Monthly Archives: November 2024

Episode 407: Cookie Cutter Shark

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Thanks to Alyx for this week’s suggestion, the cookie cutter shark!

Further reading:

If You Give a Shark a Cookie

The business end of the cookie cutter shark:

Show transcript:

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

This week we’re going to learn about a little shark suggested by Alyx, but first let’s learn about something else that might be related to the shark.

In the 1970s, the U.S. Navy started having trouble with the navigation of their submarines. The Ohio-class submarine had what was called a sonar dome that was filled with oil, and the oil helped transmit sound. But repeatedly the subs would lose navigation abilities, and investigations turned up strange chunks removed from the electric cables, the oil lines, the sound probes, and the sonar dome itself—anywhere made of rubber that was soft enough for what looked like a hole saw to damage.

The Navy thought they were dealing with a state-of-the-art weapon. The United States and the former Soviet Union were bitter enemies, so the Navy thought the USSR had invented a technologically sophisticated underwater stealth drone of some kind that could damage the subs and leave no trace—nothing but circular chunks removed from the sonar dome and its components.

Thirty submarines were damaged before the Navy figured out the cause. It wasn’t a super-secret weapon at all. It was just a little fish called the cookie-cutter shark.

The cookie cutter shark doesn’t look very scary. It only grows 22 inches long at most, or 56 cm, and is brown in color. It has lots of very sharp evenly spaced teeth on its lower jaw, but compared to a great white shark, it’s nothing to worry about. But somehow it was able to disable 30 of the world’s most advanced submarines at the time.

That’s because of how the cookie cutter shark eats, which is also how it gets its name. It picks a target fish or some other animal, such as a whale or a seal, or possibly the sonar dome of an Ohio-class submarine, and sneaks up to it. It’s just a little fish and its coloration helps it blend in with its surroundings, so most animals barely notice it. It has lips that act like a suction cup, so quick as a wink it sticks itself to the animal, bites down, and spins around. In moments it’s cut a circular chunk out of the animal’s side like a horrible cookie, which it swallows, and by the time the animal even realizes it’s hurt, the cookie cutter shark is long gone.

The shark used to be called the cigar shark because of its shape. It wasn’t until 1971 that experts realized how the cookie cutter shark eats. Until then the circular wounds on fish and whales and other animals were thought to be from lamprey bites or from some kind of parasite.

The cookie cutter shark does have teeth in its upper jaw but they’re much smaller than the lower teeth. When it sheds its lower teeth to replace them, instead of shedding just one tooth, it sheds them all at once. Like most sharks, it swallows its old teeth so it can reuse the calcium to grow new teeth.

The shark also has photophores on the underside of its body that glow greenish, which is a common way that some fish escape predators from below. A big fish looking up toward the surface of the water high above it sees a lot of light shining down from the sun, so a fish with a glowing underside just blends in. But in the case of the cookie cutter shark, it has a strip of skin on its underside without photophores, and from below that strip shows up. It’s a sort of collar that’s actually darker brown than the rest of the fish. It looks, in fact, like a tiny fish silhouetted against the surface. The would-be predator fish approaches, expecting an easy meal. Instead, the cookie cutter shark darts around and takes a big bite out of the fish, then takes off. It’s a remarkably fast swimmer, but most of the time it hangs almost motionless in the water waiting for another animal to approach. Its eyes are large and it has good vision.

Sometimes the cookie cutter shark will travel in schools, which attracts even more predators who think they’re looking at a bunch of little bitty fish. Then all the sharks get a bite.

That leads us to the uncomfortable question: has the cookie cutter shark ever bitten a piece out of a human? The answer is yes, but no one has ever died from a cookie cutter shark attack. The shark usually stays in deep water during the day and rises closer to the surface at night, so it’s not likely to encounter humans except at night. Occasionally a swimmer has been bitten, and shipwreck survivors have reported being bitten at night while waiting for rescue, which is just insult to injury. In 2023 a swimmer was bitten by two cookie cutter sharks, but he saw them and was able to just grab them both and throw them away before he was seriously hurt. That’s not something you can do with a great white.

