Category Archives: fish

Episode 155: Extreme Sexual Dimorphism

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Many animals have differences between males and females, but some species have EXTREME differences!

The elephant seal male and female are very different sizes:

The huia female (bottom) had a beak very different from the male (top):

The eclectus parrot male (left) looks totally different from the female (right):

The triplewart seadevil, an anglerfish. On the drawing, you can see the male labeled in very small letters:

The female argonaut, also called the paper nautilus, makes a delicate see-through shell:

The male argonaut has no shell and is much smaller than the female (photo by Ryo Minemizu):

Lamprologus callipterus males are much larger than females:

The female green spoonworm. Male not pictured because he’s only a few millimeters long:

Show transcript:

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

I still have a lot of listener suggestions to get to, and don’t worry, I’ve got them all on the list. But I have other topics I want to cover first, like this week’s subject of extreme sexual dimorphism!

Sexual dimorphism is when the male of a species looks much different from the female. Not all animals show sexual dimorphism and most that do have relatively small differences. A lot of male birds are more brightly colored than females, for instance. The peacock is probably the most spectacular example, with the males having a brightly colored, iridescent fan of a tail to show off for the hens, which are mostly brown and gray, although they do have iridescent green neck feathers too.

But eclectus parrot males and females don’t even look like the same bird. The male is mostly green while the female is mostly red and purple. In fact, the first scientists to see them thought they were different species.

Males of some species are larger than females, while females of some species are larger than males. In the case of the elephant seal, the males are much larger than females. We talked about the northern elephant seal briefly last week, but only how big the male is. A male southern elephant seal can grow up to 20 feet long, or 6 meters, and can weigh up to 8,800 pounds, or 4,000 kg. The female usually only grows to about half that length and weight. The difference in this case is because males are fiercely territorial and fight each other, so a big male has an advantage over other males and reproduces more often. But the female doesn’t fight, so her smaller size means she doesn’t need to eat as much.

Another major size difference happens in spiders, but in this case the female is far larger than the male in many species. For instance, the body of the female western black widow spider, which lives throughout western North America, is about half an inch in length, or 16 mm, although of course that doesn’t count the legs. But the male is only half this length at most. Not only that, the male is skinny where the female has a large rounded abdomen, and the male is brown with pale markings, while the female is glossy black with a red hourglass marking on her abdomen. Female western widows can be dangerous since their venom is strong enough to kill many animals, although usually their bite is only painful and not deadly to humans and other mammals. But while the male does have venom, he can only inject a tiny amount with a bite so isn’t considered very dangerous in comparison.

The reason many male spiders are so much smaller than females is that the females of some species of spider will eat the male after or even during mating if she’s hungry. The smaller the male is, the less of a meal he would be and the less likely the female will bother to eat him. In the case of the western black widow, the male prefers to mate with females who are in good condition. In other words, he doesn’t want to spend time with a hungry female.

If you remember episode 139, about skunks and other stinky animals, we talked about the woodhoopoe and mentioned the bill differences between males and females. The male woodhoopoe has a longer, more curved bill than the female because males and females eat a slightly different diet of insects so they won’t compete for the same food sources.

But a bird called the huia took beak differences to the extreme. The huia lived in New Zealand, although it officially went extinct in 1907. It was a wattlebird, which gets its name from the brightly colored patch of skin on either side of the face, called wattles. In the case of the huia, the wattles were orange, while the feathers over most of the body were glossy black. It also had a strip of white at the tip of the long tail. The male’s beak was fairly long and pointy, although it also curved down slightly. But the female’s beak was much longer and more slender, curving downward in an arc.

The huia lived in forests in New Zealand, where it ate insects, especially beetle grubs that live in rotting logs. People used to think that a mated pair worked together to get at grubs and other insects. The male would use his shorter, stouter bill to break away pieces of rotting wood until the grub’s tunnel was exposed, and then the female would use her longer, more slender bill to fish the grub out of the tunnel. But actual observations of the huia before it went extinct indicate that it actually didn’t do this. Like the woodhoopoe, males and females preyed on different kinds of insects. The male did break open rotting wood with its beak in a way that’s very different from woodpeckers, though. Instead of hammering at the wood, it would wedge its bill into a crevice of the wood and open its beak, and the muscles and other structures it used to do so were so strong that it could easily break pieces of wood off. This action is known as gaping and other birds do it too, but the huia was probably better at it than any other bird known.

The huia went extinct partly due to habitat loss as European settlers cleared forests to make way for farming, and partly due to overhunting. Museums wanted stuffed huias for display, and the feathers were in demand to decorate hats. And as a result, we don’t have any huias left.

Sometimes the size difference between males and females reaches extreme proportions. We’ve talked about the anglerfish several times in different episodes, and it’s a good example. It’s a deep-sea fish with a bioluminescent lure on its head that it uses to attract prey. Different species grow to different sizes, but let’s just talk about one this time, the triplewart seadevil.

