Episode 260: Danger! Newts!



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Thanks to Enzo for suggesting this week’s topic, newts from least dangerous to most dangerous!

Further reading:

One snake’s prey is another’s poison

The Corsican brook salamander is not toxic (photo by Paola Mazzei, from iNaturalist):

The smooth newt is a little bit toxic (photo by Fred Holmes and taken from this site) – this is a male during breeding season:

The Hong Kong warty newt has an orange-spotted belly and is toxic:

The chonky Spanish ribbed newt will stab you with its own toxin-covered bones (photo by Eduardo José Rodríguez Rodríguez, taken from this site):

Yeah maybe don’t touch the Japanese fire belly newt if you don’t need to:

Warning! Do not eat the California newt:

The safest newt to handle is this toy newt. I really want one:

Show transcript:

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

This week’s topic is a suggestion from Enzo, who wants to learn about newts “from least dangerous to most dangerous.” There are at least 60 species of newt known with more being discovered every year, but I’ll do my best to hit the highlights.

A newt is a type of salamander, specifically a semi-aquatic salamander in the subfamily Pleurodelinae. All newts are salamanders but not all salamanders are newts. Newts live throughout much of the northern hemisphere, including northern Africa and the Middle East, Eurasia, and North America.

Female newts lay their eggs in freshwater, usually attaching them to vegetation or in little crevices in rocks. A few weeks later, the eggs hatch into larvae with external gills. The larvae are called tadpoles like frog larvae, and they mostly eat algae and tiny insects. They metamorphose over several months just like frogs do when they develop from tadpoles, but where frogs develop their hind legs first, newt tadpoles develop front legs first. The newt tadpole finally absorbs its gills and grows lungs instead, at which point it emerges from the water as an immature newt called an eft. Efts are juvenile newts and live exclusively on land, although like other amphibians they have to keep their skin damp so you’ll usually find them in leaf litter and under rotting logs. Efts that live in North America return to the water when they become full adults, but most newts in other parts of the world stay on land the rest of their lives except during breeding season. Efts and adult newts eat worms, insects and insect larvae, slugs, frog tadpoles, and any other small animals they can catch.

The Corsican brook salamander is a type of newt that lives on the island of Corsica in the Mediterranean Sea. It grows about five inches long at most, or 13 cm, and is brown or olive-green, sometimes with a mottled pattern of orange or red on its back. It’s an exception to the rule that newts outside of North America usually live their adult lives on land. Not only does the Corsican brook salamander live in freshwater most of the time as an adult, it doesn’t even have working lungs. It spends most of its time in fast-moving streams and rivers in higher elevations, where it absorbs oxygen from the water through its skin.

As Enzo undoubtedly knows, many newts produce toxins. This is why it’s not a good idea to handle a newt, or any other amphibian for that matter, unless you’re absolutely certain it’s a species that’s not toxic. In most cases, a newt’s toxin won’t hurt you if it just touches your skin, but if it gets in a cut or if you have some of the toxin on your finger and then rub your eye or put your finger in your mouth, the toxin can make you really sick. Some newts are even deadly.

The Corsican brook salamander we just talked about is not toxic, so we’ll call it the least dangerous newt. The smooth newt, on the other hand, produces a relatively mild toxin. You’d have to actually eat a bunch of smooth newts to get sick from its toxins, and why are you eating newts at all? Stop that immediately and have a banana instead.

The smooth newt lives throughout much of Europe and parts of Asia. It grows just over 4 inches long, or 11 cm, and most of the time it’s brown with darker spots. The male also has a bright orange stripe on his belly. During breeding season, though, the male develops a wavy crest down his spine and brighter colors. Both males and females move into the water during breeding season, so both males and females develop tail fins on the top and bottom of their tails to help them swim.

The males of many newt species develop brighter colors and crests during breeding season to attract females. In the case of the Hong Kong warty newt, in breeding season the male develops a white stripe on his tail. He attracts the attention of females by wagging his tail in the water, where the white stripe shows up well even in dim light. The Hong Kong warty newt lives in Hong Kong and grows up to 6 inches long, or 15 cm. It’s brown with orange patches on its belly and its skin appears bumpy like the skin of an orange. If it feels threatened, it sometimes rolls onto its back and pretends to be dead, which not only may deter some predators, it shows off the bright orange markings on its belly. This signals to a potential predator that this newt is toxic, and another thing it does when it plays dead is secrete toxins from its skin. In other words, don’t bite this newt or touch it. It’s also a protected species in Hong Kong so you shouldn’t be trying to eat it anyway. Its eggs are toxic too.

Some newts deliver their toxins to potential predators in a way you might not expect. If an animal tries to bite the Spanish ribbed newt, it secretes toxins from special glands on its sides and then pushes the sharp points of its own ribs out through the tubercles where the poison glands are located. The pointed ribs become coated with toxins as they emerge and are sharp enough to stab a predator right in the mouth. The toxin causes severe pain when injected and can even cause death in small animals. The newt itself isn’t injured by this process, which it can do repeatedly whenever it needs to. Newts, like all amphibians, heal extremely quickly.

The Spanish ribbed newt lives in the southern Iberian Peninsula in Europe and Morocco in northern Africa. It’s larger than the newts we’ve talked about so far, growing up to a foot long, or 30 cm. It’s dark gray with rusty-red or orange spots on its sides, one spot per poison gland. It actually spends most of its adult life in the water and especially likes deep, quiet ponds and wells.

Finally, we’ve reached the most dangerous newt in the world. I’m nominating two newts for this honor because they both secrete the neurotoxin tetrodotoxin, which we’ve talked about before. It’s the same kind of toxin found in pufferfish and some frogs. The toxin can irritate your skin even if you only touch it, and if a little of the toxin gets into a scratch or cut, it can cause numbness, shortness of breath, and dizziness. If you accidentally swallow any of the toxin, you can die within six hours. There’s no antidote.

Our two most dangerous newts are the Japanese fire belly newt and the California newt. The Japanese fire belly newt grows about 5.5 inches long, or 14 cm, and lives in parts of Japan in ponds, lakes, and ditches. It has pebbly skin and is brown or black with red speckles, but its belly is bright orange or red. The California newt has slightly bumpy gray or gray-brown skin on its back but a bright orange or yellow belly. It can grow up to 8 inches long, or 20 cm. It lives in parts of California, especially near the coast and in the southern Sierra Nevada Mountains.

The reason the California newt has such a potent toxin is that its main predator, the common garter snake, has a great resistance to the toxin. Only the most toxic newts are more likely to survive if a garter snake grabs it, and only the most resistant snakes are more likely to survive eating it. It’s a predator-prey arms race that’s been going on for at least 40 million years, resulting in a newt that is boss fight level toxic to most predators but just barely ahead of the game when it comes to garter snakes. It’s likely that something similar has occurred with the Japanese fire belly newt.

If you live in the areas where these toxic newts also live, be especially careful with your pets. Keep your dog on a leash so you can be sure it doesn’t try to bite or play with one of these newts. Some people actually keep the Japanese fire belly newt as a pet, but obviously if you do this you need to be extremely careful, especially if you have pets or small children. Maybe you should get a toy newt instead.

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

Thanks for listening!


Episode 259: Indestructible Animals



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Thanks to Nicholas and Emma for their suggestions this week as we learn about some (nearly) indestructible animals!

Further listening:

Patreon episode about Metal Animals (unlocked, no login required)

Further reading:

Even a car can’t kill this beetle. Here’s why

The scaly-foot snail’s shell is made of actual iron – and it’s magnetic

The scaly-foot gastropod (pictures from article linked above):

The diabolical ironclad beetle is virtually unsquishable:

Limpet shells:

The business side of a limpet:

Highly magnified limpet teeth:

Show transcript:

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

This week we’re going to learn about some indestructible animals, or at least animals that are incredibly tough. You may be surprised to learn that they’re all invertebrates. It’s a suggestion by Nicholas, and one of the animals Nicholas suggested was also suggested by Emma.

We’ll start with that one, the scaly-foot gastropod, a deep-sea snail. We actually covered this one a few years ago but only in a Patreon episode. I went ahead and unlocked that episode so that anyone can listen to it, since I haven’t done that in a while, so the first part of this episode will sound familiar if you just listened to that one.

The scaly-foot gastropod lives around three hydrothermal vents in the Indian Ocean, about 1 ¾ miles below the surface, or about 2,800 meters. The water around these vents, referred to as black smokers, can be more than 350 degrees Celsius. That’s 660 degrees F, if you even need to know that that’s too hot to live.

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

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

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

Unfortunately, the scaly-foot gastropod is endangered due to deep-sea mining around its small, fragile habitat. Hopefully conservationists can get laws passed to protect the thermal vents and all the animals that live around them.

The scaly-foot gastropod is the only animal known that incorporates iron sulfide into its skeleton or exoskeleton, although our next indestructible animal, the diabolical ironclad beetle, has iron in its name.

The diabolical ironclad beetle lives in western North America, especially in dry areas. It grows up to an inch long, or 25 mm, and is a dull black or dark gray in color with bumps and ridges that make it look like a piece of tree bark. Since it lives on trees, that’s not a coincidence. It spends most of its time eating fungus that grows on and under tree bark.

Like a lot of beetles, it’s flattened in shape. This helps it slide under tree bark and helps it keep a low profile to avoid predators like birds and lizards. But if a predator does grab it and try to crunch it up to eat, the diabolical ironclad beetle is un-crunchable. Its exoskeleton is so tough that it can withstand being run over by a car. When researchers want to mount a dead beetle to display, they can’t just stick a pin through the exoskeleton. It bends pins, even strong steel ones. They have to get a tiny drill to make a hole in the exoskeleton first.

