Category Archives: animals

Episode 241: Weird and Wonderful Squirrels



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Our pre-launch Kickstarter page! You can see what the book cover will look like!

Thanks to Liesbet and Enzo for their suggestions this week! Let’s learn about squirrels!

Further reading:

Project Squirrel

Interspecies Breeding Is Responsible for Some Squirrels’ Black Coloring

The Indian giant squirrel, without filter (left) and with filter (right):

Some variable squirrels (see lots more at iNaturalist):

The Eastern gray squirrel:

The Eurasian red squirrel:

The fox squirrel:

White Eastern gray squirrels (photos taken from the White and Albino Squirrel Research Initiative):

A white variable squirrel spotted in Thailand (picture found here):

The African pygmy squirrel:

The least pygmy squirrel of Asia:

Show transcript:

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

It’s finally the squirrel episode! Both Liesbet and Enzo have suggested squirrels as a topic, and Enzo specifically asked about white squirrels, hybrid squirrels, and squirrels in danger. We’re going to cover all those, and also a few squirrel mysteries!

First, though, a quick note to say that the Kickstarter campaign for the Strange Animals Podcast book is definitely going to happen NEXT MONTH! It’ll go live in early October 2021. Don’t worry, I’ll let you know when so you can go pre-order a copy of the book if you want, and in fact I think I’ll do a bonus episode the first day of the Kickstarter. If you want to get an email to remind you when the campaign launches, there’s a link in the show notes to the pre-launch page where you can request an email notification on launch. You can also see what the book cover will look like! Now, on to the squirrels.

The animal we generally just call a squirrel is specifically a tree squirrel, as opposed to ground squirrels. Tree squirrels are arboreal, which means they live in trees, although they spend plenty of time on the ground too. Squirrels mostly eat nuts and seeds, including acorns and the seeds inside pine cones, but will also eat berries, flowers and buds, tree bark and sap, fungus, and sometimes insects, bird eggs, and even baby birds. Squirrels are rodents and are active in the daytime.

Squirrels can be helpful to trees even though they eat tree nuts, because most species bury nuts to dig up and eat later. The squirrel doesn’t always remember where it hid all its nuts, and in spring the buried nuts sprout and grow into new trees. Some species also hide nuts in caches, often in holes in trees.

A squirrel sleeps in a nest made of dead leaves and sticks it builds in the branches of a tree. The nest is called a drey and it’s lined on the inside with moss, grass, and other soft, warm material. A mother squirrel will line the nest with some of her fur right before her babies are born, so the nest is especially soft and warm. Some species also nest in old woodpecker holes. In winter when it’s cold, several squirrels may share the same drey to stay warm, but squirrels are usually solitary. They don’t hibernate, but like most of us, they sleep more in winter and are less active.

Most people know what a squirrel looks like, because it’s such a common animal throughout most of the world. Some squirrel species get used to humans and often live in people’s yards and in city parks. A tree squirrel has a long, fluffy tail, a long, slender body, relatively short legs, small ears, and large eyes. It’s usually gray or brown and sometimes has spots or stripes.

Some tree squirrels look different from the squirrels you may be used to, depending on where you live. Squirrels of the genus Ratufa are called giant squirrels and they’re the size of domestic cats. They live in parts of Asia, especially southeast Asia. The Indian giant squirrel lives in India, and not only is it especially big, up to 20 inches long, or 50 cm, not counting its long tail, it’s brightly colored. Different individuals and subspecies can have different shades of fur, although the belly and front legs are usually cream-colored. The rest of the body can be tan, dark brown, black, cream-colored, rusty-red, or even a dark maroon color. You may have seen pictures online of brightly colored giant squirrels, and while those are real pictures of real animals, the photographer used a filter that enhances the colors to make them look even brighter than they really are.

The Indian giant squirrel and its close relations eat fruit, nuts, flowers, and other plant material, and hardly ever come down from the tall trees where they live.

Another colorful squirrel is the variable squirrel, which also lives in southeast Asia. It’s on the small side for a tree squirrel, less than 9 inches long at most, or 22 cm, not counting the tail. There are over a dozen subspecies that vary in color and pattern, and some researchers think there may be enough differences that it’s actually more than one species of closely related squirrel. It’s a member of a genus called “beautiful squirrels,” because so many species in the genus have pretty markings. Some variable squirrels are white underneath and red-brown above, with little pointed ears outlined in white, and a reddish tail. Some are glossy black with red markings. Others can be gray, black, orangey-red, reddish-brown, brown, or white with various patterns and markings. It’s so pretty that it’s been introduced in places like Japan, Singapore, Italy, and the Philippines, where it can be an invasive species.

The eastern gray squirrel of eastern North America has also been introduced to other areas where it’s become an invasive species. It was introduced to the UK in 1876 and because it’s a large, aggressive species, the native Eurasian red squirrel has been driven almost to extinction in Britain. It’s still doing fine in the rest of its range, though. Habitat loss is also a factor in the red squirrel’s declining numbers, but the gray squirrel certainly isn’t helping.

The gray squirrel also carries a disease called the squirrel parapoxvirus that causes squirrelpox. Don’t worry, only squirrels can catch it. The gray squirrel is mostly immune to the disease, but the red squirrel isn’t. If an infected gray squirrel is bitten by a mosquito that then bites a red squirrel, the red squirrel can catch squirrelpox from the mosquito bite.

The red squirrel is a reddish-brown in color with tufts on its ears, and in winter it grows a thick undercoat to keep it warm. It also generally looks more gray in winter. Some populations of red squirrel in parts of Europe are black, or nearly black, although it still has a white belly. The red squirrel only grows up to about 9 inches long, or 23 cm, much smaller than the eastern gray squirrel, which can grow up to 12 inches long, or 30 cm. Those lengths don’t include the tail. The red squirrel generally prefers fir trees while the gray squirrel prefers deciduous trees, especially oaks, but the gray squirrel will steal food from the red squirrel no matter what kind of food it is.

In its native range in eastern North America, the eastern gray squirrel often lives alongside other species of squirrel. In 1997 an evolutionary behavioral ecologist named Joel Brown noticed that there are two species of squirrel that live in Chicago, Illinois, a large city in the middle of the gray squirrel’s range. The gray squirrel shares the city with the fox squirrel, which is about the same size and looks very similar to the gray squirrel but is more of a rusty-red color. Dr. Brown noticed that the gray squirrel mostly lives in wealthy neighborhoods while the fox squirrel mostly lives in neighborhoods where people don’t have as much money, and he wanted to figure out why.

Dr. Brown started Project Squirrel to study the mystery. The program teaches people how to tell the difference between the two species so they can report what kind of squirrels they see and where they see them. Right away he started noticing patterns. Fox squirrels live in areas where there are more predators, including feral and free-roaming dogs and cats, urban foxes and coyotes, and hawks. Gray squirrels prefer areas where there aren’t as many predators. Dr. Brown thinks it’s because the fox squirrels are bolder and on average a little larger than gray squirrels, which tend to be more shy. He even noticed a change in his own neighborhood when gray squirrels started becoming more numerous, a shift that happened right after a local leash law went into effect, meaning that fewer pets were running loose.

Project Squirrel has since expanded. There’s an app and everything if you want to take part as a citizen scientist and help solve squirrel mysteries.

Another small squirrel mystery is white squirrels. In August of 2021, just last month as this episode goes live, we had a Q&A episode where we talked about the black squirrels Connor was seeing in Michigan. Those black squirrels turned out to be melanistic eastern gray squirrels. Are white squirrels albino animals or is there something else going on?

Albinism is due to a genetic anomaly that causes an individual to lack pigment. That means its fur or hair is pure white and its skin looks pink because the lack of pigment means its blood shows through and makes it look pink. Its eyes will look red or pink for the same reason, although in some animals the eyes are pale blue instead. Humans with albinism have pale blue eyes.

But most white squirrels have dark eyes and may appear pale brown or gray instead of pure white. Instead of albinism, these squirrels are leucistic. Leucism is related to albinism but instead of a lack of pigment, a leucistic animal has reduced pigment. Sometimes the reduced pigment happens all over the body, sometimes in patches. A leucistic animal often has ordinary colored eyes and skin but pale or white fur. In some domestic species of animal, leucism is bred for or happens frequently in a population, like piebald horses and cows with white spots. It’s a common enough condition that I’ve actually seen leucistic birds while birdwatching. Humans can sometimes show a type of leucism called vitiligo that usually develops in adults, where patches of skin lose their pigment over time. It’s most noticeable on people with dark skin but it also happens to people with light skin. You can’t catch vitiligo from someone else; it’s just a genetic anomaly. Unfortunately, sometimes people who develop the condition get treated badly by others, because people are often afraid of things they don’t understand. Now you know what it is and you can share that knowledge when you need to.

In squirrels, individuals with white fur are usually in more danger from predators. Everything likes to eat squirrels, which is why most squirrel species are gray or reddish-brown as camouflage against tree trunks and branches. A white squirrel shows up like a flashing sign saying, “Snacktime!” As a result, squirrels with white fur are rare to start with and usually don’t live long enough to pass their genes along to the next generation—but in some places, they’re much more common.

In many towns in the United States and Canada, white squirrels are not just common, most squirrels are white. Some towns have white squirrel festivals as a way to promote local pride and bring tourists to the area. Why do some places have white squirrels while most don’t, and why are all the white squirrel populations in North America?

It’s all back to the eastern gray squirrel again. Most squirrel species don’t have a gene that can cause leucism, but the eastern gray squirrel does. Other squirrel species can be albinistic since that’s a genetic anomaly that can happen in any animal, but it’s the eastern gray squirrel that shows leucism most commonly. The closely related fox squirrel also sometimes exhibits leucism.

Some towns have high populations of white squirrels because people think they’re neat. If the white squirrels are in a protected area, like a city park or a college campus, there are fewer predators to start with. People who like the squirrels will leave food out for them and make sure no one hurts them, and as a result the squirrels survive to have babies. Since leucism is a genetic condition, the babies of white squirrels are more likely to be white too.

Remember the variable squirrel we talked about earlier in the episode? Some of them exhibit leucism too, usually a pale brown-white all over with dark eyes.

One thing I learned about black squirrels after last month’s Q&A episode is that some black squirrels are hybrids of eastern gray and fox squirrels. The two species are closely related and often live in the same areas, so it’s not surprising that they sometimes interbreed. Hybrid babies may inherit a genetic variant found in fox squirrels that gives them darker fur. Some researchers think that all gray squirrels with black fur may have inherited the gene for black fur color from fox squirrels in their ancestry.

For the most part, though, tree squirrels don’t hybridize very often, probably because in most places, only one species predominates in any given area. Grey squirrels and Eurasian red squirrels belong to different genera and subfamilies, so aren’t very closely related although their habitats sometimes overlap.

Enzo specifically asked about squirrels in danger, and I’m happy to report that most squirrel species are actually doing just fine. Squirrels are adaptable and can learn to live around humans. As long as they have trees to live in and enough food to support a population, they’re okay. The main danger most squirrels face is habitat loss, especially logging and clear-cutting of forests to build houses or businesses.

A subspecies of fox squirrel called the Delmarva fox squirrel was put on the endangered species list in 1967. It’s native to areas of northeastern North America. It’s about the size of the eastern gray squirrel, which it resembles since it’s gray with a white belly, although it’s usually a more silvery gray in color. By 1967 its population had declined by 90% from habitat loss and overhunting. A conservation plan put in place in 1979 focused on protecting the squirrel’s remaining habitat, restoring its habitat wherever possible, and monitoring the population carefully. The program was such a success that in 2015, the Delmarva fox squirrel was removed from the endangered species list. It’s yet another reminder that protecting an animal’s habitat is just as important as protecting the animal itself. The Delmarva fox squirrel now only lives on the eastern coasts of Maryland and Virginia, a much smaller range than before, so continued conservation efforts are in place to keep it safe and healthy.

Let’s finish with the smallest tree squirrel known, the African pygmy squirrel. It lives in tropical rainforests in parts of western and central Africa. It only grows 5.5 inches long, or 14 cm, and that includes its tail! That’s the size of a mouse. We don’t actually know a whole lot about the African pygmy squirrel, but we do know that it’s an omnivore. This is unusual for squirrels, even though most squirrel species will eat the occasional insect or bird egg. The African pygmy squirrel eats insects regularly as well as fruit, bark, and other plant materials. Unlike most squirrels, it doesn’t store food.

The African pygmy squirrel is the same size as the least pygmy squirrel that lives on three islands in southeast Asia. We know even less about the least pygmy squirrel than we do the African pygmy squirrel…or I guess you could say we know the least about the least pygmy squirrel.

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. There are links in the show notes to join our mailing list and to our merch store.

Thanks for listening!


Episode 240: The End of the Dinosaurs



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Here we go. It’s the big one, the Cretaceous-Paleogene extinction event!

Further reading:

How Birds Survived the Asteroid Impact That Wiped Out the Dinosaurs

How an asteroid ended the age of dinosaurs

Extinction event that wiped out dinosaurs cleared way for frogs

How life blossomed after the dinosaurs died

66-million-year-old deathbed linked to dinosaur-killing meteor

Show transcript:

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

Here it is, the extinction event episode that everyone’s been waiting for, or at least that everyone knows about. It’s the one that killed off the dinosaurs and ushered in the age of mammals. It’s probably the one we know most about and it’s certainly the one we have the most paintings of, usually of a T. rex staring into the sky at an approaching comet.

In episode 227 we talked about the end-Permian extinction event, which took place about 250 million years ago. The Cretaceous-Paleogene extinction event, or end-Cretaceous, took place just over 66 million years ago, which means that for almost 200 million years there was more or less smooth sailing in the world. Dinosaurs evolved during that time, and I think we can all agree that dinosaurs are fascinating animals.