The triplewart seadevil is found throughout much of the world’s oceans, preferably in medium deep water but sometimes in shallow water and sometimes as deep as 13,000 feet, or 4000 meters. The female grows to about a foot long, or 30 cm. It’s black in color, although young fish are brown. Its body is covered with short spines and it has a lure on its head like other anglerfish. The lure is called an illicium, and it’s a highly modified dorsal spine that the fish can move around, including extending and retracting it. At the end of the illicium is a little bulb that contains bioluminescent bacteria. Whatever animals are attracted to the glowing illicium, the fish gulps down with its great big mouth.

But that’s the female triplewart seadevil. The male is tiny, only 30 mm long at the most. The male doesn’t have an illicium; instead, his jaws and teeth are specialized for one thing: to bite onto the female and never let go. When a male finds a female, he chooses a spot on her underside to latch on, and once he does, his mouth and one side of his body actually fuse to the female’s body. Their circulatory and digestive systems fuse too. Before the male finds a female, he has great big eyes, but once he fuses with a female his eyes degenerate because he no longer needs them. He’s fully dependent on the female, and in return she always has a male around to fertilize her eggs. But this attachment is actually pretty rare, because it’s hard for deep-sea fish to find each other.

Another sea creature where the females are much larger and very different from the males is the argonaut, or paper nautilus. The argonaut is an octopus that lives in the open ocean in tropical and subtropical waters. Instead of living on the bottom of the ocean, though, the paper nautilus lives near the surface, and while the female looks superficially similar to a nautilus, it’s only distantly related.

The female argonaut generally grows to about 4 inches long, or 10 cm, although the shell she makes can be up to a foot across, or 30 cm. In contrast, males are barely half an inch long, or 13 mm. The female’s eight arms are long because she uses them to catch prey, with two of her arms being larger than the others. She grabs small animals like sea slugs, crustaceans, and small fish and bites it with her beak, and like other octopuses she can inject venom at that point too. But the male has tiny little short arms except for one, which is slightly larger.

Like other cephalopods, the male uses one of his arms to transfer sperm to the female so she can fertilize her eggs. In most cephalopods that means an actual little packet of sperm that the male places inside the female’s mantle for her to use later. But in the argonaut, the male’s larger modified arm is called a hectocotylus, and it has little grooves that hold sperm. The male inserts the hectocotylus into the female’s mantle, then detaches it and leaves the arm inside her. Then he leaves and regrows the arm, as far as researchers know. We don’t actually know for sure since it’s never been observed, but octopuses do have the ability to regenerate lost arms. The female usually keeps the hectocotylus and sometimes ends up with several.

At that point the female creates a shell by secreting calcite from the tips of her two larger arms. The shell is delicate, papery, and white, and it resembles the shell of the ammonite, which we talked about in episode 86. The female lays her eggs inside the shell, then squeezes inside too, although she can come and go as she likes.

There’s still a lot we don’t know about the argonaut, but we know more than we used to. In the olden days people thought the female used her two larger arms as sails at the surface of the water. Eventually scientists figured out that was wrong, but they were still confused as to why there only seemed to be female argonauts. They didn’t know that the males were so small and so different, and in fact when early researchers found hectocotyluses inside the females, they assumed they were parasitic worms of some kind. Eventually they worked that part out too.

But still, for a very long time researchers thought the argonaut’s shell was just for protecting the eggs, but it turns out that the female uses the shell as a flotation device. She can control how much air the shell contains, which allows her to control how close to the surface she stays. In a 2010 study of argonauts rescued from fishing nets and released into a harbor, if the shell doesn’t contain enough air, the argonaut will jet to the surface and stick the top of its shell above the water. The shell has small openings at this point so air can get in, and once the argonaut decides it’s enough, she seals the holes by covering them with two of her arms. Then she jets downward again until she’s deep enough below the surface that the pressure compresses the air inside the shell and cancels out the weight of the shell. This means the argonaut won’t bob to the surface but she also won’t sink, and instead she can just swim normally by shooting water from her funnel like other octopuses.

A species of cichlid fish from Lake Tanganyika in Africa, Lamprologus callipterus, also differs in size due to a shell, but not like the argonaut. Instead, the male is much larger than the female. The male can be up to five inches long, or nearly 13 cm, while the female is less than two inches long, or 4 ½ cm. The females lay their eggs in shells, but not shells they make. The shells come from snails, so the male needs to be larger so he can pick up and carry a big empty shell. The female, though, still needs to be small enough to fit inside the shell.