The beetle’s exoskeleton is so strong because of the way it’s constructed. In a late 2020 article in Nature, a team studying the beetle discovered that the exoskeleton is made up of multiple layers that fit together like a jigsaw puzzle. Each layer contains twisted fibers made of proteins that help distribute weight evenly across the beetle’s body and stop potential cracking. At the same time, the arrangement of the exoskeleton’s sections allows for enough give to make it just flexible enough to keep from cracking under extreme pressure. Of course, this means the beetle can’t fly because its wing covers can’t move, but if it falls from a tree it doesn’t need to worry about hurting itself.

Engineers are studying the beetle to see if they can adapt the same type of structures to make airplanes and cars safer.

Nicholas also suggested the limpet, another mollusk. It’s a type of snail but it doesn’t look like the scaly-foot gastropod or like most other snails. Its shell is shaped like a little cone with ridges that run from the cone’s tip to the bottom, sort of like a tiny ice-cream cone that you don’t want to eat. There are lots of species and while a few live in fresh water, most live in the ocean. The limpets we’re talking about today are those in the family Patellidae.

If you think about a typical snail, whose body is mostly protected by a shell and who moves around on a wide flat part of its body called a foot, you’ll understand how the limpet is a snail even though it looks so different superficially. The conical shell protects the body, and the limpet does indeed move around on a so-called foot, gliding along very slowly on a thin layer of mucus.

The limpet lives on rocks in the intertidal zone and is famous for being able to stick to a rock incredibly tightly. It has to be able to do so because otherwise it would get washed off its rock by waves, plus it needs to be safe when the tide is out and its rock is above water. The limpet makes a little dimple in the rock that exactly matches its shell, called a home scar, and as the tide goes out the limpet returns to its home scar, seals the edges of its shell tight to the rock, and waits for the water to return. It traps water inside its shell so its gills won’t dry out while it waits. If the rock is too hard for it to grind down to match its shell, it grinds the edges of its shell to match the rock. It makes its home scar by rubbing its shell against one spot in the rock until both are perfectly matched.

The limpet mostly eats algae. It has a tiny mouth above its foot and in the mouth is a teensy tongue-like structure called a radula, which is studded with very hard teeth. It uses the radula to rasp algae off of the rocks. Other snails do this too, but the limpet has much harder teeth than other snails. Much, much harder teeth. In fact, the teeth of some limpet species may be the hardest natural material ever studied.

The teeth are mostly chitin, a hard material that’s common in invertebrates, but the surface is coated with goethite [GO-thite] nanofibers. Goethite is a type of of iron, so while the limpet does have iron teeth, it still doesn’t topple the scaly-foot gastropod as the only animal known with iron in its skeleton. Not only does the goethite help make the teeth incredibly strong, which is good for an animal that is scraping those teeth over rocks constantly, the dense chitin fibers in the teeth make them resistant to cracking.

The limpet replaces its teeth all the time. They grow on a sort of conveyer belt and move forward until the teeth in front, at the business end of the radula, are ready to use. It takes about two days for a new tooth to fully form and move to the end of the radula, where it’s quickly worn down and drops off.

Meanwhile, even though the limpet’s shell doesn’t contain any iron, its shape and the limpet’s strong foot muscles mean that once a limpet is stuck to its rock, it’s incredibly hard to remove it. It just sits there being more or less impervious to predation. Humans eat them, although they have to be cooked thoroughly because they’re tough otherwise, naturally.

Finally, one animal that Nicholas suggested is probably the royalty of indestructible animals, the water bear or tardigrade. Because we talked about it recently, in episode 234, I won’t go over it again. I’ll just leave you with an interesting note that I missed when researching that episode.

In April of 2019, an Israeli spacecraft was launched that had dormant tardigrades onboard as part of an experiment about tardigrades in space. There were no people onboard, fortunately, because the craft actually crashed on the moon instead of landing properly. The ship was destroyed but the case where the tardigrades were stored appears to be intact.

It’s not exactly easy to run up to the moon and check on the tardigrades, so we don’t know if they survived the crash landing. Studies since then suggest they probably didn’t, but until we can actually land on the moon and send a rover or an astronaut out to check, we don’t know for sure. Tardigrades can survive incredibly cold, dry conditions while dormant. It’s not exactly the experiment researchers intended, but it’s definitely an interesting one.

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 258: Sable and Sable Antelope



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A big birthday shout-out to Penelope this week! Thanks to Isaac for this week’s topic suggestion. We’re learning all about the sable and sable antelope!

Further reading (mostly for the pictures since there’s not much content otherwise):

Woman Rescues This Sable from Becoming Someone’s Coat

Further watching:

Kruger Park, Season 15 – this one is about some sable antelope bulls fighting

Fuzzy sable face:

Sable:

Sable antelopes:

A sable antelope growth chart. I find this really interesting. NERD:

Show transcript:

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

This week we’ve got an interesting theme, with both the theme and the animals suggested by Isaac. But first, we have a birthday shout-out!

Happy birthday this week to Penelope, whose birthday is on January 15th! I hope you have the best birthday ever!

Isaac suggested the sable, which is a type of mustelid, or weasel and ferret relation, and also suggested the sable antelope! It’s the sable episode.

The word sable means black or a rich dark brown, but most of the time it’s used to refer to the fur of an animal called the sable. The fur was so highly prized in Europe and Asia that the color of the animal’s fur was used as the name of the animal itself, and has been borrowed to refer to a specific coloration of other animals like cats and dogs.

The animal called the sable is common throughout parts of Asia, especially Siberia, China, and northern Mongolia. It lives in forests and mostly hunts by sound, and will eat just about anything it can find. This includes small animals like hares, rodents, birds, and even other species of mustelid, but it will also eat carrion, berries, fish, insects, snails and slugs, and occasionally it will even manage to kill a small bovid called a musk deer. The musk deer isn’t actually a deer but is more closely related to goats and antelopes. It can stand over two feet tall at the shoulder, or 70 cm, and the male has fang-like tusks instead of antlers or horns.

For an animal that sometimes kills and eats musk deer, the sable isn’t very big. It’s long and slender like other mustelids and measures nearly 2 feet long, or 56 cm, not counting its tail, which can add another 5 inches, or 12 cm. Females are a little smaller. It’s brown all over, usually dark brown but sometimes lighter depending on where it lives, with a pale patch on its throat. It has large fox-like ears and a somewhat fox-like or cat-like face but with smaller eyes. Its legs are short but that doesn’t stop it from covering long distances every day to find enough food, more than seven miles in some cases, or 12 km.

The sable is crepuscular, meaning it’s most active during dawn and dusk. When it’s not out hunting, it sleeps in a burrow it digs among tree roots, often lined with leaves and dry grass so it’s more comfortable and warmer. The exception is during mating season when the sable is more likely to be out during the daytime. Males fight each other during this time, and when a female is deciding whether she likes a male, she and the male will play-fight and chase each other.

One unusual thing about the sable is that even though mating season is usually in summertime, and even though it only takes about a month for the babies to develop inside the mother before they’re born, the babies are born in spring. Since the sable doesn’t have access to a time machine, something else is going on.

It’s called delayed implantation or embryonic diapause, where the mother’s egg is fertilized but then stays dormant for a time before it attaches to the uterine wall and starts developing into an embryo and ultimately a baby ready to be born. This allows babies to be born at a time of year when there’s plenty of food. In the sable’s case, the fertilized eggs don’t implant for 8 months.

Sables aren’t the only mammals that practice delayed implantation. A lot of mustelids do, as well as bears, seals, armadillos, and many others. A slightly different variety of delayed implantation only happens when the mother already has a baby that’s nursing, meaning she’s still producing milk. That’s hard on the body, so in some mammals, including some rodents and marsupials, the fertilized egg waits to implant until the mother is no longer producing milk. That way the mother has more resources available to nourish the growing embryo instead of having to divide her energy between her developing embryos and her already-born babies. In other mammals, including humans, a nursing mother doesn’t usually produce eggs to be fertilized until she’s stopped producing milk for her baby.

A female sable usually has two or three babies in a litter but sometimes more. The babies are born with a little bit of fuzzy hair to help keep them warm, but like puppies and kittens they’re born with their eyes sealed shut. It takes about a month for their eyes to open. The mother weans them when they’re about two months old but continues to take care of them, first by regurgitating food for them to eat, then by teaching them how to hunt and forage for themselves.

The sable’s fur is exceptionally soft and beautiful, and as a result it’s been killed for its fur for centuries and has always been expensive to buy. One Russian population is jet black with a white tip to each hair, which was even more highly prized than the rest. But the best way to experience the beautiful fur of a sable is by petting a live one, not the skin of a dead one. Some people have started keeping sables as pets, although they’re not actually domesticated and can be difficult or even dangerous to keep.

Next, another beautiful non-domesticated animal is the sable antelope. It lives in forested savannas in parts of eastern and southern Africa. There are four subspecies, the largest of which is the giant sable antelope. That makes it sound enormous but it’s only a little bigger than other subspecies, and is critically endangered. In fact, the giant sable antelope was suspected of having gone extinct during a terrible civil war in Angola, which is the only place in Africa where it lives. Fortunately a herd of them was caught on camera trap in 2004, and the giant sable antelope is now protected.

Sable antelope cows give birth to one baby during the rainy season, which varies depending on where they live. The calves are light brown or pale reddish-brown but as they grow older, their fur becomes darker. Mature females are usually dark brown but adult males are black. Adults and older calves also have white patches on the face, belly, and rump.

The sable antelope has a short tail with a little tuft at the end, and it also has a short mane that usually stands upright like a donkey’s mane. Males are bigger than females, standing some 4 and a half feet tall at the shoulder, or 1.4 meters.

