Strange Animals Podcast

Further reading:

New species of extinct vampire-squid-like cephalopod

When teeth grow on the body

Fossil shark turns into mystery pterosaur

Scientists Had Never Seen This Elusive Whale Alive—Until Now

Show transcript:

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

This month I wasn’t sure what to cover in this episode, so I decided to just click on four random bookmarks of scientific articles that I’ve had waiting for attention, and we’ll discuss them. We haven’t done a four articles episode in a long time!

The first article is from March 2022, and it’s about the discovery of an ancient cephalopod. Cephalopods include octopuses and squid. Octopuses famously have eight arms, while squid have eight arms and two feeding tentacles. Despite its name, the deep-sea vampire squid is actually more closely related to octopuses than to squid, and a newly discovered fossil is an ancestor to both.

The fossil is 328 million years old and was discovered in Montana, in the United States, in 1988 but was only studied recently. Fossils of soft-bodied animals are incredibly rare, and this one is remarkably well-preserved. All of the animal’s arms are preserved, including the suckers, but instead of eight arms, it had ten.

Scientists have long suspected that the ancestors of modern octopuses and vampire squid had ten arms. The vampire squid has eight arms and two feeding filaments that are vestigial arms. But this is the first fossil found that shows ten arms.

The fossil is of an animal with a torpedo-like body shaped like a modern squid. Two of its arms appear to be elongated compared to its other arms. It’s about 4 and a half inches long including its arms, or 12 cm. That’s pretty much all we know about it now, but hopefully the fossil will reveal more information as it continues to be studied.

Our next article is from October 2017 and is intriguingly titled “When teeth grow on the body.” It sounds horrific, but it’s actually a study of certain catfish that grow bony plates with tiny teeth on their bodies as defense.

Catfish don’t have scales, but some species of denticulate catfish that live in South America grow bony plates that act like armor. Many of these plates are covered in thin little teeth–actual teeth, including enamel and dentin, with pulp inside. They’re called extra-oral teeth, dermal denticles, or odontodes, and the study determined that they appeared about 120 million years ago in ancient catfish that hadn’t yet evolved the bony plates. The teeth regrow when they’re lost, and in some species, males grow larger teeth than females and use them to fight other males. Imagine biting someone without needing to open your mouth.

Our next article is from November 2020, about more fossils. The fossils were discovered in a collection at the Sedgwick Museum of Cambridge and the Booth Museum at Brighton in England, and were originally found in the latter half of the 19th century by miners. A PhD student at the University of Portsmouth was studying fossilized shark spines from the collection when he realized they weren’t actually shark spines. Instead, they were jaw fragments from pterosaurs.

Pterosaurs were flying reptiles that filled many ecological niches that birds fill today. One of the species identified from the collection is called Ornithostoma, which means bird mouth, an animal that lived in the early Cretaceous, about 110 million years ago, in what is now Europe. We know very little about it except that it didn’t have teeth, but it probably ate fish.

But there were some other jaw fragments that didn’t belong to Ornithostoma, and in fact don’t match up to any known pterosaur jaws. It may belong to a new species, but the fossils are so fragmentary that there’s no way to know for sure. The rocks that the fossils came from were completely destroyed more than a century ago during phosphate mining, so unless more fragments are found in other collections, we may never learn more about this mystery pterosaur.

Our last article is from July 2022, and I have no idea why I haven’t talked about it on the podcast before now. It’s about Sato’s beaked whale, also called kurotsuchi. It’s a type of four-toothed whale with a short beak, and it’s dark gray and can grow up to 23 feet long, or 7 meters. It was only identified in 2016 as being different from the two other known species of four-toothed whales, after careful analysis, including DNA analysis, of dead individuals that had been found washed ashore.

Until the summer of 2021, no one had ever seen a living Sato’s beaked whale. Then some researchers studying orcas spotted 14 of the beaked whales swimming together between Hokkaido, Japan and the Kuril Islands. The scientists recognized that these were unusual whales and they were able to get a small skin sample from one. Genetic testing confirmed that they were indeed Sato’s beaked whales.