A moth called the rusty tussock moth is also sexually dimorphic. Its caterpillar grows around 1 to 1.5 inches long, or 3 to 4 cm, with females being a little larger than male caterpillars but otherwise very similar. But after the caterpillars pupate, they’re much different. The male moth has orangey or reddish-brown wings and a wingspan of about 1.5 inches, or almost 4 cm. The female doesn’t have wings at all. She emerges from her cocoon and perches next to it, and releases pheromones that attract a male. After the female mates, she lays her eggs on her old cocoon and dies, as does the male.

Let’s finish up with an animal you may never have heard of, the green spoonworm. It’s a marine worm that lives throughout much of the Mediterranean and the northeastern Atlantic Ocean. It lives on the sea floor in shallow water, partly buried in gravel and sand. The female grows up to about six inches long, or 15 cm, and sort of looks like a mostly deflated dark green balloon, although it may also look kind of lumpy. It also has a feeding proboscis that it can extend several feet, or about a meter.

As a larva, the green spoonworm floats around in the water, but whether it becomes male or female depends on where it settles. If it lands on the seafloor it transforms into a female and starts secreting a toxin called bonellin. Bonellin is what gives the green spoonworm its dark green color. The bonellin is mostly concentrated in the feeding proboscis and allows the spoonworm to paralyze and kill the tiny animals it eats.

But if the larva happens to land on a female green spoonworm, contact with the bonellin causes it to become a male. And the male is only a few mm long, doesn’t produce bonellin, and can’t even survive on its own. The female sucks the male into her body through the feeding proboscis, but instead of digesting him, he lives inside her and fertilizes her eggs. In return she provides him with all the nutrients he needs. A female may have more than one male living inside her, making sure that her eggs will always be fertilized.

There are lots more animals that show extreme sexual dimorphism, of course, but that at least gives you an idea of how different animals evolve to fit different environmental pressures. Weird as they seem to us, to the animals in question, it’s just normal–and it’s our appearance and how we do things that would seem weird to them. Perspective is everything.

You can find Strange Animals Podcast online at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you like the podcast and want to help us out, leave a rating and review on Apple Podcasts or whatever platform you listen on. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. We also have a Patreon if you’d like to support us and get twice-monthly bonus episodes.

Thanks for listening!

Episode 153: The White River Monster

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Let’s start out the new year with a bona fide mystery animal, the White River Monster from Arkansas! Is it a real animal? If so, is it a known animal or something new to science? If it’s a known animal, what could it be? Lots of questions, maybe a few answers! Happy new year!

Further listening:

MonsterTalk

The not exactly useful picture supposedly of the White River Monster, taken in 1971:

A northern elephant seal, AKA Mr. Blobby:

A Florida manatee:

A bull shark:

Two bottlenose dolphins:

An alligator gar (below) and a human (above):

Alligator gar WEIRD FISH FACE:

Gulf sturgeon:

Show transcript:

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

If you’ve listened to the final episode of 2019 last week, you’ll remember it was about some mystery water animals of various kinds. Well, I’ve got another water mystery for you today to start off the new year, the White River monster. I heard about this one in a recent episode of MonsterTalk, which is a great podcast I recommend if you don’t already listen to it.

The White River is in North America, originating in the mountains in northwestern Arkansas and flowing from there through Missouri, then back into Arkansas where it joins the Mississippi River. In 1915 a man near the small town of Newport, in the central Ozarks region of Arkansas, saw an enormous animal with gray skin in the river.

A few other people saw it too, but it wasn’t until July of 1937 that things really heated up. The monster returned, and this time a lot of people saw it. News of it hit the local papers and spread throughout the country, and people started showing up to look for it. Some people came prepared to kill or catch it while others just wanted to see it.

Estimates of the monster’s size varied quite a bit. A man named Bramlett Bateman, who owned a lot of the farmland along that stretch of the river, was quoted in several newspaper articles. He described the monster as being the length of three cars in one article, but in another his estimate was smaller, only 12 feet long, or 3.7 m, and four or five feet wide, or 1.2 to 1.5 meters. But it doesn’t seem that he or anyone else got a really good look at it.

It was described by numerous people as being gray-skinned. Bateman said it had “the skin of an elephant…with the face of a catfish.” I dug into as many original newspaper articles as I could find without actually paying for access to them, and very few of them have a real description of the animal. The only description given in a New York Times article from July 23, 1937 is this:

“Half a dozen eye-witnesses…reported seeing a great creature rise to the surface at rare intervals, float silently for a few minutes and then submerge, making its presence known only by occasional snorts that bubbled up from the bottom.”

Another article quotes Bateman as saying he saw the monster “lolling on the surface of the water.”

Bateman decided he was going to blow the monster up with dynamite. What is it about people whose go-to solution to seeing an unidentified animal is to throw dynamite in the water? The local authorities said, uh no, you cannot just throw dynamite into the river, but other people brought machine guns and other weapons and patrolled the river looking for the monster. A plan to make a giant net and catch the monster petered out when people found out that making and deploying a net that big is expensive and difficult.

