Monthly Archives: November 2022

Episode 304: Animals of the Paleogene

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Thanks to Pranav for suggesting this week’s topic, animals of the Paleogene, the period after the Cretaceous! Thanks also to Llewelly for suggesting the horned screamer, now one of my favorite birds.

Further watching:

Southern Screamers making noise

Horned Screamers making noise

Further reading:

The Brontotheres

Presbyornis looked a lot like a long-legged goose [art by Smokeybjb – CC BY-SA 3.0]

The southern screamer (left) and horned screamer (right), probably the closest living relation to Presbyornis:

Megacerops was really really big:

All four of these illustrated animals are actually megacerops, showing the variation across individuals of nose horn size:

Uintatherium had a really weird skull and big fangs:

Pezosiren didn’t look much like its dugong and manatee descendants:

Show transcript:

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

This week we’re going to look at some strange animals of the Paleogene period, a suggestion from Pranav. Pranav also suggested the naked mole-rat that we talked about in episode 301, but I forgot to credit him in that one.

As we talked about in episode 240, about 66 and a half million years ago, a massive asteroid smashed into the earth and caused an extinction event that ended the era of the dinosaurs. The geologic time period immediately after that event is called the Paleogene, and paleontologists study this era to learn how life rebounded after the extinction event. We’re going to learn about a few animals that evolved to fill ecological niches left vacant after dinosaurs went extinct.

These days, mammals fill a whole lot of these ecological niches, so it’s easy to assume that mammals have been successful for the last 66 million years. But while that’s true now, birds were incredibly successful for a long time. Basically for millions of years after the non-avian dinosaurs died out, it was dinosaurs 2.0 as the avian dinosaurs, better known as birds, spread throughout the world and evolved into some amazing organisms.

This included terror birds, which we talked about in episode 202. They lived in South America, except for one species from North America, and evolved really soon after the dinosaurs went extinct, appearing in the fossil record about 60 million years ago. They lasted a long time, too, only going extinct around 2 million years ago.

The earliest known terror bird was about three feet tall, or 91 cm, but its descendants became larger and more fearsome until they were apex predators throughout South America. The biggest species grew up to ten feet tall, or three meters, with a massive beak and sharp claws on its toes. It couldn’t fly but was a fast runner. You would not want a terror bird chasing you.

Lots of other birds evolved throughout the Paleogene, but most of them would look pretty familiar to us today. Paleontologists have found fossils of the ancestors of many modern birds, including penguins, hummingbirds, and parrots, which shows that they were already specialized some 25 or 35 million years ago or even more. In the case of penguins, we have fossils of penguin ancestors dating back to the late Cretaceous, before the extinction event. Those ancient penguins could probably still fly, but it didn’t take too long to evolve to be a fully aquatic bird. The species Waimanu manneringi lived around 62 million years ago in what is now New Zealand. It resembled a loon in a lot of ways, with its legs set well back on its body, and it probably spent much of its time floating on the water between dives. But unlike a loon, it had lost the ability to fly and its wings were already well adapted to act as flippers underwater.

Another bird would have looked familiar at first glance, but really weird when you gave it a second look. Presbyornis lived between about 62 and 55 million years ago in what is now North America, and it lived in flocks around shallow lakes. It was the size of a swan or goose and mostly shaped like a goose, with a fairly chonky body and a long neck. It had a large, broad duckbill that it used to filter small animals and plant material from the water and its feet were webbed…but its legs were really long, more like a heron’s legs.

When the first Presbyornis fossils were found in the 1920s, the scientists thought they’d found ancient flamingos. But when a skull turned up, Presbyornis was classified with ducks and geese. It wasn’t very closely related to modern ducks and geese, though. Researchers now think its closest modern relation is a South American bird called the screamer. Llewelly suggested the horned screamer a long time ago and now that I have learned more about these birds, I love them so much!

The screamer looks sort of like a goose but has long, strong legs and a sharp bill more like a chicken’s. It lives in marshy areas and eats pretty much anything, although it prefers plant material. It has two curved spurs that grow on its wings that it uses to defend its territory from predators or other screamers, and if a spur breaks off, which it does pretty often, it grows back. The screamer mates for life and both parents build the nest together and help take care of the eggs and chicks when they hatch.