Researchers think the whales may spend at least part of the year in tropical waters, since that’s where cookie cutter sharks live and the whales show circular bite scars from cookie cutter sharks. Not much is known about most species of beaked whale, and Sato’s beaked whale is especially mysterious. But at least we know it’s alive and well right now.

Thanks for your support, and thanks for listening!

Yes, this is a NEW episode! Thanks to Eesa, Grace, and Viki for their suggestions this week. (Actual episode starts at 3 minutes 28 seconds.)

Find the Backerkit campaign here!

Further reading:

Nix Illlustration: Esconichthys

The southern hognose snake [picture by Caudatejake – Own work, CC BY-SA 4.0]:

A beach wolf spider [photo by Memer15151 – Own work, CC BY-SA 4.0]:

Oviraptor may have looked kind of like this when alive [art by PaleoNeolitic – Own work, CC BY 4.0]:

Two halves of an esconichthys fossil:

Show transcript:

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

Oh, hi! This is a brand new episode, earlier than I expected! I noticed recently that one of the Patreon episodes I’d scheduled for September is one that I’d already run in the main feed a few years ago. I decided to just make a new episode for this week and move the episode that would have run this week to that September slot, because I have an announcement!

For our five-year anniversary I published the book Beyond Bigfoot & Nessie: Lesser-Known Mystery Animals from Around the World, with a lot of the entries taken from episodes but also some new topics added. I always intended to do a follow-up for our ten-year anniversary, and have even done a lot of work on it. It’s called Small Mysteries, focusing on smaller mystery animals that don’t get a lot of attention. It’s about half the length of Beyond Bigfoot, all or almost all chapters taken from the podcast. But at this point, I don’t think I have time to finish it. I’m staying very busy and happy, with a part-time job taking care of people’s pets while they’re on vacation, and I’m also writing fiction again.

But since that book is half-done, and a lot of people might want a copy even if I don’t add much more to it, I’m going to make it available as an ebook only. Do you remember last time I made a crowdfunding campaign, and the people who backed the campaign got a copy of the book as soon as it was published? I’m doing that again, but NOT for Small Mysteries. It’s for a different book, called The Moonhound, a cozy fantasy set in an alternate reality Smoky Mountains. The main character is a rabbit who moves to the mountains and meets a possum, and they have adventures. Even if this doesn’t interest you, there’s a $1 backer tier and if you click that, you have the option to add the Small Mysteries ebook for $2. That means the book is $3. Does that make sense? I feel like it’s confusing.

The campaign starts on July 15, 2026 and runs through August 15, 2026. If you’re listening to the episode before July 15, 2026, you can click through the link in the show notes and follow the campaign, so that you get an email when it goes live. If it’s between July 15 and August 15, 2026, click the link in the show notes and there’s the campaign! If it’s after August 15, 2026, see if there’s a link in the show notes that will take you to a place where you can buy the ebook.

Okay, that took way too long, so let’s get to this week’s episode! We have some suggestions that have come in recently, so we’ll cover a few of those animals, and we’ll finish up with a small fossil mystery in honor of the book. Thanks to Eesa, Grace, and Viki for their suggestions! A quick shout-out to Remy and Julien, and Dylan, Emily, and Michelle for their suggestions too. I’ll get to those in the 500th episode that will run at the end of August.

We’ll start with Viki’s suggestion, the hognose snake. The name hognose is used for various species of snake, most of them in North and South America, but some in Madagascar. It’s a common snake in many parts of North America, so since we talked about the eastern hognose back in episode 81, let’s talk about the southern hognose in this episode. It’s found along the coastal plain of the southeastern United States, including parts of North and South Carolina, Georgia, and northern Florida, and because it has a restricted range where people like to live too, it’s vulnerable to habitat loss. It used to live in other states too but its range has shrunk considerably since it was first described in 1766.

