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Episode 324: The Tenrec and Adalatherium

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Thanks to Eva and Leo for suggesting the tenrec!

Further reading:

Marooned on Mesozoic Madagascar

Introduction to Adalatherium hui

The lowland streaked tenrec:

The hedgehog tenrec rolls up just like an actual hedgehog [photo by Rod Waddington, CC BY-SA 2.0, via Wikimedia Commons]:

Actual hedgehog, not a tenrec:

Lesser hedgehog tenrec REALLY looks like an actual hedgehog [By Wilfried Berns www.Tierdoku.com – Transferred from de.wikipedia to Commons.Orig. source: eigene Fotografie, CC BY-SA 2.0 de, https://commons.wikimedia.org/w/index.php?curid=2242515]:

Adalatherium:

Show transcript:

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

This week we’re going to learn about a weird little animal suggested by both Eva and Leo, the tenrec of Madagascar. While we’re at it, we’re going to learn about another little animal found on Madagascar a long time ago that’s one of the weirdest mammals ever discovered.

Before we get started, though, someone sent me a book! If your name is Jennifer or someone named Jennifer mailed this book to me for you, thank you! The book is called The Last Flight of the Scarlet Macaw: One Woman’s Fight to Save the World’s Most Beautiful Bird by Bruce Bercott. Thank you so much! I did not know when I started this podcast over six years ago that one of the benefits of doing an animal podcast is sometimes people send you books about animals, which is the best thing in the world. There’s no note so I thought I’d give you a shout-out on the podcast.

As we learned in episode 318, about 88 million years ago, the island of Madagascar broke off from every other landmass in the world, specifically the supercontinent Gondwana. The continent we now call Africa separated from Gondwana even earlier, around 165 million years ago. Madagascar is the fourth largest island in the world and even though it’s relatively close to Africa these days, many of its animals and plants are much different from those in Africa and other parts of the world because they’ve been evolving separately for 88 million years.

But at various times in the past, some animals from Africa were able to reach Madagascar. We’re still not completely sure how this happened. Madagascar is 250 miles away from Africa, or 400 kilometers, and these days the prevailing ocean currents push floating debris away from the island. In the past, though, the currents might have been different and some animals could have arrived on floating debris washed out to sea during storms. During times when the ocean levels were overall lower, islands that are underwater now might have been above the surface and allowed animals to travel from island to island until they reached Madagascar.

Sometime between 25 and 40 million years ago, a semiaquatic mammal reached Madagascar in enough numbers that it was able to establish itself on the island. It was related to the ancestors of a semiaquatic mammal called the otter-shrew, even though it’s neither an otter nor a shrew. The otter-shrew lives in parts of Africa and is pretty weird on its own, but we’ll save it for another episode one day. The otter-shrew’s relative did so well in its new home of Madagascar that over the millions of generations since, it developed into dozens of species. We now call these animals tenrecs.

It’s hard to describe the tenrec because the various species are often very different in appearance. There are some things that are basically the same for all species, though. First, the tenrec has a low body temperature, although it varies from species to species and also varies depending on time of year. That’s because some species of tenrec go into torpor when it’s cold, or sometimes full hibernation. During torpor the animal’s body temperature drops even more than usual. The common tenrec hibernates up to nine months out of the year.

Second, the tenrec has a cloaca, which is really unusual in placental mammals. Birds, reptiles, and amphibians have a cloaca, which is a single opening used for excretion and often for giving birth or laying eggs too. Most mammals have separate openings for different uses.

Third, all tenrecs are pretty small with only a little short tail. The biggest is only a little over a foot long at most, or 39 cm, and most are much smaller.

Leo specifically likes the streaked tenrec, so let’s learn about it to give us a better idea of what tenrecs are like in general. There are two species of streaked tenrec and while they live in different parts of Madagascar, they mostly live in tropical rainforests. They’re considered a type of spiny tenrec because they have quills all over like a tiny porcupine or a brightly colored hedgehog. The highland streaked tenrec is black and white, while the lowland streaked tenrec is black and yellow.

The streaked tenrec’s bright coloration gives a warning to potential predators that it is pointy. If a predator doesn’t figure it out, the tenrec will raise its quills and shake them to make a little rattling sound. If that doesn’t stop the predator and it tries to bite the tenrec, the quills can detach and will lodge in the predator’s mouth. That generally gets the point across. (haha, point)

The lowland streaked tenrec also communicates by rubbing its quills together to make ultrasonic sounds. This method of sound production is called stridulation and the streaked tenrec is the only mammal known to make sound this way. It has special muscles at the base of its quills that help it move the quills to make sounds. Stridulation is mostly found in insects, including crickets.