The horned screamer has a long, thin structure that grows from its forehead and looks sort of like a horn, although it’s not a horn. It’s wobbly, for one thing, but it’s also not a wattle. It grows throughout the bird’s life and may break off at the end every so often, and it’s basically unlike anything seen in any other bird. Maybe presbyornis had something similar, who knows?

The screamer gets its name from its habit of screaming if it feels threatened or if it just encounters something new or that it doesn’t like. The screaming is actually more of a honking call that sounds like this:

[screamer call]

People sometimes raise screamers with chickens to act as guard birds. It can run fast but it can swim faster, and it can also fly although it doesn’t do so very often. Although it’s distantly related to ducks, its meat is spongy and full of air sacs that help keep it afloat in the water, so people don’t eat it. It is vulnerable to habitat loss, though.

One organism that evolved early in the Paleogene was grass. You know, the plant that a whole lot of animals eat. There are lots and lots of different types of grass, not just the kind we’re used to mowing, and as the Paleogene progressed, it became more and more widespread. But it wasn’t as ubiquitous as it is now, so even though the ancestors of modern grazing animals evolved around the same time, they weren’t grazers yet. The word graze comes from the word grass, but ancient ancestors of horses and other grazing animals were still browsers. They ate all kinds of plants, and didn’t specialize as grazers until grasses really took off and huge grasslands developed in many parts of the world, around 34 million years ago.

Because the Paleogene lasted so long, between about 66 and 23 million years ago, there’s literally no way we can talk about more than a few animals that lived during that time, not in a single 15-minute episode. We’ve also covered a lot of Paleogene animals in previous episodes, like paraceratherium in episode 50, the largest land mammal known. It probably grew up to about 16 feet tall at the shoulder, or 5 meters, and taller if you measured it at the top of its head. Other examples are moeritherium, an ancient elephant relation we talked about in episode 18, the giant ground sloth that we talked about in episode 22, and the ancient whale relation basilosaurus that we talked about in episode 132. Patrons also got a bonus basilosaurid episode this month. But I’m pretty sure we’ve never talked about brontotheres.

Brontotheres first appear in the fossil record around 56 million years ago and they lived until at least 34 million years ago. All animals in the family Brontotheriidae are extinct, but they were closely related to horses. They didn’t look like horses, though; they looked a lot like weird rhinoceroses, although remember that rhinos are also related to horses. They were members of the odd-toed ungulates, along with tapirs and the gigantic Paraceratherium.

Fossil remains of brontotheres have been found in North America, a few parts of eastern Europe, and Asia, although they might have been even more widespread. The earliest species were only about three and a half feet tall at the shoulder, or about a meter, but later species were much larger. While they looked a lot like rhinos, they didn’t have the kind of keratin hose horns that rhinos have. Instead, some species had a pair of horns made of bone that varied in shape and size depending on species. The horns were on the nose as in rhinos, but were side-by-side.

Brontotheres developed before grasslands became widespread, and instead they were browsers that mostly ate relatively soft vegetation like leaves and fruit. Grass is really tough and animals had to evolve specifically to be able to chew and digest it. In fact, the rise of grasslands as the climate became overall much drier around 34 million years ago is probably what drove the brontotheres to extinction. They lived in semi-tropical forests and probably occupied the same ecological niche that elephants do today. This was before elephants and their relations had evolved to be really big, and brontotheres were the biggest browsing animals of their time.

Brontotheres probably lived in herds or groups of some kind. They were widespread and common enough that they left lots of fossils, so many that they were found relatively often in North America even before people knew what fossils were. The Sioux Nation people were familiar with the bones and called them thunder horses. When they were scientifically described in 1873 by Othniel Marsh, he named them after the Sioux term, since brontotherium means “thunder beast.”

Two of the biggest brontotheres lived at about the same time as each other, around 37 to 34 million years ago. Megacerops lived in North America while Embolotherium lived in Asia, specifically in what is now Mongolia. Megacerops is the same animal that’s sometimes called brontotherium or titanotherium in older articles and books.

Megacerops and Embolotherium were about the same size, and they were huge, although Embolotherium was probably just a bit larger than Megacerops. They stood over 8 feet tall at the shoulder, or 2.5 meters, and were more than 15 feet long, or 4.6 meters. This is much larger than any rhinos alive today and as big as some elephants. Their legs would probably have looked more like an elephant’s legs than a rhinoceros’s.