As for the submarines, the Navy started putting fiberglass shields over the sonar dome and other softer parts of the sub, and that solved the problem. It only cost $2 billion each to repair the subs.

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. 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 406: Some Turtles and a Friend

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Thanks to Riley and Dean, Elizabeth, and Leo for their suggestions this week!

Further reading:

Groundbreaking study reveals extensive leatherback turtle activity along U.S. coastline

A bearded dragon:

The tiny bog turtle:

The massive leatherback sea turtle:

The beautiful hawksbill turtle [photo by U.S. Fish and Wildlife Service]:

Show transcript:

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

This week we’re going to learn about some reptiles suggested by four different listeners: Riley and Dean, Elizabeth, and Leo.

We’ll start with the brothers Riley and Dean. Dean wants to learn more about the bearded dragon, and that may have something to do with a certain pet bearded dragon named Kippley.

“Bearded dragon” is the name given to any of eight species of lizard in the genus Pogona, also referred to as beardies. They’re native to Australia and eat plants and small animals like worms and insects. They can grow about two feet long, or 60 cm, including the tail, but some species are half that length. Females are a little smaller than males on average.

The bearded dragon gets its name because its throat is covered with pointy scales that most of the time aren’t very noticeable, but if the lizard is upset or just wants to impress another bearded dragon, it will suck air into its lungs so that its skin tightens and the spiky scales under its throat and on the rest of its body stick out. They’re not very sharp but they look impressive. Since the bearded dragon can also change color to some degree the same way a chameleon can, when it inflates its throat to show off its beard, the beard will often darken in color to be more noticeable. Both males and females have this pointy “beard.”

Bearded dragons that are sold as pets these days are more varied and brighter in color than their wild counterparts, although wild beardies can be brown, reddish-brown, yellow, orange, and even white. Australia made it illegal to catch and sell bearded dragons as pets in the late 20th century, but there were already lots of them outside of Australia by then. Pet bearded dragons are mainly descended from lizards exported during the 1970s, which means they’re quite domesticated these days and make good pets.

Like some other reptiles and amphibians, the bearded dragon has a third eye in the middle of its forehead. If you have a pet beardie and are about to say, “no way, there is definitely not a third eye anywhere, I would have noticed,” the eye doesn’t look like an eye. It’s tiny and is basically just a photoreceptor that can sense light and dark. Technically it’s called a parietal eye and researchers think it helps with thermoregulation.

Next, Riley wants to learn about turtles, AKA turbles, and especially wants everyone to know the difference between a tortoise and a turtle. It turns out that while many turtles are just fine living on land, they’re often more adapted to life in the water. Turtles have a more streamlined shell and often flipper-like legs or webbed toes. Tortoises only live on land and as a result they have shells that are more dome-shaped, and they have large, strong legs that resemble those of a tiny elephant.

You can’t always go by an animal’s common name to determine if it’s a tortoise or a turtle, but it’s also not always clear whether an animal is a tortoise or a turtle at first glance. Take the eastern box turtle, for instance, which is common in the eastern United States. It has a domed carapace, or shell, but it’s still a turtle, not a tortoise. And, I’m happy to say, it can swim quite well. This is a relief to find out because when I was about six years old, my mom visited someone who had kids a little older than me. I didn’t know them but they were nice and showed me the swampy area near their house. At one point one of the older boys found a box turtle, took it over to a little bridge over a pond, and dropped it in the water. I screamed, and he was absolutely shocked. He said he thought box turtles belonged in the water and he was helping it, but I thought they couldn’t swim and he’d just killed the poor turtle. I have continued to think he’d killed the poor turtle until just now, when I learned they can swim, and I can’t even tell you how relieved I am. Anyway, eastern box turtles have a domed shell, yes, and stumpy club-like front legs, but their hind legs are less like elephant legs than regular turtle legs. Since box turtles can live to be 100 years old, it’s possible that that one is alive and well even now.

