept as pets too. It would have been pretty easy for someone to buy a bunch of macaques, import them on a ship, and release them into the wilderness. Or the macaques might have gotten there on their own, rafting to Australia on fallen trees washed out to sea during storms.

If there really were monkeys in Australia 90 years ago, of course, the big question is: are they still there?

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at [email protected]. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Thanks to Sam for suggesting this week’s topic, the sea bunny!

My plush sea bunny, with one of my cats, Dracula, who does not like it:

Show transcript:

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

This week we’re going to revisit an animal we haven’t talked about in a few years! Thanks to Sam for suggesting it, and for sending a whole list of questions after listening to episode 215. Episode 215 was about the cutest invertebrates, and we talked about a lot of them. This week it’s all about the sea bunny.

Before we answer Sam’s questions, let’s go over what we learned in episode 215, in case you haven’t listened to it since it came out in March of 2021. The sea bunny, or sea rabbit, is a type of nudribranch [noodi-bronk] that lives along the coastline of the Indo-Pacific Ocean, especially in tropical waters. Nudibranchs are a type of mollusk that are sometimes called sea slugs. Many are brightly colored with beautiful patterns.

Compared to some sea slugs, the sea bunny is a little on the plain side. It’s usually orange or yellow, sometimes white or even green, with tiny brown or black speckles. It looks fuzzy because it’s covered in little protuberances that it uses to sense the world around it, as well as longer, thinner fibers called spicules. It also has two larger black-tipped protuberances that look for all the world like little bunny ears, although they’re actually chemoreceptors called rhinophores. It has a flower-shaped structure on its rear end that looks kind of like a bunny tail, but it’s actually gills. It really is amazing how much the sea bunny actually resembles a little white bunny with dark speckles.

Like other nudibranchs, the sea bunny is a hermaphrodite, which means it produces both eggs and sperm, although it can’t fertilize its own eggs. When it finds a potential mate, they both perform a little courtship dance to decide if they like each other. After mating, both lay strings of eggs in a spiral pattern. The eggs hatch into larvae that are free-swimming, although the adults crawl along the ocean floor looking for food. Some nudibranch larvae have small coiled shells like snails, which they shed when they metamorphose into an adult, but the sea bunny hatches into a teeny-tiny miniature sea bunny.

One of Sam’s questions was what the sea bunny eats. It mainly eats sea sponges. The toxins present in many sponges don’t bother the sea bunny. Instead, the sea bunny absorbs the sponge’s toxins and keeps them in its body. I don’t usually bother with Reddit posts while researching episodes, but I saw one where people were discussing how toxic the sea bunny is. Someone pointed out that small as they are, it’s not a good idea to pick up a sea bunny because they are so toxic, and someone replied, “That’s good for them, because I’m going to assume they taste like Marshmallows.”

That brings us to Sam’s next question, does anything eat the sea bunny? That’s mainly a no, because they are so incredibly toxic. An animal the size of a big shark or something like that probably wouldn’t be affected by the sea bunny’s toxins, but it also wouldn’t bother with such a tiny snack. A fish or other animal small enough for the sea bunny to seem like a meal probably wouldn’t survive its toxins.

Sam also wants to know if the sea bunny travels in groups, and that doesn’t seem to be the case. It’s a mostly solitary animal most of the time. If it did gather in a group, say if a bunch of sea bunnies were munching on the same sponge at the same time, maybe we could call it a fluffle of sea bunnies, or a school of sea bunnies.

Sam also wants a better idea of how small the sea bunny is. It’s easy enough to say, oh, it’s a little less than an inch, or around 2 ½ cm, but most of us have a hard time picturing that. So here’s a comparison that will help you visualize it. If you have an ordinary paperclip, not one of the jumbo ones, it’s usually around 2.5 cm long, maybe just a bit bigger. So a big sea bunny is just barely the length of an ordinary paperclip.

Sam’s last question is one of the most important ones, and I bet at least some of our listeners are wondering the same thing. Can you keep a sea bunny as a pet?

The answer is no, sorry! Aside from the sea bunny being really toxic and not safe for your other aquarium pets or you, it would need care that’s hard for a home aquarium keeper to provide. Some experienced saltwater aquarium keepers do have some types of sea slugs, but not typically sea bunnies, not even big professional aquariums.

Fortunately for all of us, sea bunnies are popular enough these days that you can get a sea bunny plushie. I know because I have one—and I found it just two days ago as this episode goes live! I was looking through the half-priced Valentine’s Day stuff on February 15 when I found a stuffy that looked just like a sea bunny. I picked it up and sure enough, it was a sea bunny, and it was on sale! There’s a picture of it in the show notes. It’s a lot bigger than a real life sea bunny, but it’s also not toxic.

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at [email protected]. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Thanks to Charlotte, Clay, and Richard from NC for their suggestions this week!

Further reading:

Seal whiskers, the secret weapon for hunting

Elephant seals drift off to sleep while diving far below the ocean surface

Scientists Discover Remains of Antarctic Elephant Seal in Indiana River

The elephant seal and its proboscis:

The bunyip carving:

Show transcript:

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

This week we have an animal suggested by three different listeners, Charlotte, Clay, and Richard from NC. So, by popular demand, let’s learn about the elephant seal, including some elephant seal mysteries.

The elephant seal gets its name because it’s big, grayish-brown, and wrinkled. Adult male elephant seals even have a proboscis, although it’s not anywhere near as long as an elephant’s trunk. It’s basically an enlarged and elongated nose that allows the animal to make loud roaring noises to intimidate other males. This is what that sounds like:

[elephant seal roars]

There are two species of elephant seal, the northern and southern. The southern elephant seal is larger on average while the northern male has a larger proboscis on average. We talked about elephant seals briefly in episode 155, about sexual dimorphism, because males and females are much different in size. A big male southern elephant seal can grow up to 20 feet long, or 6 meters, and can weigh about 9,000 lbs, or 4,000 kg. Females are about half that length and much lighter in weight. A big male northern elephant seal can grow up to 16 feet long, or almost 5 meters, and weigh around 5,500 lbs, or 2,500 kg, while females are much smaller.

There are many reasons why male elephant seals are bigger than females, but it’s mainly because the males spend a lot of energy fighting each other. The bigger and stronger a male is, the more likely he is to win a fight and the more likely it is that other males won’t bother to challenge him. Meanwhile, females are smaller so they need less food.

