エピソード

  • Episode 407: Cookie Cutter Shark
    2024/11/18
    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 分
  • Episode 406: Some Turtles and a Friend
    2024/11/11
    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 分
  • Episode 405: Anteaters and the Capelobo
    2024/11/04
    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 分
  • Episode 404: The Kraken and Chessie
    2024/10/28
    Thanks to Ezra and Leo for suggesting these two sea monsters this week! Happy Halloween! Further reading: Legend of Chessie alive, well in Maryland Here be sea monsters: We have met Chessie and...is it us? Not actually a kraken, probably: Not actually Chessie but an atmospheric photo of a toy brontosaurus: Show transcript: Welcome to Strange Animals Podcast. I’m your host, Kate Shaw. Just a few days remain in October, so this is our Halloween episode and the end of monster month for another year! We had so many great suggestions for Halloween episodes that I couldn’t get to them all, but I might just sprinkle some in throughout the other months too. We have two great monsters to talk about this week, suggested by Ezra and Leo, the kraken and Chessie the sea serpent. First, as always on our Halloween episode, we have a few housekeeping details. If anyone wants a sticker, feel free to email me and I’ll send you one, or more than one if you like. That offer is good all the time, not just now. I don’t have any new stickers printed but I do have lots of the little ones with the logo and the little ones with the capybara. I also don’t have any new books out this year, but you can still buy the Beyond Bigfoot & Nessie book if you like. I am actually working on another book about mystery animals, tentatively titled Small Mysteries since it’s going to be all about mysteries surrounding small animals like frogs and invertebrates that often get overlooked. I’m hoping to have it ready to publish in early 2026 or so. I don’t know that I’ll do another Kickstarter for it since that was a lot of work, and I just finished a Kickstarter for more enamel pins and just can’t even think about the stress of doing another crowdfunding campaign anytime soon. Also, I hate to keep asking listeners for money. Anyway, one of the things I don’t like about Beyond Bigfoot & Nessie is that I didn’t cite my sources properly, so for the Small Mysteries book I’m being very careful to have footnotes on pretty much every page so that anyone who wants to double-check my information can do so easily. But all that is in the future. Let’s celebrate Halloween now with a couple of sea monsters! We’ll start with Ezra’s suggestion, the kraken. It’s a creature of folklore that has gotten confused with lots of other folklore monsters. We don’t know how old the original legend is, but the first mention of it in writing dates to 1700, when an Italian writer published a book about his travels to Scandinavia. One of the things he mentions is a giant fish with lots of horns and arms, which he called the “sciu-crak.” This seems to come from the Norwegian word meaning sea krake. “Krake” is related to the English word crooked, and it can refer to an old dead tree with crooked branches, or tree roots, or something with a hook on the end like a boat hook, or an anchor or drag, or various similar things related to hooks or multiple prongs. That has led to people naturally assuming that the kraken had many arms and was probably a giant squid, and that may be the case. But there’s another possibility, because in many old uses of the word krake, it means something weak or misshapen, like a rotten old dead tree. In the olden days in Norway, people thought that if you spoke about an animal by name, the spirit that protected that animal would hear you. Some historians think that whale-hunters referred to whales as krake so the whale’s protective spirit wouldn’t guess that they were planning a whale-hunt. Who would refer to a huge, strong animal like a whale as weak and crooked, after all? Whatever its origins, the kraken’s modern form is mainly due to a Danish bishop called Erik Pontoppidan. He wrote about the kraken in 1753, and embellished the story by saying the kraken could reach out of the ocean with its long arms to grab sailors or just pull an entire ship down into the water and sink it.