Brontothere nose horns weren’t true horns, since they don’t seem to have been covered with a keratin sheath, but they were formed from protrusions of the nasal bones. They might have been more like ossicones, covered with skin and hair. Megacerops had a pair of nose horns that were much larger in some individuals than others, and scientists hypothesize that males had the larger horns and used them to fight each other.

But this can’t have been the case for embolotherium. It had even bigger nose horns that were fused together in a wedge-shaped plate sometimes referred to as a ram, but they contained empty chambers inside that were a continuation of the nasal cavities. They wouldn’t have been strong enough to bash other embolotheriums with, but they might have acted as resonating chambers, allowing embolotherium to communicate with loud sounds. All individuals had these nose horns, even juveniles, and they were all about the same size, which further suggests that they had a purpose unrelated to fighting.

At about the same time the brontotheres were evolving, another big browsing animal also lived in what are now China and the United States. Two species are known, one in each country, and both stood about 5 feet tall at the shoulder, or 1.5 meters. It looked sort of like a brontothere in some ways, but very different in other ways, especially its weird skull, and anyway it was already big around 56 million years ago when brontotheres were still small and unspecialized.

Scientists aren’t sure what uintatherium was related to. It’s been placed in its own genus, family, and order, although some other uintatherium relations have been discovered that share its weird traits. Most scientists these days think it was probably an ungulate.

Uintatherium’s skull was extremely strong and thick, which didn’t leave a whole lot of room for brains. But what uintatherium lacked in brainpower, it made up for in sheer defensive ability. It had huge canine teeth that hung down like a sabertooth cat’s fangs, although males had larger fangs than females. Males also had three pairs of ossicones or horns on the top of the skull that pointed upwards. One pair was on the nose, one pair over the eyes, and one pair almost on the back of the skull. They could be as much as 10 inches long, or 25 cm, and paleontologists think that males wrestled with these horns the same way male deer will lock antlers and wrestle.

Uintatherium lived in the same habitat and probably ate more or less the same type of plants that later brontotheres did. They went extinct around the time that brontotheres evolved to be much larger, which suggests that brontotheres may have outcompeted uintatherium.

We’ll finish with one more Paleogene mammal, Pezosiren. It was only described in 2001 from several incomplete specimens discovered in Jamaica in the 1990s, and it lived between 49 and 46 million years ago.

Pezosiren was about the size of a pig, although it had a longer, thicker tail compared to pigs. It wasn’t any kind of pig, though, and in fact it was distantly related to elephants. It was the oldest known ancestor of modern sirenians. Pezosiren is also called the walking siren, because it still had four legs and probably spent at least part of the time on land, although it could swim well. Scientists think it probably swam more like an otter than a sirenian, propelling itself through the water with its hind legs instead of its tail.

Pezosiren was probably semi-aquatic, sort of like modern hippos, and already shows some details specific to sirenians, especially its heavy ribs that would help it stay submerged when it wanted to. It ate water plants and probably stayed in shallow coastal water. At different times in the past, Jamaica was connected to the North American mainland or was an island on its own as it is now, or occasionally it was completely submerged. About 46 million years ago it submerged as sea levels rose, and that was the end of Pezosiren as far as we know. But obviously Pezosiren either survived in other areas or had already given rise to an even more aquatic sirenian ancestor, because while Pezosiren is the only sirenian known that could walk, its descendants were well adapted to the water. They survive today as dugongs and manatees.

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. If you like the podcast and want to help us out, leave us a rating and review on Apple Podcasts or Podchaser, or just tell a friend. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Episode 303: Weird and Mysterious Animal Sounds

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Thanks to Emory for suggesting this week’s topic, mysterious animal sounds!

Further reading/watching:

The Story of Elk in the Great Smoky Mountains

Terrifying Sounds in the Forests of the Great Smoky Mountains

Evidence found of stingrays making noise

This New AI Can Detect the Calls of Animals Swimming in an Ocean of Noise

The wapiti [pic from article linked above]:

The stingray filmed making noise [stills from video linked to above]:

The tawny owl makes some weird sounds:

The fox says all kinds of things:

Show transcript:

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

Emory suggested we do a new episode about strange and mysterious animal sounds a while back, which is one of my favorite topics. The problem is, it’s hard to find good audio clips to share. It’s taken me a while, but I think I’ve found some good ones.