The elephant seal has thick fur that helps keep it warm, but it also has a layer of blubber like whales do. The blubber also helps make the seal streamlined so it can swim faster. Since the elephant seal spends most of its life in the water, and it does a lot of diving, it needs to be as streamlined as possible. It eats animals like fish, squid, and octopuses, but it especially likes sharks and rays.

Since a lot of the elephant seal’s favorite prey lives on or near the ocean floor, it has to dive to find it. The deepest recorded dive of an elephant seal was almost 5,700 feet, or about 1,700 meters. That’s just over a mile deep, the deepest dive made by a mammal that isn’t a whale. The elephant seal can hold its breath for well over an hour and a half. To conserve energy and maximize its time, quite often an elephant seal will actually sleep while it’s swimming downward, since a really deep dive can take a long time to descend. It might only wake up when it bumps into the sea floor, but sometimes it’s sleeping so soundly that it will just lie there at the bottom of the ocean and continue to sleep. I guess that’s why the sea floor is sometimes called the seabed.

Because the elephant seal hunts for food where there’s not much light, it often can’t rely on its vision to find its prey. Instead, it has really good hearing underwater, and it has whiskers on its upper lip that are extremely sensitive, with more nerve fibers in each whisker than in any other mammal studied. Its whiskers can sense tiny movements of water that indicate an animal moving around nearby.

Once a year, the elephant seal molts and new fur grows in, but unlike most mammals it doesn’t just lose its fur. The outer layer of its skin peels off too. It takes a lot longer for its fur to regrow because blubber doesn’t contain any blood vessels. New blood vessels have to grow around the blubber to supply the skin with extra nutrients, and during that time the seal can’t spend time in the water or it will get too cold. It stays on land during molting, cuddled up with its friends so they can all stay warmer.

It can take a month to complete the molt, and the seals don’t eat the whole time. The males also don’t eat during mating season and the females don’t eat once their pups are born, not until the pup is a month old and doesn’t need its mother constantly. Elephant seals are adapted to be able to fast for long periods, but they do lose a lot of weight and have to eat plenty of extra food afterwards to regain it.

The elephant seal is well adapted to cold. The southern elephant seal lives in the southern ocean, around Antarctica, the southern tip of Patagonia, and south of New Zealand. The northern elephant seal lives in the eastern Pacific Ocean, off the coast of Canada and Alaska. Sometimes they roam farther, though, into warmer waters, and sometimes an elephant seal will investigate a river mouth and end up traveling far inland in the river. But sometimes a seal will make a really, really long journey.

About 1,260 years ago, one particular southern elephant seal started swimming north. It swam from the Southern Ocean along the South American coast, crossed the equator, and just kept swimming. It swam into the Gulf of Mexico and eventually came to the mouth of the Mississippi River. It swam up the mighty Mississippi and into a tributary river, and eventually it ended up in what is now Indiana, where it died.

We know all this because in 1965, construction workers found a jawbone near the Wabash River and donated it to the Field Museum of Natural History in Chicago. It wasn’t properly studied until decades later except to test its age. In 2020, a team of three scientists examined what was left of the jawbone after destructive radiometric testing in the 1970s, and they were shocked to realize it came from a southern elephant seal.

There are a lot of questions associated with the discovery. Why did the seal keep swimming? Was it lost and confused, and thought it was swimming back to its home? Was it just a ramblin’ seal, tryin’ to make a livin’ and doin’ the best it could feel? There’s no way to know, but there is a clue about what happened to it at the end. There are marks on the jawbone that might be cut marks.

At the time, over 1,500 years ago, that part of North America was inhabited by the Mississippian culture, a vast empire and the ancestor of many of the modern indigenous North American peoples. This was the culture who made giant earth mounds that still exist today in parts of North America, and when they were still being used, the mounds had grand buildings on top. Scientists aren’t sure if fishers or hunters spotted the elephant seal and killed it, or if someone found it already dead and decided to not let perfectly good meat go to waste. There’s even a theory that the animal didn’t swim to North America but that its skull was brought there by traders and at some point it ended up in the river.

The two elephant seal species do look very similar, and the scientists didn’t have the full original jawbone to study, so they also suggest it might actually have been a northern elephant seal. For a northern elephant seal to travel to Indiana without human help would be just as hard or even harder than a southern elephant seal, because there is no easy water passage from the Pacific coast of North America to Indiana. The seal would actually have to travel through the Arctic Ocean to the North Atlantic, then swim south to the Gulf of Mexico or the Gulf of St. Lawrence.

There is a big possibility that at least some stories of river monsters from the olden days were actually elephant seals that swam so far upstream in a river that the people who saw it didn’t know what the animal was. Even today, when many of us carry around tiny computers in our pockets that allow us to access all of humanity’s knowledge and also make phone calls, seeing an elephant seal in a place where it doesn’t belong would be terrifying.

We think that’s what happened long ago in Victoria in Australia. We talked about it in episode 351, in our episode about the bunyip. An Aboriginal sacred site near Ararat, Victoria once had the outline of a bunyip carved into the ground and the turf removed from within the figure. Every year the local indigenous people would gather to re-carve the figure so it wouldn’t become overgrown, because it symbolized an important event. At that spot, two brothers had been attacked by a bunyip. It killed one of the men and the other speared the bunyip and killed it. When he brought his family and others back to retrieve his brother’s body, they traced around the bunyip’s body.

The bunyip carving was 26 feet long, or 8 meters. Unfortunately it’s long gone, since eventually the last Aborigine who was part of the ritual died sometime in the 1850s and the site was fenced off for cattle grazing. But we have a drawing of the geoglyph from 1867. It’s generally taken to be a two-legged sea serpent type monster with a small head and a relatively short, thick tail. Some people think it represents a bird like an emu.

But if you turn it around, with the small head being the end of a tail, and the blunt tail being a head, suddenly it makes sense. It’s the shape of a seal.

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at [email protected]. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

This week we take a look at some of the many animals that were discovered last year!

Further reading:

‘Blob-Headed’ Catfish among New Species Discovered in Peru

New Species of Dwarf Deer Discovered in Peru

Hylomys macarong, the vampire hedgehog

Hairy giant tarantula: The monster among mini tarantulas with ‘feather duster’ legs

Woods Hole Oceanographic Institution and partners discover new ocean predator in the Atacama Trench

Never-before-seen vampire squid species discovered in twilight zone of South China

The blob headed catfish [photo by Robinson Olivera/Conservation International]:

A new mini tarantula [photo by David Ortiz]:

Show transcript:

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

This week is the 8th year anniversary of this podcast, so thanks for listening! It’s also our annual discoveries episode, where we’ll learn about a few animals that were discovered last year–in this case, in 2024.