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    12 分
  • Episode 403: Predator X
    2024/10/21
    Thanks to Eesa for suggesting this week's topic, the pliosaur Predator X! Further reading: Predator X / Pliosaurus funkei [you can find lots of interesting pictures here, some artwork and some skeletal diagrams] Kronosaurus had a big skull with big teeth: Show transcript: Welcome to Strange Animals Podcast. I’m your host, Kate Shaw. We’re one week closer to Halloween, and that means the monsters are getting more monster-y, at least in name, although I wouldn’t want to meet this one in person. It’s referred to as Predator X, and thanks to Eesa for suggesting it! Fortunately for everyone who likes to swim and boat in the ocean, Predator X has been extinct for around 145 million years. It’s a type of marine reptile called a pliosaur, Pliosaurus funkei, but there was nothing funky about it. It was huge, fast, and incredibly strong. Also, the funky part of the name comes from the couple who originally discovered the first specimen, who had the last name of Funke. We only have two Predator X specimens right now, both of them found in the same rock formation from a Norwegian island. The remains were first discovered in 2004 but the process of recovering them took many years. Because winters in Norway are very cold, the exposed rocks were subject to freezing temperatures that had broken a lot of the fossils into fragments, and some of the fossils crumbled into pieces as they dried out. All told, 20,000 pieces were recovered and painstakingly fit back together like a gigantic jigsaw puzzle made of fossilized bones. Neither specimen is complete but we have enough bones that scientists can estimate the animal’s size when it was alive—and it was huge! It probably grew up to 39 feet long, or 12 meters, and some individuals would certainly have been bigger. Initial estimates were even longer, up to 50 feet, or over 15 meters, but that was before the specimens were fully studied. Like other pliosaurs, predator X had a short tail and big teeth in its long jaws. Its head was massive, around 7 feet long, or 2 meters, and its front flippers were probably about the same length. It had four flippers, and researchers think its front flippers did most of the work of swimming, with the rear flippers acting as a rudder, but it could probably use its back flippers for a little extra boost of speed when it needed to. But it was a strong, fast swimmer no matter what, probably as fast as a modern orca, and very maneuverable. It had to be, because it ate other marine reptiles like plesiosaurs that were themselves very fast swimmers. It undoubtedly also ate sea turtles and fish, and probably pretty much anything else it could catch. It didn’t eat whales because this was long, long before whales evolved. Predator X got its nickname from reporters back when the paleontologists thought it was 50 feet long. It didn’t have a name yet so it got called Predator X because that sounded impressive (and it is), but it isn’t the only giant pliosaur known. Kronosaurus was originally described in 1924 from fossils discovered in Australia, and current estimates of its size agree that it could probably grow to around 33 feet long, or 10 meters. This may be a low estimate, though, because the size of the biggest skull found might have been over 9 feet long, or 2.85 meters, although the skull isn’t complete so its full size is just an estimate. Pliosaurs do have big heads, but if Kronosaurus’s skull really is longer than predator X’s skull, it was probably a bigger animal overall. Kronosaurus’s fossils have only been found in an ancient inland sea that covered most of Queensland and Central Australia until about 100 million years ago. It was probably a relatively shallow, cold sea, and although it had all the marine animals you’d expect for the time, like sharks, ammonites, ichthyosaurs, plesiosaurs, lungfish, sea turtles, and lots more, Kronosaurus was the apex predator. It was so big and deadly that a full-grown Kronosaurus didn’t have to worry ...
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    7 分
  • Episode 402: The Hoop Snake and Friends
    2024/10/14
    Thanks to Nora and Richard from NC this week as we learn about some scary-sounding reptiles, including the hoop snake! Further reading: The Story of How the Giant “Terror Skink” Was Presumed Extinct, Then Rediscovered San Diego’s Rattlesnakes and What To Do When They’re on Your Property Snake that cartwheels away from predators described for the first time Giant new snake species identified in the Amazon The terror skink, AKA Bocourt's terrific skink [photo by DECOURT Théo - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=116258516]: The hoop snake according to folklore: The sidewinder rattlesnake [photo taken from this article]: The dwarf reed snake [photo by Evan Quah, from page linked above]: The green anaconda [photo by MKAMPIS - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=62039578]: Show transcript: Welcome to Strange Animals Podcast. I’m your host, Kate Shaw. As monster month continues, we’re going to look at some weird and kind of scary, or at least scary-sounding, snakes and lizards. Thanks to Nora and Richard from NC for their suggestions this week! We’ll start with the terror skink, whose name should inspire terror, but it’s also called Bocourt’s terrific skink, which is a name that should inspire joy. Which is it, terror or joy? I suppose it depends on your mood and how you feel about lizards in general. All skinks are lizards but not all lizards are skinks, by the way. The terror or possibly terrific skink lives on two tiny islets, which are miniature islands. These islets are themselves off the coast of an island called the Isle of Pines, but in French, which I cannot pronounce. The Isle of Pines is only 8 miles wide and 9 miles long, or 13 by 15 km, and is itself off the coast of the bigger island of New Caledonia. All these islands lie east of Australia. Technically the islets where