Like most tenrecs, the streaked tenrec has a long, thin snout and short legs. It spends a lot of its time digging for earthworms and other invertebrates, and it also eats fruit. It lives in family groups that sleep in shallow burrows. Also, it’s super cute. Just don’t lick it.

Another tenrec with spines is the hedgehog tenrec, which looks and acts incredibly like a hedgehog even though it’s not related. That’s yet another example of convergent evolution. The lesser hedgehog tenrec and the greater hedgehog tenrec, which by the way belong to different genera, are nocturnal animals that live in open forests, savannas, and people’s gardens in Madagascar. During the day it stays hidden in dead leaves or brush, or in a hollow of a tree trunk, and at night it comes out to find insects and other small animals to eat. If it feels threatened, it will roll up into a ball to protect its belly while turning itself into a very pointy mouthful. Its spines don’t come loose the way the streaked tenrec’s do, but they’re sharp. Sometimes a hedgehog tenrec will back up quickly toward a potential predator. If it backs into the predator’s nose, suddenly the predator discovers it’s not all that hungry and its nose hurts and it’s just going to leave.

Many species of tenrec resemble shrews. They’re smaller than a mouse, which they otherwise resemble except that they have a long nose and short tail, and they don’t have quills. Most tenrecs have 6 or 8 babies at a time, but some have more. The common tenrec can have up to 32 babies at a time. It has 29 teats! That’s the most teats known in any mammal.

All this is amazing, but while I was researching the tenrec I learned about an even weirder animal that lived on Madagascar at the end of the Cretaceous. That animal wasn’t a dinosaur, though. It was a mammal.

It was discovered by a team of paleontologists in 1999, but they didn’t actually know they’d discovered it. They thought the piece of rock only contained a small crocodyliform. When preparation of the specimen started in 2002, the scientist working on it received an incredible surprise. In addition to fossil remains of both an adult and a baby crocodyliform, there was an almost complete, articulated skeleton of a weird mammal. All three animals may have been buried suddenly by debris carried by a flash flood, which is why they’re so well preserved.

Most mammals that lived alongside dinosaurs were really small, maybe the size of rats at most, but Adalatherium was about the size of a cat. It may have actually grown larger than a cat, because the only specimen we have is an individual that wasn’t fully grown. It was built sort of like a little badger, with a broad body, short legs, short tail, and short snout.

Adalatherium is a member of a group of mammals called Gondwanatheria, which arose in the southern hemisphere around the time that the supercontinent Gondwana was breaking apart. We only have a few fossils of these animals so paleontologists still don’t know how they’re related, but Adalatherium is a big deal because it’s so detailed and almost the whole skeleton is preserved. Paleontologists have known for a long time that these Gondwanatheria were probably not related to modern mammals, but until Adalatherium was discovered no one realized just how weird these animals were.

If you could go back in time to look at Adalatherium when it was alive, you might not think it was all that weird. Also, you’d be a little distracted because dinosaurs would probably be trying to eat you. Most of the weird details probably weren’t visible, but they’re very obvious to scientists studying the fossilized bones. For instance, Adalatherium had a lot of vertebrae in its backbone, more than other mammals—at least 30 total thoracic and lumbar vertebrae. Humans have 17 total and cats have 20, to give you a comparison with modern mammals.

Adalatherium also had weird legs, with its front legs not really seeming to match its rear legs. Its front legs are longer with a strong shoulder, while its rear legs are short and bowed. Paleontologists think it might have been a burrowing animal, which would explain why its rear legs are strangely shaped compared to its front legs, but it could probably run pretty fast too. It also had unusual double grooves on its anklebones.

Another weird thing about Adalatherium was its skull. The parts of the skull that made up the nasal cavity had lots of little holes in it, called foramina, for nerves and blood vessels to pass through. This isn’t unusual in itself, but Adalatherium had more foramina than any other mammal ever examined, living or extinct. One of the foramen was on top of the snout and doesn’t match up with anything seen in any other mammal. Adalatherium probably had a whole lot of very sensitive whiskers, but for all we know, all the foramina were for some other sensory structure, one that was unlike any found in modern mammals.

Adalatherium lived at the end of the Cretaceous, and it’s possible it went extinct along with the non-avian dinosaurs. Gondwanatheria in general all went extinct by around 43 million years ago and as far as we know, no living descendants are still around. But we know very little about these interesting mammals. Hopefully more fossils of Gondwanatheria in general, and Adalatherium in particular, will turn up soon so we can learn more.