The southern hognose grows about two feet long, or 61 cm, and like other hognose snakes, its nose turns up like a little pig’s snout. The shape of its nose actually may help it dig into leaf litter and dirt to hide. Some individuals are brown or gray, some are red or yellowish. It has darker blotches on its upper side and adults have white bellies. It has a big head that makes some people believe it’s venomous, but it’s actually harmless to humans and most animals.

The only animals that really need to worry about the hognose are amphibians, like toads, frogs, and salamanders, although it will also eat lizards, small mammals like mice, and even large insects. It especially likes to eat toads, and while some toads are toxic, the hognose snake is resistant to toad toxins. A toad will frequently puff itself up to make it appear larger and make it hard for a snake to swallow, but the hognose has a solution for that too. It has big teeth at the rear of its upper jaws, like fangs in the back of its mouth. It uses those teeth to puncture puffed-up toads so they deflate, just like a horrible balloon.

But the most memorable thing about the hognose is what it does when it feels threatened. Phase one is aggression. The snake will flatten its neck to look more threatening, raise its head like a cobra, and hiss and strike—but without biting. It’s just trying to scare you away. If that doesn’t work, the snake puts phase two into effect. It will flop down and roll onto its back like it’s dead, its tongue hanging out of its mouth. It even emits a foul musky smell from its cloaca. If you call its bluff and roll drama queen snake onto its belly, it will turn onto its back again, because it’s really insistent that it’s dead.

Since we’ve already scared away a lot of people who don’t like snakes, let’s learn about a spider next. Grace suggested we talk about the wolf spider, and also wonders if wolf spiders live in northern California.

Wolf spiders are common throughout the world, and while they look scary, they bite people very rarely and their venom is weak, no worse than a bee sting. The wolf spider with the biggest legspan is Hogna ingens, with a legspan less than 5 inches across, or 12 cm. It lives on one island in the Maderia archipelago, and is a beautiful soft gray with white stripes on the legs. The Carolina wolf spider is the most common one found in North America. A big female can have a legspan of four inches, or 10 cm, but its body is not much more than an inch long, or 35 mm, and the spider actually weighs less than an ounce. That’s barely 28 grams, or just a little heavier than five sheets of printer paper.

The wolf spider is a hunting spider, mostly solitary, and most species don’t spin webs. When a female lays her eggs, she attaches the egg case to the underside of her abdomen so she can take them with her while she hunts insects. When the eggs hatch, the teensy babies ride around on the top of her abdomen for a few weeks until they’re big enough to not need their mother’s protection.

Some species of wolf spider will dig a burrow to rest in, and will jump out and grab any insect that happens by, while other species of wolf spider rest in rock crevices and other small spaces. Males are smaller than females and often have flashier patterns. The Carolina wolf spider is mainly gray or brown with darker and lighter longitudinal stripes down the head and body.

Most species of wolf spider won’t come into your house, but if you do have a wolf spider in your house, you should actually consider yourself lucky. They love to eat cockroaches and ants, which are house pests. The wolf spider hunts mostly by sight and has good vision, and its eyes will even demonstrate eyeshine of various colors, depending on species, if you shine a flashlight around in the dark. Maybe don’t do that if you’re afraid of spiders.

And yes, there are wolf spiders in northern California, because there are wolf spiders in just about every part of the world except for Antarctica! Northern California actually has at least six species of wolf spider. One species does actually build a web, and there’s even a species that lives on the beach. That’s the beach wolf spider, which is a pale sandy color with darker and lighter stripes to help it blend in with sand and pebbles. It’s quite small but it moves really fast, and it’s mostly nocturnal. It lives not just in northern California but throughout beaches in North and Central America.

Next, Eesa sent a list of suggested animals, including oviraptor. I could have sworn we already covered oviraptor, but we haven’t! It’s a really interesting dinosaur, so let’s take a look now.

Oviraptor is a name that means “egg thief,” and it got this name because it was found near fossilized eggs. It lived in what is now Asia about 75 million years ago, and the first specimen was found in Mongolia (still my favorite country) back in 1923. The partial specimen was found lying across a nest of dinosaur eggs. When the dinosaur was described in 1924, it was given the name egg thief because the paleontologist Henry Fairfield Osborn assumed it died while robbing a nest to eat the eggs.