In late September 2018, in the Great Smoky Mountains in North Carolina, some hikers recorded a terrifying animal sound. The sound wasn’t a mystery for long, though, because they soon saw the animal making it. Here’s what it sounded like:

[elk bugle]

It’s the bugle of a male elk, which I’m going to call wapiti to avoid confusion. It’s a sound that wasn’t heard in the Smoky Mountains for at least a century. The eastern wapiti was once common throughout eastern North America but was driven to extinction in the late 19th century, although the last wapiti in North Carolina was killed almost a century earlier than that. All North American wapiti almost went extinct by about 1900, and hunters and conservationists worked to get nature preserves set aside to save it and its habitat. Starting in the 1990s, wapiti from western North American subspecies were reintroduced in the southeast, with reintroductions in the Smokies starting in 2001. There are now at least 200 wapiti living in the mountains, probably more. I’ve seen them myself and they’re beautiful animals!

The wapiti is a type of deer. We talked about it way back in episode 30 along with the moose. Various species of wapiti live throughout Europe and Asia as well as North America, although it’s been hunted to extinction in many areas. As we mentioned in episode 30, the name elk is used for the moose in parts of Europe, which causes a lot of confusion, which is why I’ve chosen to call it by its Algonquin name of wapiti.

The wapiti is a really big animal, one of the biggest deer alive today. Only the moose is bigger. It’s closely related to the red deer of Eurasia but is bigger. A male, called a bull, can stand about 5 feet tall at the shoulder, or 1.5 meters, with an antler spread some four feet wide, or 1.2 meters. Females, called cows, are smaller and don’t grow antlers. Males grow a new set of antlers every year, which they use to wrestle other males in fall during mating season. At the end of mating season the wapiti sheds its antlers.

The bugling sound males make during mating season is extremely loud. The sound tells females that the bull is strong and healthy, and it tells other bulls not to mess with it.

[elk bugle]

Our next sound is from an animal that scientists didn’t realize could even make sounds. There’ve been reports for a long time of stingrays making clicking noises when they were alarmed or distressed, but it hadn’t been documented by experts. A team of scientists recently decided to investigate, with their report released in July of 2022. They filmed stingrays of two different species off the coasts of Indonesia and Australia making clicking sounds as divers approached. They think it may be a sound warning the diver not to get too close. This is what it sounds like:

[Stingray making clicking sounds]

One exciting new technological development is being used to detect underwater sounds and hopefully help identify them. It’s called DeepSqueak, because it was originally developed to record ultrasonic calls made by mice and rats. This is an example of a mouse sound slowed down enough that humans can hear it, specifically a male mouse singing to attract a mate, which we talked about in episode 8:

[mouse song]

But DeepSqueak also works really well to detect sounds made by whales and their relatives, and researchers are currently using it to determine whether offshore wind farms cause problems for whales.

With DeepSqueak and other listening software, it turns out that a lot of animals we thought were silent actually make noise. For instance, this sound:

[Pelochelys bibron]

That’s a grunting sound made by the southern New Guinea giant softshell turtle.

And here’s a caecilian, a type of burrowing reptile that we talked about in episode 82:

[Typhlonectes compressicauda]

Let’s finish with a strange and mysterious sound heard on land. In January and February of 2021, some residents of London, England started hearing a weird sound at night.

[mystery sound]

Because the animal making the sound moved around so much, some people thought it must be a bird. One suggestion is that it was a tawny owl, especially the female tawny owl who makes a chirping sort of sound to answer the male’s hoot. This is what the male and female tawny owl sound like:

[owl sounds]

The tawny owl also sometimes makes an alarm call that sounds like this:

[tawny owl alarm call]

But the sound didn’t really match up with what residents were hearing. Here it is again:

[mystery sound]

Finally someone pointed out that red foxes make a lot of weird sounds, mostly screams and sharp barks, but occasionally this sound:

[fox sound]

That seems to be a pretty good match for what people were hearing in early 2021, although since no one got a look at the animal they heard, we can’t know for sure. So it’s still a mystery.