Both males and females have horns, though. Antelopes are bovids, which means they have true horns like cattle and goats, not antlers like deer that are shed every year. The sable antelope’s horns are really impressive, too. They’re dark gray or black and arch up and back from the head like really big goat horns. A female can have horns up to 3 and a half feet long, or 102 cm, while a male can have horns 0ver 5 feet long, or 165 cm. That’s right, his horns can be longer than he is tall. Sable antelopes are so spectacular that when you think of an antelope, you probably think of an animal that has horns like this.

Unfortunately, those horns have caused the sable antelope to be a target for big game hunters who want the horns as a trophy. These days, though, the biggest threat is habitat loss as humans fence their grasslands to graze livestock.

During the rainy season, the sable antelope lives in small herds of up to 30 females and their young, who share a territory with a single bull. The herd is led by the oldest females who know where the best places are to graze and find water. When the herd moves, the male usually follows right behind to make sure everyone stays together.

The sable antelope eats tree leaves and some kinds of grass, and spends the hottest parts of the day lying down and chewing its cud because, like other bovids, it’s a ruminant. The calves are always in the middle of the resting herd and the adults lie facing outward so they can watch for danger and meet it with their horns. When the adults are moving around to graze, young calves stay in a group called a creche, watched over by a few adults.

During the dry season when there’s not as much to eat, herds will come together to graze in the best pastures with access to water. When young males mature, the older male drives them away from the herd to fend for themselves. Young bulls often form small bachelor herds or may be solitary.

When a bull challenges another bull in an attempt to take control of his territory, they fight with their horns, although they don’t usually injure each other. The sable antelope also uses its horns to fight off and sometimes even kill predators like lions and leopards.

This is the only reliable audio I could find of a sable antelope. There’s a link to the original video in the show notes. The sound is of a bull who’s stuck in the mud, although he later manages to get out.

[sable antelope 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 for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!


Episode 257: Some Animals of Belize



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A big birthday shout-out this week to Yori!!!

I was fortunate enough to visit the country of Belize in December and saw lots of amazing animals! I’ve chosen four to highlight in this week’s episode.

Further reading:

There may be more bird species in the tropics than we know

The adorable proboscis bat, my favorite:

Proboscis bats all in a row (photograph by me!):

The black howler monkey has a massive hyoid bone that allows it to make big loud calls:

The white-crowned manakin is impossibly cute:

The mealy parrot is cheerful and loud:

A morning view and night view from our villa balcony, photos by me!

Show transcript:

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

Let’s start the new year off right with an episode about some animals I saw in person recently during my vacation to Belize!

But first, we have our first birthday shout-out of the year! A very happy birthday to Yori, whose birthday is on the 8th of January! I hope you have a great day!

Belize is a country on the eastern coast of Central America on the Caribbean Ocean, just south of Mexico and north of Guatemala. It used to be called British Honduras but has been an independent country since 1981. The coast is protected by a series of coral reefs that are so little studied that there are probably dozens if not hundreds of animals and plants waiting to be discovered around them. Belize is serious about protecting the reefs and about conservation in general, which is great because it has some of the highest animal and plant life diversity in the Americas.

My brother and his family had made vacation plans for Belize in spring of 2021, about the time the Covid-19 vaccine was rolling out and things were looking up. They rented a big villa with more bedrooms than they needed so they generously invited me and one of my cousins to join them. I didn’t mention the trip on the podcast because I was worried it would end up canceled. But we were able to visit in mid-December, with negative Covid tests coming and going, and wearing our masks appropriately in all public areas.

Belize is absolutely gorgeous. We stayed right on the coast in an upstairs flat with a big balcony that overlooked the ocean. We spent most of the time relaxing on the beach or the balcony and eating amazing food, but we did go on two excursions.

We all went on a riverboat wildlife tour of the Monkey River, and a few days later my brother and cousin and I went on a birdwatching expedition to the nearby Cockscomb Basin Wildlife Sanctuary. We had to get up at 5am for that one but it was worth it. In both excursions we saw lots of animals of all kinds, so many that it was hard for me to choose which ones to highlight in this episode.

One animal that I fell in love with on the Monkey River is the proboscis bat. Belize has a lot of bat species but I didn’t expect to see any, much less up close.

The proboscis bat lives throughout Central America and the northern half of South America. It’s only about 2.5 inches long, or 6 cm, and gets its name from its pointed nose. It lives near water, especially wetlands, because it eats insects that live around water like mosquitoes and caddisflies. It’s so small that it sometimes gets caught in spiderwebs, especially of the big spider Argiope submaronica, [ar-JY-opee] a species of orbweaver spider that holds its legs in an X pattern while it’s on its web. Different species live throughout the world, especially in warm places. It does actually eat the bats it catches, which is hard on the bat but a nice big meal for the spider. There’s two sides to every story.

How, you may ask, did I manage to see a bat up close during broad daylight while on a boat? The proboscis bat spends the day on a tree trunk or branch or log near the water, especially in shady areas, and our guide was able to ease the boat up to not one but two different trees with bats asleep on them. The proboscis bat is gray-brown with darker and lighter markings that help it blend in against bark, and it sleeps perched on the side of the tree with its head pointing down. It literally looks like a little bump on a log that way. But it’s not usually alone. It lives in small groups and everyone roosts on the same tree during the day, and the best thing is that they roost in a row one above the other, head to tail. Nothing to see here, just a row of bumps on this log.

The second group of proboscis bats we saw we got a little too close to and suddenly all the bats took off in all different directions. Everyone else in the boat yelped and ducked except me, although I think they were mostly just startled. I could tell the bats were about to fly and just sat there thinking, “Oh no, we’ve disturbed the bats!” and then their amazing little wings unfolded and they all flew away. I’m still sorry we bothered them but it was a wonderful sight. Bats are so great.

Another animal we saw and heard on our Monkey River trip was the black howler monkey. It gets its name from the male’s appearance because males have mostly black fur while females are more golden.

It’s pretty big for a monkey, with a big male growing over two feet long, or 65 cm, not counting its tail. Females are smaller. The black howler’s tail is as long as its body and is prehensile to help it navigate through the trees. Its tail only has hair on the upper side, with the lower side bare to help it grab onto tree limbs more securely. Part of the reason the black howler monkey uses its tail so much to climb around in trees is that its arms can’t move as far as the arms of many primates, and that’s because of something called the hyoid bone.

The hyoid bone is found in a whole lot of animals, not just howler monkeys. In humans it’s shaped like a little horseshoe and it’s found near the top of the throat. While everyone has a hyoid bone, it’s larger and more prominent in men, and it causes the bump in the throat sometimes called an Adam’s apple. A lot of muscles attach to the bone, including the tongue, and it helps us talk and breathe properly. But in howler monkeys, the hyoid bone is much larger and shaped more like a cup. Air resonates in the cup, which is how howler monkeys make such loud, deep, booming calls. Male howler monkeys have much larger hyoid bones than females, but having such an enlarged hyoid bone restricts the range of motion in the arms.

The black howler monkey is really loud. It’s especially noisy at sunrise when males in a troop roar together to let other troops know where they are and to announce that they’re the biggest, baddest males around and no one better mess with them. These sounds can be heard three miles away, or 5 km.

The black howler monkey lives in forests and spends most of the time in the trees, eating fruit, leaves, and flowers. Its diet isn’t all that high in caloric energy, though, so unlike many species of monkey, the black howler spends a lot of time just lazing around in trees, resting or napping.

We only saw two howler monkeys on our Monkey River trip even though they’re common throughout the area. We all got out of the boat and our guide grabbed a machete, which I think was pretty much just for show because the trail we were on was obviously well traveled and wide. We were going to hike 15 or 20 minutes into the rainforest to find a troop of howlers, but there had been so much rain in the last week that the trail was ankle-deep in mud. We were all sliding around and my sister-in-law actually lost a shoe and had to fish it out of the mud. We were all relieved when after only about five minutes we came across a young male howler and stopped to watch him.

He was sitting way way up high in the treetops, naturally, and there were definitely other monkeys around him that we couldn’t see because after a few minutes we spotted an even younger monkey walking along a branch. It was mid-morning by then and the male was eating, so when our guide banged his machete on a tree trunk and imitated the territorial call of a male howler, the male up in the tree only responded half-heartedly. I got audio and you should be able to tell which call is our guide and which call is the monkey because the guide was so much louder, since he was so close to me.

[guide and howler monkey sounds]

We also saw a LOT of birds! As you may know, birdwatching is one of my hobbies, so I was excited and amazed at the variety of birds in Belize. I did some birding on my own with my cousin along, and my brother came with us one early morning on an actual birdwatching trip with a local guide. I’m going to be on the Casual Birder podcast soon talking about the birds I saw on the trip, although I’m not sure yet when it will air. I’ll let you know or you could just subscribe to the Casual Birder Podcast now and beat the rush.

Anyway, one bird we saw is a tiny adorable little floof called the white-crowned manakin. It only grows about 4 inches long at most, or 10 cm, and has red eyes, a short tail, and looks superficially like a wren in shape. The female is olive-green with a gray head but the male is glossy black with a bright white cap that he can raise up in a fluffy crest. He looks like the lead singer of an edgy indie band.

The white-crowned manakin is a common bird throughout parts of Central and South America. The reason I decided to talk about it in this episode is because of a study released in November 2021 that discovered the white-crowned manakin isn’t actually a single species. Genetic studies found that some isolated populations of the bird are different enough from the others to be considered a completely different species. These populations may look similar but their plumage patterns and songs are very different from the main population too. Since there are so many birds in South America that aren’t very well studied, conservationists are concerned that other known bird species may actually have genetically different populations that look very similar. If we don’t know what birds are rare, we don’t know how to protect them.