Let’s start in Peru, a country in western South America. A 2022 survey of organisms living in the Alto Mayo region was published at the very end of 2024, revealing at least 27 new species and potentially more that are still being studied. One of those new species is a fish called the blob headed catfish.

The new fish has been placed in the bristlemouth armored catfish genus, but as you can probably guess from its name, it has a big blobby head and face. Scientists have no idea why it has a blob head. It lives in mountain streams and that’s about all we know about it right now.

Another animal found in the same survey is a new mouse. It lives in swampy forests and is semi-aquatic, including having webbed toes. It’s dark gray in color and is probably closely related to the Peruvian fish-eating rat, which is mostly brown in color and was only described in 2020.

Another new species from Peru is a type of small deer, called a pudu, that has been named Pudella carlae. It’s one of those “hidden in plain sight” discoveries, because until 2024 it was thought to be the same as the northern pudu that also lives in Ecuador and Colombia. The new deer is only 15 inches tall, or 38 cm, and is dark brownish-orange in color with black legs and face. It only lives in Peru, mostly in high elevations. It’s also the first deer species discovered in the 21st century, although hopefully not the last.

While we’re talking about mammal discoveries, we have to talk about the vampire hedgehog just because of its name. It was actually described at the very end of 2023, but it’s such an interesting animal that we’ll say it’s a 2024 discovery.

The vampire hedgehog was actually discovered a whole lot earlier than 2023, but no one noticed it was new to science for a long time. A small team of researchers studying soft-furred hedgehogs decided to collect DNA samples from all the museum specimens they could find. One of the specimens was in the archives of the Smithsonian National Museum of Natural History, collected in 1961 but never studied. When the scientists compared its DNA to the other specimens they’d found, it didn’t match up. Not only that, a closer look showed that it had fangs. Naturally, they named it the vampire hedgehog and went searching for living ones.

The vampire hedgehog lives in parts of Vietnam and is a member of the soft-furred hedgehogs, also called gymnures, hairy hedgehogs, or moonrats. Instead of spines, moonrats have bristly fur and long noses that make them look like shrews, but hairless tails that make them look like rats. They’re not rodents but are closely related to other hedgehogs. They eat pretty much anything but especially like to eat meat. This includes mice and frogs, along with various invertebrates.

As for the vampire hedgehog’s fangs, both males and females have them, but males have bigger fangs. Scientists don’t know yet what the hedgehogs use their fangs for. It could be they help the animals keep a better hold on wiggly prey, but it could be the hedgehogs just think big fangs look good on other hedgehogs so they’re one way the animals decide on a mate.

Just a few weeks ago we talked about the biggest tarantula in the world, the goliath birdeater, but did you know that there are tiny tarantulas too? The genus Trichopelma contains miniature tarantulas with body lengths measured in millimeters, and a new one was described in 2024 from western Cuba. But the great thing is, this tiny tarantula is the largest of the two dozen species known. Of the four specimens found so far, the largest body length is 11.2 millimeters—a veritable giant among miniature tarantulas!

The new species has been named Trichopelma grande, and the males, at least, have been discovered in trap-door burrows in the ground. No female specimens have been observed yet. Ground-dwelling tarantulas usually have a lot less hair on their legs, while tarantulas that live in trees are the ones with especially hairy legs, but T. grande is ground-dwelling but has very hairy legs. Or at least the males do. We don’t know about females yet.

Now let’s talk about some ocean animals, and we have to go back to Peru for our first one. The Atacama Trench is also called the Peru-Chile Trench because it’s about 100 miles, or 160 km, off the coast of both countries. At this spot a continental plate in the ocean is pushing underneath the South American plate, and it’s incredibly deep as a result. It’s been measured as 26,460 feet below the ocean’s surface, or 8,065 meters. That’s five miles deep!

Not a lot of animals live near the bottom, where the water pressure is intense and there’s not much to eat, but little crustaceans called amphipods are fairly common in the trench. Amphipods are common animals throughout the world’s oceans and freshwater, with almost 10,000 species discovered so far. There’s even a terrestrial amphipod called the sandhopper. Amphipods look a little bit like tiny shrimp, although there are some giant species. Giant in this case means 13 inches long, or 34 cm, but most are like the miniature tarantulas and are measured in millimeters.

In 2023 a new amphipod was discovered near the bottom of the Atacama Trench, and it was described in 2024 as a new species in its own genus. It grows just over an inch and a half long, or almost 4 cm, and appears white because of its lack of pigment. And most interesting of all, it’s a predator that catches and eats other species of amphipod.

Our last 2024 discovery is one that I find extremely exciting. We talked about the vampire squid way way way back in episode 11, before some of my listeners were even born, and while it has the word squid in its name, it’s not exactly a squid. It’s also not exactly an octopus. It’s the last surviving member of its own order, Vampyromorphida, which shares similarities with both squids and octopuses. And as of 2024, the vampire squid is not the only member of its own order, because they’ve found a second vampire squid!

The vampire squid is a deep-sea animal that grows about a foot long, or 30 cm, and eats whatever organic material floats down from far above. That could mean part of a dead amphipod or it could mean fish poop, the vampire squid is not picky. The new species of vampire squid was found around 3,000 feet below the surface, or a little over 900 meters, in the South China Sea. A genetic study determined that it does seem to be a new species, and the scientific name Vampyroteuthis pseudoinfernalis has been proposed. The official description hasn’t yet been published, but that just means we’ll probably get to talk more about it in a future episode.

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at [email protected]. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

I’m a bit under the weather this week, so here’s a Patreon episode about a weird bird!

Further reading:

Hoatzin nestling locomotion: acquisition of quadrupedal limb coordination in birds

Show transcript:

Welcome to the Patreon bonus episode of Strange Animals Podcast for mid-November, 2019!

We’re going to learn about a mystery bird today. When I say mystery bird, I don’t mean that people aren’t sure if it exists. It definitely exists. You can go to South America and look at it if you like, because fortunately it’s not rare or endangered. But scientists aren’t completely sure what it’s related to, because it’s a really weird bird.