Riley also wants everyone to know not to take a turtle from the woods, which is a very good rule to live by. In fact, it’s important not to take any wild animals from the woods no matter how cute they are. To continue our example, eastern box turtles have small territories that they defend from other box turtles. If you take the turtle out of its territory even for just a few days, when you return it to the woods, another turtle may have already taken over and will chase it away. Turtles don’t travel very fast and are vulnerable to being hit by cars and eaten by lots of different predators, so without a safe territory where it can hide and find food, it can die very quickly.

One of the turtles Leo suggested we learn about was the bog turtle. It’s the smallest turtle in North America, with a carapace barely four inches long, or 10 cm. It lives in a few parts of the eastern United States, and likes marshy areas with slightly acidic water. It spends a lot of time in the water, but also plenty of time on land. It eats worms, slugs, snails, water plants, berries, insects, and even small frogs when it can catch them.

The bog turtle is so small that pretty much anything big enough to swallow it will eat it. Its main defense is to bury itself in soft mud and hide. It’s almost completely black or dark gray in color, but it does have a bright orange spot on each side of its neck.

The bog turtle is critically endangered due to habitat loss, pollution, and poaching for the illegal pet trade. Conservationists are working to improve its habitat, and in the meantime some zoos and aquariums are helping with a captive breeding program. Since a bog turtle isn’t old enough to lay eggs until it’s at least 8 years old, the species as a whole reproduces slowly.

Leo also suggested hawksbill and leatherback turtles, and Elizabeth wants to learn about sea turtles in general. We talked about sea turtles way back in episode 75, so it’s definitely time to revisit the topic.

Seven species of sea turtle are alive today, and you can tell they’re turtles and not tortoises because they have streamlined shells and flippers instead of feet. They migrate long distances to lay eggs, thousands of miles for some species and populations, and usually return to the same beach where they were hatched. Female sea turtles come ashore to lay their eggs in sand, but the males of most species never come ashore. The exception is the green sea turtle, which sometimes comes ashore just to bask in the sun. Once the babies hatch, they head to the sea and take off, swimming far past the continental shelf where there are fewer predators. They live around rafts of floating seaweed call sargassum, which protects them and attracts the tiny prey they eat.

Six of the extant sea turtles are relatively small. Not small compared to regular turtles, small compared to the seventh living sea turtle, the leatherback. It’s much bigger than the others and not very closely related to them. It can grow some nine feet long, or 3 meters, and instead of having a hard shell like other sea turtles, its carapace is covered with tough, leathery skin studded with tiny osteoderms. Seven raised ridges on the carapace run from head to tail and make the turtle more stable in the water, a good thing because leatherbacks migrate thousands of miles every year. Not only is the leatherback the biggest and heaviest turtle alive today by far, it’s the heaviest living reptile that isn’t a crocodile. It has huge front flippers, is much more streamlined even than other sea turtles, and has a number of adaptations to life in the open ocean.

The leatherback lives throughout the world, from warm tropical oceans up into the Arctic Circle. It mostly eats jellyfish, so it goes where the jellyfish go, which is everywhere. It also eats other soft-bodied animals like squid. To help it swallow slippery, soft food when it doesn’t have the crushing plates that other sea turtles have, the leatherback’s throat is full of backwards-pointing spines. What goes down will not come back up, which is great when the turtle swallows a jellyfish, not so great when it swallows a plastic bag. It’s endangered due to pollution, accidental drowning when it gets caught in fishing nets, and habitat loss of its nesting beaches.

The hawksbill, or hawkbill sea turtle grows to a much more reasonable size, around three feet long, or 90 cm, and mostly lives around tropical reefs. It has a more pointed, hooked beak than other sea turtles, sort of like a hawk, which gives it its name. You might think it eats fish with a beak like that, but it mostly eats jellyfish and sea sponges. It especially likes the sea sponges, some of which are lethally toxic to most other animals. It also doesn’t have a problem eating even extremely stingy jellies and jelly-like animals like the Portuguese man-o-war. The hawkbill’s head is armored so the stings don’t bother it, although it does close its eyes while it chomps down on jellies. Its meat can be toxic due to the toxins it ingests. People used to kill hawksbill sea turtles for their multicolored shells, but these days it’s a protected species like all sea turtles.