The largest terrestrial animals ever to live were dinosaurs, specifically the sauropods. Sauropods were just unimaginably huge. They were like walking buildings that ate plants, and even that doesn’t give a good idea of their size. Some sauropods had extremely long tails as well as very long necks, which increased their length. Right now the largest sauropod known was probably Argentinosaurus that might have grown as long as 118 feet, or 36 meters, but paleontologists keep finding bigger and bigger sauropods. Some sauropods had extremely long necks that they held up like a giraffe. The tallest was probably Barosaurus, estimated as being 72 feet tall, or 22 meters. And we won’t even get into estimates of how much these massive animals weighed. They make the biggest elephant that ever lived look like a toy elephant.

Sauropods ate plants, with the low-necked species eating low-growing plants and the high-necked species eating tree leaves, although even saying that much is controversial. There’s a lot we don’t know about sauropods in general, since most sauropod fossils are incomplete and many species are only known from one or a few bones. But we do know some surprising things about sauropods. We have a lot of sauropod tracks, which helps us understand how their feet looked and whether they had claws, but it also tells us that some species of sauropod traveled in herds. Paleontologists do generally agree that many sauropods migrated, since animals that big would soon exhaust all the food in one area if they didn’t.

Sauropods were extremely successful and lived all over the world. There were plenty of sauropods alive 66 ½ million years ago, and then…there were no sauropods alive ever again.

These days, there’s so much evidence that a massive asteroid killed off the dinosaurs that pretty much everyone agrees, but when the idea was first proposed in 1980, it was extremely controversial. When I was a kid I remember reading dinosaur books that still said the extinction of the dinosaurs was a mystery but that many scientists thought it was due to disease or volcanoes.

The asteroid strike hypothesis was proposed by the physicist Luis Alvarez and his son, Walter. They worked with a small team of other scientists, including two chemists, Helen Michel and Frank Asaro, to investigate a strange anomaly in rock strata. Rocks dating to the end of the Cretaceous period and the beginning of the Paleogene period are separated by a thin layer of clay that’s visible throughout the world, or at least wherever the rocks remain and can be examined. It’s called the Cretaceous-Paleogene boundary, or K-Pg boundary, although in older books and websites it’s called the K-T boundary. It occurred just over 66 million years ago. The Alvarezes were curious about this layer, and during their investigations they found out that the clay is full of an element called iridium.

Iridium is a silvery-white metal chemically related to platinum, and it’s rare. At least, it’s rare on Earth. It’s a common component of asteroids, which was one of the main reasons why the Alvarezes came to their hypothesis that the K-Pg boundary was the result of a massive asteroid impact. Other scientists had made similar suggestions in the decade or so leading up to the Alvarezes’ theory, but the iridium discovery provided the proof everyone wanted.

Iridium wasn’t the only thing found in the K-Pg boundary layer, either. There were other platinum-group metals present in high concentrations—much higher than found on Earth, and in fact these elements are referred to as rare-earth metals for that reason. In some places, the K-Pg boundary contains grains of shocked quartz and microtektites. We’ll discuss those in a minute.

As we’ve discussed before in various episodes, the earth’s surface is always moving around. It’s slow to us, with continents moving around at the same dizzying speed that our fingernails grow, but over millions of years that adds up. Continents move around and crash into each other, forming new mountain ranges that then wear down to plains, and where continental plates pull apart or push together the crust can weaken and allow magma to erupt through as volcanoes. Ocean levels rise and fall. In other words, a crater made 66 million years ago might have disappeared as all this geologic activity goes on.

But then, we found the crater. The crater.

The Chicxulub crater is in Mexico, specifically the Yucatán Peninsula at the southern portion of the Gulf of Mexico. You can’t see it when you’re walking around because it’s buried under 2,000 feet of soil, or 600 meters, that has built up over the last 66 million years. Two geophysicists found it in the 1970s while surveying for petroleum, but it wasn’t until 1990 that they were able to verify that it was a crater. Asteroid impacts leave clues behind that the geophysicists recognized.

The first clue is shocked quartz. Quartz is a common crystalline mineral throughout the world, and it has a certain structure that’s familiar to geologists. In shocked quartz, that structure has been deformed by intense pressure, but not high temperature. It was first noticed after nuclear bomb tests, and after that scientists recognized it in meteor craters.

The second clue is little pieces of glass called tektites. They’re different from obsidian, which is a type of glass formed by volcanic activity. Tektites are usually shaped like droplets or little blobs, but sometimes they’re round. They’re only found around big impact sites and only for relatively recent meteor impacts, because they don’t last forever.

The Chicxulub crater is actually kind of old for its tektites to still be around, except for two things. First, the tiniest tektites, the microtektites, ended up in the K-Pg boundary layer, as I mentioned earlier. Second, we actually have a fossil site in North Dakota, in the middle of North America up near Canada, that seems to date to literally the day of the asteroid impact, and there are tektites all over the site, including clogging the gills of fish. The tektites match the chemical signatures of the Chicxulub crater so we know that’s where they came from.

Before we talk about the North Dakota fossil bed, let’s discuss what exactly happened on the day the asteroid hit the earth. Because we’ve found the asteroid’s crater, we know a lot about the asteroid itself. Most researchers estimate that it was about 6 miles across, or 10 km. It approached the earth at an angle, traveling about 12 km a second. That’s 7.5 miles per second. It hit the earth right on the coast, partly in the ocean, partly on land, forming a crater about 110 miles across, or 180 km, and 12 miles deep, or 19 km.

The asteroid smashed into the Earth so fast that it was completely buried in about the time it takes you to blink. There really wasn’t time for any dinosaurs to look up and wonder what that bright light was, because the time between the asteroid entering earth’s atmosphere and smashing into the earth was maybe five seconds.

The megatsunami resulting from the impact would have been unbelievably huge. Waves may have been a mile high, or over 1.5 km. The initial impact would have thrown water more than 7.5 miles into the air, or 12 km, and when that water fell back down it would have set up another megatsunami. Not only that, the impact actually shook the whole earth like a massive earthquake, which caused landslides all over the place and set up even more tsunamis. It’s like shaking a snowglobe to watch the fake snow swirl around and around, only instead of fake snow it was ocean.

At the same time, everything near the impact site was instantly on fire. It was on fire because the asteroid was traveling so fast that it was glowing white-hot with incandescent heat just from pushing against air molecules, and when it hit the Earth, all that heat had to go somewhere. Also, everything exploded. The water exploded up and outward, the land exploded up and outward. A lot of water turned instantly to steam. The asteroid itself disintegrated and tiny bits of it were carried high into the atmosphere along with ash, dust, molten glass created by the blast, and anything else that was nearby and not instantly incinerated.

The shockwaves from the impact acted as a magnitude 12 earthquake, with follow-up shocks estimated at about magnitude 9 occurring across the entire planet. Volcanoes erupted as a result, pumping even more ash and gases into the atmosphere. All the trees were flattened for about 930 miles around the impact, or 1500 km.

Within a few hours of the impact, fireballs of molten rock and glass were falling across the world, setting fires on land and heating the surface of the ocean to boiling temperature in many areas. And it was already getting really dark as the massive amounts of debris and dust and ash and smoke and everything else spread across the earth.

Okay, deep breath. This happened a long, long time ago and most animals died so quickly they didn’t feel anything. Look out the window if you’re feeling stressed and see how calm it is? Maybe it’s raining where you live or maybe it’s night-time and you can hear frogs or crickets calling, maybe an owl if you’re lucky. It might be daytime and you can hear cars passing by, or a dog barking somewhere, people talking. Whew. Okay, back we go to that awful day 66 million years ago, back to the fossil site found in North Dakota.

Back then, the middle of North America was a shallow sea. The first tsunami wave was probably 30 feet tall, or 9 meters, when it reached the mouth of a river emptying into the sea. It pushed the river backwards and washed hundreds of freshwater fish onto a sand bar. To add insult to injury, or just injury to injury, while the fish were stranded and flopping around trying to get back in the water, globs of molten glass and rocks rained down on them. Then another wave pushed up the river and covered the dead and dying fish with a lot of sand and sediment, which preserved them.

The site was discovered in 2013 and the findings were published in 2019. It’s not just fish at the site, although there are unbelievable numbers of fish. There are also tree trunks and branches that show evidence of burning, ammonites and other marine animals that were washed up the river, even part of a triceratops and a hadrosaur. One charred trunk is covered in amber, which is fossilized tree resin. The amber is full of tektites, which were caught in the resin when it was soft.

Every time I say tektite I think of those spidery things in Zelda, which makes this whole situation seem even worse.

None of the animals at the site show evidence of being eaten by anything. Some researchers estimate that the event took place less than an hour after the asteroid impact. There’s also a layer of clay on top of the sediment that contains high levels of iridium.

In all, roughly 75% of all life on earth went extinct following the asteroid impact. Many animals that survived the immediate aftermath of the impact died out months or years later, and many more scraped along for hundreds or thousands of years before finally going extinct. The massive amounts of dust and ash in the atmosphere blocked sunlight for the next several years or even longer, which means plants died throughout the world. Poisonous gases in the atmosphere led to acid rain that killed more plants and animals. The ocean temperature dropped considerably, as did the overall temperature of the earth, leading to freezing temperatures that would have killed off even more animals. Deep-sea animals fared better than most, but many plankton went extinct very soon after the impact and that meant animals that ate the plankton also went extinct.

But, of course, not everything went extinct. If it had, I wouldn’t be recording this episode and you wouldn’t be listening to it. Awful as it sounds, the Cretaceous-Paleogene extinction event wasn’t nearly as bad as the end-Permian extinction. Full recovery is estimated to have taken as much as 9 million years, when it took 50 million years for the earth to fully recover from the end-Permian extinction.

One thing that isn’t generally known is that things had been getting rough on earth for a couple of million years before the asteroid hit. Some species were already in decline due to climate change. The asteroid just made everything intensely worse.

The first plants to recolonize the blasted wastelands were ferns, lots and lots and lots of ferns. Ferns are tough plants and thrive in areas where nothing else can grow, and ferns grow quickly and provide food for lots of animals. Within a hundred years of the impact the world was carpeted with ferns.

Some dinosaurs did survive, of course, but we call them birds. They would have looked very birdlike even 66 million years ago. Most birds that survived were ones that lived on the ground instead of in trees. Researchers think many birds survived because they were able to eat seeds, which would have remained as a food source even after the plants that dropped the seeds had all died. Insects and other invertebrates that eat rotting leaves would have been just fine, and many birds could find and eat them too.

Mammals also survived the asteroid impact, of course. Look, here we are! We’ve done quite well for ourselves. 66 million years ago most mammals were small and rodent-like, and the ones that survived probably mostly lived in burrows and ate seeds and other plant material or small animals like insects.

Surprisingly, frogs did really well after the asteroid impact. Frogs are small and can survive in small microhabitats. While most of the frogs in North America went extinct, plenty of frogs survived in other parts of the world that weren’t so close to the impact site, and as soon as conditions improved, more species evolved than ever before. That’s why frogs across the world look so similar. They may not all be closely related, but they all faced the same environmental pressures at the same time.

Once plants started to recover, things took a turn for the better as birds, fish, mammals, reptiles, amphibians, insects, and other animal groups suddenly didn’t have to watch out for dinosaurs or the other big predators that had gone extinct. Sauropods and other giant herbivores weren’t eating up all the plants. Life evolved rapidly to fill the available ecological niches, and animals started getting bigger and bigger.

In late 2019, scientists released details of a fossil site found in Colorado, in the western United States. It has an unbroken record of rocks dating from before the asteroid impact to about a million years afterwards. It gives us an excellent record of the changes that took place.

In the years after the impact, there’s not a lot to see, just lots of ferns and some rat-sized mammals. Within 200,000 years palm forests had replaced the ferns and cat-sized mammals were common. By 400,000 years after the impact, plants and trees with nuts evolved and many mammals were the size of dogs. By 700,000 years after, the relatives of modern bean and pea plants appeared, forests were varied and healthy, and the mammals were the size of wolves or bigger. There were animals other than mammals too, including a five-foot-long crocodilian, or 1.5 meters, with teeth adapted to crush turtle shells.

The ancestors of whales evolved about 50 million years ago around what is now India and its neighbors, when a little animal called Indohyus spent a lot of time in the water. It was about the size of a raccoon, which it resembled in some ways, except that its bones were unusually heavy for its size. This helped it stay underwater without effort. The hippopotamus has the same kind of heavy bones for the same reason, and Indohyus was actually related to the hippo’s distant ancestor. Within five million years, descendants of animals like Indohyus were fully aquatic and looked a lot like dolphins with small legs. As whales got bigger and faster, predators evolved too, including the largest shark that ever lived, Megalodon. The first baleen whales evolved around 25 million years ago and ultimately grew to the gigantic sizes of some of the whales alive today.

Every time you feel sad that you’ll never see a real live dinosaur like a sauropod, remember that you live at the same time as the undisputed largest animal that has ever lived, the blue whale. It can grow up to 98 feet long, or 30 meters, and possibly longer. That’s as long as a ten-story building is high. It’s twice the length of Megalodon! If you have the money and time, you can actually charter a boat that will take you out to look at blue whales because they’re still alive!

I guarantee you that millions upon millions of years from now, in some far-distant future that we can’t even imagine, there will be scientists who study whales and write whatever those future people use as books, and there will be young people who read those books and look longingly at drawings of whales. They’ll know about dinosaurs, sure, and those will always be popular, but it’ll be the whales that really catch people’s imagination. There will be the far-future equivalent of movies where people successfully clone whales or bring them back from the past, and the details will be all wrong but no one will know because no one in that far future time will actually know what whales really look like! But you know, and that is the most amazing fact I can ever share with you.

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. There are links in the show notes to join our mailing list and to our merch store.

Thanks for listening!


Episode 239: Mystery Crocodiles



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Thanks to Pranav and Max for their suggestions. Let’s learn about some mystery crocodiles (and crocodile mysteries) this week!