The last animal we’ll cover today is another bird, the mealy parrot, also called the southern mealy Amazon parrot. It’s a big parrot, mostly green, that lives in rainforests in parts of Central and South America. Like other parrots, it’s a smart, social animal that lives in flocks. It gets its name because many individuals have paler feathers on their back and upper wings that make them look like they’ve been dusted with flour, and meal is another word for flour. It mostly eats fruit, nuts, berries, and other plant material, including flowers. It’s still a common parrot but habitat loss, hunting, and trapping of birds to sell as pets on the black market has caused their numbers to decline recently. If you decide you want a pet parrot, make sure you buy yours from a reputable breeder who is selling domesticated parrots, not wild-caught ones.

Because we started birding so early, we were lucky enough to hear the mealy parrots calling, something they do early in the day and at night. We also heard some howler monkeys in the distance. But while we kept hearing a whole flock of mealy parrots, they were always just out of sight. We would hurry as quietly as we could up the trail and they would retreat ahead of us, calling cheerfully as though taunting us. It was actually really funny. Then, finally, just when I’d started to assume I would never see the wild parrots we kept hearing, there they were! And there were lots of them! We also saw a small flock of red-lored parrots that look similar but have a red band just above their upper bill, lots of keel-billed toucans, the national bird of Belize, and lots lots more!

This is some audio I took of the mealy parrots calling while we were trying to spot them.

[mealy parrot calls]

We didn’t see a jaguar or a manatee during our visit to Belize, but I did learn how to properly pronounce the word spelled T-A-P-I-R. There are lots of different pronunciations throughout the world, but from now on I’m going with the Belizean one of TAP-eer. We didn’t see a tapir either but we did see crocodiles and green iguanas and a couple of basilisks and lots more. I was even brave enough to get in a kayak and paddle around ON THE OCEAN, admittedly in very calm, shallow water with my family around to encourage me, and saw some kind of small rays, moon jellies, and a crab. I’m scared of the ocean but as soon as I started seeing jellies from my kayak I got a lot less scared and a lot more interested, so I’m proud of myself for facing my fears.

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

Thanks for listening!


Episode 256: Mammoths and the End of the Ice Ages



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Further reading:

Million-year-old mammoth genomes shatter record for oldest ancient DNA

Mammoth Genome Project (with pictures of cave art and ancient carvings of mammoths)

The most famous cave painting of a mammoth, from a cave in France:

Sivatherium:

Show transcript:

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

It’s the last Monday of 2021, which means the very last extinction event episode. There’ve been way more extinction events in earth’s long history than the five we’ve covered this year, and not all of the extinction events I chose to highlight were even necessarily the biggest. This one, for instance.

You may have noticed a pattern when I talk about ice age megafauna. So many animals went extinct about 11,000 years ago. That’s this week’s topic, the end-Pleistocene extinction event.

The Pleistocene is often called the ice age, or ice ages since it consisted of multiple glaciation periods separated by warmer times when the glaciers would retreat for a while. It started roughly 2.6 million years ago and is considered to have ended 11,700 years ago. Keep in mind, as always, that these dates are just a shorthand to help scientists refer to changes in earth’s history. There was no one day where the sun rose and everything had abruptly changed from one era to another. The changes took place over a long time, hundreds of thousands of years, with different parts of the world changing more quickly or slowly than others depending on local conditions.

At the beginning of the Pleistocene, the world’s continents were roughly in their present positions. Two continental plates in what is now Central America collided very slowly over millions of years, which caused the land to buckle up and magma to erupt through the earth’s crust as volcanoes. The volcanoes created islands in the Central American Seaway, a section of ocean between North and South America that connected the Atlantic and Pacific Oceans. By around 5 to 10 million years ago, the volcanoes and land continued to be pushed up, and sediment from rivers filled in between them, until finally instead of islands there was actual land that connected North and South America. That land is called the Isthmus of Panama and it allowed the great American interchange where animals from North America could cross into South America, and vice versa, but that’s a topic for another episode.

Another result of the Isthmus of Panama’s formation is that the Atlantic and Pacific Oceans were more separated. Instead of ocean currents circulating between North and South America, they were cut off and new currents formed. Ocean currents help distribute warm water to colder areas and cold water to warmer areas, which affects air and land temperatures too. Around 2.5 million years ago, the ocean current changes had changed the entire overall temperature of the earth, making it much cooler overall. That wasn’t the only cause of the ice ages, but it was a major factor.

The earth gradually became cooler and dryer, a process that had already started due to other causes and was accelerated by the ocean current changes. As the global temperature dropped, more and more water was locked up in huge glaciers called ice sheets, at first around the poles and then farther south. This meant sea levels dropped a lot. North America was connected to Asia by a stretch of grassland steppe called Beringia that had formerly been submerged.

As the temperatures dropped and the climate changed, animals and plants had to adapt. The ancestors of modern elephants had lived in Africa for millions of years, but they started migrating to other parts of the world around 3 million years ago. Because they were already big, they were good at retaining heat in their bodies and became quite successful as the climate grew cooler and cooler. They evolved long hair to stay even warmer and spread throughout much of the world, including Europe, Asia, and North America. You may know them as mammoths, which were closely related to the modern Asian elephant. The first mammoth known was the South African mammoth that lived around 5 million years ago and stood about 12 feet tall at the shoulder, or 3.7 meters.

We actually know a lot about the various species of mammoth because we have so many remains. Our own distant ancestors left cave paintings and carvings of mammoths and other animals in many parts of the world, we’ve found lots of fossilized remains, and we have lots of subfossil remains too. Because the mammoth lived so recently and sometimes in places where the climate hasn’t changed all that much in the last 10,000 years, namely very cold parts of the world with deep layers of permafrost beneath the surface, sometimes mammoth remains are found that look extremely fresh.

Before people understood extinction and related natural concepts, some people who lived in areas where dead mammoths occasionally weathered out of the permafrost thought they’d only died recently. That’s how fresh the dead animals looked. The people didn’t know what the animals were, though, and assumed that since they were only ever seen partially buried, they must be underground animals. In parts of Siberia, people thought mammoths lived underground and if they accidentally came to the surface, they died.

In February of 2021, a genetic study of mammoth DNA found in teeth was published in Nature. Nature is one of the most important scientific journals in the world and they don’t just publish any old genetic study these days, now that DNA is so much easier to sequence than it used to be. In this case, though, the DNA came from three mammoth teeth that were more than one million years old and possibly around 1.5 million years old. The teeth were found in the 1970s in different places. Before DNA was successfully found in the teeth, the oldest DNA sequenced was from a horse bone that was about 780,000 years old at the most.

Genetic material breaks down relatively quickly once an animal dies, becoming more and more fragmented as the years pass by. That’s why we don’t have any dinosaur DNA—they just lived too long ago for any usable genetic material to remain. The mammoth genetic study is a big deal since it’s pushed back scientists’ ability to sequence ancient DNA, at least of some samples. In the case of both the mammoth teeth and the ancient horse bone, the remains were preserved in permafrost that slowed the fragmentation of the DNA.

The study found that one of the teeth belonged to an early woolly mammoth and the other two were from early steppe mammoths, but it’s not as simple as it sounds. The two steppe mammoth teeth looked alike but their genetic story was very different. One had genetic markers that identified it as an ancestor of woolly mammoths–but the other didn’t. The one that didn’t is called the Krestovka sample and was found in Russia. Researchers aren’t sure yet if it’s actually a new species or subspecies, but it was obviously part of a population isolated from other steppe mammoths.

But it gets even more complicated, because Columbian mammoths from North America do show that some of their ancestors were related to the Krestovka sample–and Columbian mammoths are also related to woolly mammoths. Researchers suspect that the Columbian mammoth was a species that developed from hybrids of the Krestovka steppe mammoths and woolly mammoths. Over half a million years ago, there were enough of these hybrid mammoths that they were actually numerous enough to form their own stable species. Hybrid speciation is still a relatively new concept but as genetic studies get more sophisticated, we’re getting more evidence of it happening.

Researchers are hopeful that even older genetic samples can eventually be sequenced, but there’s a hard limit to DNA found in permafrost. That limit is 2.6 million years, which is when the permafrost began forming. And that brings us back to the ice age.

Mammoths weren’t the only animals adapted to cold conditions, of course. They weren’t even the only elephant lineage that adapted to the cold. Mastodons aren’t actually that closely related to mammoths but they are an elephant relation.

The woolly rhinoceros was about the size of living rhinoceros species but was covered in thick fur. It had a massive hump on its shoulders that was made up of fat reserves and muscle, much like modern bison. It went extinct about 10,000 years ago.

A giraffe relation, Sivatherium, lived in Africa and parts of Asia during the Pleistocene. Its neck wasn’t as long as a modern giraffe’s but it was still tall, over 7 feet tall at the shoulder, or more than 2 meters, and almost 10 feet tall including the head and neck, or 3 meters. The males had two pairs of ossicones that resembled antlers, a large pair on its head and a smaller pair over its eyes. Ossicones are bony projections usually covered with skin and hair, and modern giraffes have ossicones too.

Mammals weren’t the only megafauna, though. Mega just means big, and fauna just means animal. There were megafauna birds and reptiles too, such as the Asian ostrich. It lived throughout much of Asia and the Middle East until around 8,000 years ago and was related to the modern ostrich. The wonambi was an Australian constrictor snake, not related to the snakes living in Australia now, that could grow up to 30 feet long, or 9 meters.

So what happened to cause the extinction of all these amazing animals? Surely we know more about this extinction event than we do about older ones since it happened so recently, right?

Actually, no. Although it feels significant to us now, the end-Pleistocene extinction event actually wasn’t very big compared to the others we’ve discussed this year. A lot of ice age megafauna are still around, including bears, wolves, moose, reindeer, horses, bison, elephants, giraffes, lions, tigers, camels, kangaroos, tapirs, ostriches, condors, and lots more. Even humans are ice age megafauna since we spread throughout the world during the Pleistocene.