But even Osborn wrote that he might be wrong about the dinosaur, and in the 1990s new discoveries of oviraptor nesting sites proved this was the case. Oviraptor wasn’t stealing eggs, it was protecting them, because they were its own eggs. It probably actually ate fruit, seeds, and other plant material, along with small animals like lizards.

Oviraptor was a small dinosaur that was a little more than six feet long, or about 2 meters, and was the height of a medium to large dog. It walked on its hind legs. It had feathers on its arms and tail, and probably also had feathers over much of its body. It didn’t have teeth but it did have a beak that would have probablylooked a lot like a parrot’s beak. Its arms had three small claws but probably looked a lot like a wing in many ways, although scientists don’t think oviraptor could fly.

In other words, oviraptor probably looked a lot like a big, weird chicken, and like a chicken and many other birds, scientists think it sat on its eggs to keep them warm.

When a bird incubates its eggs, it’s not like you dropping down to sit on a chair. The bird’s feet are typically on either side of the eggs, and the bird squats down carefully so that its underside makes gentle contact with the eggs without crushing them. Female chickens and many other birds have a spot on the lower breast that doesn’t have any feathers, called a brood patch, which contains extra blood vessels just under the skin. This helps keep the eggs warm and is a soft part of the hen’s body, which helps cushion the eggs. We don’t know, but it’s possible oviraptor had something similar to a brood patch, and its feathered arms and tail also helped protect the eggs from cold air and rain. We now have numerous specimens that died while sitting on nests, probably buried in sandstorms, so we know that oviraptor basically brooded its nest the way modern birds do.

Finally, let’s finish with our small mystery fossil. It’s called Esconichthys apopyris and it lived about 308 million years ago in what is now the state of Illinois in North America. 308 million years ago, Illinois was a tropical area and partly covered by a warm, shallow sea. In a particular place known as the Mazon Creek formation, for a few million years conditions were just right to preserve dead animals and plants in astounding detail. A river carried dead plant materials and mud into an estuary along the ocean’s edge, where it sank and settled to the bottom of the sea floor. When an animal died, if it wasn’t eaten by something else, its body sank into this soft muddy mess. The bacteria in the mud produced carbon dioxide that combined with iron also present in the mud, which formed a mineral called siderite. This mineral encased the dead animal and slowed decay long enough for a detailed impression of the body to form in the mud. As the centuries passed and the mud became stone, the fossilized body impression was surrounded by a protective ironstone nodule. That’s why we know about the soft-bodied animals from the area, even though soft-bodied animals rarely leave fossil evidence.

Mazon Creek is where the Tully monster lived, which we talked about in episode 339, but the Tully monster isn’t the only mystery animal discovered there. Another one was Esconichthys.

We have lots of Esconichthys fossils, partly because it seems to have been extremely common, but also because it was a vertebrate. That means it had a notochord, a type of backbone. Most of the fossils we have are body impressions, so we do know a lot about what Esconichthys looked like when it was alive. What we don’t know is what it actually was.

Esconichthys was named for the Earth Science Club of Northern Illinois, ESCONI, and the latter half of its name means fish. But it doesn’t actually seem to have been a fish, even a larval fish. It grew up to about 3 inches long, or 8 cm, and had a pair of very obvious eyes, two pairs of feathery external gills, and a single fin on the underside of its tail. It didn’t have legs or any other fins. Some individuals had wide-set eyes, others had eyes that are close together, which may indicate two separate species, but we don’t know.

Esconichthys fossils are sometimes referred to as ghosts, because the limbless body with two dots for eyes does kind of look like a cartoon ghost. Other people call Esconichthys fossils grasshoppers or blades. This is because the animal’s gills were quite long and are often preserved pointing away from the rest of the body, or sometimes the rear of the body is folded upward. This can make it look roughly like a grasshopper or a pocket knife with one blade unfolded.