Further reading:

Huge prehistoric croc ‘river boss’ prowled waterways

Extinct “horned” crocodile’s ancestry revealed

New species of crocodile discovered in museum collections

Rediscovery of “Lost” Caiman Leads to New Crocodilian Mystery

The Orange Cave-Dwelling Crocodiles

The horned crocodile’s fossil skull:

A baby Apaporis River caiman, looking fierce but cute (picture from link above):

An orange crocodile (later released, picture from link above):

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw. We’ve got a crocodile episode this week you can really sink your teeth into. Thanks to Pranav and Max for their suggestions! (Yes, I do have a cold but hopefully I don’t sound too bad. I got a covid test today to make sure it’s just a cold, and it’s just a cold.)

We talked about crododilians in episode 85, so if you want to learn more about the saltwater crocodile or how to tell the American crocodile from the American alligator and so forth, that’s the episode to listen to. This episode is going to talk about mystery crocodiles!

The partial skull of a massive extinct crocodilian discovered in Queensland, Australia over a century ago was finally described in June of 2021. All we have is the partial skull from an animal that lived between 2 and 5 million years ago, but researchers can estimate the size of the whole animal by comparing the dimensions of its skull with its closest living relation. That happens to be an animal called the false gharial that lives on a few islands in South Asia, including Java and Sumatra. It’s the only living member of the subfamily Tomistominae, which used to be common worldwide. The false gharial can grow as long as 16 feet, or 5 meters, but its extinct Australian cousin was much bigger. The new species, Gunggamarandu maunala, may have grown up to 23 feet long, or 7 meters.

A smaller extinct crocodile, called the horned crocodile, lived in Madagascar until only about 1,400 years ago. It grew a little over 16 feet long, or 5 meters. It had two projections at the back of its head that look like horns, although they weren’t actually horns and probably weren’t all that big or noticeable when the crocodile was alive.

Like Gunggamarandu, the horned crocodile’s fossils were discovered almost 150 years ago but only definitively described in 2021. In this case, though, the delay was because no one could decide where the horned crocodile belonged in the crocodilian family tree. The Nile crocodile lives on Madagascar now, and some researchers assumed that the horned crocodile was either a close relation of the Nile croc or its ancestor. Since new evidence points to the Nile crocodile being a fairly recent arrival to the island, that’s not likely, so researchers analyzed the fossil remains and reclassified the horned croc as a member of the dwarf crocodiles in 2007. Finally, though, a research team analyzed the horned croc’s DNA and determined that it belongs in its own genus and is most closely related to the ancestral species of all living crocodiles. This suggests that crocodiles evolved in Africa and spread throughout the world from there.

Researchers aren’t sure what caused the horned croc to go extinct, but it may have been a combination of factors, including a drying climate on Madagascar, the arrival of humans, and the arrival of the Nile crocodile.

Speaking of the Nile crocodile and DNA, a 2011 genetic study of the Nile crocodile resulted in a surprising discovery. The study tested not just DNA samples gathered from 123 living Nile crocodiles but from 57 crocodiles mummified in ancient Egypt. The goal was to see if there were differences between modern crocodiles and ones that lived several thousand years ago, and to determine whether maybe there was a subspecies of Nile crocodile that hadn’t been recognized by science. Instead, they discovered that what was previously known as the Nile crocodile is actually two completely different species!

The Nile croc lives in Africa and is a large, aggressive animal that can grow just over 19 feet long, or almost 6 meters. The West African croc also lives in Africa and is a smaller, less aggressive animal that can grow up to 13 feet long, or 4 meters. Since crocodiles of all species show a lot of variation in size and appearance, no one realized until 2011 that there were two species living near each other. They’re not even all that closely related.

After the finding was published, zoos across the world tested their crocodiles and discovered that a lot of their Nile crocs are actually West African crocs.

Something similar happened more recently, in 2019, when a team of scientists did a genetic study of the New Guinea crocodile. They gathered DNA from 51 museum specimens from 7 different museums, and compared them to living New Guinea crocodiles. They were hoping to determine if there are actually two species of crocodile living in different parts of New Guinea, which had been suspected for a while. It turns out that yes, there are two separate species! Knowing exactly what kinds of animals live in a particular environment helps conservationists protect them properly.

In 1952 a subspecies of the spectacled caiman was discovered by science, called the Apaporis River caiman. It lives in Colombia, South America and is relatively small as crocs go, maybe 8 feet long at most, or 2.5 meters. After that, though, it wasn’t seen again. This was partly due to how remote and hard to navigate its habitat is, and partly due to a dangerous political situation, with rebel forces occupying the jungle where the crocodiles live. A peace treaty signed in 2016 made it safe for scientists to travel to that area at last, and a Colombian biologist named Sergio Balaguera-Reina visited with various indigenous tribes of the area to ask about the Apaporis caiman and learn everything they knew about it.

At night, he and two local people paddled upriver in a canoe and searched for the caimans—and he found lots of them. He caught as many as he could to take DNA samples before releasing them again. When he got home, he tested the DNA and made a surprising discovery. Even though the Apaporis caimans look very different from another subspecies of spectacled caiman found in other parts of South America, their DNA is quite similar. That means the differences, especially the Apaporis caiman’s much narrower snout, are due to selective pressures in its environment. Balaguera-Reina is working on figuring out the causes of the Apaporis caiman’s physical differences.

The Siamese crocodile was once common throughout South Asia, but habitat loss has had a major impact on the species and for a long time it was thought to be extinct in the wild. It grows up to 13 feet long at most, or 4 meters, and is not very aggressive. It’s kept in captivity in crocodile farms, where it’s bred and killed for its meat and skin, but a lot of those farms have multiple species of closely related crocodiles and they can and do interbreed, meaning that the Siamese crocodiles in the farms are most likely hybrid animals.

In 2001 a team of conservationists traveled to Thailand to search for tigers, and one of their camera traps recorded a Siamese crocodile just walking along the river like it was no big deal. The photograph was especially lucky because it shouldn’t have even happened. The camera traps used actual film, not digital cameras which were still expensive and not very good back then. The rolls of film could capture 36 pictures before the film ran out, but the crocodile appeared on the 37th picture. Film is manufactured in long strips, then cut into pieces and rolled up and put in little canisters for a photographer to put in the camera, and the roll is a little longer than it needs to be because the ends have to be anchored in place. This particular strip of film just happened to be long enough to take 37 pictures instead of 36. If it hadn’t been, the conservationists wouldn’t have known the crocodile was still alive.

A follow-up expedition to look specifically for crocodiles discovered more of them. Since then a captive breeding program was set up, and in 2013 the first hatchlings were released into the wild.

Sometimes when a crocodile is killed, interesting things turn up in its stomach. This is what happened in 2019 when a crocodile farm in Queensland, Australia necropsied one of their saltwater crocs to see what he had died of. The croc was over 15 feet long, or 4.7 meters, and was about 60 years old. When they opened up his stomach, they found a piece of metal and six screws, the kind of metal called an orthopedic plate. It’s used to join two pieces of broken bone or strengthen an injured bone so it won’t break.

Medical devices like this are always etched with a serial number, but the metal was inside the croc’s belly for so long that the serial number was corroded off by stomach acid. This would have taken decades to happen, so the crocodile had to have eaten the metal decades ago, possibly as long as 40 years ago.

The farm contacted the police but so far they haven’t been able to trace what might have happened. The croc wasn’t bred on a farm but had been caught wild. The farm owner sent pictures of the plate to a surgeon, who determined that yes, it was probably from a human, not an animal, and that it looks like a type of plate used in Europe. The farm owner hopes the discovery will one day help solve a missing persons case.

Let’s finish with an interesting discovery in the rainforests of Gabon, a small country on the west coast of central Africa. The Abanda caves in the area are extensive, not very well explored, and full of bats and insects. A man named Olivier Testa, a professional explorer who often leads scientific expeditions into remote areas, heard a rumor about a population of orange [I read this as strange instead of orange and was too lazy to fix it] crocodiles living in the cave system. A lot of people would have just laughed, because everyone knows crocs and other reptiles like hot weather, sunshine, and warm water to hunt in. But when Testa got the opportunity to join an expedition into the cave system in 2010, he remembered the crocodiles.

Guess what they found in the cave. I bet you all guessed correctly. There really were crocodiles in the caves, specifically African dwarf crocodiles, and the biggest ones did look slightly orangey in color. Crocs don’t live in caves, but there they were. The following year the expedition returned, and this time they were there to find out more about the crocs.

A crocodile expert named Matthew Shirley came along, and he figured out why the crocodiles were in the cave. There are an estimated 50,000 bats living in the cave system, so many that the crocodiles could basically just reach up and snap bats off the walls to eat. There are lots of crickets in the cave too, and young crocs eat lots of insects.

As for the orange color of the older crocs, that comes from the water in the cave. Bats have to pee just like every other animal does, and where they roost over the water they pee into the water, naturally. So much bat urine actually has an effect on the water composition, turning it extremely alkaline. This affects the skin color of animals that stay in it for a long time, as the older crocs have.

The cave crocodiles appear to spend the dry season in the caves, eating bats and avoiding humans who hunt crocs. During the rainy season, they emerge from the caves to mate and lay their eggs in rotting vegetation outside.

This is the first population of crocodiles ever found that spends time in caves deliberately. Some researchers speculate that the crocodiles could eventually evolve into a new subspecies of dwarf crocodile that’s especially adapted to the cave system.

You know what we call those? We call them dragons.

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 that way.

Thanks for listening!


Episode 238: The Pink Fairy Armadillo and Two Adorable Friends



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This week we’ve got three adorable little animals to learn about! Thanks to Simon and Thia, Elaine, and Henry for their suggestions!

Further reading:

Turning the spotlight on the rusty-spotted cat (Wildlife SOS)

The cute and fuzzy pink fairy armadillo:

The cute and fuzzy rusty spotted cat:

The cute and fuzzy baby Arctic tern:

Adult Arctic terns:

Show transcript:

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

This week we’ve got three strange and adorable animals for you, all listener suggestions because I’m getting really behind on those. Thanks this week to Simon and Thia, Elaine, and Henry!

First, Simon and Thia suggested the pink fairy armadillo. That’s one we covered briefly in a Patreon episode back in 2018, but it deserves to be featured in the main feed because it’s so strange and cute. It lives in deserts and grasslands of central Argentina, South America, but since its range is so restricted and it spends most of its life underground and is rarely seen by humans, we don’t know much about it.

The pink fairy armadillo is the smallest armadillo species known. It only grows about 4.5 inches long, or 11.5 cm, small enough to sit in the palm of your hand. It’s protected by a leathery shell that runs from its nose along the top of its head and down its back to its bottom, and the shell is segmented like a regular armadillo’s shell except that it’s a delicate pink. The fluffy fur on the animal’s sides and tummy is white. It has a short spade-shaped tail, but the rear of its body is flattened, and it uses its flat bottom to compress dirt in the tunnels as it digs. It has a small head, short legs, and gigantic front claws. Its hind claws are big too.

It spends almost all of its life underground, digging shallow tunnels and eating small animals like worms, insect larvae, snails, and insects like ants, which it probably hunts by scent. It has a good sense of smell but its eyes are tiny and its ears don’t show at all, although it does have good hearing. It can dig extremely quickly. It loosens the soil with its huge front claws, kicks it back with its hind claws, and then does a quick reverse to tamp the new dirt heap into a firm column with its flat bottom. This keeps the floor of its burrow clear so the armadillo can breathe properly and helps keep the burrow from collapsing.

Almost the only time the pink fairy armadillo surfaces is when it reaches an obstacle it can’t dig through or around, and then its claws are so big it has trouble walking on hard surfaces. This is bad if it tries to cross a road. Most sightings of pink fairy armadillos are of roadkill animals. Sometimes it surfaces after heavy rain when its burrows are flooded.

The reason the pink fairy armadillo’s shell is pink is that blood vessels show through it. Researchers think it can regulate its temperature according to how much blood flows through the vessels beneath the shell. The shell is only attached to the body by a membrane along the spinal column and doesn’t protect it as well as other armadillo shells do, but then it’s almost always underground so the shell probably mostly protects it from rocks and roots.

The pink fairy armadillo doesn’t do well in captivity, usually dying from stress within a day or two of capture, and since it’s almost always underground it can be hard to find and study. It’s threatened by habitat loss, climate change, poaching, and the use of pesticides. It’s extremely sensitive to changes in temperature and soil.

The pink fairy armadillo has a similar-looking but slightly larger relative, the greater fairy armadillo, which can grow up to 7 inches long, or 17.5 cm. It’s also a burrowing armadillo that lives in South America, which has an additional conservation problem. It’s considered by locals to be the spirit of a dead baby, so if a local sees it they usually kill it.

Next, Elaine suggested the rusty spotted cat. It’s a tiny cat that lives in forests and grasslands in South Asia, especially in India and Sri Lanka, and although it resembles a tiny domestic cat, it’s not all that closely related to domestic cats or their wild cousins.

The rusty spotted cat is reddish-gray with darker stripes on the face and small rusty-red spots over most of its body. It’s about half the size of a domestic cat and grows up to 19 inches long at most, or 48 cm, not counting its tail, which adds another 12 inches or so to its length, or 30 cm. This is where I tried to measure my cats with the soft plastic tape measure I use for sewing, but they thought it was a toy so I never did figure out how long they are. Also, my tape measure has holes in it now from claws and teeth. The rusty spotted cat only weighs up to about 4 pounds, or 1.8 kg. Keep in mind that these numbers are for the biggest possible rusty spotted cats. Most are much smaller. They’re basically kitten-sized.

The rusty spotted cat is mostly nocturnal and eats small animals like mice and other rodents, birds, lizards, and insects. It mostly hunts on the ground and mostly only climbs trees to escape predators. It’s a fierce hunter and can be very aggressive despite its small size, so even though it’s really cute and some people want to keep it as a pet, it’s very wild and not friendly. You’re way better off adopting a small domestic cat. Besides, the rusty spotted cat is endangered in the wild due to habitat loss and hunting for its fur, so we shouldn’t be keeping it as pets.