The hoatzin [pronounced what-seen] is a large bird, over two feet long, or 65 cm. It’s shaped sort of like a pheasant, with a chunky body, long neck and small head, and a long tail made of stiff feathers like a hawk’s. Its face has no feathers and blue skin, it has red eyes, and it has a spiky feather crest on its head. It’s black and chestnut brown with some darker and lighter streaks, and is a softer brown underneath. It’s a really pretty bird, in fact, with a strong bill. But it really doesn’t resemble any other bird alive today.

The hoatzin is the only species in its genus, and the only genus in its family, and the only family in its order. It’s basically not really related to any other bird alive today, although in 2012 its genome was sequenced and found to be most closely related to cranes and plovers—but only very distantly. In fact, a 2015 study determined that the hoatzin started evolving separately from other birds 65 million years ago, right after the Cretaceous-Paleogene extinction event that killed off the non-avian dinosaurs.

We only have a few fossils of hoatzin ancestors, but they show that it was much more widespread in the past and lived in what is now North America and Europe. But these days it only survives in northern and central South America. It likes swampy areas and forests near rivers or other water.

The hoatzin eats plants—specifically leaves and buds, although it also eats some flowers and fruit. And leaves require a lot of digesting before the body can make use of the nutrients. The hoatzin’s digestive system is unlike any other living bird’s, because the hoatzin is a foregut fermenter. Its crop, which most birds only use to store extra food temporarily when the stomach is full, acts as a bacterial fermentation chamber—two chambers, in fact, since it’s divided into two sections. This acts like the rumen of a cow. Its crop is so big it doesn’t have room on its body for big flight muscles, so it’s not a strong flyer. It mostly stays in trees and bushes, eating leaves, flapping its big wings for balance and display, and hanging out with other hoatzins.

The hoatzin’s digestive system has a weird side effect. It smells bad. It’s supposed to smell like manure. It’s sometimes called the stinkbird and, fortunately for the hoatzin, almost no one wants to eat it as a result.

As you probably know, birds developed from dinosaurs. It’s easy to forget that, since birds have evolved structures like toothless beaks and front legs modified for flight and they no longer have lizard-like tails. But the hoatzin retains something from its dinosaur ancestry that is a startling reminder.

The hoatzin is a social bird that lives in small flocks. It breeds during the local rainy season and builds its nest over water when the forest floods due to rain. The female lays two or three eggs, and when the babies hatch, they can climb around in the branches near the nest right away. This means they can hide from predators instead of being helpless in the nest. And the reason a hoatzin chick can climb so well is partly because it has big feet, and partly because it has finger claws on its wings: specifically a thumb claw and one finger claw, which are fully functional and make it look a lot like a fuzzy baby dinosaur.

Not only does the baby hoatzin use these claws for climbing, a study published in May 2019 shows that the baby hoatzin uses its wings differently when climbing than it does as an adult bird. Obviously, birds fly by flapping both wings at the same time. But the baby hoatzin climbs by using its limbs in an alternating motion. You know, the way you would climb a tree. Or the way a small dinosaur would climb a tree.

But primitive and dinosaur-like as this trait is, researchers have discovered that it developed relatively recently. That is, as the hoatzin’s distant ancestors evolved from a small dinosaur into a primitive bird, it lost the claws on its front legs as they became more and more modified into wings. But at some point, the hoatzin re-developed those claws. Researchers think it’s what is called an atavistic trait, which you may remember from way back in the Patreon episode where we talked about horses with extra toes. In other words, the genes to grow claws on the front limbs are still present in birds, but are suppressed by other genes, since claws just get in the way when you’re flying. But occasionally a small mutation causes the claws to grow anyway, and in the case of the hoatzin, it proved so useful that those babies with claws survived better than those without claws, and therefore lived to pass on their genes. But the claws are no longer useful once the babies grow up and learn how to fly, so they lose them as adults.

Hoatzin chicks climb using alternating motions of the wings, but swim by moving both wings together. Oh, didn’t I mention that the babies swim? They have to, because sometimes a predator attacks and they have to get away fast. They can’t fly yet, and they can’t climb all that quickly, so they drop out of the branches and fall into the water below. That’s why the parent birds build the nests over water. The babies can swim just fine, and they swim to safety and climb back up into the branches where their parents can find them.

The hoatzin isn’t the only bird that has wing claws as a baby. Some species of turaco do too. The turaco lives in Africa and shares many traits with the hoatzin, so for a long time people thought the two were related. But now we know they’re not and that the similarities are due to convergent evolution.

Thanks for your support, and thanks for listening!

Thanks to Siya, Sutton, Owen, and Aksel for suggesting this week’s topic, the Goliath birdeater tarantula and the fire ant!

Further listening:

The TEETH Podcast

Further reading:

Tropical fire ants traveled the world on 16th century ships

The Goliath birdeater tarantula, bigger than some kittens:

Fire ants:

Show transcript:

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

This week we’re going to talk about two invertebrates, a spider and an insect. Thanks to Siya, Sutton, Owen, and Aksel for suggesting them!

We’ll start with the spider, which Siya and Sutton both suggested. It’s the goliath tarantula, also called the goliath birdeater. You know it has to be a big spider if it’s called a birdeater. We’ve talked about it before, but not in a long time.

The goliath birdeater is the heaviest spider in the world. If you think of the usual spider, even a big one, it’s still pretty lightweight. Let’s use a wolf spider as an example, which is found just about everywhere in the world. It’s a hunting spider that doesn’t spin a web, and while different species vary in size, the biggest is the Carolina wolf spider found in many parts of North America. A big female can have a legspan of four inches across, or 10 cm, with a body up to an inch and a half long, or 35 mm—but it weighs less than an ounce. That’s barely 28 grams, or just a little heavier than five sheets of printer paper.

In comparison, the goliath birdeater tarantula can weigh over 6 ounces, or 175 grams. That’s heavier than a baseball, or two packs of cards. Its legspan can be as much as 12 inches across, or 30 cm with a body length of about 5 inches, or 13 cm. It’s brown or golden in color and lives in South America, especially in swampy parts of the Amazon rainforest. It’s nocturnal and mostly eats worms, large insects, other spiders, amphibians like frogs and toads, and occasionally other small animals like lizards or even snakes. And yes, every so often it will catch and eat a bird, but that’s rare. Birds are a lot harder to catch than worms, especially since the Goliath birdeater lives on the ground, not in trees.

Because it’s so large, the goliath looks like it would be incredibly dangerous to humans. It does have fangs and can inflict a venomous bite, but it’s not very strong venom. The danger comes from a very different source, because the goliath birdeater is famous for its urticating spines.