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. If you like the podcast and want to help us out, leave us a rating and review on Apple Podcasts or Podchaser, or just tell a friend. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Episode 302: The Coatimundi and a Mysterious Friend

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Thanks to Oceana, Leo, and Alexandra for suggesting the coatimundi this week!

Further reading:

Caught red handed: The mystery of an unusual Panamanian plant’s dispersal

The coatimundi has a long tail and a long nose:

The olingo sitting on a cloud cycad seed pod. Mystery solved!

The olingo in daylight:

My new podcasting studio!

Show transcript:

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

This week we’re going to talk about an animal suggested by several people. Thanks to Oceana, Leo, and Alexandra for suggesting the coatimundi, also called the coati! We’re also going to learn about a related animal mystery that was the subject of a Patreon episode earlier this year, because it ties in so well.

The coatimundi looks superficially like a type of monkey, or maybe a lemur, but it’s not a primate at all. It belongs to the family Procyonidae, which includes raccoons, kinkajous, and a few others. Procyonids are native to the Americas, and some scientists think they may be very distantly related to canids. Since a lot of Procyonids have bushy ringed tails, at one point the red panda was classified as a relation, but it’s since been reclassified into a family all its own that doesn’t appear to be related.

The coati lives in much of South America, Central America, and southern North America, including Mexico and parts of the American southwest. It’s mostly gray-brown or reddish-brown in color, with some white markings around the eyes and muzzle. Males are much bigger than females on average, but in general the coati isn’t that much bigger than a domestic cat. It has a long, thick tail that sort of resembles a cat’s tail except that it’s even longer in relation to its body. Some coatis have rings around the tail but some don’t. It depends on the species and the individual.

The coati uses its long tail to help it balance in trees, since it does a lot of climbing. Its hind feet can rotate so that they’re backwards, which means it can climb down trees headfirst. Procyonids can all do this, but so can some unrelated animals like weasels, due to convergent evolution. The coati also uses its long tail to keep track of its friends when they’re traveling through long grass. It sticks its tail straight up so that it’s visible above the grass. Since female coatis live in social groups of up to 40 individuals, keeping track of friends is important.

The coatimundi doesn’t worry too much that predators might see its tail sticking up and run over for a coati-sized snack. While jaguars, cougars, large eagles, and a few other predators do eat coatis, for the most part other animals leave them alone. The coati has sharp teeth, sharp claws, and it’s strong and fast for its size. It can be ferocious when it needs to, and of course it has its equally ferocious friends to help out. Plus, the coati is intelligent. In a 2013 study, the female coati’s brain was found to have a very large frontal cortex, which is the part of the brain that handles sociability. Male coatis had smaller frontal cortexes, since males spend most of the time by themselves or in small bachelor groups except during mating season. And as we’ve learned when talking about other animals, the more complex an animal’s social structure, the more intelligent it’s likely to be.

The coati’s ears are small and its snout is long and thin and turns slightly upwards, which makes it look a little like a piggy nose. But unlike a pig’s nose, the coati’s is extremely flexible. It uses its nose to root around in leaf litter and dirt to find food. It’s an omnivore that’s happy to eat pretty much anything, from fruit and other plant material, to insects and other invertebrates, including tarantulas, to eggs and small animals. It has a strong sense of smell and clever front paws that help it dig up grubs, termites, and other yummy things. It sleeps with its nose tucked into its belly fur and its long tail wrapped around it.

When a female coati is ready to have babies, called kits, she leaves her group and builds a little nest in a tree. She gives birth there and takes care of her kits alone for about six weeks. At that point the babies can travel well and the whole family rejoins the other females and their offspring. The females take turns babysitting younger kits and watching for danger.

Next, let’s learn about another Procyonid, this one associated with a mystery. But to learn about the mystery we need to start not with an animal, but with a plant. Zamia pseudoparasitica is a type of cycad that only lives in the montane cloud forests in western Panama, in Central America. Even though the cycad is a plant that resembles a palm tree, this particular plant grows in the treetops instead of on the ground.

Because Z. pseudoparasitica is a mouthful, I’m going to call it the cloud cycad.

The cloud cycad has a short trunk without branches, but its leaves are almost 10 feet long, or 3 meters. They look like palm fronds. It grows on other trees, clinging to the branches with its roots, but it doesn’t actually parasitize the tree. That’s why its name is pseudoparasitica: pseudo means false, so it only looks like a parasitic plant growing on a bigger plant.