Esconichthys has been proposed as a larval lungfish or a larval amphibian, but it doesn’t really match either animal group. It’s the most common fossil found at the Mazon Creek formation by far, preserved in amazing detail, but scientists still have no idea what it is or what it might be related to.

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s.

Thanks for listening!

Further reading:

Giant early whale Basilosaurus hunted the calves of other whales

Show transcript:

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

Let’s look at some extinct whale ancestors this month, basilosaurids.

We talked about the ancestors of whales in episode 72, about weird whales. After mosasaurs went extinct at the same time as the non-avian dinosaurs, 66 million years ago, basilosaurids evolved to fill the ecological niche they left. Mosasaurs were big marine reptiles while basilosaurids were big marine mammals, but in many ways basilosaurids looked more like mosasaurs than they did modern whales.

Basilosaurids differed from their ancestors in that they were fully aquatic. They didn’t come out of the water at all and probably couldn’t. They did still have hind legs, but they were tiny and scientists think the animal probably only used the legs to help stay in place while mating. The hind legs were really small in comparison to the body, only 14 inches long, or 35 cm, in a 52-foot specimen, or 16 meters. Tyrannosaurus rex would look at that and say, “you’ve got really small legs, bruh.” Its front legs were larger and more flipper-like, although it still had an elbow joint that modern whales have lost, although modern seals still have an elbow joint.

The reason Basilosaurids have a name that sounds an awful lot like a dinosaur name is because the person who described the first one scientifically thought it was a reptile. That was a man named Richard Harlan, an early paleontologist, who thought the fossils he was sent belonged to a marine reptile, possibly a mosasaur relation. In 1839 he named it Basilosaurus, which means “king lizard.” Then he took the fossils to another Richard, Richard Owen, who gave them a second look. Owen pointed out that the teeth didn’t look anything like reptile teeth and that the animal was probably some kind of whale. He and Harlan decided to rename the animal Zeuglodon, but it was too late! The first name was published, and Basilosaurus stayed king lizard despite not being a reptile. That didn’t stop many paleontologists from using Zeuglodon instead for quite a while, which has caused all kinds of confusion.

Fossils of that particular species are especially common in the southern United States, so common in some places that the fossilized vertebrae were sometimes used as house supports. We talked about Basilosaurus in the paleontological frauds episode, because bones from six different basilosaurs formed the fake sea serpent skeleton exhibited around the United States and Europe in 1845.

Basilosaurus did look a little bit like a sea serpent in that it was very long and relatively slender, and its body wasn’t rigid like a modern whale’s. It grew up to 66 feet long, or 20 meters, and probably longer, and is sometimes described as eel-like. It probably had small flukes at the end of the tail, but it didn’t swim like a modern whale. Its vertebrae were large, hollow, and filled with fluid. This made Basilosaurus buoyant but probably also meant it had trouble diving very deeply.

There are only two species in the genus Basilosaurus, although there are lots of other Basilosaurids in other genera. The other Basilosaurus was slightly smaller and is most well known from an incredible bone bed in Egypt called Wadi al Hitan.

Around 35 million years ago, Wadi al Hitan was a shallow coastal area full of life. It wouldn’t have looked all that weird to us at first glance, because a lot of the animals and plants that lived there were early relations of the ones that are still around today. These included sea cows that ate marine plants, various crocodilians, sea turtles, sea snakes, lots of birds, including pelicans, and lots of fish, including sawfish, sharks, and rays. There was even a kind of elephant living along the coast of this warm, shallow sea, Moeritherium, which probably looked more like a hippo or tapir than an elephant.

There were also whales, specifically a type of dolphin-like animal called Dorudon. Dorudon was also a basilosaurid, but it only grew about 16 feet long, or 5 meters. It ate fish and other small animals and probably looked a lot like a miniature Basilosaurus—in fact, it was initially thought to be a juvenile Basilosaurus when it was first discovered. Dorudon may actually be a direct ancestor of modern whales, although we don’t know for sure.