the skink lives are off the coast of another islet that is itself off the coast of the Isle of Pines, which is off the coast of New Caledonia, but where exactly it lives is kept a secret by the scientists studying it. The skink was described in 1876 but only known from a single specimen captured on New Caledonia around 1870, and after that it wasn’t seen again and was presumed extinct. Colonists and explorers brought rats and other invasive animals to the New Caledonian islands, which together with habitat loss have caused many other native species to go extinct. But in December 2003, a scientific expedition studying sea snakes around the New Caledonian islands caught a big lizard no one recognized. Once the expedition members realized it was a terror skink, alive and well, they took lots of pictures and videos of it and then released it back into the wild. Since then, more specimens have been discovered during four different expeditions, but only on the islets, not on any of the bigger islands. It’s so critically endangered that its location has to be kept secret, because if someone captures some of the lizards to sell on the illegal pet market, the species could easily be driven to extinction. The terror skink is gray-brown with darker stripes, a long tail, and a slightly downturned mouth that makes it look grumpy. It grows about 20 inches long, or 50 cm, including its tail. This is really big for a skink, so technically it’s a giant skink. It gets the name terror skink from its size and from its teeth, which are large and curved like fangs. It mainly eats one particular species of land crab, which is why its jaws are so strong and its teeth are so sharp, so it can bite through the crab’s exoskeleton. Another lizard with a spooky name that has been presumed extinct is the gray ghost lizard, suggested by Richard from NC. It’s more properly called the giant Tongan ground skink, and it’s native to some more South Pacific islands—specifically, the Tongan Islands.
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    17 分
  • Episode 401: El Gran Maja and Other Giant Eels
    2024/10/07
    Thanks to Murilo for suggesting El Gran Maja for our first monster month episode of 2024! Further reading: The Loch Ness Monster: If It’s Real, Could It Be an Eel? Further watching: Borisao Blois's YouTube channel [I have not watched very many of his videos so can't speak to how appropriate they all are for younger viewers] El Gran Maja, YouTube star: The European eel [photo by GerardM - http://www.digischool.nl/bi/onderwaterbiologie/, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=284678]: A supposed 21-foot eel, a product of trick photography: The slender giant moray eel [photo by BEDO (Thailand) - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=40262310]: Show transcript: Welcome to Strange Animals Podcast. I’m your host, Kate Shaw. It’s monster month, where we talk about weird, mysterious, and sometimes spooky creatures! This year I’ve decided to be less spooky and more weird, so let’s kick off the month with an episode all about gigantic eels. Thanks to Murilo for suggesting our first giant eel, El Gran Maja. El Gran Maja is an eel that is supposed to live off the coast of northern Puerto Rico, and it’s supposed to grow 675 meters long. That’s 2,215 feet, or almost half a mile. That is an excessive amount of eel. Obviously, an eel that big couldn’t actually exist. By the time its front end noticed danger, its back end could already be eaten by a whole family of sharks. But maybe it was based on a real eel that grows really long. Let’s take a look at some eels we know exist, and then we’ll return to El Gran Maja and learn some very interesting things about it. Eels are fish, but not every animal that’s called an eel is actually an eel. Some are just eel-shaped, meaning they’re long and slender. Electric eels aren’t actually eels, for instance, but are more closely related to catfish. Most eels live in the ocean at the beginning and end of their lives, and freshwater in between. For example, the European eel has a life cycle that’s pretty common among eels. It hatches in the ocean into a larval stage that looks sort of like a transparent leaf. Over the next six months to three years, the larvae swim and float through the ocean currents, closer and closer to Europe, feeding on plankton and other tiny food. Toward the end of this journey, they grow into their next phase, where they resemble eels instead of leaf-shaped tadpoles, but are still mostly transparent. They’re called glass eels at this point. The glass eels make their way into rivers and slowly migrate upstream. Once a glass eel is in a good environment it metamorphoses again into an elver, which is basically a small eel. As it grows it gains more pigment until it’s called a yellow eel. Over the next decade or two it grows and matures, until it reaches its adult length—typically around 3 feet, or about a meter. When it’s fully mature, its belly turns white and its sides silver, which is why it’s called a silver eel at this stage. Silver eels migrate more than 4,000 miles, or 6500 km, back to the Sargasso Sea to spawn, lay eggs, and die. One place where European eels live is Loch Ness in Scotland, and in the 1970s the idea that sightings of the Loch Ness Monster might actually be sightings of unusually large eels became popular. A 2018 environmental DNA study brought the idea back up, since the study discovered that there are a whole, whole lot of eels in Loch Ness. The estimate is a population of more than 8,000 eels in the loch, which is good since the European eel is actually critically endangered. But most of the eels found in Loch Ness are smaller than average, and the longest European eel ever measured was only about 4 feet long, or 1.2 meters. An eel can’t stick its head out of the water like Nessie is supposed to do, but it does sometimes swim on its side close to the water’s surface, which could result in sightings of a string of many humps undulating through the wate...