Conservationists are working to protect the rusty spotted cat by educating people who live in the area about what the cat is. While a mother rusty spotted cat is out hunting, she leaves her kittens in a little nest in long grass. If she makes her nest in a cultivated field, like a tea plantation, sometimes a worker harvesting or caring for the plants will find the kittens. People are basically good at heart and want to help baby animals, so a lot of times the worker will take the kittens home thinking they’re abandoned. A conservation group called Wildlife SOS is working to teach people to leave the babies alone, and when they hear about someone who’s found a kitten, they send someone out to learn where the kitten was found and when, and will reunite the kittens with their mother. Wildlife SOS also helps other animals in India, including leopards and elephants. There’s a link in the show notes if you want to find out more and maybe donate to the program to help these adorable teeny-tiny wildcats.

Finally, Henry suggested the Arctic tern, a bird that lives…pretty much everywhere, in fact, not just the Arctic. It breeds along the coasts in the northern parts of the northern hemisphere, including parts of Canada, Greenland, northern Europe, and Siberia, but after its babies are grown and the short northern summer comes to an end, it takes off for the southern hemisphere and spends the winter—which is summer in the southern hemisphere—around South Africa and Australia and New Zealand, all the way down to the Antarctic. When that summer ends, it flies back north to breed again. That’s an astoundingly long migration.

The Arctic tern spends most of its life flying above the ocean, hunting for small animals like fish, krill, amphipods, and crabs. It’s not a picky eater, though. It will also eat worms, insects, and berries, although it mostly eats these land foods when it’s nesting. It’s a beautiful bird that looks a little like a seagull, but is more lightly built and slender than most gulls. It’s white and pale gray with a black cap that extends down the back of the neck, a red bill, and short red legs and webbed feet. Its tail is forked like a swallow’s tail and it has long wings, which allow it to catch even the smallest sea breeze and fly extremely fast. Its wingspan is about 2.5 feet across, or 75 cm.

The Arctic tern mates for life. Even though the male and female have traveled literally around the world separately for most of the year, they both return to the same nesting ground, find each other, and start their summer courtship. The pair will fly high together with the female chasing the male, and then they’ll fly lower where the male will catch a little fish and offer it to the female. On land, they’ll do a little courtship dance where they raise and lower their tail and wings while strutting around together. Finally the pair decides where they want to build a nest.

The nest isn’t fancy, just a little scooped out place in the ground with maybe some grass in it. Parents take turns keeping the eggs warm and defending the nest from potential predators. It’s an aggressive bird and will even attack polar bears and drive them away, even though it’s just a delicate little bird. It will dive at the predator’s face and peck with its strong, sharp bill. Once the babies hatch, both parents feed the chicks until they learn how to fly.

An Arctic tern chick is possibly the cutest bird you will ever see, at least today. It’s gray and white with short legs, and it’s super super fluffy. The coloration helps it blend in with the rocks around the nesting site.

The Arctic tern travels over 40,000 miles every single year, or more than 70,000 km, and still manages to find its way back to the same breeding colony. How does it know where it is and where it’s going? Like many birds, it can sense the earth’s magnetic field. It combines this sense with where the sun is in the sky and can pinpoint exactly where it is in the world and where it needs to go. It’s like having built-in Google Maps.

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. There are links in the show notes to join our mailing list and to our merch store.

Thanks for listening!


Episode 237: Geckos and Other Arboreal Reptiles



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Thanks to Riley, Richard, and Aiden and Aiden’s unnamed friend for suggestions this week! We’re going to learn about some geckos and other reptiles that live in trees. Thanks also to Llewelly for a small correction about lions. Also, I mispronounced Strophurus–it should be more like Stroff-YOUR-us but I’m too lazy to fix it.

Further reading:

Cancer Clues Found in Gene behind ‘Lemon Frost’ Gecko Color

A chameleon’s feets:

A rare healthy lemon frost domestic leopard gecko (photo taken from article linked above):

An ordinary leopard gecko:

I don’t remember what kind of gecko this is (golden spiny-tailed?) but I love it:

A crested gecko looking surprised:

The green iguana:

A black mamba. Watch out!

Flying snake alert!

The draco lizard with its “wings” extended (male) and the draco lizard with its “wings” folded (female):

A parachute gecko showing how it works:

Show transcript:

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

This week we’re going to learn about some reptiles, specifically reptiles that live in trees. This is a suggestion from Riley, who wanted to hear about arboreal reptiles in general and the crested gecko in particular. Thanks also to my brother Richard, who suggested the dragon-tailed gecko. An anonymous reviewer also suggested the leopard gecko so we’ll learn about that one too. Specifically, the anonymous reviewer said “me and my friend Aiden suggest either red foxes or leopard geckos.” We actually covered the red fox in episode 138, about city animals, and in episode 106, about domestication, but we’ve only mentioned the leopard gecko briefly way back in episode 20.

Arboreal animals have some traits in common, whether they’re reptiles or mammals or something else. In general, an animal that spends most of its time in trees is small and lightweight, either has long legs or very short legs, may have a long tail to help it balance, and may also have various adaptations to its feet to help it maneuver through branches.

This is the case with the chameleon, which is arboreal and has weird feet. Its feet look more like mittens. The feet are called zygodactylous, which means it has two toes pointing forward and two pointing backwards. A lot of birds have feet like this too. Chameleons have other adaptations for arboreal life, like prehensile tails that can twine around a twig to help it keep its balance. The chameleon really deserves its own episode some day, so let’s move on to learn about some geckos.

The biggest gecko known grows up to two feet long, or 60 cm, but most are much smaller. There are more than 1,800 species known and they’re all really interesting and honestly, adorable. They’re mostly nocturnal and eat small animals like insects. About 60% of all gecko species have toe pads that allow them to walk up walls and windows and even across ceilings.

Like many other lizards, most geckos species can drop their tail if a predator attacks. The tail thrashes around on its own for several minutes, distracting the predator so the gecko can escape. The gecko later regrows a little stumpy tail, but it can’t drop it a second time. Many species of gecko store fat in the tail, so it needs that tail. A genus of gecko called the fish-scaled gecko, which lives on Madagascar and nearby islands, has big scales that come loose easily if an animal tries to bite it or if a scientist tries to capture it. The predator gets a mouthful of scales while the gecko runs off. The scales grow back eventually and can be lost again.

Scientists are always interested in animals that can regenerate parts of the body, to learn how that works. A study published in 2017 identified the type of cells that allow the gecko to regrow the part of its spinal cord that’s lost with its tail. In 2018, the same team published their discovery that geckos renew brain cells. This is amazing, since humans and many other animals are born with all the brain cells they’ll ever have, and if something happens to injure the brain, the damage can’t be repaired. Maybe one day people will be able to heal their brains just like the gecko does.

Most species of gecko don’t have eyelids. Instead, the gecko has a protective scale over its eyeball. To remove dust and other debris from the scale, the gecko licks its eyes.

The leopard gecko grows about 11 inches long, or almost 28 cm, and is one of the species that doesn’t have toe pads. That makes it easier to keep in captivity, since it’s less likely to climb out of its terrarium. It’s a handsome lizard that’s yellowish or orangey in color with black spots, but baby leopard geckos actually have black stripes. It’s native to parts of the Middle East and south Asia where it’s mostly hot and dry, and in the wild it spends its day in a burrow and only comes out at night to hunt.

The leopard gecko has been kept as a pet for so long that some people consider it the first truly domesticated lizard. It’s easy to take care of and is usually comfortable around people. Breeders select for brighter colors than are found in wild geckos, including various color and pattern morphs.

One color variety of domestic leopard gecko is called the lemon frost morph, an especially attractive coloration. It’s a pastel yellow with white underneath and brown or black speckles that form broad bands over the lizard’s back. It’s really pretty and when the trait cropped up unexpectedly around 2015, its owner started breeding for the color. Lemon frost babies were rare and incredibly expensive, with people paying up to $2,000 for a single gecko.

Unfortunately, people soon learned that lemon frost geckos were prone to a type of rare skin cancer that affects the iridophores, which are pigment-producing cells. Up to 80% of all lemon frost morphs develop the cancer. Geneticists have discovered that the color morph is due to a single mutation in a single gene, but that the change in that gene also makes the gecko susceptible to cancer. Scientists are now trying to figure out more about how it works in hopes of learning how to prevent skin cancer in humans.

The dragon-tailed gecko is one name for the golden spiny-tailed gecko, one of twenty species in the genus Strophurus. All Strophurus geckos are from Australia and they all spend most of their lives in trees and shrubs. Unlike other geckos, Strophurus geckos don’t drop their tails when threatened. Instead, they have a unique way of deterring predators. A Strophurus gecko can squirt an incredibly smelly liquid from tiny pores in its tail. If it feels threatened, instead of dropping its tail, it will raise its tail up and wave it back and forth as a warning. It also opens its mouth to reveal a bright yellow or blue lining, which alerts the potential predator that this is not a lizard it wants to mess with. If that doesn’t scare the predator away, it will squirt liquid at its face. The liquid is sticky and smells horrible, and if it gets in an animal’s eyes it can cause eye irritation.

Strophurus geckos grow up to 5 inches long, or 13 cm, and species may look very different from each other. Some are drab and spiny, some are smooth and brighter in color. The dragon-tailed gecko has a broad reddish or golden stripe down the top of its tail.

The crested gecko is native to a collection of remote Pacific islands called New Caledonia. It can grow more than 10 inches long, or 25 cm. It has tiny spines above its eyes that look like eyelashes and more spines in two rows down its back, like a tiny dragon. It can be brown, reddish, orange, yellow, or gray, with various colored spots, which has made it a popular pet. These days all pet crested geckos were bred in captivity, since it’s now protected in the wild.

The crested gecko spends most of its time in trees, and not only does it have adhesive toe pads, it also has tiny claws. Most geckos don’t have claws. It can drop its tail like other geckos, but it doesn’t grow back. This doesn’t seem to bother the gecko, though.

The crested gecko was discovered by science in 1866, but wasn’t seen after that in so long that people thought it was extinct. Then it was rediscovered in 1994, so hurrah for the crested gecko!

Let’s move on from geckos to some other arboreal reptiles. A lot of reptiles live mostly in trees, and not all of them are small. The green iguana, for instance. It’s native to southern Mexico into parts of South America but has been introduced in many other places in the Americas, where it’s often considered an invasive species. In warm weather it lives in trees, although it will climb down to the ground in cool, rainy weather, and it can grow up to six and a half feet long, or 2m.

Although the iguana can be really long, most of its length is tail. It has an incredibly long tail for its size. It’s not that heavy, either, with the biggest green iguana ever weighed only a little more than 20 lbs, or 9.1 kg. Most are much lighter. It has long legs and long toes with claws, which makes it a good climber. It uses its tail to balance. It’s usually a drab olive-green or brown in color, although babies are brighter green with reddish spots and some adults are more orange in color. The tail is patterned with broad stripes. It has spines along its back and down its chin, and males develop a large dewlap that hangs down under the neck.

Although the iguana looks like a small dragon, it eats leaves, flowers, fruit, and other plant material, although it will also sometimes eat a grasshopper or snail and even bird eggs every so often. Many people keep green iguanas as pets, but they can be hard to keep healthy in captivity.

Another big reptile that lives in trees is the black mamba, a snake that lives in parts of Africa. It’s a slender snake that can be black in color, but that’s actually rare. The name black mamba comes from the inside of the snake’s mouth, which is black. When it feels threatened, it will raise its head high and open its mouth as a threat display. It can even flatten its neck to look like a hood like some cobras do. You really don’t want to see this threat display, because the black mamba’s venom is deadly and it’s an aggressive snake. Without treatment and antivenin, someone who is bitten can die within 45 minutes.

The mamba’s body can be gray, gray-green, brown, or brownish-yellow. It can grow nearly 15 feet long, or 4.5 meters, which makes it the second-longest venomous snake in the world, after the king cobra that we talked about in our Q&A episode last week.

The black mamba mostly lives in open forests and savannas, and it’s equally at home on the ground and in trees. It hides in termite mounds or in holes in trees at night, then comes out in the morning to warm up in the sunshine. Then it goes hunting, usually for small animals like rodents but also for larger ones like the rock hyrax. The rock hyrax can grow almost two feet long, or 50 cm, and looks kind of like a big rodent even though it’s not a rodent. It’s actually most closely related to the elephant. The black mamba will sneak up on a hyrax, bite it quickly, and then just wait until it dies to swallow it whole. The mamba also hunts birds and bats, which is why it spends so much time in the trees.

Some reptiles are so well adapted to living in trees that they can glide from tree to tree, like the flying snakes we talked about in episode 56. Flying snakes live in southeast Asia, and of course they can’t really fly. A flying snake has ridged scales on its belly that help it climb trees, and when it wants to move from one tree to another, it can flatten its body by flaring its ribs. This gives it more surface area to catch air, like a long skinny Frisbee. It’s been measured as gliding as far as 100 meters, or 109 yards, which is just a little longer than an American football field.

The largest species of flying snake, the golden tree snake, can grow over four feet long, or 1.3 meters. It’s striped black, gold, and yellow although some may be green and black. It eats small animals it finds in trees, including frogs, birds, bats, and lizards. It’s venomous, but its venom is weak and not dangerous to humans.

Many lizards can glide too, including the draco lizard. The draco lizard is common throughout much of southeast Asia and spends almost its whole life in trees, eating insects like ants and termites. It’s a small, slender lizard that only grows about 8 inches long at most, or 20 cm, and that includes its very long tail. Many gliding animals, like the flying squirrel, have gliding membranes called patagia that stretch from the front legs to the back legs, but the draco lizard is different. It has greatly elongated ribs that it can extend like wings, and the skin between the ribs acts as a patagium. This skin is usually yellow or brown so that the lizard looks like a falling leaf when it’s gliding.