The cloud cycad starts out by growing upward from a branch as much as 65 feet above the ground, or 20 meters, but as it gets bigger and heavier, it slips down around the branch and hangs upside down. Then its trunk starts bending upward to get more light, so it grows in a sort of U shape.

The term for a plant that lives on other plants without being a parasite is epiphytic. Many epiphytic plants get their nutrients from rain, decomposition of leaves and other organic material near their roots, and other external sources since they don’t have access to soil. They’re often really good at absorbing water quickly too. Spanish moss, some ferns, lichens, and orchids are all good examples, but only one cycad is epiphytic, our cloud cycad.

The cloud cycad produces large yellow or orange seeds in cones, and when the seeds are ripe they have a pungent smell. But here’s the mystery about this strange plant: how do its seeds get dispersed to other trees? The cloud cycad never grows on the ground, and researchers think any seeds that fall to the ground just lie there until something eats them.

An animal has to be helping in some way, possibly by eating the seeds and pooping them out somewhere else. That’s why so many seeds are encased in sweet-tasting tissues. People suspected that fruit bats were the main seed disperser, but no one knew for sure.

In late 2019, a team of young scientists decided to get to the bottom of the mystery. They climbed trees and placed cameras pointing at cloud cycads to see what animals visited them. This was hard work, as you can probably imagine, because those trees are really big; but finally they got the cameras set up. Then, in early 2020, right before Panama went into lockdown due to Covid-19, they had to go back and climb the same trees to retrieve the cameras. Then they had to download the photographs from each and go through them.

Lots of animals were caught on camera, including seven species of mammal. Monkeys, kinkajous, and opossums all gave the seed cones a sniff or two, but only one animal actually collected the seeds. And that animal was the olingo!

The northern olingo is a Procyonid, and is probably the coatimundi’s closest relation. It’s gray-brown in color with a rounded face and short muzzle, small round ears that are low on its head, and claws that help it climb around in trees. It’s mostly nocturnal and mostly eats fruit, and it spends most of its time in the treetops. It’s a slender animal that grows about 20 inches long, or 50 cm, not counting its tail, which is about as long as its body and which it uses for balance. If you look closely, its tail has very faint rings of dark and light fur.

We don’t know a whole lot about the olingo, but we now know it probably eats the seeds of the cloud cycad because it’s been caught on camera grabbing up to four of the seeds at a time and carrying them off.

The scientists still have a lot of work to do to find out more about how the olingo helps disperse the cloud cycad’s seeds, assuming it actually does. The team thinks the olingo might cache seeds like some squirrels do, hiding them in various places around its treetop territory until it’s hungry. If so, in at least some cases, just like with squirrels, some of the seeds are forgotten and germinate to grow new plants.

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. If you like the podcast and want to help us out, leave us a rating and review on Apple Podcasts or Podchaser, or just tell a friend. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Episode 301: Hairless Mammals

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Thanks to Liesbet for this week’s suggestion, about two mammals that have evolved to be hairless!

Happy birthday this week to Declan and Shannon!

The hairless bat has a doglike face and a doglike tail but (and this is important) it is not a dog [photos from this site]:

The naked mole-rat’s mouth is behind its teeth instead of the usual “my teeth are in my mouth” kind of thing:

Show transcript:

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

This week we have a suggestion from Liesbet, who asked about furless animals. We’re going to learn about two mammals that don’t have fur, and they’re not ones you may be thinking of.

But first, we have two birthday shout-outs! Happy birthday to Declan and Shannon! I hope both your birthdays are so amazing that whatever town you live in finishes off the day by giving you the key to the city. What do you do with the key? I don’t know, but it sounds like something to brag about.

Mammals are famous for having hair, but not all mammals actually have hair. Cetaceans like whales and dolphins have lost all their hair during their evolution into marine animals, although before a baby whale is born it has a little bit of fuzzy hair on its head. Other mammals, like humans, pigs, walruses, and elephants, have evolved to only have a little hair. There are also domesticated mammals that have been bred to have no hair, like sphynx cats and Chinese crested dogs.

There are other domesticated hairless mammals, though, including two types of guinea pig. The skinny pig only has a little bit of fuzzy hair on its face and ears, while the baldwin pig only has a tuft of hair on its nose. But the animals we’re going to talk about today are hairless animals you may not have heard of.