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    11 分
  • Episode 400: Four no wait Five Mysteries!
    2024/09/30
    To donate to help victims of Hurricane Helena: Day One Relief - direct donation link World Central Kitchen - direct donation link It's the big 400th episode! Let's have a good old-fashioned mystery episode! Thanks to Richard from NC for suggesting two of our animal mysteries today. Further reading: A 150-Year-Old Weird Ancient Animal Mystery, Solved The Enigmatic Cinnamon Bird: A Mythical Tale of Spice and Splendor First ever photograph of rare bird species New Britain Goshawk Scientists stumbled onto toothy deep-sea "top predator," and named it after elite sumo wrestlers Bryde's whales produce Biotwang calls, which occur seasonally in long-term acoustic recordings from the central and western Pacific A stylophoran [drawing by Haplochromis - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=10946202]: A cinnamon flycatcher, looking adorable [photo by By https://www.flickr.com/photos/neilorlandodiazmartinez/ - https://www.flickr.com/photos/neilorlandodiazmartinez/9728856384, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=30338634]: The rediscovered New Britain goshawk, and the first photo ever taken of it, by Tom Vieras: The mystery fish photo: The yokozuna slickhead fish: The Biotwang maker, Bryde's whale: Show transcript: Welcome to Strange Animals Podcast. I’m your host, Kate Shaw. We’ve made it to the big episode 400, and also to the end of September. That means monster month is coming up fast! To celebrate our 400th episode and the start of monster month, let’s have a good old-fashioned mysteries episode. We’ll start with an ancient animal called a stylophoran, which first appears in the fossil record around 500 million years ago. It disappears from the fossil record around 300 million years ago, so it persisted for a long time before going extinct. But until recently, no one knew what the stylophoran looked like when it was alive, and what it could possibly be related to. It was just too weird. That’s an issue with ancient fossils, especially ones from the Cambrian period. We talked about the Cambrian explosion in episode 69, which was when tiny marine life forms began to evolve into much larger, more elaborate animals as new ecological niches became available. In the fossil record it looks like it happened practically overnight, which is why it’s called the Cambrian explosion, but it took millions of years. Many of the animals that evolved 500 million years ago look very different from all animals alive today, as organisms evolved body plans and appendages that weren’t passed down to descendants. As for stylophorans, the first fossils were discovered about 150 years ago. They’re tiny animals, only millimeters long, and over 100 species have been identified so far. The body is flattened and shaped sort of like a rectangle, but two of the rectangle’s corners actually extend up into little points, and growing from those two points are what look like two appendages. From the other side of the rectangle, the long flat side, is another appendage that looks like a tail. The tail has plates on it and blunt spikes that stick up, while the other two appendages look like they might be flexible like starfish arms. Naturally, the first scientists to examine a stylophoran decided the tail was a tail and the flexible appendages were arm-like structures that helped it move around and find food. But half a billion years ago, there were no animals with tails. Tails developed much later, and are mainly a trait of vertebrates. That led to some scientists questioning whether the stylophoran was an early precursor of vertebrates, or animals with some form of spinal cord. The spikes growing from the top of the tail actually look a little bit like primitive vertebrae, made of calcite plates. That led to the calcichordate hypothesis that suggested stylophorans gave rise to vertebrates. Then, in 2014,
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    21 分