We do have hints of what might have caused the end-Pleistocene extinction event, and one big hint comes from what happened in Australia. Like the rest of the world, Australia’s climate was cooler and dryer during the ice ages and animals that had adapted to the cold lived throughout the continent. This included diprotodon that we talked about in episode 224, along with kangaroos, wombats, koalas, and other marsupial mammals that were bigger than the ones living today. But extinctions in Australia started a lot earlier than they did in the rest of the world, around 45,000 years ago. There’s also no corresponding extinction event among marine animals. By about 40,000 years ago almost 90% of all species of Australian megafauna had gone extinct, while smaller animals and marine animals were mostly just fine.

One specific event that happened around 45,000 years ago was the colonization of Australia by humans. Humans had visited and even lived in Australia as far back as 70,000 years ago, but by 45,000 years ago they were really spreading throughout the land. The animals of Australia had never encountered smart, fast tool-users before and didn’t know what to do except try to avoid them. Humans had weapons like spears that could kill at long range, and humans worked together to kill animals that before then had no predators due to their size. Humans also drink a lot of water because we developed in a part of Africa where water is abundant. Fresh water isn’t nearly as abundant in Australia, so humans would stake out water sources and keep other animals away.

The Australian extinctions were probably a combination of climate change, humans hunting large animals that reproduced slowly, and humans outcompeting animals for water sources. The same causes probably led to extinctions in other parts of the world, but because humans took longer to spread to continents like the Americas that are far away from Africa, those extinctions mostly took place later than in Australia. It’s also important to note that Africa showed almost no extinctions at the end of the Pleistocene. Researchers think this is because the animals of Africa evolved alongside humans and knew how to deal with us.

Natural climate change was definitely a contributing cause to the extinctions, though. Ice sheets melted, glaciers retreated, and the world warmed over the course of just a few thousand years. Animals that were well adapted to the cold had to move to places where it was still cold, but those places didn’t always have the right foods or enough food. The sea levels rose too, cutting off access to parts of the world. Beringia became covered with ocean again, for instance, where it remains today, separating Asia from North America.

Humans probably finished off the mammoths by hunting the last ones to extinction, but some populations survived much later than the 10- to 12,000 years ago commonly given as their extinction date. There were still mammoths alive in the world only 4,000 years ago and maybe only 3,700 years ago—but only on an island where humans didn’t live.

Wrangel Island is located in the Arctic Ocean near western Siberia, more than 85 miles from the nearest coast, or 140 km. It has low mountains and sea cliffs and is cold and dry most of the year, which is the kind of climate mammoths preferred.

The woolly mammoths that lived on Wrangel Island were probably cut off from the mainland when sea levels rose and flooded Beringia. They lived on for thousands of years after their mainland relations had gone extinct. Gradually the mammoths became more and more inbred, leading to genetic defects at a much higher rate than in a healthy population. Even so, the mammoths might have managed to survive even longer except for one thing. Around 1700 BCE, humans arrived on the island. Shortly afterwards, the mammoth was extinct.

Wrangel Island is a nature sanctuary these days and home to lots of animals, including polar bears, walruses, Arctic foxes, seals, reindeer, musk ox, and wolves. All of these are considered ice age megafauna, so although the mammoths are gone, other megafauna remain.

While we don’t know for sure that humans played a big part in the end-Pleistocene extinction event, we sure didn’t help. We can’t blame our ancient ancestors for their actions but we can learn from their mistakes. We’re in the middle of another extinction event right now, often called the Holocene extinction or Anthropocene extinction, directly due to our actions. Habitat loss, pollution, overhunting, and human-caused climate change are driving more species of animal and plant to extinction every year.

It can feel overwhelming, but there are lots of small things you can do to help. Just picking up trash and putting it in the waste bin or remembering to take your reusable bags to the grocery store can make a difference. No one person can fix all the world’s problems, but if everyone does a little bit to help, the big problems get smaller and more manageable. If everyone pitches in, we can make the world a cleaner, better place for animals and for people.

Happy new year! Let’s make it a great one!

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

Thanks for listening!


Episode 255: Reptiles with Something Extra



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Thanks to Ethan and Simon this week for their suggestions! This week we’re looking at some extinct reptiles that each have a little something extra (and unexpected).

Further reading:

Two Extinct Flying Reptiles Compared

Cretaceous ‘Four-Limbed Snake’ Turns Out To Be Long-Bodied Lizard

Kuehneosaurids may have resembled big Draco lizards although they weren’t related:

Big turtle:

Purussaurus was big enough to eat even really big turtles (from Prehistoric Wildlife):

Meiolania had a pointy head and a pointy tail:

Not a snake with legs after all:

Show transcript:

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

This week we’ll learn about an extinct reptile suggested by Ethan, some extinct turtles suggested by Simon, and an extinct snake that might not be a snake at all. All these animals had physical details you wouldn’t expect, as we’ll see.

First, though, a reminder that I have five Kickstarter backers who haven’t sent me their birthday shout-out names and birthdays yet! I sent messages to them last month and haven’t heard back, so if you backed the Kickstarter and added on the birthday shout-out, but never got the opportunity to send me your names and birthdays, please message me as soon as possible! The shout-outs start in January!

So, on to the extinct reptiles that each have something a little extra. Let’s start with Ethan’s suggestion, the kuehneosaurids. Kuehneosaurus, kuehneosuchus, and their relations lived around 225 million years ago in what is now England. The first dinosaurs lived around the same time but kuehneosaurids weren’t dinosaurs. They were lizard-like reptiles that grew about two feet long, or 70 cm, including a long tail, and probably lived in trees and ate insects. Oh, and they had wings.

They weren’t technically wings but extended ribs. Kuehneosaurus’s wings weren’t all that big, although they were big enough that they could act as a parachute if the animal fell or jumped from a branch. Kuehneosuchus’s wings were much longer. In a study published in 2008, a team of scientists built models of kuehneosuchus and tested them in a wind tunnel used for aerospace engineering. It turned out to be quite stable in the air and could probably glide very well.

We don’t know a whole lot about the kuehneosaurids because we haven’t found all that many fossils. We’re not even sure if the two species are closely related or not. We’re not even sure they’re not the same species. Individuals of both were uncovered in caves near Bristol in the 1950s, and some researchers speculate they were males and females of the same species. Despite the difference in wings, otherwise they’re extremely similar in a lot of ways.

Generally, researchers compare the kuehneosaurids to modern Draco lizards, which we talked about in episode 237, even though they’re not related. Draco lizards are much smaller, only about 8 inches long including the tail, or 20 cm, and live throughout much of southeastern Asia. They have elongated ribs that they use to glide efficiently from tree to tree, and they eat insects. Draco lizards can fold their wings down and extend them, which isn’t something the kuehneosaurids appear to have been able to do.

Next, let’s look at Simon’s turtles. Stupendemys geographicus lived a lot more recently than the kuehneosaurids, only about 6 million years ago in northern South America. It was a freshwater turtle the size of a car: 13 feet long, or 4 meters. As if that wasn’t impressive enough, the males also had horns—but not on their heads. The male Stupendemys had projections on its shell, one on either side of its neck, that pointed forward and were probably covered with keratin sheaths to make them sharper and stronger. Males used these horns to fight each other, and we know because some of Stupendemys’s living relations do the same thing, although no living species actually have horns like Stupendemys. They’re called side-necked turtles and most live in South America, although they were once much more widespread.

Stupendemys probably grew to such a huge size because there were so many huge predators in its habitat. It lived in slow-moving rivers and wetlands, where it probably spent a lot of time at the river’s bottom eating plants, worms, crustaceans, and anything else it could find. It was too big and heavy to move very fast, but a full-grown turtle was a really big mouthful even for the biggest predator in the rivers at the time, Purussaurus.

Purussaurus was a genus of caiman, related to crocodiles, that might have grown up to 41 feet long, or 12.5 meters. We don’t know for sure since the only Purussaurus fossils found so far are skulls. It ate anything it could catch, and we even have Stupendemys fossils with tooth marks that show that Purussaurus sometimes ate giant turtles too. One Stupendemys fossil has a 2-inch, or 5 cm, crocodile tooth embedded in it.

Stupendemys is the largest freshwater turtle known and the second-largest turtle that ever lived. Only Archelon was bigger, up to about 15 feet long, or 4.6 meters. Archelon was a marine turtle that lived around 70 million years ago. We talked about it in episode 75.

Simon also told me about another turtle genus, Meiolania, which lived in what is now Australia and parts of Asia around 15 million years ago. It might even have remained in some areas as recently as 11,000 years ago. The shell, or carapace, of the largest species grew over 6.5 feet long, or 2 meters. Even the smallest species had a carapace over 2 feet long, or about 70 cm. Since the fossils of smaller species have only been found on islands, researchers think the small size may have been due to island dwarfism. It probably lived on land and ate plants. It also had horns, but not on its shell. These horns were actually on its head, although they aren’t technically horns.

The horn-like projections pointed sideways and its tail also had spikes at its end. That meant it couldn’t pull its head under its shell to protect it like most other turtles can, but on the other hand, anything that tried to bite its head or tail would get a painful mouthful of spikes.

We don’t know a whole lot about Meiolania, including if it’s related to living species of turtle. When the first fossils were found, early paleontologists thought they were lizards, not turtles. What we do know, though, is that people ate them. Bones of some species appear in the middens, or trash sites, of ancient people in Australia, and there’s evidence that they were hunted to extinction within a few hundred years after humans settled where the turtles lived. That would also explain why the island-dwelling species seemed to have lived longer than the mainland species, since people didn’t live on the islands where they’ve been found.

Finally, we’ll finish with Tetrapodophis amplectus, leading to the philosophical question about whether a snake with legs is really a snake. That’s the same question researchers were asking themselves too until very recently. Tetrapodophis was only described in 2015 and was initially determined to be an early snake that had four legs.