The monster was mostly reported in an eddy of the river that stretched for about a mile and was unusually deep, about 60 feet deep, or 18 meters. The river is about 75 feet wide at that point, or 23 meters. The Newport Chamber of Commerce hired a diver from Memphis named Charles B. Brown, who brought an eight-foot harpoon with him when he descended into the river. He didn’t find anything, but the tourists had fun.

Suggestions as to what the monster might be ranged from a sunken boat that sometimes bobbed briefly to the surface to a monstrous catfish. Many people were convinced it was a huge fish of some kind, especially an alligator gar.

Eventually sightings tapered off and the excitement died down until June of 1971, when it started being seen again. Again the size estimates were all over the place, with one witness saying it was the size of a boxcar, which would be about 50 feet long, or 15 meters, and 9 feet wide, or 2.8 meters. Another witness said it was only 20 feet long, or 6 meters. Some witnesses said it had smooth skin that looked like it was peeling all over, had a bone sticking out of its forehead, and it made sounds that one witness described as similar to both a horse’s neigh and a cow’s moo. On July 5, 1971, three-toed tracks 14 inches long, or 36 cm, were also found on an island together with crushed plants that showed a huge animal had come out of the water.

This time, at least, no one tried to dynamite or even net the monster. Instead, in 1973 Arkansas passed a law creating the White River Monster Refuge along that section of the river, to protect the monster. But no one has seen it since.

There is a photo of the monster taken in 1971, but it’s a blurry Polaroid that was reproduced in a newspaper and the original lost. The photo was taken by a man named Cloyce Warren, who was out fishing with two friends. Warren said it had “a spiny ridged backbone and [was] splashing all around.”

So what could the White River Monster be? Is it a misidentified known animal, a completely unknown animal, or just a hoax?

Obviously people are seeing something in that part of the White River. But it’s reportedly so big that if there was a population living anywhere in the river, it would be spotted all the time. So maybe it’s an animal that only sometimes strays into the White River and actually lives in the much larger Mississippi River—or even in the Gulf of Mexico, where it sometimes swims upriver.

Cryptozoologists and other interested people have made suggestions over the years. One suggestion is that it’s an elephant seal. The northern elephant seal is an enormous animal, although it’s nowhere near 50 feet long. The male is much larger than the female, up to 16 feet long, or 4.8 meters, and bulky with blubber that keeps it warm when diving deeply for food in the Pacific Ocean where it lives.

But wait, the Pacific Ocean? You mean it doesn’t live in the Gulf of Mexico?

Nope, the endangered elephant seal only lives in the Pacific. And the Pacific Ocean is separated from the Gulf of Mexico by a whole lot of the North American continent.

A man named Joe Nickell, who’s a paranormal investigator and who was interviewed on MonsterTalk episode 204, has suggested the White River Monster is a manatee—specifically the Florida manatee, which is a subspecies of West Indian manatee. In the winter it mostly lives around Florida but in summer many individuals travel widely. It’s sometimes found as far north as Massachusetts along the Atlantic coast, and as far west as Texas in the Gulf of Mexico.

The manatee is large, up to 15 feet long, or 4.6 meters, with females being somewhat larger than males. Its skin is gray but since it moves slowly, it can look mottled in color due to algae growing on its skin, and it sometimes also has barnacles stuck to it the way some whales do. It has a pair of front flippers with three or four toenails, no hind legs, and a paddle-like tail. It eats plants and only plants, and is completely harmless to humans, fish, and other animals. Also because it moves slowly and spends a lot of time at the surface, since it’s a mammal and has to breathe air, it’s vulnerable to being injured by boats.

In the 1970s there were only a few hundred manatees alive and it nearly went extinct. It was listed as an endangered species and after a lot of effort by a lot of different conservation groups, it’s now only considered threatened. So while people might recognize a manatee these days, back in the 1970s it was practically unknown everywhere except southern Florida since it was so rare. And in the decades before 1971, people didn’t travel as much and didn’t know much about increasingly rare animals that didn’t live in their particular part of the world.

In other words, it’s completely possible that people from Arkansas would see a manatee in 1915, 1937, and 1971 and not know what it was. But could a manatee really travel that far from the ocean and survive?

The Mississippi River empties into the Gulf of Mexico in Louisiana in the United States. Texas is to the west of Louisiana, then Mississippi, Alabama, and Florida to the east. In other words, it’s well within the known range of the Florida manatee. Manatees are known to sometimes travel up the Mississippi. This happened most recently in October of 2016 when a manatee traveled as far as Memphis, Tennessee before it was found dead in a small lake connected to the river. That’s a distance of 720 miles, or 1,158 km, and that was with wildlife officials trying to capture it to return it to the Gulf. That same year a manatee also traveled as far as Rhode Island along the Atlantic coast. Memphis is actually much farther up the Mississippi than the White River is, so if the manatee had branched off into the White River it might have led to new sightings of the White River Monster.