Many species of tarantula have special setae, hairlike structures called urticating spines, that can be dislodged from the body easily. If a tarantula feels threatened, it will rub a leg against its abdomen, dislodging the urticating spines. The spines are fine and light so they float upward away from the spider on the tiny air currents made by the tarantula’s legs, and right into the face of whatever animal is threatening it. The spines are covered with microscopic barbs that latch onto whatever they touch. If that’s your face or hands, they are going to make your skin itch painfully, and if it happens to be your eyeball you might end up having to go to the eye doctor for an injured cornea. Scientists who study tarantulas usually wear eye protection.

The goliath birdeater tarantula is considered a delicacy in northeastern South America. People eat it roasted. Apparently it tastes kind of like shrimp.

Next, Owen and Aksel wanted to learn about fire ants. I couldn’t believe that we’ve never talked about fire ants before!

Fire ant is the name for any of the more than 200 species in the genus Solenopsis, but it’s typically used to refer to the species Solenopsis invicta. It’s native to tropical South America but has been introduced to parts of North America, Australia, China, Taiwan, India, Africa, and many other places where the climate is tropical or sub-tropical.

The fire ant initially became so invasive due to Spanish galleons in the 16th century, which carried trade goods around the world. A ship that’s meant to carry a lot of cargo is built so that it needs to be weighted down to a certain degree to sail safely. A lot of times if a Spanish ship didn’t have enough goods in its hold to make it weigh enough, the captain would bring a few tons of soil onboard to make up the difference. Then, when the ship got to its next port where it was supposed to pick up new cargo, it would just dump the dirt wherever it was. It didn’t matter to the fire ant if the dirt was dumped into the water, because fire ants are prepared for their nests getting flooding. They cling together and form huge rafts that the wind pushes to shore. But more often, the dirt would get dumped on land for other ships to re-use.

A team of scientists figured out where the invasive fire ant populations came from by comparing the genetic signatures of 192 different populations. They hypothesized that the ants with the highest genetic diversity were the original population, and that as the ants were moved around the world by ship, genetic diversity would get lower and lower, since all the ants were descendants of the original colony or colonies transported accidentally in the dirt. They mapped out the genetics, then compared the results to Spanish trade routes in the mid-1600s, and it all matched up.

The fire ant made it to the United States in the late 1930s or early 1940s, the West Indies around 1980, and Australia around 2001. These days a lot of fire ants end up transported to new areas in golf course sod imported from Florida.

A fire ant colony consists of a queen, thousands of worker ants, and larger soldier ants that protect the workers and especially the queen. Some colonies have more than one queen. The ants eat anything, including seeds and insects, and even small animals, but also including dead animals they find. The colony can have as many as a quarter million ants. The nest is underground and entrances can be far from the nest itself, and nests can be so large that they can cause structures built over them to collapse.

Invasive animals of any kind aren’t good for the native animals, and the same is true for the fire ant. The fire ant specializes in colonizing areas where humans have disturbed the ground, whereas native ants often have trouble surviving in disturbed areas. The fire ants crowd out native ants and can destroy some native plants.

But the main reason why people don’t like fire ants is that they bite and they’re venomous. The bites cause a burning sensation and painful swelling, but some people are allergic to the venom and can actually die from ant bites. Luckily, that’s rare, but the bites are still painful.

Some countries have spent millions of dollars trying to eradicate the fire ant, including Australia and New Zealand. New Zealand seems to have succeeded, but Australia is still struggling to get the invasion under control. Fortunately, a lot of animals eat fire ants, which helps. One of the animals that especially loves to eat fire ants is the wolf spider, so now we’ve come full circle in this episode.

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at [email protected]. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

If you are wishing that I’d gone into more detail about fire ant attacks, you might like the TEETH podcast. It’s the only podcast where you’ll hear wild animal attack stories directly from the survivors, hosted by a wilderness guide and attack survivor himself. I’ll put a link in the show notes so you can go listen. It’s appropriate for all ages. I don’t think they’ve actually covered a fire ant attack, but they’ve got lots of other fascinating accounts.

This week we’re going to learn about some animals that seem to have individual names!

Further reading:

Bottlenose dolphins can use learned vocal labels to address each other

How Do Dolphins Choose Their Name?

Vertical transmission of learned signatures in a wild parrot

Baby Parrots Learn Their Names from Their Parents

Study: African Elephants Address Each Other With Name-Like Calls

Marmoset Monkeys Use Names to Communicate with Each Other

The green-rumped parrotlet (photo by Rick Robinson, taken from this site):

Show transcript:

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

This week we’re going to learn about some animals that seem to be using names to refer to other individuals or themselves.

Let’s start with bottlenose dolphins, because they’re well-studied and scientists have known about this particular aspect of their society for over a decade. Every bottlenose dolphin has a signature whistle that identifies it to other dolphins. The signature whistles can be complex and the dolphin may add or change details to indicate its mood or other information. It’s not precisely a name in the way humans would think of it, but it is an identifier.

The dolphin creates its own signature whistle when it’s young. Some dolphins pattern their whistles on their mother’s signature whistle, while others mimic their siblings or friends. Some seem to pattern theirs on a distant acquaintance, which sounds to me like they just like something about an unusual whistle and decide to incorporate it into their own whistle. As dolphins grow up, females typically don’t change their whistles, but males often do. Male dolphins often pair up together and remain bonded, and a pair may change their signature whistles to be similar.

When a dolphin is trying to find a friend it can’t see, it will mimic that friend’s signature whistle. If a mother can’t see her calf and is worried, she’ll do the same, and her calf will answer by repeating its signature whistle. A lost calf will imitate its mother’s whistle. But it’s even more complicated than it sounds, because a group of dolphins who get together to forage may choose a shared whistle that the whole group uses. This helps them coordinate their behaviors to work together. Each member of the group uses a slightly different version of the group whistle, which means that each member can identify who’s speaking.

Other cetaceans seem to use a similar kind of name. Sperm whales, for instance, have a unique click sequence that they use to announce themselves when approaching other whales. The signature clicks always appear at the beginning of a sequence and don’t vary.

Bottlenose dolphins and many other cetaceans are extremely social animals. So are parrots. Studies of parrot calls indicate that parrots appear to have signature calls that they use the same way as dolphins do, to identify themselves to other parrots and as a way for other parrots to call for them. A study of wild green-rumped parrotlets in Venezuela discovered that the birds give a unique signature call to each baby while it’s still in the nest, and the baby continues to use its call its whole life, often with small changes.