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 126: The Hedgehog and the Moonrat

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This week thanks to Romy, who suggested the topic of hedgehogs! And researching hedgehogs led me to their only close relation, the moonrat.

Hedgehogs are adorable:

Pictures of listener QuillviaPlath’s adorable friend Delilah, an African pygmy hedgehog. Delilah has crossed the Rainbow Bridge since these pictures were taken, but QuillviaPlath has a rescue hedgehog named Lily now and will soon be adopting another rescue named Toodles too!

Moonrats are a little less adorable but still cute:

Show transcript:

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

This week we’re going to learn about a humble little animal that’s well-known in much of Europe, Asia, and Africa, but totally unknown in the Americas except as a pet. It’s the hedgehog, a suggestion from Romy. Thank you, Romy! We’ll also learn about the hedgehog’s closest relation, the moonrat.

There did actually used to be a hedgehog native to North America, but it went extinct some 50 million years ago. The hedgehogs alive today pretty much haven’t changed in about 15 million years. The North American hedgehog is called Silvacola and only grew a few inches long, or maybe 7 cm. It lived in what is now British Columbia, Canada. We don’t know if it had quills, but the hedgehogs living in Europe at the same time as Silvacola lived had already evolved quills, so maybe it did.

I have seen exactly one hedgehog in my life, a pet named Button. I got to pet her and everything. She was very sleepy, though, because it was daytime and hedgehogs are nocturnal. But I can verify that hedgehogs do have spines on the back and sides, although if you pet the hedgehog properly you won’t get your fingers poked by the spines. I can also verify that hedgehogs are adorable.

But other than adorable and prickly, what are hedgehogs? Are they related to porcupines? Are they related to hogs? Do they really live in hedges?

The answers are no, no, and yes. Thanks for listening. You can find Strange Animals—ha ha, just kidding!

There are a number of hedgehog species in five separate genera. A few species have been domesticated, although it’s illegal in many places to keep a wild hedgehog as a pet. In some places it’s illegal to keep a hedgehog as a pet at all, since hedgehogs can become invasive pests if released into the wild in areas where they shouldn’t be. This has happened in New Zealand and a few other places, where introduced hedgehogs have no natural predators and have become so numerous they’ve caused damage to the local ecosystems. The hedgehog is an omnivore, and will eat bird eggs, insects, frogs and toads, snails, plants, and pretty much anything else. It’s especially damaging to shore birds that nest on the ground. But in its natural habitat, the hedgehog plays an important role as both a predator of small animals, including garden pests, and as prey to larger animals like foxes, badgers, and owls.

The hedgehog will also eat small snakes, and actually has some natural immunity to certain snake venoms. Of course, if a snake injects enough venom it will overwhelm the hedgehog’s protections and make it sick or kill it anyway. It also has resistance to toxins and will eat toxic toads that would kill other animals. But the hedgehog’s best protection is its spines, more properly called quills. If a hedgehog feels threatened, it will roll itself into a tight ball with its quills sticking out.

The quills are hairs that are hollow and stiffened with keratin. Good old keratin. You know, keratin is the same tough material that fur and fingernails and rhinoceros horns and hooves and baleen are made of. European hedgehogs are famous for the number of fleas they carry, a specific species of flea called the hedgehog flea. Who named that? They were a genius. Hedgehog fleas won’t infest dogs or cats. They only like hedgehogs.

The hedgehog is a good digger and sometimes digs burrows to sleep in during the day. It’s adaptable to many habitats but likes woodlands, meadows, and, yes, hedgerows where it can find lots of food. It has a pig-like snout, short legs, a little stub of a tail, and small ears. Baby hedgehogs are born with a protective membrane over their quills. It grows to around a foot long, or 30 cm, although many of the species are typically smaller than that. Most hedgehogs are brown but some are naturally cream-colored, a rare variety called blonde. This color is bred for in domesticated hedgehogs. Button the hedgehog is blonde with a dark spot on her back, which is why she’s named Button.

The population of West European hedgehogs has decreased substantially in the last few decades, which has conservationists worried. A 2016 study reported that the population has declined over 7% in the UK over the last 50 years, with similar declines in parts of Europe like Sweden and Belgium. Researchers speculate this may be due to habitat loss.

The hedgehog can hibernate although it doesn’t always. It may hibernate in piles of leaves or sticks, or in a burrow it digs underground, or somewhere else that’s protected from predators and cold. If you’ve gathered wood for a bonfire, make sure to check the pile for sleeping hedgehogs before you get the matches out.

One of the most persistent legends about the hedgehog is that it rolls on fruit, especially apples, in order to stick its quills into the fruit. Then it goes home to its burrow, carrying the fruit on its quills to eat later.