Paleontologists think Dorudon used Wadi al Hitan as a calving ground. About half of the Dorudon fossils found there are of calves. But there are also fossils of Basilosaurus, and it was there to hunt.

In 2016, a complete skeleton of a Basilosaurus was discovered at Wadi al Hitan. Complete skeletons are incredibly rare in the fossil record, and this one was beautifully preserved. It even had the remains of its last meals preserved in the space that had once been its stomach, the first time preserved stomach contents had ever been found associated with a basilosaurus. Paleontologists knew Basilosaurus was a meat-eater because of its teeth, but they assumed it probably mostly ate fish. There were remains of a big fish in the stomach, but there were also remains of two young Dorudons. The remains are in pieces with bite marks on the skulls, which suggests that basilosaurus hunted like orcas do, where they bite the skulls of humpback whale calves.

Basilosaurids had small brains compared to modern whales and didn’t have the adaptations that would indicate it could echolocate. However, it did have a slightly asymmetrical skull, which is something needed for echolocation. Researchers think this was the first adaptation that later led to echolocation, and it probably helped the animal hear better underwater.

Finally, one important thing. If a big basilosaurus fought a megalodon shark, who would win? The answer is, this would never happen because megalodon didn’t evolve until 23 million years ago while basilosaurids all died out by about 33 million years ago. Sorry, I’m no fun. Also, megalodon would have won because megalodon was a better swimmer.

Thanks for your support, and thanks for listening!

Further reading:

http://messybeast.com/genetics/hybrid-equines.htm

Show transcript:

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

I stumbled across an interesting mystery animal recently and thought it would make a great topic for a Patreon episode. It’s supposed to be a hybrid animal, but as we’ll soon learn, it can’t possibly be what it’s said to be.

The animal is called a jumar or jumart, or sometimes a kumrah. The oldest record of a jumar dates to 1546 but there are many other accounts up to the beginning of the 20th century. The jumar is supposed to be the hybrid offspring of a horse and a cow, usually a bull and a mare. Sometimes it was supposed to be the offspring of a bull and a donkey mare.

Whatever its supposed origins, the jumar was said to look like a horse except for cow-like hindquarters and head, although with no horns. The hooves were usually solid like a horse’s hooves but occasionally cloven. A jumar was supposed to be stronger but smaller than an ordinary mule, which is a cross between a horse and a donkey.

There are plenty of reports of jumars, including individuals examined by naturalists, so it’s obviously a real animal. Could it really be a horse-cow hybrid? How closely related are horses and cows, anyway?

Not closely related AT ALL. The horse is almost as closely related to whales as it is to cows. They belong to totally different orders, and if you remember from the hybrids episode, it’s unusual for a hybrid to result from animals that share a genus, but extremely rare for animals that only share a family. Order is a step above family. There is literally no way that a horse and a cow could crossbreed successfully, but if somehow they did, the baby would not survive long enough to be born.

So the jumar can’t be a horse-cow hybrid, but at the same time, the jumar was a real animal. So what was it?

The first hint of a solution came from a French naturalist who lived in the 18th century. He wrote in 1771 about two dead jumars he bought and dissected. Both of them turned out to be ordinary mules. Specifically, they were hinnies, which are the offspring of a female donkey and a male horse. Most mules are offspring of a male donkey and a female horse.

Part of the reason that the hinny is a less common hybrid is because of the differences in chromosomes between horses and donkeys. Horses have 64 chromosomes, donkeys have 62. Mules and hinnies have 63 and are almost always sterile. In the case of a pair of animals with mismatched chromosomes, a baby is more likely to result when the father has the lower chromosome count, as is the case with the male donkey. A male horse has more chromosomes than a female donkey, so it’s less likely that a baby will result. Hinnies are almost always smaller than horses or mules because the mother donkey is a smaller animal than the mother horse.