The manatee can live in fresh water perfectly well. One species, the Amazonian manatee, is a fully freshwater animal that never leaves the South American rivers where it lives. But despite its size, the manatee doesn’t have a lot of blubber or fat to keep it warm. The farther away it travels from warm water, the more likely it is to die of cold.

But while an errant manatee might explain some White River Monster sightings, it doesn’t fit with all of them. Other animals from the Gulf of Mexico sometimes find their way up the Mississippi too. It’s a huge river, and since an ocean animal doesn’t understand what a river is, it doesn’t know it’s never going to reach the ocean again unless it turns around. Most marine animals can’t survive for long in fresh water, but some animals, like the manatee, can tolerate fresh water much better. That’s also the case for the bull shark.

In 1937, the same year the White River Monster was spotted for the second time, a five-foot bull shark, or 1.5 meters, was caught in Illinois, which is even farther upstream from the Gulf of Mexico than Tennessee and Arkansas. Bull sharks live throughout much of the world’s oceans in warmer water near coasts and are often found in rivers and lakes, although they don’t live as long in fresh water as they do in salt water. The largest bull shark ever measured was 13 feet long, or 4 meters, so a large one is about the size of a manatee.

Occasionally a dolphin travels up the Mississippi River, but marine dolphins can’t survive for long in fresh water and will die soon if they can’t make their way back to the ocean. A dolphin in fresh water starts to develop skin lesions and then the skin begins to peel, leading to bacterial infection and death. Remember that some witnesses in 1971 described the White River Monster as a gray animal with peeling skin.

Nine different species of dolphin and many species of whale live in the Gulf of Mexico. Of those, only the bottlenose dolphin lives close to the coast and is usually the species that accidentally travels into fresh water and can’t find its way out. The bottlenose dolphin isn’t any larger than the manatee, up to about 13 feet long, or 4 meters.

1971 was an active hurricane year, including the category 5 Hurricane Edith that killed 37 people in mid-September. Marine animals that can travel quickly, like dolphins and sharks, will flee to calmer waters when a hurricane approaches, and while that usually means out to sea, it wouldn’t be out of the question for a frightened dolphin or other large marine animal to make its way into the Mississippi by accident ahead of a hurricane, especially a hurricane as big as Edith.

Another possible identity for the White River Monster is one that was suggested in 1937, the alligator gar. It’s a freshwater fish that lives throughout the Mississippi River and other rivers and lakes in the southern United States and parts of northern Mexico. The alligator gar gets its name because of its toothy jaws, which do resemble an alligator’s, and it can grow up to ten feet long, or 3 meters. It’s a really weird fish and eventually I’ll probably do a full episode on it and its relatives, just as I have a full episode planned about the manatee. It has gills like other fish, but it can also breathe air through its swim bladder, which is lined with lots of blood vessels that absorb oxygen. Every so often an alligator gar will come to the surface and gulp air to replenish the oxygen in its swim bladder, so it would be seen at the surface briefly but periodically as was described by many witnesses. This is also the case for the manatee and dolphin, who breathe air.

The alligator gar is an ambush predator, which means it waits in the water without moving much at all until an animal approaches. Then it shoots forward and grabs it. It mostly eats small fish, invertebrates of various kinds, and waterfowl like ducks.

The final possibility of the White River Monster’s identity is the gulf sturgeon. It’s a subspecies of the Atlantic sturgeon that lives in the Gulf of Mexico, although it’s also known from various rivers in the southeastern United States. The reason it’s found in rivers is that the gulf sturgeon is anadromous [a-NADro-mus], the term for a fish that migrates from the ocean into fresh water to spawn. The salmon is the most famous anadromous fish, which fights its way upriver to spawn and then die. In the case of the gulf sturgeon, it hatches in fresh water and lives there for the first two years or so of its life before making its way downstream to the ocean. Then it returns to freshwater to spawn every spring, usually the same river where it was hatched, and goes back to the ocean in autumn.

The gulf sturgeon fits a lot of the descriptions of the White River Monster sightings. It’s covered with five rows of scutes that project from the back and sides in a sort of low sawtooth pattern, which fits the “spiny ridged backbone” that Cloyce Warren reported seeing in 1971, and its elongated snout has sensory barbels like a catfish, which matches Bramlett Bateman’s 1937 description of the monster having the face of a catfish. It’s gray, gray-green, or brownish in color with a lighter belly, and it can grow up to 15 feet long, or 4.5 meters, although most are about half that length.