The male draco also has a brightly colored dewlap under its chin that it can extend to attract a mate. When a female is ready to lay her eggs, she climbs down from her tree, finds some soil that’s soft enough for her to stick her head into to make a little hole, and then lays her eggs in the hole and covers them with dirt to hide them.

The draco lizard is beautiful and looks like a tiny dragon, and I want one to live in my garden and every time I go out to water my plants or pull weeds, I want it to fly down and ride around on my shoulder.

To bring us full circle, some geckos can also glide using thin membranes of skin around their body, legs, tail, and toes that act as patagia. They’re called parachute geckos, which is just perfect.

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 just tell a friend. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us that way.

Thanks for listening!


BONUS Q&A Episode!



It’s our bonus question and answer episode, which turned out to be ridiculously long but hopefully interesting!

Further listening/watching:

The Axolotl Song

~~~Buy my books!~~~

Whiskers used to have two eyes and a nose. In the background, Dracula (left) and Poe (right):

Black squirrel!

King cobra!

Pufferfish, puffed:

Dog nose:

Show transcript:

Welcome to the bonus Q&A episode of Strange Animals Podcast! I’m your host, Kate Shaw, and this is a little extra episode where I answer listener questions. So let’s jump right into it.

To start us off, Simon and Thia wanted to know how I first became interested in animals. I really don’t know! When I was little, I didn’t want to play with dolls, I wanted to play with my stuffed animals. I actually have a toy cat named Whiskers who I’ve had since I was four. Whiskers is older than all my teeth! I especially loved horses as a kid and since my family couldn’t afford to buy me a horse, I took riding lessons and read everything I could find about horses, fiction and nonfiction. All that reading about horses led to reading about other animals, and the more I read, the more interested I became in animals of all kinds.

Next, Melissa of the awesome podcast Bewilderbeasts asked, “What was the fact or episode that really slapped you out of left field, like, ‘I didn’t see that coming AT ALL’?”

OH MY GOSH, how many times has that happened to me? The most astounding fact I can think of isn’t actually about an animal at all but about trees. While I was researching the Temnospondyl episode, which had a related Patreon episode that ran at about the same time, I came across the fact that when trees first developed, nothing could break down the tough compound called lignin that hardens a tree’s cells to make wood and bark. When a tree died, its trunk just stayed where it fell forever, and this happened for at least 50 million years and possibly 100 million years. 100 million years of tree trunks just lying all over the ground! You wouldn’t be able to walk anywhere! You’d have to climb over hundreds of millions of fallen tree trunks, although naturally as the years passed the older ones would get buried deeper and deeper in the earth. But there would always be more!

This blew my mind, and later I came back to it, determined to do more research and make sure it was accurate. I did a whole lot of research, because it just didn’t seem possible, and that information ended up in episode 214.

As for an animal that blew my mind, I still have trouble believing ice worms are real. They’re worms that live in snow and ice! We covered them last August in episode 185 and I’m still reeling.

Next, Llewelly asks what my favorite extinct animal is, or animals. Why would you make me choose? This is so hard. Okay, fine, I’ll narrow it down to hoofed Pleistocene megafauna like the giant deer and elasmotherium and so many other animals with weird horns and ossicones and things like that. What really gets me is that they lived so recently! Many of them only died out 11,000 years ago, and some were probably around much more recently in a few isolated areas. It also really reminds me to appreciate the megafauna that’s still around. We live at the same time as giraffes!

Next, Richard E. asked, “Does your job involve the study of animals and/or is the pod something that you really wanted to do?” Tracie also asked what my background is, if I’m a professor or zookeeper or something similar. Helenka also asked my background and how I got interested in strange animals.

I’m kind of embarrassed that I never have pointed out that I’m not an animal expert, to steal a phrase from the awesome podcast Varmints! I actually work as a test proctor, AKA invigilator, in a large community college, so my work doesn’t have anything to do with animals. My background is in elementary education although I didn’t teach long. Basically I got my K-8 teaching certification and M.Ed., did some substitute teaching afterwards, and ended up getting my current job instead of taking a teaching position. I still love teaching, so when I decided I wanted to start a podcast, I knew it would be nonfiction. My undergraduate degree is in English literature, and I took so many history courses that I minored in history almost by accident, so I’m really good at research and can write an essay about any topic in the world in very little time. I didn’t know it when I was in college, which was long before podcasts existed anyway, but I have the perfect background for creating a nonfiction podcast.

Liesbet has three questions about the podcast: what inspired me to start it, what motivates me to keep going without missing any episodes, and what I enjoy most about it. I’m so pleased that someone noticed I’ve never missed a single episode! Not that it would be the end of the world if I did, of course, but if I did, I’d feel bad thinking about people who were looking forward to listening to the new episode and were disappointed when there wasn’t one.

Here is the raw, honest truth about why I started Strange Animals Podcast. It was several things combined and the whole story is kind of dumb. First, my friend Kevin makes a great pop culture podcast called The Flopcast, and after I’d listened to it for a while I thought, “Hey, that sounds like fun. I think I’ll start a podcast.” About the same time, I was listening to a back episode of a podcast I will not name, and it gave some misinformation about the Irish elk, specifically the outdated theory that it went extinct because its antlers were too big. I mentioned that in episode 4 and how I kept thinking about it and got kind of angry that a large, influential podcast hadn’t bothered to do enough research about an animal that lots of people are interested in. I decided I could do better and that my podcast would be about animals. Also at the same time, I was trying to find a good podcast about mystery animals that was well researched and didn’t skate off into speculation too much. I couldn’t find one that satisfied me, so I had to make one myself.

I wasn’t exactly sure what my focus would be when I first started the podcast. You can kind of tell when you listen to the first six months or so of the podcast that I was trying out new things and figuring out what worked best and what I liked best. I’m still figuring that out, for that matter.

It’s hard to decide what I like best about making the podcast. I like the whole process, except maybe not the frustrating parts of recording and editing. I think my favorite part has to be when I uncover information I find really exciting. I get to share that information with everyone who listens! It’s fantastic!

Next, let’s get into some questions about animals.

Pranav asked if I would explain how poisons work, which is a great question and also just a tiny bit alarming. No one eat anything Pranav cooks for you unless he’s eating some too. Actually, of course, he’s just wanting to learn more about poisonous animals, and I’ll talk about venomous animals too.

A poisonous animal contains toxins somewhere in its body, like the hooded pitohui bird that we talked about in episode 222 that has poisonous feathers. The poison stops other animals from trying to eat it. In the case of the hooded pitohui, its poison causes your skin to burn when you touch it, so an animal that tries to bite it will have a burning mouth. If it actually eats any of the poison, the animal can die. Many amphibians secrete toxins through their skin, like the poison dart frog, and many other animals concentrate toxins in their muscles or internal organs.

A venomous animal has toxins that it can inject into a wound to hurt or kill another animal. Some snakes can inject venom with special fangs, but some amphibians have pointed ribs that are sharp enough to stab a potential predator. The ribs will project through the amphibian’s sides through tiny spots that are filled with toxins. The toxins coat the points of the ribs, and if the predator tries to bite down, it gets those toxins stabbed right into its mouth. Some fish have spines that are coated in toxins, and of course many insects, arachnids, and other invertebrates have stingers that inject toxins.

Generally, a poisonous animal absorbs toxins from a food it eats, often a toxic insect, and instead of getting sick, it uses those toxins to protect it from predators. A venomous animal usually produces its own toxins in its body, especially animals that use venom to kill or disable prey. It costs energy for the animal to make venom, and it doesn’t want to waste it. That’s why snakes will sometimes give what are called dry bites in self-defense, where it bites but doesn’t inject any venom. It’s hoping that the pain of the bite itself will make a potential predator retreat without the snake needing to use venom.

Different toxins have different effects, naturally, and animals produce so many different kinds of toxins that we could talk about it all day and not even cover them all. Instead, let’s quickly discuss two animals, one venomous and one poisonous.

Our venomous example is the king cobra. It can grow over 18 feet long, or 5.5 meters, and lives in southern Asia. It mostly eats other snakes and some lizards. Its venom contains numerous toxins that do different horrible things. The neurotoxins in its venom affect the central nervous system, which can cause all sorts of issues like dizziness, pain, blurred vision, sleepiness, and even paralysis. Other toxins in the venom are called cardiotoxic because they affect the heart, making it weak so that circulation of blood slows down. If a king cobra bites you and injects venom, you can die within 30 minutes as the venom basically just shuts your body down, one process at a time. If your heart stops or your diaphragm becomes paralyzed so you can’t breathe, that’s it for you. Fortunately, in ordinary situations the king cobra is shy and avoids people, so if you don’t bother it, it won’t bite you.

Our poisonous example is the pufferfish. Some species of pufferfish are incredibly poisonous. You may have heard about fugu, which is considered a delicacy even though it’s so poisonous that in Japan and some other countries, chefs have to be specially trained and licensed to prepare the fish to eat. The part of the fish that’s considered tastiest is also the part that’s most poisonous, the liver. It contains tetrodotoxin, which is a neurotoxin that stops your nerves from sending the tiny electrical signals that allow them to move. If you’re poisoned with tetrodotoxin, you start to feel dizzy and sick, then you start having difficulty speaking and moving, then you have trouble breathing, and then, ultimately, you’re paralyzed and can’t breathe, at which point you die. Since the toxin doesn’t affect your brain, you remain completely aware of what’s happening to you but there’s nothing you can do about it. There’s no antidote. Fortunately, you have the option of not eating fugu. Also, it turns out that the pufferfish’s poison comes from a type of bacteria, so fish raised in careful conditions in captivity aren’t poisonous.

Most poisonous and venomous animals are harmless to humans!

Next, Connor wrote and said, “I recently moved to Michigan from West Virginia and noticed a lot of black squirrels around. Are they a different species/sub-species or just melanistic individuals?”

I looked into this and sure enough, Michigan and other areas around the Great Lakes are known for a large population of black squirrels. I’ve never seen a black squirrel but now that I’ve looked at pictures of them, they are awesome and I wish I had some in my yard.

The eastern gray squirrel is the most common species of squirrel in eastern North America, and a black morph of that species and other squirrel species is not that unusual. The color difference is due to a small mutation in the gene that controls how much pigment the squirrel’s fur contains. Connor is right that the coloration is due to melanistic individuals.

But that doesn’t explain why there are so many black squirrels in Michigan and surrounding areas. No one’s completely sure why that is. In other animals, including the gray wolf and the leopard, melanistic individuals are more common in areas where there’s thick vegetation that blocks a lot of sunlight. A dark-colored wolf or leopard is better camouflaged in the shadows, which allows it to sneak up on prey. But the squirrel isn’t a predator, and black squirrels don’t seem to be any more common in heavily forested areas compared to more park-like areas.

One suggestion is that black squirrels find it easier to stay warm in cold weather, because dark fur absorbs more heat than gray fur. This actually does seem to have some basis in fact. Black squirrels are much more common in northern areas, including parts of Canada where the eastern gray squirrel ordinarily doesn’t live. Black squirrels are correspondingly rare in more southern areas where winters are mild, which explains why I’ve never seen one. Then again, the fox squirrel is also common in eastern North America, often living in the same areas where eastern gray squirrels live, and they also have a black morph, but black fox squirrels mostly live in the southeast. So it’s a mystery.

Black squirrels are the same as ordinary colored squirrels. They just look different. That reminds me that I have an episode about squirrels planned for some time later this year, especially unusual squirrels.

Next, Anna has a question about dogs. She says, “We have a dog named Sadie, who is a beagle mix. She is much more aware of the sounds and smells around us and often howls and barks at things that we can’t see. How do dogs have such a strong sense of smell and good hearing?”

The wild ancestors of dogs were wolves. Wolves are generally nocturnal, and as a result, dogs have sensitive hearing and smell to find prey when it’s dark. A dog can hear in the ultrasonic range, which refers to sounds higher than human hearing. Humans can hear sounds up to 20,000 hertz, while dogs can hear sounds up to 50,000 hertz. A dog also has a lot of muscles in its ears that allow it to turn its outer ear to find sounds. While some dog breeds have lapped-over ears, wolves and many dog breeds have pricked-up ears that act as little satellite dishes to gather up as many sounds as possible. If you cup your hands behind your ears, you can get a sense of how this helps. A dog also has a relatively large ear canal, which is the inside part of the ear. A large ear canal allows more sound vibrations in. Cats actually have even better hearing than dogs, but cats don’t have nearly the same ability to smell.

A dog’s sense of smell is incredible. Humans have about six million olfactory receptors in our noses. That sounds like a lot, but a dog has over 200 million olfactory receptors! It can also process all those smells incredibly well in its brain, so that with training a dog can detect unbelievably faint smells. That’s why dogs are used to sniff out dangerous items like bombs and illegal drugs, or find people who are buried in rubble after an earthquake or other disaster, or track down people who are lost. Dogs can even learn to detect the smell of some diseases, including cancer, malaria, and tuberculosis.

A dog’s nose is much different from a human nose. If you have a dog, or can borrow a friend’s dog, sit down and take a look at their nose. Ha ha, the dog just licked you in the face! That’s hilarious! The dog’s nose has nostrils in the front but if you look carefully, you’ll see that the nostril openings continue along the sides of its nose, in a little slit. There’s also a little fold of tissue inside the nose. The tissue separates the air into two streams. One stream goes into the lungs, but the other gets circulated into the nose to come in contact with all those olfactory receptors. Then, when the dog breathes out, the air goes out the side slits instead of out the main nostrils, so it doesn’t push any odors out of the nose. A dog’s nose works best when it’s damp, which is why a healthy dog has a wet nose.

When you hear a sound, you can usually tell which direction it’s coming from by turning your head, because the sound will be slightly louder in one ear than the other and your brain can make sense of this difference. Dogs can tell which direction a smell is coming from because its brain can tell which nostril is picking up more of the smell.