Like any other animal, mules are sometimes born with genetic issues that may affect their appearance. One relatively common issue is a type of dwarfism that can affect certain bones in the body, which makes the animal’s conformation look different from an ordinary mule’s. A disorder called chondrodysplasia, which can have a number of different causes, results in the upper portion of the animal’s skull being underdeveloped. This means its face appears dished like a cow’s face, its upper jaw may be much shorter than its lower jaw, and its eye sockets and forehead may look more cow-like too.

It’s most likely, then, that jumars are just horses, mules, or hinnies with a genetic abnormality. That would also explain why no one talks about jumars anymore. These days if a weird-looking foal is born, the owner calls the vet, who recognizes a genetic issue right away. In the olden days people didn’t know what caused genetic issues and assumed it had something to do with parentage. If a mare had a baby that looked a little bit like a cow in some ways, that must be because its father was a bull.

If you remember the Patreon episode we had a long time ago about horses with extra hooves on one or more feet, it’s probable that this is the trait leading to reports of jumars with cloven hooves. We even have one account from 1830 by a veterinarian who examined a jumar who had three legs with ordinary horse hooves but one leg with a cloven hoof that looked like a cow’s.

That’s pretty much it for the jumar, but a quick reminder as we finish talking about hybrid horses and donkeys, if you cross a zebra with a donkey, the resulting offspring has stripes and is called a zedonk, my favorite word.

Thanks for your support, and thanks for listening!

Further reading:

Faceless Fish and the deep-sea voyages that found it

Long-Lost ‘Faceless’ Fish Shows Up Near Australia

Ipnops:

The faceless cusk [photo taken from the second article linked above]:

A tripod fish:

Show transcript:

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

It’s a fish episode! These are also deep-sea fish, and you know how much I love deep-sea animals.

Let’s talk first about some fish in the family Ipnopidae, including one deep-sea fish with the pleasing name of Ipnops. We know of three species of ipnops so far, but there may be more that scientists just haven’t found yet. Some scientists think there’s actually only one species, since all three species look almost identical but just live in different parts of the deep sea.

Ipnops is sometimes called the grideye spiderfish. If you don’t know what it looks like, you may think the word spider in its name is the weird part. It’s not, and in fact I’m not sure where that comes from. It could be that the fish’s transparent fins look kind of like spiderwebs. Other fish in its family are called spiderfish too but are also sometimes called lizardfish. It feels like someone was in a goofy mood when naming these fish and just started saying random animal names.

Ipnops only grows a little over 6 inches long at most, or 16 cm. It’s slender for its size, although its head is wider than its body. Its head is black but the color fades on the body until the tail is light gray.

No, the weird thing about ipnops is its eyes. It doesn’t precisely have eyes, certainly not eyeballs. Instead it just has a thin layer of retinal cells spread across a divot in the top of its head, also called a photosensitive membrane or plate. These plates show up as yellow against the black head. Researchers think the fish can’t see the way we think of seeing, but it can probably sense bioluminescent light. Since it lives at the bottom of the deep sea where little to no light penetrates from the surface, it makes sense that ipnops doesn’t really need eyes.

We still don’t know very much about ipnops or most of its relatives. It eats small crustaceans and all individuals produce both eggs and sperm. Ipnops eggs hatch into tiny larval fish that live near the surface of the ocean and have extremely large ordinary eyeballs. How these eyeballs transform into a retinal membrane is a mystery known only to ipnops.

The family that ipnops belongs to, Ipnopidae, includes many species that are called tripod fish, and tripod fish are very weird too even though they have regular eyeballs, usually tiny ones. There are quite a few tripodfish known, many of them only discovered recently by deep-sea rovers. Most are no larger than ipnops, but some have fins that are much longer than their body.