The gulf sturgeon usually migrates in groups, but occasionally one can get separated from its group and find its way into a stretch of water by itself. It also doesn’t eat much during the summer when it’s in freshwater. In the winter it lives just off the coast in shallow water, where it’s a bottom feeder. It sucks up invertebrates from the sea floor, feeling for them with their barbels. It gains lots of weight during the winter and then loses it all in the summer. Sturgeons do sometimes jump out of the water, especially in summer–as much as fix feet out of the water. No one’s sure why. Also during the summer, the sturgeon makes a sound like a creaky hinge.

I think it’s probable that the White River Monster sightings are of more than one type of animal, and while we can make an educated guess as to which animals might have been spotted and misidentified, we can’t know for sure. So while at least some of the sightings may have been of a manatee or a gulf sturgeon or another of the animals we talked about today, there’s also the possibility that something else occasionally swims up the Mississippi from the Gulf and into the White River. Hopefully, next time the White River Monster appears, someone gets a really good look at it and some good pictures so we know for sure.

This is what a sturgeon sounds like, by the way:

[sturgeon creaky sound]

You can find Strange Animals Podcast online 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 if you’d like to support us and get twice-monthly bonus episodes.

Thanks for listening!

Episode 152: The Freshwater Seahorse and Other Mystery Water Animals

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This week let’s look at some (mostly) smaller mystery animals associated with water! Thanks to Richard J., Janice, and Simon for the suggestions!

Further reading:

What Was the Montauk Monster?

The black-striped pipefish. Also, that guy has REALLY BIG FINGERTIPS:

The Pondicherry shark, not looking very happy:

A ratfish. What BIG EYES you have!

The hoodwinker sunfish, weird and serene:

The Montauk monster, looking very sad and dead:

Show transcript:

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

Let’s finish off the year with an episode about a few mystery animals, specifically a few mystery animals associated with water. Thanks to Richard, Janice, and Simon for the suggestions!

We’ll start off with a mystery suggested by Richard J, but not the Richard J. who is my brother. A different Richard J. Apparently half the people who listen to my podcast are named Richard, and that’s just fine with me.

Richard wanted to know if there are there such things as freshwater seahorses. We’ve talked about seahorses before in episode 130, but seahorses are definitely marine animals. That means they only live in the ocean. But Richard said he’d heard about a population of seahorses native to Lake Titicaca in Bolivia, which is in South America. I put it on my suggestions list, but Richard was on the case. He sent me a link to an article looking into the mystery, which got me really intrigued, so I bumped it to the top of my list. Because I can do that. It’s my podcast.

Freshwater seahorses are supposedly known in the Mekong River and in Lake Titicaca, and sometimes you’ll see reference to the scientific name Hippocampus titicacanesis. But that’s actually not an official scientific name. There’s no type specimen and no published description. Hippocampus is the generic name for many seahorse species, but like I said, they’re all marine animals and there’s no evidence that any live in freshwater at all. Another scientific name supposedly used for the Mekong freshwater seahorse is Hippocampus aimei, but that’s a rejected name for a seahorse named Hippocampus spinosissimus, the hedgehog seahorse. It does live in parts of the Indo-Pacific Ocean, including around Australia, especially in coral reefs, and sometimes in the brackish water at the Mekong River’s mouth, but not in fresh water.

On the other hand, there’s no reason why a seahorse couldn’t adapt to freshwater living. A few of its close relatives have. There are a few species of freshwater pipefish, and in the world of aquarium enthusiasts they are actually sometimes called freshwater seahorses. The pipefish looks like a seahorse that’s been straightened out, and most of them are marine animals. But some have adapted to freshwater habitats.

This includes the black-striped pipefish, which is found off the coasts of much of Europe but which also lives in the mouths of rivers. At some point it got introduced into the Volga River and liked it so much it has started to expand into other freshwater lakes and rivers in Europe.

The pipefish is closely related to the seahorse, but while it does have bony plates like a seahorse, it’s a flexible fish. It swims more like a snake than a fish, and it can anchor itself to vegetation just like a seahorse by wrapping its tail around it. It mostly eats tiny crustaceans and newly hatched fish, since it swallows its food whole. It usually hides in vegetation until a tiny animal swims near, and then it uses its tube-shaped mouth like a straw to suck in water along with the animal. Just like the seahorse, the male pipefish has a brooding pouch and takes care of the eggs after the female deposits them in his pouch.

So where did the rumor that seahorses live in the Mekong come from? The Mekong is a river in southeast Asia that runs through at least six countries, including China, Thailand, Cambodia, and Vietnam. Parts of it are hard to navigate due to waterfalls and rapids, but it’s used as a shipping route and there are lots of people who live along the river. Like all rivers, it’s home to many interesting animals, including a type of giant softshell turtle that can grow up to six feet long, or 1.8 meters, a type of otter, a bunch of enormous fish, including three species of catfish that can grow up to almost ten feet long, or 3 meters, and a giant freshwater stingray that can grow up to 16 feet long, or 5 meters, and of course lots more animals that aren’t as big or as impressive, but which are still important to the river’s biodiversity. But there’s no evidence of seahorses anywhere throughout the Mekong’s 2700 mile length, or 4,350 km.