The study set up video cameras to monitor 16 nests of a large wild population of the parrots. The population has been well studied and is used to using nesting tubes that scientists have set up for them. This makes it easier for the scientists to monitor nesting behaviors. In this case, to test whether the names had something to do with genetics or not, the scientists sneakily moved half of the eggs from one nest to another, so that half the parents unknowingly raised some chicks that weren’t actually related to them.

Despite the egg switcharoo, all the chicks were given names that were similar to the parents’ signature calls. The parents started using a specific signature call soon after the eggs hatched, and the babies started imitating it. Gradually each baby added its own specific flourish to the call that made it their own, so while you can say that the parents named their babies, it’s just as true to say that the babies named themselves. The parrots use the signature calls to announce themselves, but also to call for friends, siblings, and parents.

Elephants are also extremely social animals. Recent studies of African savanna elephant calls indicate that elephants also have an identifying rumble sound that acts as a name. In fact, it acts more like a name as humans use names than the signature sounds made by dolphins and parrots. An elephant will use a specific rumble when addressing another elephant, but the rumble isn’t the speaker’s name, it’s the recipient’s name. It’s the difference between me saying, “Hi, I’m Kate. How are you?” and me saying, “Hi, Kelly, how are you?” when I’m talking to my friend Kelly. Dolphins and parrots seem to be saying something like, “Kate here, I’m swimming this way.”

Marmosets seem to use names the same way that elephants do. Marmosets are a type of small monkey native to Central and South America, which live in treetops and eat fruit and other plant material, and the occasional insect. A 2024 study found that marmosets that know each other address individuals with specific sounds, whether or not they’re related.

All the animals we’ve talked about today are incredibly social, just like humans are. In the case of dolphins, parrots, and marmosets in particular, it’s easy for individuals to travel and forage together but be out of sight of one other. Having a way to track friends and family members when you can’t see them is important to keep a group together.

Studies about animals using names are becoming more common, with both the marmoset study and the elephant study published in 2024. It may not seem like a big deal, but using a specific vocal label for a specific individual is a huge indicator of linguistic intelligence. We haven’t known a lot about it before recently because the recordings of animals communicating was time-consuming and difficult to categorize. Now we have sophisticated computer programs that can compile the information for us, so that scientists can study it more easily. I wouldn’t be a bit surprised if more and more studies start finding animals that use names.

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at [email protected]. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Thanks to Eilee and Alexis for their suggestions this week, two amazing frogs!

Further reading:

Paradoxical frog: The giant tadpole that turns into a little frog

Fungus is wiping out frogs. These tiny saunas could save them.

How to build a frog sauna

The paradoxical frog [photo by Mauricio Rivera Correa – http://calphotos.berkeley.edu, CC BY-SA 2.5, https://commons.wikimedia.org/w/index.php?curid=6703905]:

The Vietnamese mossy frog [photo by H. Zell – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=81804225]:

Show transcript:

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

Let’s start 2025 off right with an episode about frogs! Thanks to Alexis and Eilee for their suggestions.

Let’s start with Eilee’s suggestion, the paradoxical frog. The paradoxical frog is a type of tree frog that lives in South America. Like other frogs, it likes ponds and shallow lakes. Some individuals are green and some are brown, and a frog may have darker stripes or splotches, or might just be plain. The tadpoles eat algae and other tiny food, while the adults eat insects.

As with most frogs, the paradoxical frog hatches into a larval stage called a tadpole or pollywog, which is fully aquatic. It later metamorphoses into its adult form as a frog. Most tadpoles start out very small and grow larger, then metamorphose into a juvenile frog which then grows to fully adult size. But while the paradoxical frog’s tadpole starts out small, it can grow to as much as 11 inches long, or 28 centimeters! It’s the largest tadpole in the world as far as we know.

So how big is the adult frog if the tadpole is so enormous? About 3 inches long, or 7.5 cm, from snout to vent. That’s why it’s called the paradoxical frog, because a paradox is something that seems contradictory to expectations. Instead of the ordinary way of things, where a small tadpole grows into a bigger frog, in this case a big tadpole grows into a smaller frog. It’s sometimes called the shrinking frog.

One interesting detail is that not all of the tadpoles are that big. If a female lays her eggs in a small body of water that’s likely to dry up, or that doesn’t have a lot of food available, or if there are a lot of predators in the water, the tadpole metamorphoses quickly and doesn’t grow very big. But if the tadpole is in a better location it matures much more slowly, which allows it to reach much larger size before metamorphosing.

I should also mention that the 11-inch-long tadpole that is the largest ever measured was actually raised in captivity. In the wild, the largest paradoxical frog tadpole ever measured was 6 ½ inches long, or almost 17 cm. That’s still really big, but not that ridiculously big. But the confusing thing is that the tadpole is big and bulky, up to four times the size of the adult frog. Where does all that mass go after it transforms?

Early scientists who learned about the paradoxical frog wondered the same thing. They were so confused that they suggested that the frog actually came first and later metamorphosed into the tadpole, which then metamorphosed into a fish. But the main reason the tadpole is so long is its tail. When it metamorphoses into a frog, it absorbs the tail and therefore appears to shrink. The bulkiness of the tadpole’s body matches the bulkiness of the frog’s body. And unlike most frogs, which metamorphose into juvenile frogs that still have some growing to do, the paradoxical frog metamorphoses into a completely adult frog. It’s as big as it will ever get and fully mature, ready to mate and lay eggs.

Next, Alexis wanted to learn about the Vietnamese mossy frog. It lives in parts of Vietnam, Laos, and other nearby areas. It prefers mountainous rainforests and the female often chooses to lay her eggs in a tree hollow or even a rock cavity where water has collected. Instead of laying her eggs in the actual water, though, she lays them on rocks or branches above the water. The eggs don’t dry out because of the high humidity in rainforests, and when they hatch, the tadpoles fall into the water.

The tadpoles take a long time to mature, anywhere from four to eight months depending on how warm it is while they’re developing. They grow quite large, although not anywhere near the size of the paradoxical frog tadpole.

A big female Vietnamese mossy frog can grow up to 3 ½ inches long, snout to vent, or 9 cm, and is chubby and round. It’s nocturnal and spends the day hiding on mossy rocks or among plants in the water, then comes out at night to hunt insects like crickets as well as other small animals like worms.