So, do hedgehogs actually do this? Probably not. Some observers say hedgehogs will roll in leaves and allow the leaves to stick to its quills, possibly as a form of camouflage. It would be easy for one to accidentally pick up a small rotten apple this way, giving rise to the legend, although the quills aren’t strong enough to hold a large apple without breaking. The sites I read online all say that hedgehogs don’t bring food back to the burrow to eat later, but T.H. White shares an anecdote to the contrary in his Book of Beasts. This is a translation of a 12th century bestiary, and his anecdote appears in a note on page 95. The text repeats the story of hedgehogs carrying apples home, and White adds:

“The Hedgehog constructs a humble nest in ditches, and there it hibernates. In 1939, the present translator dug out such a nest, near an orchard, with an Irish laboring companion who proceeded to tell him that hedgehogs carried apples to their nests on their spines—an anecdote which the translator had just been reading in this manuscript, eight hundred years older than the Irishman. The latter asserted the truth of his statement with passion, pointing to the apples, which were indeed there, and had punctured bruises on them. But the creature had probably trundled them there with its nose, subsequently making the punctures when it curled up to sleep on top of them.”

I haven’t found anyone else who reports seeing a hedgehog push an apple home with its nose, or anything else for that matter. But the apples were in the hedgehog’s nest. T.H. White saw them. It could be the apples had fallen from a nearby tree and rolled into the ditch on their own, and the hedgehog just happened to nest on them. Then again, one source I found mentions that hedgehogs may anoint themselves with apple juice to help repel fleas and other parasites. This seems a little on the farfetched side, but the hedgehog does do a weird thing called anointing that might have something to do with controlling parasites. No one’s sure what it’s for.

Anointing seems to be triggered when a hedgehog encounters a new or unusual odor. The hedgehog starts foaming at the mouth, often contorting its body oddly, and then it licks the foam onto its quills. This happens with domesticated hedgehogs as well as wild ones, and one site I read mentions that it may happen if you handle a pet hedgehog after putting hand lotion on.

So what is the hedgehog related to? It’s not a rodent, so it’s not related to porcupines. It’s a placental mammal so it’s not related to echidnas, which are monotremes. Both porcupines and echidnas evolved quills for protection independently. The hedgehog is probably most closely related to the shrew, but the other member of its family is an animal called the moonrat.

The moonrat lives in Southeast Asia, specifically Thailand, Borneo, and Myanmar, and shares a lot of characteristics with the hedgehog, like being omnivorous and digging burrows, but it doesn’t have quills. It looks a lot like the Virginia opossum, or as it’s properly called around where I live, the possum. But the possum is a marsupial, and again, the moonrat, like the hedgehog, is a placental mammal. It also looks a little like a rat, but the rat is a rodent and the moonrat isn’t a rodent.

The moonrat has a relatively long, skinny tail that’s mostly bare of fur and is actually scaly, which makes its tail look kind of like a snake. It also hisses like a snake (it’s not a snake). (Also going to point out that the possum hisses too.) The moonrat also has a long, thin muzzle, small rounded ears, and short legs. It grows to about a foot and a half long, not counting the tail, which can be nearly as long as the body. A foot and a half is about 40 cm. One subspecies of moonrat has light gray or white fur on its head and forequarters except for a black mask, while the rest of its body is black. Another subspecies is mostly white.

The moonrat prefers jungles and forests and is mostly nocturnal. It eats pretty much anything, but it especially likes insects, crabs, worms, and frogs, and will even eat fish when it can catch one.

One interesting thing about the moonrat is its smell. The moonrat marks its territory with a scent that smells like ammonia. You know what else smells like ammonia? Cat pee. That is not a good smell, if you’ve ever had to clean out a cat’s litter box that should have been cleaned out a lot earlier. It also smells kind of like rotten onions. As a result of its scent glands for marking territory, the moonrat smells pretty bad to human noses. But people do occasionally eat it, just as they sometimes eat hedgehogs.

People are omnivores too, after all. But, you know, maybe don’t eat animals that smell like ammonia.

You can find Strange Animals Podcast online at a new URL! I finally had to move to a real podcast hosting platform since I had topped out the memory and usage available without one. Our website is now at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. I will keep the old website up but it won’t be updated. The podcast feed shouldn’t change unless I’ve really messed something up, in which case you probably aren’t hearing this.

If you have questions, comments, or suggestions for future episodes, or just want a sticker, email us at strangeanimalspodcast@gmail.com. We also have a Patreon at patreon.com/strangeanimalspodcast where you can get bonus episodes for as little as one dollar a month donation.

Thanks for listening!