For instance, the hairless bat, which lives in parts of Southeast Asia. Its dark gray body is almost completely hairless, although it does sometimes have little patches of fuzz on the head and tail, and longer bristles around the neck. It’s nocturnal and eats insects, but since it’s a fairly large bat, around 6 inches long, or 15 cm, it can eat fairly large insects. It especially likes grasshoppers, termites, and moths.

The hairless bat roosts in colonies of up to a thousand individuals, and it lives in caves, hollow trees, or rock crevices. Although it uses echolocation, it doesn’t have a nose leaf like many microbats have, but instead has a little doglike snout. Its tail is skinny like a little dog’s tail instead of being connected to the hind legs or body by patagia. It has a little throat pouch that secretes strong-smelling oil.

It also has a sort of pocket on either side of the body. Originally people thought that mother bats used these pouches to carry their babies, since hairless bats usually have two babies at a time. Instead, it turns out that mother bats leave their babies at home when they go out to hunt, and the pockets are used for something else. The pockets are formed by a fold of skin and the end of the wing fingers and membranes fit into them. The bat uses its hind feet to push the wings into the pockets, sort of like stuffing an umbrella into the little cover that it comes in when you first buy it. This allows the bat to run around on all fours without its wings getting in the way. Since most bats can’t walk on all fours at all, this is pretty amazing.

Our other hairless animal today is the naked mole-rat, which is not a mole or a rat. It is a type of rodent but it’s more closely related to porcupines than to rats. It lives in tropical grasslands in parts of East Africa and spends almost its entire life underground. It lives in colonies of up to 300 individuals, and the colony’s tunnels and nesting burrows are extensive, often covering up to 3 miles, or 5 km. It eats roots of plants and the colony carefully only eats part of each root so that they don’t kill the plant. The roots continue to grow, providing the colony with lots of food.

The naked mole-rat grows about 4 inches long, or 10 cm, although dominant females are larger. It has tiny eyes and doesn’t see very well, since most of the time it doesn’t need to see, and it has a chonky body but short, spindly legs. It pretty much has no hair except for whiskers and some tiny hairs between the toes, and its skin is so pale it’s almost translucent. It digs with its protruding front teeth, and these teeth are not in its mouth. They grow out through the skin and the animal’s mouth is actually behind the teeth. This way the mole-rat can dig without getting dirt in its mouth, but it sure looks weird to us.

But that’s not even close to the weirdest thing about the naked mole-rat. We haven’t even scratched the surface of weirdness!

The naked mole-rat lives underground in a part of the world where it’s always warm, and its tunnel system has no exits to the surface except for temporary exits when new tunnels are being excavated, because the dirt has to go somewhere. Its environment is so consistent in temperature that it doesn’t need to regulate its body temperature like every other mammal known. It’s ectothermic, which is sometimes called cold-blooded. Reptiles and amphibians are ectothermic but all other mammals known are endothermic. It’s kind of our thing. But the naked mole-rat is different. Its metabolism is extremely low, and as a result it can live for more than 30 years when most rodents the same size are lucky to live 2 or 3 years.

The naked mole-rat’s skin isn’t just hairless, it also lacks neurotransmitters. This means its skin doesn’t feel pain. The animal also lives in an environment that’s remarkably low in oxygen, and scientists think this contributes to the fact that the mole-rat never shows evidence of cancer except in captivity where its environment is higher in oxygen.

The naked mole-rat’s colony is led by a dominant female, called a queen, and she’s the only female in the colony that has babies. When a female achieves dominance, either by founding a new colony, taking over after the current queen dies, or defeating the current queen in a fight, she then grows larger and becomes able to reproduce. Only a few males in the colony mate with her. All the other members of the colony are unable to reproduce. They’re considered workers and help take care of the queen’s babies, maintain tunnels, forage for food, or act as soldiers to keep snakes and other predators out. If this sounds like the way some insect colonies are structured, especially bees and ants, you’re right. It’s called eusociality and the mole-rat is the only type of mammal known with this sort of social structure. There’s another type of mole-rat from southern Africa that’s also eusocial, but it has fur.

All that is so weird that I almost forgot the mole-rat is hairless. That now seems like the most normal thing about it.

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