The reason it’s called the mossy frog is because it looks for all the world as though this frog is covered in moss, or maybe is just made out of moss. It’s green and brown in color and its skin is covered in little bumpy structures called tubercules. This helps it blend in incredibly well in the rainforest, where moss is pretty much everywhere. If it feels threatened and it can’t jump into the water to hide, it will play dead.

This is what a Vietnamese mossy frog sounds like:

[frog beeping]

As we’ve talked about in other frog episodes, frogs throughout the world are declining in numbers because of a fungus that infects their skin. The effects of this fungus are worse in cold weather, so a team of scientists speculated that helping the frogs stay warm might help them stay healthier in winter and even help them recover from the infection. They tested their hypothesis by offering infected frogs a variety of temperatures in their enclosure. The frogs could pick where they wanted to spend their time. The frogs liked the warm areas but didn’t spend all their time in them, but they all recovered from the infection. Frogs who were given an overall warm environment also recovered, but not as fast. Frogs who had an ordinary enclosure without warmer areas remained infected with the fungus. Even better, frogs who had recovered from infection with the warm environment also showed resistance to later infections.

The team worked to develop plans that allow people to easily build what they call frog saunas. They don’t require electricity or fuel, just sunshine. When the saunas are placed near ponds or other areas with frogs, the frogs find them quickly and use them. There’s a link in the show notes if you want to learn how to make a frog sauna for your own back yard.

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at [email protected]. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Thanks to Pranav for suggesting this week’s massive topic!

Further reading:

When did the Isthmus of Panama form between North and South America?

Florida fossil porcupine solves a prickly dilemma 10-million years in the making

Evidence for butchery of giant armadillo-like mammals in Argentina 21,000 years ago

Glyptodonts were big armored mammals:

The porcupine, our big pointy friend:

Show transcript:

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

This week, at long last, we’re going to learn about the great American interchange, also called the great American biotic interchange. Pranav suggested this topic ages ago, and I’ve been wanting to cover it ever since but never have gotten around to it until now. While this episode finishes off 2024 for us, it’s the start of a new series I have planned for 2025, where every so often we’ll learn about the animals of a particular place, either a modern country or a particular time in history for a whole continent.

These days, North and South America are linked by a narrow landmass generally referred to as Central America. At its narrowest point, Central America is only about 51 miles wide, or 82 km. That’s where the Panama Canal was built so that ships could get from the Atlantic Ocean to the Pacific and vice versa without having to go all around South America.

It wasn’t all that long ago, geologically speaking, that North and South America were completely separated, and they had been separated for millions of years. South America was part of the supercontinent Gondwana, while North America was part of the supercontinent Laurasia.

We’ve talked about continental drift before, which basically means that the land we know and love on the earth today moves very, very slowly over the years. The earth’s crust, whether it’s underwater or above water, is separated into what are called continental plates, or tectonic plates. You can think of them as gigantic pieces of a broken slab of rock, all of the pieces resting on a big pile of really dense jelly. The jelly in this case is molten rock that’s moving because of its own heat and the rotation of the earth and lots of other forces. Sometimes two pieces of the slab meet and crunch together, which forms mountains as the land is forced upward, while sometimes two pieces tear apart, which forms deep rift lakes and eventually oceans. All this movement happens incredibly slowly from a human’s point of view–like, your fingernails grow faster than most continental plates move. But even if a plate only moves 5 millimeters a year, after a million years it’s traveled 5 kilometers.

Anyway, the supercontinent Gondwana was made up of plates that are now South America, Africa, Australia, Antarctica, and a few others. You can see how the east coast of South America fits up against the west coast of Africa like two puzzle pieces. Gondwana actually formed around 800 million years ago, then became part of the even bigger supercontinent Pangaea, and when Pangaea broke apart around 200 million years ago, Gondwana and Laurasia were completely separate. North America was part of Laurasia. But Gondwana continued to break apart. Africa and Australia traveled far away from South America as molten lava filled the rift areas and helped push the plates apart, forming the South Atlantic Ocean. Antarctica settled onto the south pole and India traveled past Africa until it crashed into Eurasia. By about 30 million years ago, South America was a gigantic island.

It’s easy to think that all this happened just like taking puzzle pieces apart, but it was an incredibly long, complicated process that we don’t fully understand. To explain just how complicated it is, let’s talk for a moment about marsupials.

Marsupials are mammals that are born very early and finish developing outside of the mother’s womb, usually in a special pouch. Kangaroos, wallabies, koalas, wombats, and Tasmanian devils are all marsupials, and all from Australia. But marsupials didn’t originate in Australia and are still present in other parts of the world.

The oldest known marsupial appears in North America about 65 million years ago, which was part of the other supercontinent on Earth at the same time as Gondwana, called Laurasia. About the time marsupials were spreading out across Laurasia, from North America all the way to China, Laurasia and Gondwana were connected for a while along the northern edge of South America. Animals were able to cross from Laurasia to Gondwana before the two supercontinents split apart again. Marsupials spread from Laurasia and across Gondwana before the continent of Australia separated about 50 million years ago. Marsupials did so well in Australia that researchers think that before Australia was fully separated from Gondwana, marsupials actually started spreading back out of Australia and into Gondwana again.

While marsupials were doing extremely well in Australia, in South America, birds were the dominant vertebrate for a long time. We talked about terror birds in episode 202. Phorusrhacidae is the name for a family of flightless birds that lived from about 62 million years ago to a little under 2 million years ago. They were carnivores and various species ranged in size from about 3 feet tall to 10 feet tall, or 1 to 3 meters, and had long, strong legs that made them fast runners. The terror bird also had a long, strong neck, a sharp hooked beak, and sharp talons on its toes.

Other birds in North America were likewise huge, but could fly. Those were the teratorns, which are related to modern New World vultures. Since they had huge wingspans and could fly long distances easily, they could just fly between North and South America if they wanted to, so teratorns were found on both continents starting around 25 million years ago. They only went extinct around 10,000 years ago. The largest species known, Argentavis magnificens, lived in South America around six million years ago. It’s estimated to have a wingspan of at least 20 feet, or 6 meters, and possibly as much as 26 feet, or 8 meters. That’s the size of a small aircraft.