Tetrapodophis lived around 120 million years ago in what is now Brazil in South America. It grew about a foot long, or 30 cm, and had a slender, elongated body with small but well-developed legs. Is it a lizard with snake-like characteristics or an early snake that hadn’t completely lost its legs yet?

It had hooked teeth and we know it ate small animals because one specimen actually has the fossilized remains of its last meal in its fossilized digestive system. Initially researchers thought it might have been a burrowing animal, using its small legs to help it grab onto items and push itself forward.

The type specimen was a complete skeleton, which is really rare. Unfortunately it was illegally exported and the paleontologist who described the species didn’t bother to at least invite a Brazilian paleontologist to study the Brazilian fossil. He was also incredibly rude when asked about it so I’m not going to give you his name, but he seems to be a really sketchy guy, which is too bad.

He also made some mistakes that might not have been mistakes. If a person is dishonest in one area, they’re probably dishonest in other areas too. When he described Tetrapodophis, he mischaracterized some aspects of its anatomy to make it seem more snake-like. A new study published in November 2021 corrects those mistakes and determines that instead of being a flashy exciting snake with legs, Tetrapodophis was most likely just a small member of the lizard family Dolichosauridae. I’m happy to report, by the way, that one of the lead authors of the new study is named Tiago Simões, a paleontologist from Brazil.

Dolichosaurs were marine lizards with small legs and snake-like bodies and were actually pretty closely related to mosasaurs. You know, the marine reptiles that lived at the same time as dinosaurs and could grow more than 50 feet long in some species, or 15 meters.

There’s some controversy in the mosasaur camp too, because some researchers think mosasaurs were most closely related to snakes while others think they were most closely related to monitor lizards. It just goes to show that scientific knowledge is forever growing and adapting to new information as it comes to light, but that answers aren’t always clear.

What is clear is that extinct reptiles are awesome, but you probably already knew that.

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

Thanks for listening!


Episode 254: The Saola and the Striped Bunny



Thanks to Elaine for suggesting the saola this week!

Further reading:

The saola: rushing to save the most ‘spectacular zoological discovery’ of the 20th century

Striped rabbit revealed in Laos forest

Saola horns:

A saola from a 1999 camera trap (photo taken from link above):

A female saola (named Martha) who unfortunately only survived in captivity a few weeks (photo taken from link above):

A striped bunny!! The Annamite striped rabbit:

Show transcript:

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

This week’s topic is a remarkable hoofed animal suggested last year by Elaine, the saola, and another remarkable animal I learned about while researching the saola. Both animals are newly discovered by science.

The scientific story of the saola starts in May of 1992. The Southeast Asian country of Vietnam had established a new nature reserve a few years before and wanted to learn more about the kinds of animals and plants living there. A team of scientists surveyed the area and one of the things they found was a skull with horns they didn’t recognize. The horns were long and straight and very close together.

They knew the skull came from an animal new to science, so they tried to find one to see what it looked like alive. But they couldn’t find one. It wasn’t until 1998 that a scientist saw a live saola, a female captured by hunters and kept in captivity until it died a few weeks later.

The saola is an antelope-like bovid that looks a lot like an oryx. We talked about the Arabian oryx in episode 218 and there are other species of oryx that live in parts of Africa. Oryx have long, straight horns that grow side by side too. But genetic analysis of saola remains indicates that the saola is much more closely related to cattle than to oryxes. The saola was described formally in 1993 and placed in its own genus, Pseudoryx, meaning false oryx.

The saola stands about 3 feet tall at the shoulder, or 92 centimeters, and is mostly chocolate brown with white markings on the head and a black stripe down its spine. Both males and females have horns, although males grow longer horns. The horns grow side by side, usually only a few inches apart, or about 8 or 9 centimeters, and are dark brown or black. They grow up to about 20 inches long, or 50 centimeters, and are often about the same distance apart at their tips as they are at the base of the skull. People sometimes call the saola the Asian unicorn because it’s so rare and its horns look sort of like unicorn horns, although they grow back from the skull instead of forward and aren’t spiral shaped. So, not actually very much like unicorn horns.

The saola also has a short tail, slender legs, and a short muzzle, but its tongue is over 6 inches long, or 15 centimeters. It’s rough like a cat’s tongue and it uses it to groom itself, just like a cat, and to help it gather the plants it eats, unlike a cat. It lives in forested mountains and migrates to lower elevations in winter, although its fur is thick and soft to keep it warm in higher elevations. It also has special pores around its eyes that secrete a special fluid it uses to mark plants and rocks the way many antelopes do. Because the saola hasn’t been observed in the wild, we don’t know if it’s marking its territory or just letting other saola know where it is.

The saola is critically endangered, mostly due to poaching. A team of forest guards patrols the park looking for traps that hunters set. Poachers often hunt animals in the park not because the hunters are hungry but because they can make a lot of money selling exotic animals to other countries as so-called medicine. The saola isn’t considered to have any medicinal uses, though, so while a hunter will sometimes kill one to eat, mostly it just gets caught in traps set for other animals. Since it’s so rare to start with, every saola killed in this way could ultimately cause the entire species to go extinct.

Conservationists are working hard to help the saola and its habitat. Logging has been banned in the park and the forest guards are on the lookout for illegal logging activity too. The forestry service is working to educate the local people that the saola only lives in their mountains and nowhere else in the world, which is something for them to be proud of. The park is near the border of another country, Laos, which is also helping with conservation efforts since the saola probably lives there too. You won’t find a saola in any zoos, though, because it doesn’t do well in captivity.

Other animals new to science have been discovered in the park and nearby areas, specifically around the Annamite Mountains along the border of Vietnam and Laos. This includes a new species of rabbit.

In 1996 a biologist named Rob Timmins was looking through a market in Laos when he saw three dead rabbits for sale as food. But these rabbits didn’t resemble any rabbits known from the area. They had short ears, reddish rumps, and dark brown stripes. Stripy rabbits! There is a similar-looking species that lives a thousand miles away, or 1,600 kilometers, in the mountains of Sumatra and Indonesia. The Sumatran striped rabbit is brown with darker brown stripes and blotches, but it’s been known to science since 1880. Timmins was the first scientist to see the Laotian rabbits.

Timmins bought the rabbits, of course, so they could be studied. Genetic studies determined that the rabbits are a distinct species, although it’s closely related to the Sumatran striped rabbit. It was described as a new species in 2000 and camera traps have since taken pictures of it in Vietnam, but we still know very little about it and its cousin in Sumatra.

Both species of striped rabbit are threatened by hunting and habitat loss. Hopefully they can be protected, along with their mountain homes, and a captive breeding program started to ensure their survival. Also, I would like one as a pet.

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

Thanks for listening!


Episode 253: The Sand Striker



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This week let’s learn about a weird marine worm and its extinct ancestor!

Further reading:

Eunice aphroditois is a rainbow, terrifying

The 20-million-year-old lair of an ambush-predatory worm preserved in northeast Taiwan

Here’s the money shot of the sand striker with its jaws open, waiting for an animal to get too close. The stripy things are antennae:

The fossilized burrow with notes:

Show transcript:

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

This week we’re going back in time 20 million years to learn about an animal that lived on the sea floor, although we’ll start with its modern relation. It’s called the sand striker and new discoveries about it were released in January 2021.

Ichnology is the study of a certain type of trace fossil. We talked about trace fossils in episode 103, but basically a trace fossil is something associated with an organism that isn’t actually a fossilized organism itself, like fossilized footprints and other tracks. Ichnology is specifically the study of trace fossils caused by animals that disturbed the ground in some way, or if you want to get more technical about it, sedimentary disruption. That includes tracks that were preserved but it also includes a lot of burrows. It’s a burrow we’re talking about today.

Because we often don’t know what animal made a burrow, different types of burrows are given their own scientific names. This helps scientists keep them organized and refer to a specific burrow in a way that other scientists can immediately understand. The sand striker’s fossilized burrow is named Pennichnus formosae, but in this case we knew about the animal itself before the burrow.

The sand striker is a type of polychaete worm, and polychaete worms are incredibly successful animals. They’re found in the fossil record since at least the Cambrian Period half a billion years ago and are still common today. They’re also called bristle worms because most species have little bristles made of chitin. Almost all known species live in the oceans but some species are extremophiles. This includes species that live near hydrothermal vents where the water is heated to extreme temperatures by volcanic activity and at least one species found in the deepest part of the ocean that’s ever been explored, Challenger Deep.

A polychaete worm doesn’t look like an earthworm. It has segments with a hard exoskeleton and bristles, and a distinct head with antennae. Some species don’t have eyes at all but some have sophisticated vision and up to eight eyes. Some can swim, some just float around, some crawl along the seafloor, and some burrow in sand and mud. Some eat small animals while others eat algae or plant material, and some have plume-like appendages they use to filter tiny pieces of food from the water. Basically, there are so many species known—over 10,000, with more being discovered almost every year, alive and extinct—that it’s hard to make generalizations about polychaete worms.

Most species of polychaete worm are small. The living species of sand striker generally grows around 4 inches long, or 10 centimeters, and longer. We’ll come back to its size in a minute. Its exoskeleton, or cuticle, is a beautifully iridescent purple. It doesn’t have eyes, instead sensing prey with five antennae. These aren’t like insect antennae but look more like tiny tentacles, packed with chemical receptors that help it find prey.

The sand striker lives in warm coastal waters and spends most of its time hidden in a burrow in the sand. It’s especially common around coral reefs. While it will eat plant material like seaweed, it’s mostly an ambush hunter.