But there is a hint about where the rumor of a Mekong seahorse could have come from. One researcher named Heiko Bleher chased down the type specimens of the supposed Mekong seahorse in a Paris museum, which were collected in the early 20th century by a man named Roule. Roule got them in Laos from a fisherman who had nailed the dried seahorses to his fishing hut. The fisherman told Roule the seahorses were from the Mekong, but when they were further studied in 1999 Roule’s specimens were discovered to actually be specimens of Hippocampus spinosissimus and Hippocampus barbouri. Both are marine fish but do sometimes live in brackish water at the mouth of the Mekong. So the fisherman wasn’t lying, but Roule misunderstood what he meant.

As for the freshwater seahorse supposedly found in Lake Titicaca, that one’s less easy to explain. Titicaca is a freshwater lake in South America, specifically in the Andes Mountains on the border of Bolivia and Peru. It’s the largest lake in South America and is far, far above the ocean’s surface—12,507 feet above sea level, in fact, or 3,812 meters. It’s also extremely deep, 932 feet deep in some areas, or 284 meters. It’s home to many species of animal that live nowhere else in the world. Why couldn’t it be home to a freshwater seahorse too?

Titicaca was formed when a massive earthquake some 25 million years ago essentially shoved two mountains apart, leaving a gap—although technically it’s two gaps connected with a narrow strait. Over the centuries rainwater, snowmelt, and streams gradually filled the gaps, and these days five rivers and many streams from higher in the mountains feed water into the lake. Water leaves the lake by the River Desaguadero and flows into two other lakes, but those lakes aren’t connected to the sea. Sometimes they dry up completely. So Titicaca isn’t connected to the ocean and never was, and even if it was, seahorses are weak swimmers and would never be able to venture up a river 12,000 feet above sea level. Some 90% of all fish in the lake are found nowhere else in the world. There’s just simply no way a population of seahorses could have gotten into the lake in the first place, even if they could survive there.

That doesn’t mean there aren’t any freshwater seahorses out there ready to be discovered, of course. But I don’t think you’re going to find any in Lake Titicaca. And I have no idea how the rumor got started that any live there.

From a tiny seahorse let’s move on to a small shark, another topic suggested by Richard J. The Pondicherry shark grows to about 3.3 feet, or 1 meter, and once lived throughout the Indo-Pacific, especially in coastal waters. It’s considered critically endangered, but it’s so rare these days that we hardly know anything about it except that it’s harmless to humans, eats small fish and other small animals, and was once common. But until the mid-2010s, scientists were starting to worry it was already extinct. Then in 2016 two different Pondicherry sharks were photographed in two different places—and not where anyone had expected to find it. Some tourists took a photo of one in a river called the Menik and a freshwater fish survey camera caught a photo of one in the Kumbuk River. Both rivers are in Sri Lanka. Since then researchers have spotted a few more. The shark is protected, and hopefully the excitement around the shark’s rediscovery has helped people in the area learn about it so they know not to bother it. Some sharks tolerate fresh water and brackish water quite well, so it’s not surprising that the Pondicherry shark has moved into the rivers where it has less competition from commercial fishing boats.

Our next water mystery is actually not really a mystery, just a really strange-looking fish related to sharks. This one was suggested by my aunt Janice who doesn’t actually listen to the podcast but who likes to send me links to strange animal articles that she comes across on the internet. This one is called Chimaera Monstrosa, sometimes called the rat fish.

The rat fish mostly lives in the deep sea, although it’s sometimes seen in shallower water, and can grow up to 5 feet long, or 1.5 meters. It’s mostly brown but has white markings. Its body looks more or less like a regular plump shark-like fish, but it has great big round green eyes, relatively long pectoral fins, and a very long tail that tapers to a point. The tail gives it its common name, since it kind of resembles a rat’s tail. It eats whatever it can catch on the ocean floor, including crustaceans and echinoderms.

Ratfish, and other chimaeriformes, are most closely related to sharks, and like sharks they have skeletons that are made of cartilage instead of bone. Since they’re rarely seen and look really weird, every so often someone catches one and posts about it online, and then my aunt sends me a link. They are really interesting fish, though.

Simon also sent me an article about an interesting fish a while back, the hoodwinker sunfish. We talked about the sunfish, or mola mola, in episode 96. The hoodwinker sunfish, or mola tecta, was only discovered in 2017 despite its large size. So far it’s known to live in the South Pacific around New Zealand, Australia, South Africa, and Chile, but only off the southernmost parts of those countries. But in early 2019 one washed up in Southern California.