The hawksbill is also biofluorescent! Researchers only found this out by accident in 2015, when a team studying biofluorescent animals in the Solomon Islands saw and filmed a hawksbill glowing like a UFO with neon green and red light. So you never know what other secrets sea turtles might be hiding.

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. 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 405: Anteaters and the Capelobo

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Thanks to Molly and Mila for suggesting the anteater and its relations this week!

Further reading:

How anteaters lost their teeth

The giant anteater has a long tongue and a little mouth, and adorable babies:

The giant anteater has a weird skull [photos by Museum of Veterinary Anatomy FMVZ USP CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=72183871]:

The tamandua is like a mini giant anteater that can climb trees:

The silky anteater looks like a weird teddy bear [photo by Quinten Questel – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=30287945]:

Show transcript:

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

This week we’re going to talk about some unusual mammals, suggested by Molly and Mila. It’s a topic I’ve been meaning to cover for almost two years and now we’re finally going to learn about it! It’s the anteater and its close relations, including a creepy anteater cryptid that would have fit in just fine during monster month.

A lot of animals are called anteaters because they eat ants, but the anteaters we’re talking about today belong to the suborder Vermilingua, meaning “worm tongue.” That’s because they all have long, sticky tongues that they use to lick up ants, termites, and other insects. Anteaters are native to Central and South America and are closely related to sloths, and more distantly related to armadillos.

The sloth and anteater share a common ancestor who lived around 60 million years ago, a little animal that mainly ate worms and insect larvae and probably lived in burrows. Because its food was soft and didn’t need a lot of chewing, when a mutation cropped up that caused its teeth to be weak, it didn’t matter. It wasn’t using its teeth anyway. When the first anteaters evolved from this ancestral species, they didn’t need teeth either, and gradually they lost their teeth entirely. Modern anteaters have no teeth at all.

Sloths also evolved from this weak-toothed ancestor, and sloths eat plants. Plants need a lot of chewing, and most animals that eat plants have really strong teeth, but sloths retained the genetics for weak teeth. They don’t even have an enamel coating on their teeth, and instead of grinding molars, their teeth are basically soft little pegs. Luckily for the sloth, the little peg teeth do continue to grow throughout its life, so it never wears its teeth down so far it can’t chew.

Anteaters, sloths, and their distant relation the armadillo all share the same type of vision from their shared ancestor too. They can’t see colors at all but have good vision in low light, which is why scientists think they all evolved from an animal that spent most of its time underground hunting for worms. Anteaters have strong claws that allow them to dig into termite and ant nests, and armadillos spend a lot of time in burrows they dig. We don’t actually know what the common ancestor of these related animals looked like because we haven’t found any fossils of it yet.

In the past, scientists thought that pangolins and aardvarks were related to anteaters because they all have similar adaptations to a similar diet, but that’s just another example of convergent evolution. We talked about pangolins and aardvarks back in episode 65, as well as the giant anteater.

The giant anteater is the one most people know about. It earns the name giant because it can grow almost eight feet long, or 2 1/2 meters, if you include the tail. Its fur is brown and cream with a distinctive black stripe from its chest to its back that scientists used to think acted as camouflage. Because the black fur is outlined with white, making it stand out, scientists now think it’s used as a warning to potential predators, because the giant anteater can be dangerous. If it feels threatened, it will rear up on its hind legs, using its long tail as a prop, to slash at a predator. Its claws are so big that it knuckle-walks on its forepaws.

The female anteater has one baby at a time and while it’s small, it rides on her back. Its black stripe matches hers exactly so that potential predators don’t notice it. The giant anteater’s tail has especially long, thick fur, and it will wrap the tail over its head like a blanket in cold weather.

You know how a cartoon character can cram its head into a bottle and its head stays bottle-shaped? It kind of looks like the giant anteater did that. Its head is small and its snout is shaped like a tube, with nostrils and a tiny mouth at the end. It can’t open its jaws very far.