At night the sand striker remains in its burrow but pokes its head out with its scissor-like mandibles open. When the chemical receptors in its antennae detect a fish or other animal approaching, it snaps its mandibles on it and pulls it back into its burrow. Its mandibles are so strong and sharp that sometimes it will cut its prey in half and then, of course, it pulls both halves into its burrow to eat. If the prey turns out to be large, the sand striker injects it with venom that not only stuns and kills it, it starts the digestive process so the sand striker can eat it more easily. It does all this so quickly that it can even catch fish and octopuses. The mandibles are at the end of a feeding apparatus called a pharynx, which it can retract into its body.

If a person tries to handle a sand striker, they can indeed get bitten. The sand striker’s mandibles are sharp enough to inflict a bad bite, and if it injects venom it can make the bite even more painful. Not only that, the sand striker’s body is covered with tiny bristles that can also inflict stings, with a venom strong enough that it can cause nerve damage in a human that results in permanent numbness where the person touched it. Don’t pet a sand striker.

Remember how I said the sand striker grows 4 inches or longer? That’s actually the low end of its size. The average sand striker is about 2 feet long, or 61 centimeters, but it can sometimes grow 3 feet long, or 92 centimeters, or even more. Sometimes a lot more.

In January 2009, someone noticed something in a float along the side of a mooring raft in Seto Fishing Harbor in Japan. The mooring raft had been in place for 13 years at that point and no one knew that a sand striker had moved into one of the floats. It had a nice safe home to use as a burrow. Sand strikers grow quickly and this one was living in a more or less ideal situation, so it just grew and grew until when it was found, it was just shy of 10 feet long, or 3 meters. Even so, it was still only about an inch thick, or 25 millimeters.

There are unverified reports of even longer sand strikers, some up to 50 feet long, or 15 meters. Look, seriously, do not pet it. Since sand strikers spend most of the time in burrows, it’s rare to get a good look at a full-length individual in the wild and we don’t know how long they can really get.

In case you’d forgotten, though, we started the episode talking about a fossilized burrow. In a fossil bed in northeast Taiwan, a team of paleontologists uncovered hundreds of strange burrows dating to about 20 million years ago. The burrows were L-shaped and as much as 6.5 feet long, or 2 meters, and about an inch across, or 2.5 centimeters. Even more confusingly, the fossilized sediment showed feather-like shapes in the upper section of the burrows.

The team of scientists studying the burrows had no idea what the feather-like structures were. The burrows were mysterious from start to finish anyway, since they were so much larger than most burrows in the seafloor.

They decided to do something unusual to solve some of the mysteries. They reached out not only to marine biologists but to marine photographers and aquarium keepers to get their insights. And, as you’ve probably guessed by now, the fossilized burrows most closely match those of the sand striker.

They even found out what the feather-shaped structures were. When a sand striker grabs a fish or other prey and drags it into its burrow, a lot of time it’s still alive, at least at first. Its struggles to get away can cause the sides of the burrow to shift. The sediment can’t collapse all the way because the worm lines it with mucus, so the partial collapsing and shifting results in feathery shapes.

These fossilized burrows are the first trace fossils known to be made by a marine ambush predator, which is pretty awesome. It’s even more awesome that some modern sand strikers are using the same type of burrows over 20 million years later.

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

Thanks for listening!


Episode 252: Mini Rex



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Thanks to Zachary for suggesting this topic! Let’s learn about some sightings of what look like miniature theropod dinosaurs running around in the American Southwest!

Further reading:

All About Birds: Wild Turkey

A collared lizard running (photo by Joe McDonald from this page):

Basilisks running:

A female wild turkey:

A male wild turkey (note the tuft of hair-like feathers sticking forward, called a beard) (picture from this page):

Show transcript:

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

Thanks to Zachary for his email a while back that helped shape this episode. Zachary has kept a lot of different kinds of pets, which we had a nice conversation about, and one of the reptiles he’s kept as a pet is in this episode. I’ll reveal which one at the end.

But first, a small correction, maybe. Paul from the awesome podcast Varmints! messaged me to point out that the word spelled A-N-O-L-E is pronounced a-NOLL, not a-NO-lee. I’d looked it up before I recorded so that confused me, so I looked it up again and it turns out that both pronunciations are used in different places and both are correct. So if you’ve always heard it a-NOLL, you’re fine, but now I can’t decide which pronunciation I should use.

This week we’re going to learn about an interesting mystery of the American southwest. Even though non-avian dinosaurs went extinct 66 million years ago, occasionally someone spots what they think is a little dinosaur running along on its hind legs. They’re sometimes called mini rexes.

Many reports come from the American southwest, especially Colorado, Arizona, and Texas. For instance, in the late 1960s two teenaged brothers were looking for arrowheads near their home in Dove Creek, Colorado when they were startled by an animal running away from them at high speed. The boys said it looked like a miniature dinosaur, only about 14 inches tall, or 35 centimeters. It was kicking up so much dust as it ran on its hind legs that the boys had trouble making out details. They did note that it seemed to be brown and possibly had a row of spines running down its back, maybe even two rows of spines, similar to an iguana’s. It had long hind legs and shorter front legs that it held out in front of it as it ran.

The animal left behind three-toed footprints that the boys followed until they disappeared into some brush. The boys were familiar with turkey footprints but these were different, with the toes closer together and no rear-pointing toe prints.

In April 1996, in Cortez, Colorado, a woman saw an animal run past her house on its hind legs, seemingly from a nearby pond. It was greenish-gray and stood about 3.5 feet tall, or about a meter. It had a long neck and long, tapering tail. She didn’t notice its front legs but its hind legs had muscular thighs but were thinner below the hock joint.

One night in July 2001, a woman and her grown daughter were driving near Yellow Jacket, Colorado when they noticed an animal at the edge of the road. At first the driver thought it was a small deer and slammed on the brakes so she wouldn’t hit it, but when it darted across the road both women were shocked to see what looked like a small dinosaur pass through the headlight beams of the car. They reported it was about 3 feet tall, or 91 centimeters, and that it had no feathers or fur. Its legs were thin and long, while its arms were tiny and held out in front of its body. It had a slender neck, a small head, and a long tapering tail.

The witnesses in both the 1996 sighting and the 2001 sighting noted that the animal they saw ran gracefully. They also all agreed that the animals’ skin appeared smooth.

Lots of dinosaurs used to walk on their hind legs, but the reptiles living today are all four-footed. There are a few lizards that run on their hind legs occasionally, though, and one of them lives in the American southwest. The collared lizard, also called the mountain boomer, will run on its hind legs to escape predators. Females are usually light brown while males have a blue-green body and light brown head. The name collared lizard comes from the two black stripes both males and females show around their necks, with a white stripe in between. During breeding season, in early summer, females also have orange spots along their sides.

The collared lizard can run up to 16 miles an hour, or 26 kilometers per hour, for short bursts on its hind legs. It uses its long tail for balance as it runs, and its hind legs are three times the length of its front legs. This makes it a good jumper too. It mostly eats insects but will occasionally eat berries, small snakes, and even other lizards. It hibernates in winter in rock crevices.

While the teenaged boys probably saw a collared lizard in the 1960s, the other two sightings we just covered sound much different. The collared lizard typically only grows up to 14 inches long, or 35 centimeters, including its long tail.

A few other lizards are known to run on their hind legs, such as the basilisk that lives in rainforests of Central and South America. It’s famous for its ability to run across water on its hind legs. It’s much larger than the collared lizard, up to 2.5 feet long, or 76 centimeters, including its long tail. It holds its front legs out to its sides when running on its hind legs, and the toes on its hind feet have flaps of skin that help stop it from sinking. It has a crest on its head, and the male also has crests on his back and tail. It can be brown or green in color.

The basilisk is sometimes kept as an exotic pet. In 1981 in New Kensington, Pennsylvania, four boys playing along some railroad tracks saw a green lizard that they thought was a baby dinosaur. It was 2 feet long, or 61 centimeters, and had a crest and an extremely long tail. It ran away on its hind legs but one of the boys, who was 11 years old, managed to catch it. It startled him by squealing and he dropped it again, and this time it got away. It sounds like an escaped pet basilisk.

But let’s go back to our mini rex sightings from 1996 and 2001, the ones of dinosaur-like animals running gracefully on their hind legs with a long neck and long tail. These don’t sound like lizards at all. When lizards run on their hind legs, they don’t look much like how we imagine a tiny raptor dinosaur would look. They appear awkward while running, with their arms sticking out and their heads pointing more or less upward. While all the lizards known that can run on their hind legs have long tails, they all have relatively short necks.

There’s another type of animal that’s closely related to the dinosaurs, though, and every single one walks on its hind legs. That’s right: birds! All the birds alive today are descended from dinosaurs whose front legs evolved for flight. Even flightless birds are well adapted to walk on two legs.

Let’s look at the details of those two sightings again. Both were of animals estimated as about three feet tall or a little taller, or up to about a meter, with long neck, small head, long tapering tail held above the ground, and long, strong legs that were nevertheless thin. Both also appeared smooth. In one of the sightings, the front legs were tiny and held forward; in the other, the witness didn’t notice the front legs.

My suggestion is that in these two sightings, at least, the witnesses saw a particular kind of bird, a wild turkey. That may sound ridiculous if you’re thinking of a male turkey displaying his feathers, but most of the time turkeys don’t look round and poofy. Most of the time, in fact, the wild turkey’s feathers are sleek and its tail is an ordinary-looking long, skinny bird tail instead of a dramatic fan. Its feathers are mostly brown and black, the upper part of its long neck is bare of feathers, as is its small head, and its legs are long and strong but relatively thin. It also typically stands 3 to 3.5 feet tall, or up to about a meter, although some big males can stand over 4 feet tall, or 1.2 meters. As for the front legs seen by witnesses in 2001, a full-grown male turkey has a tuft of long, hair-like feathers growing from the middle of his breast, called a beard. It sticks out from the rest of the feathers and might look like tiny arms if you were already convinced you were looking at a dinosaur instead of a bird.