This is the case for the tripod spiderfish—look, it’s another spiderfish—that lives at the bottom of the deep sea in many parts of the world. It’s been found at a depth of almost 3 miles, or 4,700 meters, which is so deep that it’s also sometimes called the abyssal spiderfish, although that’s also a name given to a different type of tripod fish that’s closely related. It’s big compared to many of its close relations, up to 17 inches long, or 43 cm, but its fins can grow over a yard long, or about a meter. Its tail and pelvic fins have elongated rays that allow it to stand on the bottom of the ocean, and since the bottom of the ocean is usually pretty oozy and muddy, it needs the fins to be really long so it doesn’t end up sinking into the ooze. It also has little pads on the end of the fins that help keep it from sinking. Scientists think the struts that lengthen the rays can be stiffened so that the fish can stand on them for long periods of time, but when the fish needs to swim, it can loosen the struts so they’re flexible.

If you’re not familiar with the word tripod, it means ‘three feet’ or ‘three legs.’ You’ve probably seen one before because that’s the thing that people use to prop up a camera. A camera tripod has three long legs that you can adjust so that your camera sits at just the right height to take good pictures, and it’s sturdy so the camera won’t shake. This is exactly how the tripodfish uses its elongated fins except that it’s not taking pictures. It’s just trying to find food. It stands motionless facing into the current, and spreads its pectoral fins out. It can’t see in the darkness of its deep-sea home, but it feels small fish or crustaceans that come near and stumble into its fins. It uses the pectoral fins to guide the animal toward its mouth, and then it goes chomp with its needle-like teeth.

Like ipnops, the tripodfish produces both eggs and sperm and can fertilize its own eggs if it can’t find a mate. This is important in the deep sea, especially when your main way of finding food is standing completely still for very long periods of time.

Another weird fish isn’t related to the family Ipnopidae. It’s called the faceless cusk or faceless cusk-eel, because its body is shaped sort of like an eel’s. Like ipnops, its body is slender but its head is larger, and in fact quite a lot larger in the case of the faceless cusk. Its head is rounded and bulbous, and the fish looks at first glance like it doesn’t have any of the ordinary sensory organs we expect to find on a face, except for nostrils.

The faceless cusk’s mouth is tiny and is on the underside of its head, with the head actually drooping down so that it hides the mouth. It has eyes, but they’re covered in skin and only visible in small individuals. It has a pale body but black fins and it can grow more than 18 inches long, or over 46 cm.

The faceless cusk is a deep-sea fish and was discovered in 1874. This was when the HMS Challenger expedition brought one up in its dredging nets from a depth of about two and a half miles down, or over 4 km. After that it wasn’t seen again until 1951, when a different scientific expedition collected five individuals.

In 2017, yet another scientific expedition, this one off the eastern coast of Australia, found a weird-looking fish that looked like it didn’t have a proper face. The scientists could tell it was a type of cusk-eel, but not one they’d ever heard of. It wasn’t until one of the expedition members was flipping through an old book about the Challenger expedition that they realized this fish was already known to science.

We know almost nothing about the faceless cusk. We don’t even know what it eats or how it finds its food. It lives near the bottom of the sea where the water is barely above freezing temperature.

The deepest-living fish ever discovered is a different species of cusk-eel. It’s been found living in the Puerto Rico Trench over 5 miles below the ocean’s surface, or 8 km. It’s called Abyssobrotula galatheae and it typically only grows about 6 inches long, or 15 cm. It resembles the faceless cusk in many ways even though they belong to different genera. It has tiny eyes that are covered with skin and probably don’t function, its mouth is also tiny and is underneath its head, and its head is oversized compared to its slender body and droops to hide the mouth. It’s mostly yellowish in color.

We know a little more about Abyssobrotula than we do the faceless cusk. It eats polychaete worms along with small crustaceans, which it finds on the ocean floor. Even though its mouth is quite small, it has lots of pointy teeth that help keep its prey from escaping once it bites down. Because the faceless cusk is so similar, it’s probable that it eats the same type of food.

The great thing about the fish we’ve talked about today is that they’re not especially spectacular. They’re just regular fish doing regular fish things, they just happen to be adapted to the deep sea. Because the deep sea is such an extreme environment in many ways, the fish evolve to look and act very different from the fish we’re used to seeing. If we lived in the deep sea ourselves, we’d probably look at a trout and think it was the weirdest fish we’d ever seen.

Thanks for your support, and thanks for listening!