Strange Animals Podcast

By: Katherine Shaw
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  • Summary

  • A podcast about living, extinct, and imaginary animals!
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Biological Sciences Nature & Ecology
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Episodes
  • Episode 407: Cookie Cutter Shark

    Episode 407: Cookie Cutter Shark
    Nov 18 2024
    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.
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    6 mins
  • Episode 406: Some Turtles and a Friend

    Episode 406: Some Turtles and a Friend
    Nov 11 2024
    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,
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    12 mins
  • Episode 405: Anteaters and the Capelobo

    Episode 405: Anteaters and the Capelobo
    Nov 4 2024
    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 for...
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    11 mins

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