A dog’s sense of smell is so acute, and so important to the animal, that a dog that loses its vision can often do just fine. It can smell its way around. Naturally, some dog breeds have a better sense of smell than others, and some individuals are better at smelling than others too.

Don’t feel bad about your sense of smell, though. Humans may not be as good at smelling as dogs are, but we can train ourselves to be more sensitive to faint odors. The next time you take a walk, pay attention to what you’re smelling and I bet you’ll notice a lot more scents than you realize.

Next, Helenka also wanted to know about my writing. Thank you so much for asking! Now I can plug my books and also tell you how the strange animals podcast book is coming along!

I mostly write fantasy fiction. I have a steampunk adventure book available called Skytown, and a related collection of short stories about the same characters from the book, which is called Skyway. Sometimes I get the titles confused because they’re really similar, but Skytown is called that because there’s a city in the book that can only be reached by air, which in this fantasy world is mostly airships. The main characters are two young women named Jo and Lizzy, friends who are airship pirates. It’s a lot of fun, and the short story collection actually tells how Jo and Lizzy met and what they did together right up to the start of the novel. If that sounds interesting, I’d love it if you could pick up a copy of one or both books. They’re published by small independent publishers, who don’t make a lot of money and have trouble getting books into physical stores. There’s a link in the show notes.

Okay, so now I get to tell you all about the Strange Animals Podcast book! I’ve been working on it all year and it’s getting really close to being done. The title is Beyond Bigfoot and Nessie: Lesser-Known Mystery Animals from Around the World, and most of the material is taken directly from mystery animal episodes from the last four-plus years, BUT I’ve made sure to update the chapters as much as possible and I’ve added some new chapters.

I’ve decided to self-publish the book, so I’m planning a Kickstarter to cover the costs of hiring a cover artist and things like that. I’d like to run the Kickstarter in October, which would give me time to get it published hopefully in time for the holidays in case people want to order copies to give as gifts. We’ll see how that goes, though. There’s a ton of work that goes into running a successful Kickstarter, and although I don’t need a whole lot of funding for the book, it still worries me that maybe no one will be interested and it won’t meet its funding goal and I’ll have to pay for everything out of pocket. I’m already kind of broke this year from paying about $5,000 to the emergency vet to save my cat Poe’s life, but honestly, if the choice is between having Poe running around and playing or self-publishing a book, I will choose Poe every single time.

Anyway, one way or another I’ll make sure the Beyond Bigfoot and Nessie book is available to buy before the podcast’s fifth year anniversary in February 2022!

Finally, this wasn’t sent in as a question but I thought it would be a nice way to finish off the episode. In a really nice review, a listener who I think is named Meg said “I think she’s southern like me but not sure.” Yes, I am southern, although I don’t have much of an accent. I was born in Georgia and grew up in East Tennessee, where I live now.

Thanks to everyone who sent in questions! We’ll probably have another Q&A episode eventually, maybe next year, so feel free to send me your questions! I think I got everyone’s questions answered this time, but if I missed yours, definitely let me know. The best way to get in touch with me is through email, strangeanimalspodcast@gmail.com.

To finish us off, Richard from NC wanted me to play the Axolotl song. I won’t play the whole thing, because it’s kind of long, but here’s a clip and there’s a link in the show notes. It’s by an animator and musician called Joel Veitch. I’ve had this song stuck in my head ever since Richard sent me the link, so now you will too. Also, I promise I’ll make a whole episode about the axolotl soon.

Thanks for listening!


Episode 236: Updates 4 and a Mystery Snake!



Sign up for our mailing list! We also have t-shirts and mugs with our logo!

It’s our fourth annual updates and corrections episode! I’ve already had to make a correction to this episode!

Further reading:

Cassowary, a rare emu-like bird, attacks and kills Florida man, officials say

The dog Bunny’s Facebook page

3D printed replicas reveal swimming capabilities of ancient cephalopods

Enormous ancient fish discovered by accident

A rare observation of a vampire bat adopting an unrelated pup

Pandemic paleo: A wayward skull, at-home fossil analyses, a first for Antarctic amphibians

Neanderthals and Homo sapiens used identical Nubian technology

Entire genome from Pestera Muierii 1 sequenced

Animal Species Named from Photos

Cryptophidion, named from photos:

The sunbeam snake showing off that iridescence:

Show transcript:

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

 

It’s our fourth annual updates and corrections episode, and to keep it especially interesting we’ll also learn about a mystery snake. Make sure to check the show notes for lots of links if you want to learn more about these updates.

 

First, we have a small correction from episode 222. G emailed with a link about a Florida man who was killed by a cassowary in 2019, so cassowaries continue to be dangerous.

 

We also have a correction from episode 188, about the hyena. I called hyenas canids at one point, and although they resemble canids like dogs and wolves, they’re not canids at all. In fact, they’re more closely related to cats than dogs. Thanks to Bal for the correction!

 

In response to the talking animals episode, Merike told about a dog who uses computer buttons to communicate. The dog is called Bunny and she’s completely adorable. I’ll link to her facebook page. I have my doubts that she’s actually communicating the way it looks like she is. She’s obviously a clever dog but I don’t think she understands the English language so well that she can choose verbs like “is” from her list of words. I think she’s probably mostly taking unconscious cues from her owner. But I would be happy to be proven wrong.

 

Following up from our recent deep-sea squid episode, a team of paleontologists studying ancient cephalopods 3-D printed some replicas of what the animals would have looked like while alive. Then they took the models into a swimming pool and other water sources to study how their shells affected the way they could move through the water. They discovered that a type of cephalopod with a straight shell, called an orthocone, probably mostly moved up and down in the water to find food and could have moved extremely fast in an upward or downward direction. A type of cephalopod with a spiral shaped shell, called a torticone, also spun slightly as it moved around. The same team has previously worked with 3-D models of ammonoids, which we talked about in episode 86. The models don’t just look like the living animals, they have the same center of balance and other details, worked out mathematically.

 

Speaking of ancient animals, a collector in London bought a fossil found in Morocco thinking it was part of a pterodactyl skull. When the collector asked a palaeontologist to identify it, it turned out to be a fossilized coelacanth lung. The collector donated the fossil for further study, and the palaeontologist, David Martill, worked with a Brazilian coelacanth expert, Paulo Brito, to examine the fossil.

 

The fossil dates to the Cretaceous, about 66 million years ago, and is bigger than any coelacanth lung ever found. Modern coelacanths grow a little over six feet long at most, or 2 meters, but the estimated length of this Coelacanth is some 16 ½ feet, or 5 meters. The fossil is being donated to a university in Morocco.

 

We talked about vampire bats way back in episode 11, and I love bats and especially vampire bats so I try to keep an eye on new findings about them. Everyone thinks vampire bats are scary and creepy, but they’re actually social, friendly animals who don’t mean to spread rabies and other diseases to the animals they bite. It just happens.

 

Vampire bats live in colonies and researchers have long known that if a female dies, her close relations will often take care of her surviving baby. Now we have evidence that at least sometimes, the adoptive mother isn’t necessarily related to the birth mother. It’s from a recently published article based on a study done in 2019.

 

A team researching how unrelated vampire bats form social bonds captured 23 common vampire bats from three different colonies and put them together in a new roost where their interactions could be recorded by surveillance cameras. One particular pair of females, nicknamed Lilith and BD, became good friends. They groomed each other frequently and shared food. If you remember from episode 11, vampire bats share food by regurgitating some of the blood they drank earlier so the other bat can lap it up. Since vampire bats can starve to death in only a few nights if they can’t find blood, having friends who will share food is important.

 

During the study, Lilith gave birth to a baby, but shortly afterwards she started getting sick. She had trouble getting enough food and couldn’t groom or take care of her baby as well as a mother bat should. Her friend BD helped out, grooming the baby, sharing food with Lilith, and eventually even nursing the baby when Lilith got too sick to produce milk. After Lilith died, BD adopted the baby as though it was her own. By the time the study ended, BD was still caring for the baby bat.

 

We talked about spiders in the Antarctic in episode 221, and mentioned that Antarctica hasn’t always been a frozen wasteland of ice and snow. In a new study of fossils found in Antarctica, published in May of 2021, the first Antarctic amphibian skull has been identified. It lived in the early Triassic, not long after the end-Permian mass extinction 252 million years ago. It’s been named Micropholis stowi and is a new species of temnospondyl that was previously only known from South Africa. The skull, along with other fossils from four individuals, was discovered in the Transantarctic Mountains in 2017 and 2018, and the research team studied them from home during the 2020 pandemic lockdowns.

 

In news about humans and our extinct close relations, a new finding shows that Neanderthals and humans used the same type of tools. Researchers studied a child’s tooth and some stone tools, all found in a cave in the mountains of Palestine, and determined that the tooth was from a Neanderthal child, not a human. The tooth was discovered in 1928 but was in a private collection until recently, so no one had been able to study it before now. The tools are a specific type developed in Africa that have only been found associated with humans before. Not only that, but until this finding, there was no evidence that Neandertals ever lived so far south.

 

The child is estimated to have been about nine or ten years old, which is the age when you’re likely to lose a baby tooth as your adult teeth start growing in. I like to think about the child sitting next to their Mom or Dad, who were either creating new tools or using ones they’d already made to do something like cut up food for that evening’s dinner. Maybe the child was supposed to be helping, and they were, but they had a loose tooth and kept giving it a twist now and then, trying to get it to come out. Then, finally, out it popped and bounced onto the cave floor, where it was lost for the next 60,000 years.

 

Researchers have just announced that they’ve sequenced the genetic profile of a woman who lived in what is now Romania about 35,000 years ago. Judging from her skull shape and what is known about ancient humans in Europe, the team had assumed she would be rather restricted in her genetic diversity but that she would show more Neanderthal ancestry than modern humans have. Instead, they were surprised to find that the woman had much more genetic diversity than modern humans but no more Neanderthal genes than most human populations have these days.

 

This was a surprise because modern humans whose prehistoric ancestors migrated out of Africa show much less genetic diversity than modern humans whose ancestors stayed in Africa until modern times. Researchers have always thought there was a genetic bottleneck at some point during or not long after groups of humans migrated out of Africa around 80,000 years ago. Lots of suggestions have been made about what might have caused the bottleneck, including disease, natural disaster, or just the general hardship of living somewhere where humans had never lived before. A genetic bottleneck happens when a limited number of individuals survive long enough to reproduce—in other words, in this case, if so many people die before they have children that there are hardly any children left to grow up and have children of their own. To show in the general population as it does, the bottleneck has to be widespread.

 

Now researchers think the genetic bottleneck happened much later than 80,000 years ago, probably during the last ice age. Humans living in Europe and Asia, where the ice age was severe, would have had trouble finding food and staying warm.

 

I’m getting close to finishing the Strange Animals Podcast book, which I’ll talk about a little more in our Q&A episode later this week. It’s a collection of the best mystery animals we’ve covered on the podcast, along with some new mystery animals, and I’m working hard to update my research. If you remember back in episode 83, about mystery big cats, we discussed the Barbary lion, which was thought to be an extinct subspecies of lion that might not actually be extinct. Well, when I looked into it to see if any new information had turned up, I found more than I expected. I rewrote those paragraphs from episode 83 and I’ll read them here as an update:

 

Lions live mostly in Africa these days, but were once common throughout southern Asia and even parts of southern Europe. There even used to be a species called the American lion, which once lived throughout North and South America. It only went extinct around 11,000 years ago. The American lion is the largest species of lion ever known, about a quarter larger than modern African lions. It probably stood almost 4 feet tall at the shoulder, or 1.2 meters. Rock art and pieces of skin preserved in South American caves indicate that its coat was reddish instead of golden. It lived in open grasslands like modern lions and even in cold areas.

 

Much more recently, the Barbary lion lived in northern Africa until it was hunted to extinction in the area. The Barbary lion was the one that battled gladiators in ancient Rome and was hunted by pharaohs in ancient Egypt. It was a big lion with a dark mane, and was thought to be a separate subspecies of lion until genetic analysis revealed in 2006 that it wasn’t actually different from Panthera leo leo.

 

The last wild Barbary lion was sighted in 1956, but the forest where it was seen was destroyed two years later. The lions in a few zoos, especially in Ethiopia and Morocco, are descended from Barbary lions kept in royal menageries for centuries.

 

Lions are well known to live on the savanna despite the term king of the jungle, but they do occasionally live in open forests and sometimes in actual jungles. In 2012 a lioness was spotted in a protected rainforest in Ethiopia, and locals say the lions pass through the reserve every year during the dry season. That rainforest is also one of the few places left in the world where wild coffee plants grow. So, you know, extra reason to keep it as safe as possible.

 

Finally, we’ll finish with a mystery snake. In 1968, during the Vietnam War, the United States Naval Medical Research Unit discovered a small snake in central Vietnam. It was unusual enough that they decided to save it for snake experts to look at later, but things don’t always go to plan during wartime. The specimen disappeared somewhere along the line. Fortunately, there were photographs.

 

The photos eventually made their way to some biologists, and in 1994 a paper describing the snake as a new species was published by Wallach and Jones. They based their description on the photos, which were good enough that they could determine details like the number of scales on the head and jaw. They named it Cryptophidion annamense and suggested it was a burrowing snake based on its characteristics.

 

Other biologists thought Cryptophidion wasn’t a new species of snake at all. In 1996 a pair of scientists published a paper arguing that it was just a sunbeam snake. The sunbeam snake is native to Southeast Asia, including Vietnam, and can grow over 4 feet long, or 1.3 meters. It’s chocolate-brown or purplish-brown but has iridescent scales that give it a rainbow sheen in sunshine. It’s a constricting snake, meaning it squeezes the breath out of its prey to kill it, but it only eats small animals like frogs, mice, and other snakes. It’s nocturnal and spends a lot of its time burrowing in mud to find food.

 