In addition to giant predator birds, South America had crocodilians that could grow over 30 feet long, or 9 meters, and possibly as much as 40 feet long, or 12 meters. And, of course, it had ancestral forms of animals we’re familiar with today, like sloths, anteaters, armadillos, opossums, monkeys, capybaras, and lots more. Some of these were incredibly large too, like the giant ground sloth that was as big as an African elephant and the glyptodon that was related to modern armadillos. Glyptodon had a huge bony carapace and rings of bony plates on the end of its thick tail that made it into a club-like weapon, and it was the size of a car. Both the giant ground sloths and the glyptodonts were plant-eaters, as were the notoungulates.

The notoungulates are an extinct order of hoofed animals that lived throughout South America. They were probably most closely related to rhinoceroses, horses, and other odd-toed ungulates, but they’re completely extinct with no living descendants. Some were tiny and actually looked and probably acted more like rabbits than horses, while others were massive. We talked about trigodon in episode 387, and it and many of its close relations in the family Toxodontidae were the size and build of a modern rhinoceros. Trigodon even had a small horn on its forehead. A closely related group, Litopterna, is also a completely extinct order of ungulates, which were mostly smaller and more deer-like than the notoungulates.

The Pleistocene is also called the ice age, but it’s more accurate to say that it was a series of ice ages with long periods of warmer weather in between–tens of thousands of years of warmer climate, then a colder cycle that lasted tens of thousands more years. When the glaciers were at their maximum, with ice sheets covering some parts of the world over a mile thick, or a kilometer and a half, sea levels were considerably lower because so much of the world’s water was frozen solid. That exposed more land that would ordinarily be partially or completely underwater, and it also led to a dryer climate overall. At the same time, volcanic activity in the ocean separating what is now North and South America had been building up volcanic islands for millions of years. All these factors and more combined to form the Isthmus of Panama, also called Central America, that is basically a land bridge connecting the two continents.

This started around 5 million years ago and the isthmus was fully formed by about 3 million years ago, or at least that’s the most accepted theory right now. A 2016 study suggested that the land bridge started forming far earlier than that, possibly as early as 23 million years ago, possibly 6 to 15 million years. Studies are ongoing to learn more about the timeline.

What we do know is that once the land bridge opened up, animals started migrating into this new area. Animals from North America migrated south, and animals from South America migrated north. It didn’t happen all at once, of course. It was a slow process as various animal populations expanded into Central America over generations. Some animals had trouble with the climate or couldn’t find the right foods, while others did really well and expanded rapidly.

The ancestors of some animals that made it to North America and are still around include the Virginia opossum, the armadillo, and the porcupine. Meanwhile, the ancestors of llamas, horses, tapirs, deer, canids, felids, coatis, and bears traveled to South America and are still there, along with many smaller animals like rodents. Many other animals migrated, survived for a while, but later went extinct. This included a type of elephant called the gomphothere and saber-toothed cats that migrated south, while ground sloths, terror birds, glyptodonts, capybaras, and even a type of notoungulate migrated north.

You may notice that more animals that migrated south survived into modern times. South America was much warmer overall than North America, and most animals that traveled north had trouble adapting to a colder climate and competing with animals that were already well-adapted to the cold. Animals traveling south encountered warmer climates early, and if they were able to tolerate hot weather they didn’t have to worry about any climactic shocks on the rest of their journey south. As a result, North American animals were able to establish themselves in larger numbers, which helped them adapt even faster since more babies were being born and surviving.

One South America to North America success story is the porcupine. Porcupines are rodents, and there are two groups, referred to as old world and new world porcupines. Those are not great terms but that’s what we have right now. The old world porcupines are found in parts of Africa, Asia, and Italy, although they were once more widespread in Europe, while new world porcupines are found in parts of North and South America. Old world porcupines live exclusively on the ground and are larger overall than new world ones, which spend a lot of time in trees. Surprisingly, the two groups are only distantly related. They evolved spines separately. They’re also only very distantly related to hedgehogs.

The one thing everyone knows about the porcupine is that it has quills, long sharp spines that make hedgehog spines look positively modest. Porcupine quills are dangerous. They’re modified hairs, and actual hair grows in between the quills, but they’re covered in strong keratin plates and are extremely sharp. They also come out easily and regrow all the time. A porcupine can hold its spines down flat so it won’t hurt another porcupine, which is what they do when they mate.

Only one species of porcupine lives in North America, called the North American porcupine. It lives throughout much of the northern and western part of the continent, from way up in the far north of Canada down to central Mexico, although it doesn’t live in most of the southeast. We don’t know if the North American porcupine developed after South American porcupines migrated north, or if it developed much earlier, around 10 million years ago. Porcupine experts have been arguing about this for years, because there aren’t very many porcupine fossils to study.

Then a nearly complete fossil porcupine was discovered in Florida. It was such a big deal that the scientific team that discovered it decided to create an entire college course for paleontology students to help study the specimen. The resulting study was published in May of 2024, and the results suggest that the North American porcupine evolved a lot longer ago than the Isthmus of Panama formed.

The North American porcupine had to change a lot to withstand the intense cold when its ancestors were tropical animals. The North American porcupine is very different from its South American cousins. It spends less time in trees and doesn’t have a prehensile tail, it eats a lot of bark instead of mostly leaves, and it has thick insulating fur between its quills. The fossilized specimen discovered in Florida still had a prehensile tail and didn’t have the strong jaw it needed to gnaw bark off trees, but it already showed a lot of adaptations that are seen in the North American porcupine but not in South American species.

Ultimately, of course, a lot of large animals went extinct around 12,000 to 10,000 years ago, the end of the Pleistocene. Animals like mammoths that were well-adapted to cold died out as the climate warmed, and so did their predators, like dire wolves and the American lion. The notoungulates and other megaherbivores in South America went extinct too.

One animal that I haven’t mentioned yet that migrated south successfully was Homo sapiens. Maybe you’ve heard of them. Until very recently, the accepted time frame for humans migrating into South America was about 16,000 years ago, although not everyone agreed. But in July of 2024, a new study pushed that date back to 21,000 years ago.

The study examined glyptodont fossils found in what is now Argentina. The fossils were found on the banks of a river and were determined to show butchering marks from stone tools. The bones were dated to almost 21,000 years ago, which means that humans probably moved into South America a lot earlier than that. It takes time to travel from Central America down to Argentina.

One detail most people don’t know about when it comes to the Great American Interchange is how marine animals were affected. It was exactly opposite for them. Instead of a new land to explore, which caused very different animals to encounter each other for the first time, the Isthmus of Panama cut populations of marine animals from each other. They’ve been evolving separately ever since. So I guess whether a land bridge is bad or good depends on your point of view.

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at [email protected]. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

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