Anteaters eat ants, although they also love termites and will eat other small insects and insect larvae. The giant anteater uses its massive front claws to dig into anthills. Then it flicks its tongue really fast, catching insects with a combination of tiny hooklets on the tongue and sticky saliva. An anteater’s tongue is over two feet long, or 60 cm, so long that when the anteater isn’t actually eating, the tongue rolls up at the back of its skull. The base of its tongue is attached not to its throat but to its sternum, also called the breastbone.

A feeding anteater eats as many insects as it can catch in a minute or two, then moves on to find a new anthill. It does this to avoid as many stings and bites as possible. Because the anteater doesn’t have teeth, it crushes insects against the top of its mouth before swallowing them, and its stomach acts like a bird’s crop. The anteater may deliberately eat sand or grit the way birds do to help pulverize the insects it’s eaten. Its eyesight isn’t very good so it hunts mostly by scent.

To conserve energy, the anteater’s body temperature is low to start with and drops when the animal is asleep. This is another trait it shares with its relations, the sloth and the armadillo.

There are three other species of anteater alive today, the silky anteater, and the northern and southern tamanduas. The tamandua, both northern and southern, looks like a miniature giant anteater but is typically less than half its size. The southern tamandua lives throughout much of South America while the northern tamandua lives throughout Central America, and both species look very similar. They don’t have the black warning stripe that the giant anteater has, though, and because they’re smaller and lighter, they can climb trees to find insects, which allows them to live in the same areas as giant anteaters without competing with them for food. They eat ants, termites, and the larvae of lots of other insects, and will also eat fruit. The tamandua has a partially prehensile tail that helps it climb trees.

The silky anteater is also called the pygmy anteater, because it’s the smallest species, only growing about 18 inches long, or 45 cm. That includes its partially prehensile tail. It lives in Central America and much of northern South America, and unlike the giant anteater that prefers savannas and open forests, the silky anteater lives in lowland rainforests because it spends its life in trees.

The silky anteater also doesn’t look much like the giant anteater. It kind of looks like a weird teddy bear with a long tail, and kind of looks like a weird sloth with a long tail. Its fur is short but fluffy, light brown or cream-colored, and some scientists think this makes it look like the seed pod of the silk cotton tree that’s common throughout its range and which it prefers. It sleeps curled up in a ball that also helps it look more like a seed pod.

The silky anteater has two long, sharp claws on its front feet, which it uses to climb trees, break open wasp nests, and defend itself from predators. Its hind feet have four claws that aren’t as long. It eats lots of wasps and wasp larvae, but it also eats other insects and even fruit. It has a tiny head and a long snout, but its snout is nowhere near as long as the giant anteater’s, or even the tamandua’s.

You might not think of any of these anteaters as scary, and in fact the silky anteater is so cute I want to pet it even though that would be a bad idea, but they can definitely be dangerous. The giant anteater in particular can kill jaguars and has even killed humans who try to capture or hurt it. Maybe that’s why one of the forms of the cryptid called the capelobo is a hairy man with a giant anteater’s head and claws.

The capelobo is a legend from Brazil that’s sort of like a Brazilian werewolf. In its animal form it looks like a tapir but with a dog-like head, but it can transform into its humanoid form where it looks like a monstrous giant anteater. It’s supposed to scream in the woods like someone in danger, and when people come to help, it catches them and squeezes them to death. Then it drinks their blood and eats their brains like some sort of terrible anteater zombie-vampire, which is not a phrase I ever thought I’d utter.

One suggestion about the capelobo squeezing people to death is that this is a story to help children stay away from giant anteaters. Remember that they stand up on their hind legs with their arms outstretched when they’re ready to fight. To a little kid, that looks an awful lot like a person with their arms out for a big hug. Don’t hug the capelobo, and don’t hug the giant anteater either.

The capelobo’s body is supposed to be heavily armored or even made of stone, except for its belly button. That’s the only place where it’s vulnerable, so to kill the capelobo, someone has to shoot it right in the naval. That sounds really hard, especially if it’s chasing you. Fortunately, it’s not a real animal—although to be on the safe side, maybe don’t go wandering into the Brazilian forest at night.

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. 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!