Wallach and Jones, along with other scientists, argued that there were too many differences between the sunbeam snake and Cryptophidion for them to be the same species. But without a physical specimen to examine, no one can say for sure if the snake is new to science or not. If you live in or near Vietnam and find snakes interesting, you might be the one to solve this mystery.

 

You can find Strange Animals Podcast online 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 just tell a friend. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us that way.

 

Thanks for listening!


Episode 235: Deep-Sea Squid



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This week we visit the weirdest squid in the deep sea!

I was a guest on Tim Mendees’s After Hours that’s now up on YouTube! It’s mostly about my writing but we talk about all kinds of stuff, including cephalopods! There is some bad language but it’s not all that bad and it’s mostly toward the end.

Further reading/watching:

Elusive Long-Tailed Squid Captured on Film for First time

See Strange Squid Filmed in the Wild for the First Time (ram’s horn squid)

Multiple observations of Bigfin Squid (Magnapinna sp.) in the Great Australian Bight reveal distribution patterns, morphological characteristics, and rarely seen behaviour

Untangling the Long-Armed Mystery of the Bigfin Squid

Drawing of a long-arm squid and an actual long-arm squid:

Asperoteuthis mangoldae, which really should be called the long-tailed squid:

 

Verany’s long-armed squid, with its tentacles mostly retracted (so not looking very long-armed):

Verany’s long-armed squid with tentacles extended:

Drawing of a paralarval Verany’s long-armed squid:

The ram’s horn squid, floating along doop doop doop:

Drawing of the coiled internal shell of the ram’s horn squid:

A clawed armhook squid mama with her egg cluster:

Bigfin squid!

Another bigfin squid! Good grief look at that!

Show transcript:

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

Before we get started, a quick announcement that I was a guest on a YouTube show called After Hours recently! I was there mostly to talk about my writing, but naturally animals came up too, especially cephalopods. There’s a link in the show notes if you want to watch the show. There is a little bad language, but not too bad and it’s more toward the end.

Anyway, in a not-exactly coincidence, this week we’re going to look at some of the weirdest deep-sea squids known. Yes, weirder than the flying squid we talked about in episode 101. We don’t know much about any of them, but they’re definitely not what you expect when you think about squid.

Let’s talk first about Asperoteuthis acanthoderma, the long-arm squid. It’s also sometimes called the thorny whiplash squid because it has little pointy tubercules in its skin and long, whiplike feeding tentacles. It lives in the deep sea and has been found in both the Pacific and the Atlantic Oceans, although very rarely. Despite its name, its feeding tentacles are much longer than its arms, although its arms are pretty long too. A squid’s body is generally more or less torpedo-shaped and is called a mantle. It has eight arms and two feeding tentacles that are usually longer than the arms. Many squid species have relatively short arms compared to mantle length.

The feeding tentacles in long-arm squid are very slender and delicate, and they’re easily broken off after the animal dies and has washed around in the water for a while. One intact specimen has been found and measured, though. It had a mantle length of almost a foot and a half long, or 45 cm, but its total length, including the tentacles, was 18 feet, or 5.5 meters. The tentacles were 12 times the mantle length.

Using that ratio, one large specimen found in 2007, which was 6 1/2 feet long, or 2 meters, including both mantle and arms, is estimated to have measured up to 24 feet long when it was alive, or over 7 meters. Most of its length is due to its incredibly long, thin feeding tentacles.

So what does the long-arm squid eat with those long, delicate tentacles? We don’t know. We don’t know most things about the long-arm squid.

Another species of Asperoteuthis is Asperoteuthis mangoldae. So little is known about it that it doesn’t even have an informal name. It was only described in 2007 and has only been found around the Hawaiian islands in the Pacific Ocean. It looks similar to the closely-related long-arm squid but without the incredibly long feeding tentacles. Instead, it has a sort of tail, so I nominate it to be called the long-tailed squid. It was caught on video for the first time in 2019 by a deep-sea rover. You’re going to hear a lot about deep-sea rovers in this episode. There are lots of links in the show notes to articles with embedded video of various squids, which is really interesting to watch.

Asperoteuthis mangoldae is a long, slender squid. I couldn’t find any measurements so it could be that’s just not known right now. The species in this genus have an extension of the mantle, on the side opposite of the arms, that looks like an extra fin but that doesn’t seem to be used as a fin. In the long-tailed squid, this extra fin is as long as its mantle and arms and feeding tentacles all measured together. Most of the time the thin flaps of skin on either side of the so-called tail are extended, making it look like a really long fin, but when the squid feels threatened and needs to flee, it collapses the fin part around the middle section so that it reduces drag in the water. That way the squid can move faster. Researchers speculate that the tail section may make the squid look much larger to potential predators, and possibly may imitate an organism called a siphonophore that has stinging cells.

Another squid called Verany’s long-armed squid is Chiroteuthis veranii. It’s related to the long-arm squid we talked about at the beginning of the episode, but they’re placed in different genera. It lives throughout the world’s oceans, often in the deep sea although not as deep as some of the species we’re talking about today. Unlike most squid, whose arms are all about the same length, two of its arms are much wider and longer than the others.

Like the other long-arm squid, its feeding tentacles are incredibly long and thin. The mantle is quite small, up to 8 inches long, or 20 cm, with the legs about the same length as or a little longer than the mantle, but the total length of this squid, including the feeding tentacles, is over four feet, or 130 centimeters. Most of the time the feeding tentacles are retracted, though, so they’re no longer than the arms, and they’re protected by the two largest arms. When the squid sees a tiny fish or crab or other small animal it wants to eat, it can shoot its retracted tentacles out at high speed to catch it. It’s probable that other species of long-armed squid hunt the same way.

A squid’s eggs hatch into an initial form called a paralarva. This is actually the case for other cephalopods too, including octopuses. The paralarvae usually just look like teeny-tiny miniature versions of the adult, but with stubby little arms. In the case of Verany’s long-armed squid, though, the larval squid looks sort of like a little rod. It’s long and thin, mostly transparent, and has a gladius, also called a pen, that sticks out the end of the mantle on the opposite side from the arms. The pen of a squid is named after an ink pen, although the other name, gladius, refers to the shape of a type of ancient Roman sword. It’s a vestigial shell but located inside the squid’s body. The tail of the long-tailed squid we just talked about is given structure by the gladius, so it’s possible that its paralarvae look rod-like, like those of Verany’s long-armed squid.

Speaking of internal shells, the ram’s horn squid has a coiled internal shell. This is unique among all the squid known to be alive today, so the ram’s horn squid is the only living member of its own order and its own family and its own genus. Technically it’s not really considered a squid although it is a closely related cephalopod. It’s small, with a mantle length only about an inch and a half long, or 4.5 centimeters. Its eight arms are quite short and it has two feeding tentacles that are about the same length as its mantle. Its mantle has an outer covering that extends down almost to the squid’s eyes, and it’s big enough that the squid can pull its eyes and legs and tentacles under this covering. The spiral shell resembles that of a nautilus, but it’s inside the squid instead of the nautilus living inside the shell. The shell contains gas that the squid uses to adjust its buoyancy.

For a long time researchers were confused as to how the ram’s horn squid oriented itself in the water. The empty shells from dead squid wash ashore pretty often, and experiments with them show that they want to float with the big end of the shell pointing downward. That confused the researchers, since that would mean the squid floats around with its arms downward too, which means that the photophore on the tail end of its mantle points upward. A photophore is a light-emitting organ, which is common in deep-sea animals. Usually an animal wants its light to point downwards, which means that larger animals looking up toward the surface see a little light sparkling amid the light shining down from the surface instead of seeing a squid-shaped shadow against the surface.

Then, in late 2020, a deep-sea rover exploring the northern section of the Great Barrier Reef off the coast of Australia got a video of a ram’s horn squid in the water. It was the first time a living one had ever been observed. In the video, the squid is floating with its arms pointing upward, flapping the fins on its mantle to move along in the water. Mystery solved! There’s still a lot we don’t know about the ram’s horn squid, but at least we know it doesn’t swim around upside-down.

Another squid that has only recently been seen alive in the wild from a deep-sea rover is the clawed armhook squid. My brother Richard alerted me to this one in a Twitter thread. The clawed armhook squid lives in the northern Pacific Ocean and has a mantle length of about seven inches, or 18 cm. Its arms are about the same length as its mantle. It gets its name from the female, which has small hooks on her arms to help her keep hold of her egg cluster. She lays about 3,000 eggs in a tube-like cluster that looks sort of like a gray cloth bag that’s open at both ends. Most squid lay their eggs on the sea floor and leave them, usually dying soon after, but the clawed armhook squid holds her egg cluster until the eggs hatch. She makes sure the eggs get enough oxygenated water by pumping water through the middle of the bag. She also swims away from anything that might want to eat her eggs or her, although she can’t swim very fast since she has to use her arms to hold onto the egg cluster. She usually stays in deep water far from shore while the eggs are developing, because there are fewer predators there than in her usual habitat nearer shore. In 2001 a rover spotted a mother squid with her egg cluster at 8,200 feet below the surface, or 2500 meters. That’s more than a mile and a half down, or two and a half kilometers.

Unfortunately for the mother squid, after she lays her eggs, she can’t use her arms for anything except holding and taking care of them, and that includes eating. She just doesn’t eat once she lays her eggs, and while we’re not sure how long it takes for them to hatch, it may be as much as nine months. It’s most likely that she dies after her babies hatch. All the female squids seen with egg clusters have been missing their feeding tentacles, and researchers think the squid may actually bite off her own tentacles so they don’t get in the way of her eggs.

Finally, the family Magnapinnidae, also called bigfin squids, were mysteries for over a century. For a long time they were only known from paralarval and juvenile individuals. Five species are known but there may be more, but no scientist has ever been able to study an adult except through photographs and videos made by deep-sea rovers.

All squid have fins of some kind on the mantle to help it move around. Different species, naturally, have varying sizes and shapes of fins. In the bigfin squid, as you may have guessed, the fins are very big. They look more like wings and can be almost as large as the entire mantle. But that’s not the really weird thing about these squid, although it was the most obvious thing when all we knew about them were young specimens. The arms and tentacles of squid don’t develop to their full length until the squid is an adult. The bigfin squid’s arms and tentacles are very long and they’re also very different from all other squids.

In 2001, a deep-sea rover used by an oil company in the Gulf of Mexico caught video of a large, unusual squid. Fortunately, one of the men operating the rover remotely asked for a copy of the squid video for his girlfriend, who was interested in deep-sea animals. His girlfriend asked around, trying to find out what kind of squid it was, and eventually contacted a squid expert at the Smithsonian National Museum of Natural History. The squid expert is named Mike Vecchione and when he saw the video, he freaked out. He’d never seen anything like this squid before. He says he jumped out of his chair and started yelling in excitement.

Then, once he calmed down, he contacted all his squid expert colleagues, who also freaked out, and eventually they found more footage of the weird squid taken by other oil rig rovers. The workers operating the rovers had no idea that the squid was a scientific mystery so hadn’t thought to contact any scientists. Finally the squid was identified as an adult bigfin.

In 2015, a deep-sea rover in a scientific expedition caught video of two bigfin squid near Australia, and in 2017 it saw three more. It also spotted some juvenile bigfin squid in the same area. Even better, the rover was able to use lasers to get a much more accurate estimate of the squid’s size than ever before. All five were different sizes, so they were probably five different individuals.

The bigfin squid has very thin arms and tentacles, referred to as vermiform. That means worm-shaped, which gives you an idea of how thin we’re talking. The largest bigfin squid measured by the rover in 2015 and 2017 had a mantle length of about 6 inches, or 15 cm, and a fin width of 5.5inches, or 14 cm, but the longest arm or tentacle length was 5.5 feet, or 1.68 meters. Measurements of other bigfin squid suggest it can grow up to 26 feet long, or 8 meters, and maybe even longer.

In the bigfin squid, the arms and tentacles are the same size. In other squids, the tentacles are usually longer and look different from the arms. The great length of the arms and tentacles of the bigfin squid comes from what’s called a distal filament that grows from the tip of the arm or tentacle. The filaments are sometimes missing, so it’s possible that they’re sometimes damaged and lost or maybe bitten off. The squid seems to use its arms and tentacles the same way instead of using its arms for some things and its tentacles for other things.

The bigfin squid holds its arms and tentacles differently from any other squid, in what’s called a crane pose or elbow pose. It’s not clear from the articles I read, but it seems to be that if you don’t count the distal filaments, the arms and tentacles are not actually all that long in comparison to its mantle. When it’s hunting, the squid holds them out from its body with the extremely long filaments hanging down. It looks like the squid has elbows that way. Squid don’t have elbows because squid, like other cephalopods like octopuses, don’t have any bones. We talked about how octopuses move without bones in episode 142 if you’re interested, and it’s the same for squid.

The bigfin squid can retract the filaments by coiling them up. One researcher said the coiled-up filaments look sort of like an old-fashioned phone cord, which will mean nothing to my younger listeners but the rest of us just thought, “Oh yeah, that makes total sense.” The filaments are sticky and trap tiny animals and particles of food drifting in the water. If you remember way way way back in episode 11 where we talked about the vampire squid, it uses its feeding tentacles the same way, including being able to retract them, but the vampire squid and the bigfin squid are not very closely related at all.

A research sub investigating a WWII shipwreck spotted a bigfin squid 3.7 miles below the surface, or 6,000 meters, which made it the deepest squid ever recorded. Imagine looking out the window of a submarine, assuming they have windows, trying to see details of a shipwreck, and suddenly there’s a massive squid with incredibly long, thin arms looking back at you.

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 that way.

Thanks for listening!


Episode 234: Sun Bears, Water Bears



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Thanks to Enzo and Lux for their suggestions! Let’s learn about the sun bear and the water bear this week!

Sun bear just chillin:

Sun bears got long tongues:

The water bear, AKA tardigrade, is not actually a bear. For one thing, it has twice the number of legs as bears have:

Show transcript:

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

It’s summer in the northern hemisphere, which means hot weather and sunshine and, if you’re lucky, a trip to the lake or ocean. To celebrate summertime, let’s talk about two animals suggested by Enzo and his sister Lux. They wanted to hear about the sun bear and the water bear. Get it? Sun and water?

Enzo’s suggestion is the sun bear, which we talked about a little bit way back in episode 76, but which is a fascinating animal that deserves a lot more attention.

The sun bear lives in southeast Asia in tropical forests and is most closely related to the black bear. It has silky black fur, although some are gray or reddish, and a roughly U-shaped patch of fur on its chest that varies in color from gold to almost white to reddish-orange. Its muzzle is short and is lighter in color than the rest of its face, usually gray. It has small ears too. It’s the world’s smallest bear, only around three feet long from head to tail, or 150 cm, and four feet tall when standing on its hind legs, or 1.2 meters. Researchers think its chest spot acts as a threat display. When a sun bear stands on its hind legs, the chest spot is really obvious, which may warn potential predators away. Even so, tigers and leopards will attack and eat sun bears.

The sun bear spends a lot of time in trees, more than any other bear. It has long claws that it uses for climbing and to tear open logs to get at insect larvae. It eats a lot of termites and especially loves honey, which it licks from the hive with its long tongue–up to 10 inches long, or 25 cm. It also eats a lot of plant material, especially fruit and acorns. It will catch and eat birds and small animals, or sometimes larger animals like deer, but it mostly eats insects and fruit.

The female sun bear makes her den in a hollow tree to give birth. She has one or two cubs at a time, and like other bear cubs they’re born extremely small and with their eyes and ears sealed shut. This is the case with animals like dogs and cats too, but newborn bears are tiny compared to how big the mother bear is. The eyes and ears continue developing after the cub is born, but it’s a few months before it can see and hear properly. A cub remains with its mother for almost three years.

Other than mothers and babies, the sun bear is solitary. Adults don’t typically interact except to mate, although adult sun bears kept in captivity will play together. A 2019 study of sun bears came to a surprising conclusion that they communicate with each other by mimicking facial expressions. This is something humans do all the time, of course, and apes do too. Dogs also mimic facial expressions. Humans, apes, and dogs are all intensely social animals, so researchers have always assumed that the mimicking of facial expressions is important because of that sociability. I mean, that just makes sense. If you see a friend approaching and they have a big smile on their face, naturally you’re going to smile too. But here are these solitary bears with facial communication just as well-developed as in apes. Researchers think it may be a trait that’s so important to mammals as a whole that it develops even in species that don’t spend a lot of time interacting.

The sun bear is threatened by habitat loss and hunting, but it does well in captivity and is popular in zoos. Conservation efforts are in place to protect the sun bear in the wild as well as continue a healthy captive breeding program around the world.

Lux wanted to hear about the water bear, which is also called the tardigrade or the moss piglet. I can’t believe we haven’t covered the tardigrade before—we even have one in our new logo! Patrons may remember parts of this section from a Patreon bonus episode from 2017, but I’ve updated it a lot.

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. Pictures of the water bear are taken with an electron microscope because otherwise they just look like a teensy little dot.

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 or a bear’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 to 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.

One thing to remember is that different species of tardigrade are good at withstanding different extreme environments. Not every tardigrade is able to do everything we just talked about. They’re tough, but they’re not invulnerable. 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 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.

The tardigrade’s DNA gets fractured during dehydration but it’s incredibly successful at repairing its DNA upon rehydration, which explains a big part of its success. In 2016, Japanese researchers sequenced the genome of the species of tardigrade that best resists radiation. In the process, they discovered a new protein in the tardigrade’s genome, which they named DSUP, short for damage suppressor. Even more interesting, when cultured human cells were given the ability to create DSUP, after exposure to X-rays, they showed half the DNA damage that non-DSUP cells showed.

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.

The tardigrade is probably most closely related to arthropods, like insects and spiders. Their closest relatives were probably lobopodians, extinct wormlike organisms with stubby legs. The famous Hallucigenia creature is a lobopodian, which we talked about in episode 69 about the Cambrian explosion. There’s still a lot we don’t know about the tardigrade’s ancestry, since we have so few fossilized water bears, but many researchers think their oldest ancestors were probably much bigger than the microscopic or nearly microscopic living animals. In other words, maybe once there were water bears you could pick up and hug. Well, they probably weren’t that big, but I like to imagine it. I think that if you hugged a water bear too hard, it would make this noise: [little prrrt sound]

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 that way, and don’t forget to join our mailing list. There’s a link in the show notes.

Thanks for listening!


Episode 233: The Astonishing Aye-Aye



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Thanks to Elaine, Molly, and Oliver for suggesting the aye-aye! I guess it’s an idea whose time has finally come.

Further reading:

Gimme six! Researchers discover aye-aye’s extra finger

Ah yes, I have many many many fingers:

S p i d e r h a n d s:

A baby aye-aye (blep):

Show transcript:

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

I can safely say that this week’s episode is brought to you by popular demand. It was suggested by not one, not two, but three different listeners, two of them very recently. Elaine wanted to know about the aye-aye, and then Molly wanted to know about the aye-aye, and then Oliver wanted to know about the aye-aye. I think it’s high time we all learned about the aye-aye, because it’s a weird and amazing animal.

The aye-aye is a primate, specifically a type of lemur, but it doesn’t look like other lemurs. It kind of looks like a weird possum at first glance. Its shaggy fur is brown or yellowish but the hairs are tipped with white, which gives it a frosty appearance. Its face is white or pale gray. Its eyes are large, very round, and orange or yellow, and it has really big ears sort of like a bat’s ears. It grows up to three feet long, or 90 cm, including its really long tail.

To picture what an aye-aye looks like, imagine a little monkey with brownish fur tipped with white, with a tail longer than its body that’s thickly furred like a squirrel’s tail. Its head looks like a squirrel or possum, but with big orangey staring eyes and big bat ears that are sort of stuck out to the sides of its head instead of on top. Its hind feet look like monkey feet with an opposing digit to help it grab onto branches, because it lives in trees. But its hands look like SPIDERS. The fingers of its hands are extremely long and thin like spider legs. That’s what it looks like.

The aye aye’s fingers are long for an interesting reason, and if you don’t already know, I bet you would never be able to guess. Go on, guess. Just shout it out. I won’t hear it but everyone around you will hear you shout, “THE AYE-AYE’S FINGERS LOOK LIKE SPIDER LEGS BECAUSE IT WANTS TO SCARE PREDATORS INTO THINKING IT’S TWO SPIDERS WITH A MONKEY FRIEND.” You would be wrong, sorry, but that’s a good guess.

No, the aye aye uses its fingers to find grubs and other insects hidden in rotting wood or under bark, just like a woodpecker. Here’s how that works, and you’re not going to believe it, but it’s true. The aye aye is a primate, which means it has five fingers just like monkeys and apes and humans, but again, they’re extremely long and thin. The middle finger is even thinner than the others. It looks like a jointed twig. If it really was a spider, other spiders would ask what happened to that leg because it’s so much thinner than the other legs.

The aye aye uses the thin finger to tap-tap-tap on tree branches and trunks at night, and it listens with its huge ears to the echoes of its tapping. That’s echolocation, just like bats and a few other animals use to navigate, but the aye aye uses it to listen for hollow places in the tree where insects are hiding. It can also hear the tiny movements of insects. Its ears are just that sensitive.

When the aye aye locates an insect, it chews a hole into the wood and then uses its long fingers to fish the insects out. It has claws at the end of its fingers that help it catch the insects, although the claws are actually just claw-like fingernails. Primates don’t have claws, we have nails, and that includes the aye-aye. It doesn’t just eat insects, though. It eats fruit, seeds, various kinds of fungus, honey, flowers, and flower nectar. It actually eats more plant material than insects. It may also eat frogs, since some frogs in Madagascar lay their eggs in small holes in trees that are filled with rainwater, but it’s also possible that the aye-aye doesn’t care about frogs or frog eggs or tadpoles. Frogs definitely use the little holes the aye-aye chews as perfect little nurseries for their eggs.

The aye-aye is native to the forests of Madagascar and mostly lives along the east coast. It spends the day sleeping in trees, in a nest it makes out of twigs and dead leaves. Since it may travel more than a mile at night while it forages, it doesn’t always sleep in the same nest. It can make a new one in less than an hour, and then it crawls inside and wraps its long tail around it and falls asleep, cozy and warm.

The aye-aye hardly ever comes down to the ground. It’s mostly solitary except during mating season, although sometimes a few aye ayes will forage together. When aye-ayes do forage together, it’s usually a male and female, or one female and more than one male, or just two or more males. Female aye-ayes are more aggressive than males and they don’t want anything to do with other females.

The aye aye has so many non-primate characteristics that I hardly know where to start. For one thing, it’s nocturnal. Very few primates are nocturnal. It echolocates to find its food, which is completely weird. Also, its incisors grow continuously like a rodent’s. Incisors are those squarish front teeth. Since it uses its incisors to chew holes in wood, they need to keep growing or they’d get worn down to nothing eventually. The aye-aye’s incisors are very similar to a squirrel’s, and in fact is skull and jaw are also very similar to those of a squirrel. You know what that means. Yes, convergent evolution! It’s everywhere! Its skull and teeth look so much like a big squirrel’s that when scientists first examined the aye-aye back in the 18th and early 19th centuries, they classified it as a rodent. It wasn’t until 1931 that it was recognized as a primate, and even today some researchers think it’s not as closely related to primates as is currently thought. Genetic studies do indicate that it’s most closely related to lemurs, though. The aye-aye also has fewer teeth than lemurs and other primates, only 18 in all.

If you shine a light at an aye-aye at night, its eyes will reflect some of the light just like a cat. This is due to a specialized layer in the eye called the tapetum lucidum, which reflects light toward the retina so the animal can see better in the dark. Very few primates have a tapetum lucidum because most primates are diurnal, or active during the day, instead of nocturnal like the aye-aye.

Most nocturnal animals don’t see colors very well or at all. Naturally, they don’t need to since colors are hard or impossible to see in low light. But when researchers studied aye-aye genetics to learn more about how color vision developed in primates, including humans, they were in for a big surprise. The aye aye is completely nocturnal, but it still has the gene to see colors related to green and blue. Researchers have no idea why this is the case, although naturally they have some theories.

One theory is that the aye-aye uses its color vision to find flowers, especially blue flowers. Another theory is that it can see ultraviolet, which allows it to see urine marks left by other aye-ayes, since urine glows in ultraviolet light. The most ultraviolet light is available at dusk, which is when an aye-aye first ventures out to see what’s going on in its territory.

But let’s go back to the aye-aye’s fingers again. I just can’t get over its fingers. Not only is the skeletal middle finger just plain weird-looking, it’s weird compared to all other animal fingers. That one middle finger has what’s called a ball and socket joint, which is just not a joint found in fingers. You may not be familiar with the term, but you know what a ball-and-socket joint is because you have some in your own body. Your leg bones fit into your hip bone with ball-and-socket joints and your upper arm bones fit into your shoulders the same way. This allows you to move your arms and legs all around, whereas your fingers mostly just bend down, and a little bit up and sideways. But the aye-aye’s thin middle finger is incredibly flexible because of its ball-and-socket joint. All its other fingers have ordinary finger joints.

But wait, there’s more about the aye-aye’s fingers. In 2019, results of a study of the aye-aye’s unusual hands were published, and I just want to point out that the lead author of that paper is quoted as saying, “When you watch [an aye-aye] move, it looks like a strange lemur walking on spiders.” I’m not the only one who thinks their hands look like spiders!

Anyway, the study intended to learn more about the tendons in an aye-aye’s hands. But the researchers found a little structure on the wrist that no one had ever noticed before. It’s a small pseudo-thumb, or false thumb, which acts as an extra digit and helps the aye-aye climb through trees.

The pseudo-thumb isn’t just a little nubbin that helps it balance. No, it’s basically a real digit. It has bone and cartilage inside, muscles that allow it to move just like a regular thumb, and it even has a little thumbprint. It’s also strong. Researchers think that the aye-aye’s other fingers are so specialized that they’re not much help in climbing, so it developed an extra thumb.

Strange and specialized as the aye-aye is, it’s not the only animal we know of that had long, thin fingers that it used to tap on trees to find insects. 55 million years ago an animal called Labidolemur kayi lived in Europe and North America and shared many characteristics with the aye-aye. It was a little smaller than the aye-aye but had the same rodent-like teeth and two long thin fingers. Labidolemur kayi shared an ancestor with both rodents and primates, although it wasn’t a direct ancestor of the aye-aye. The aye-aye developed its rodent-like teeth and long thin fingers independently. Say it with me again: convergent evolution!

The aye aye is not only the only member of its own genus, it’s the only member of its own family. There used to be another species called the giant aye-aye that was at least twice the size of the living aye-aye, but it went extinct an estimated 1,000 years ago. Yes, just one thousand years ago, that’s all. We don’t know much about the giant aye-aye because all we have are some subfossil remains.

The aye-aye is endangered due to habitat loss and persecution by locals, who think it’s bad luck due to its weird appearance. It was actually thought to be extinct in 1933, but in 1957 researchers stumbled across one and probably breathed a sigh of relief that we hadn’t lost the aye-aye after all. In 1966 nine aye-ayes were taken to a small forested island off the eastern coast of Madagascar. The island is a nature reserve, and the aye ayes settled right in and are doing well there. At least now, if deforestation continues on the mainland of Madagascar, the aye-aye will be safe from extinction. Since then aye-ayes have also been introduced to another island and several nature reserves and national parks. It’s also kept in some zoos, and the first aye-aye was born in captivity in 1992.

The female aye-aye has one baby every few years, and she takes care of it by herself. Baby aye-ayes have green eyes and floppy ears.

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