That’s not to say that all mini-rex sightings are of turkeys, of course, but some of them probably are. The wild turkey lives throughout much of the United States, including most of Colorado. Since birds are the closest animals we have to dinosaurs these days, though, that’s still pretty neat.

Finally, the reptile Zachary kept as a pet was the collared lizard. I didn’t want to say so at the beginning and potentially spoil part of the mystery for some people!

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

Thanks for listening!


Episode 251: Modern Mimics and HIREC



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This week let’s look at some animals that have evolved rapidly to adapt to human-caused environmental pressures. Thanks to Otto and Pranav for their suggestions!

Further reading:

Long-term changes of plumage between urban and rural populations of white-crowned sparrows (Zonotrichia leucophrys)

A light-colored peppered moth (left) and darker-colored peppered moths (right):

Soot is hard to clean off buildings and other items (image from this page):

A white-crowned sparrow in the California countryside:

A (deceased museum specimen being photographed) white-crowned sparrow from the city of San Francisco, CA (taken from the study linked above):

A decorator crab that has attached bits of plastic and other trash to its body (image from this page):

The hermit crab sometimes uses trash instead of shells to hide in:

Show transcript:

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

This week we have two listener suggestions. Otto suggested we learn about camouflage that mimics modern things, and Pranav suggested animals that show rapid evolution due to humans.

We’ve talked about animals that use camouflage in lots of episodes, especially episode 191, Masters of Disguise. If you want to learn more about camouflage itself, that’s a good one to listen to. In addition, rapid evolution due to humans is a hot area of research right now. It even has its own scientific term, human-induced rapid evolutionary change, often shortened to the acronym HIREC.

Let’s start this episode with the story of a humble moth, because it’s a classic example of both HIREC and modern camouflage.

The peppered moth lives throughout much of the northern hemisphere. Its wingspan is a little over 2 inches across, or about 6 centimeters, and its caterpillar looks just like a little twig. Not only that, the caterpillar can change its coloring to match the twigs of the tree it’s on. But it’s not the caterpillars we’re talking about today.

The peppered moth gets its name from the coloring of its wings, which are white with black speckles, like pepper spilled on a plate. The pattern of speckles is unique to each individual, with some moths having more pepper speckles than others. Some moths have so many speckles that they look gray. But in the 19th century, geneticists studying moths in England noticed that the peppered moth seemed to be changing color as a species. Specifically, some of the peppered moths were completely black.

Black peppered moths had never been documented before 1811. They were still rare in the mid-19th century, but by 1900 almost all of the peppered moths in cities in England were black. Scientists noticed this and tried to figure out what was going on.

Pollution is what was going on. The industrial revolution was in full swing, but all those factories and trains and even ordinary houses were burning coal. Burning coal results in soot that’s carried on smoke and settles on everything. If you have a coal fire in your house, your walls and furniture are going to end up dark with soot. My aunt and uncle renovated a house from the late 19th century and had a lot of trouble cleaning soot from the walls and woodwork, even the old curtains that had been in the house. Similarly, when I lived briefly near Pittsburgh, Pennsylvania, there were still a lot of brick and stone buildings that were black from soot, but one beautiful old church had recently been cleaned and it turned out that the stone it was built from was pale gray, not black.

It wasn’t coal soot getting on the moths, though. It was coal soot on the trees where the moths spent most of their time. Most tree trunks are gray, but with all that coal soot in the air, the trees were coated with it and were much darker gray or even black. A light-colored moth that settled on a black tree branch showed up to predators, but a black moth on the same branch was camouflaged. The black moths survived more often to lay eggs while the white or gray moths didn’t, passing on the genetic likelihood that their babies would grow up to be dark-colored instead of light-colored.

It wasn’t just peppered moths that this happened to, either. More than 100 species of moth were documented to be dark gray or black during this time when they were ordinarily much lighter in color. Scientists call this industrial melanism.

Soot is made up of tiny particles that work their way into the crevices of wood and stone and everything else they come in contact with. You can’t just wipe or rinse it off. It’s acidic too and will kill plants, especially lichens that grow on trees, and it even eats away at stone and brick. It’s dangerous to breathe because the tiny particles lodge in your lungs and eventually stop you from being able to absorb oxygen as efficiently. If you’ve heard of the infamous London smog from the olden days, a big contributor to the smog was coal smoke. In 1952 a five-day smog event in London killed an estimated 12,000 people. That led directly to the Clean Air Act of 1956, and these days London doesn’t have that kind of deadly smog anymore.

Once factories and homes switched to electricity, natural gas, or other alternatives to burning coal, and trains switched to diesel fuel, trees stopped being coated with soot. Older trees that had survived were still dark, but young ones grew up with normal colored trunks and branches. Gradually, the black moths became less and less numerous compared to light-colored moths.

Cities in general result in rapid evolution of animals, including how they camouflage themselves. A study published in May of 2021 found that some birds living in cities are developing different colored feathers. Specifically, white-crowned sparrows living in San Francisco, California have much duller, darker feathers on their backs than white-crowned sparrows living outside of the city. Other studies have found that birds in cities sing much louder and at a higher pitch than birds in the countryside, since they have to compete with traffic and other noise.

A Swiss study on the effects of light on ermine moths indicated that while moths who developed from caterpillars collected from the countryside showed a normal attraction to light, moths from caterpillars collected in the city ignored the light. Since moths often die when they collide with electric lights, the city moths who survived to lay eggs were the ones who didn’t fly into a hot lightbulb.

Another study compared the genomes of white-footed mice that live in various parks in New York City with white-footed mice that live in state parks well outside of the city. The mice in city parks showed a lot less genetic diversity, naturally, since those mice are isolated populations. Mice can’t take cabs to visit mice in other parks, much less leave the city for a vacation. But the city mice showed another surprising difference. Their digestive systems have adapted to a much different diet than their country cousins. Some researchers suggest that the city mice may eat more junk food, which people throw away and the mice find, while other researchers think it’s just a difference in the kinds of insects and plants available in city parks for the mice to eat. Either way, it’s a distinct genetic difference that shows how the city mice are evolving to adapt to their urban environments.

Another example is a type of reptile called the crested anole. It’s related to the iguana and is native to the Americas. There are lots of species and subspecies of anole, many of which live on islands and show distinct adaptations to various habitats. The crested anole lives in Puerto Rico and on some nearby islands and grows up to 3 inches long, or 7.5 cm, not counting its long tail. The male is more brightly colored than the female, usually green or brown with darker spots. It’s not related to the chameleon but it is able to change color. It eats small animals, including insects, worms, even other anoles. Anoles are really interesting animals that deserve their own episode one day, so let’s just talk about how the crested anole that lives in cities has adapted to urban life.

One thing the crested anole is known for is its ability to climb right up tree trunks and even perch head-down in a tree. Its toe pads have microscopic scales and hairs that help them adhere to smooth surfaces, something like a gecko’s toes. But there’s a big difference in a tree trunk, no matter how smooth it is, and a pane of glass. Anoles in cities can climb up and down windows and painted walls. Researchers examined the toe pads of city crested anoles and compared them to the toe pads of crested anoles who lived in the countryside. They found that the city anoles had larger toes with more scales, and they even had longer legs. The research team also raced anoles along various surfaces and filmed them in slow motion to study how they were able to maneuver, which sounds like a great day at work.

The crested anoles have only lived in cities for a few decades, so their differences from country anoles evolved very quickly. But not all species of anole can adapt as well and as rapidly as the crested anoles have. Other city anole species don’t show differences from their country cousins.

Human-induced rapid evolutionary change isn’t restricted to cities. Trophy hunters who target the biggest animals with the biggest horns or antlers and leave smaller individuals alone have resulted in only smaller males with smaller horns or antlers surviving to breed. Many populations of bighorn sheep now actually only have small horns. Similarly, elephants have been killed for their tusks for long enough that many elephants are being born without tusks, because tuskless elephants are the ones that survive to breed. Entire populations of some fish species are smaller overall after many generations of being caught with nets, because only the individuals who are small enough to escape the nets survive to breed.

I tried hard to find more examples of animals that camouflage themselves to blend in to human-made items like roads. I’m sure this is happening throughout much of the world, but I couldn’t find any scientific studies about it. If any of you are thinking of going into biology, that might be an interesting field of study. But I did find one other example.

Self-decoration is a type of camouflage I don’t think we’ve talked about before. It’s where an animal decorates its body with items that help it blend in with its surroundings. Some caterpillars will stick little bits of lichen or other plant pieces to their bodies to help them hide, and some invertebrates of various kinds actually pile their own poop on their back as a disguise.

A group of crabs called decorator crabs will stick plants, sponges, and other items to their backs, and different species have preferences as to what items they use. Some species prefer stinging or toxic decorations, such as certain sea anemones which they basically pick up and plant on their backs. Researchers think the sea anemones actually benefit from being used as camouflage, because crabs are messy eaters and the anemones can catch and eat pieces of food that float away from the crab’s mouthparts. A decorator crab’s carapace is often rough in texture with tiny hooks to help things stick to it like Velcro.

Some decorator crabs don’t seek out particular decorations but just make use of whatever small items they find in their local environment. In the past few decades, scientists, divers, and other people who find crabs interesting have noticed more and more decorator crabs using little pieces of trash as decoration. This includes fragments of plastic and pieces of fishing nets.

This is similar to what’s happening with hermit crabs, which we talked about in episode 182. In many places hermit crabs are using trash like bottle caps instead of shells since there’s so much trash on beaches these days. This is your reminder to pick up any trash you find on the beach, but be careful not to cut yourself and also make sure you’re picking up actual trash and not a camouflaged crab.

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