The mystery sunfish was measured at almost 7 feet long, or 2.1 meters. An intern at the University of California at Santa Barbara found it, but didn’t know what it was. But once photos of the fish were posted online, two experts from Australia recognized it immediately—but because it showed up so far out of its known range, they were cautious about IDing it from just a photo. That’s despite the fact that one of the experts, Marianne Nyegaard, was actually the person who named the species. She asked for samples and more photos, and when she got the results, it really was a hoodwinker sunfish. But what was it doing in the warm waters of the northern Pacific instead of the cold southern waters? No one knows except the sunfish.

Let’s finish with another mystery animal you may have heard of. On July 12 or 13, 2008, depending on which source you consult, three friends visited Ditch Plains Beach, two miles away from the little town of Montauk in New York state in eastern North America. It was a hot day and the beach was crowded, and when the three noticed people gathered around something, they went to look too. There they saw a weird dead animal that had obviously washed ashore. One of the three took a picture of it, which appeared in the local papers and then the local TV news along with an interview with the three. From there it went viral and was dubbed the Montauk monster.

The monster was about the size of a cat, but with shorter legs and a chunkier body, and a relatively short tail. It didn’t have much hair but it did have sharp teeth, and the front part of its skull was exposed so that it almost looked like it had a beak. Its front paws were elongated with long fingers, almost like little hands.

So what was the monster? People all over the world made guesses, everything from a sea turtle without a shell to a diseased dog or just a hoax. Some people thought it was a mutant animal that had been created in a lab on one of the nearby islands, escaped, and died trying to swim to the mainland.

But while no one knows what happened to the animal’s body, scientists have studied the photo and determined that it was probably a dead raccoon that had been washed into the ocean. The waves had tumbled the animal’s body around through the sand long enough to rub off most of its remaining fur and some of its facial features, and then it washed ashore during the next high tide. It was also somewhat bloated due to gases building up inside during decomposition. It’s the animal’s teeth and paws that made the identification possible, since both match a raccoon’s exactly. Remember that raccoons have clever front paws that help them open locking trash bins, as we learned in episode 138.

So the Montauk monster isn’t actually a mystery, except what happened to it, but don’t be discouraged. There are still lots of genuinely mysterious animals in the ocean, from misplaced sunfish to creatures no one has ever seen yet. Maybe you’ll be the one to discover them.

You can find Strange Animals Podcast online 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 and get twice-monthly bonus episodes.

Thanks for listening!

Episode 151: Fossils with other fossils inside

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Thanks to Pranav who suggested this week’s amazing topic, animals that fossilized with the remains of their last meal inside!

Indrasaurus with a lizard inside. Yum!

Baryonyx:

Rhamphorhynchus (left, with long wing bones) and its Fish of Doom (right):

The fish within a fish fossil is a reminder to chew your food instead of swallowing it alive where it can kill you:

The turducken of fossils! A snake with a lizard inside with a bug inside!

Show transcript:

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

This week we have a listener suggestion from Pranav, who has sent me so many amazing suggestions that he has his own page on the ideas spreadsheet. When he emailed me about this one, he just suggested cool fossils, but the links he provided had a really interesting theme that I never would have thought about on my own. This week we’re going to learn about some fossil animals that have fossils of their last meal inside them!

We’ll start with a recent discovery of a new microraptor species, Indrasaurus wangi, which lived about 120 million years ago. It was an interesting animal to start with, because it had arms that were very similar to bird wings, although with claws, but its hind legs also had long feathers that made it almost like a four-winged animal. It was found in 2003 in northeastern China, but when researchers were studying it in 2019 they found something amazing. Not only did it have an entire lizard skeleton where its stomach once was, showing us that it swallowed its prey whole, the lizard itself was a species new to science.

We know what else Indrasaurus ate because more Indrasaurus fossils have been found in the area, many of them so well preserved that its fossilized stomach contents have been preserved too. It ate mammals, birds, lizards, and fish—basically anything it could catch.

Another species that was similar to Indrasaurus, called Anchiornis, also called a four-winged bird-like dinosaur, was found with what appears to be a gastric pellet in its throat. The pellet contains the bones of more than one lizard and was probably ready to be horked up the way many carnivorous birds still regurgitate pellets made up of the indigestible parts of their prey, like bones, scales, and fur.

The fossilized remains of food inside a fossilized organism has a term, of course. It’s called a consumulite. It’s a type of bromalite, which is a broader term for any food or former food found in a fossilized organism’s digestive tract. The term bromalite also includes coprolites, which are fossilized poops.

Naturally, it requires a high degree of preservation for consumulites to form, and a high degree of skill to reveal the often tiny and delicate preserved details. And consumulites are important because they let us know exactly what the animal was eating.

Consumulites aren’t limited to prey animals, either. A small armored dinosaur, a type of ankylosaur, called Kunbarrasaurus, which lived around 115 million years ago in what is now Australia, was a herbivore. The type specimen of the species, which was described in 2015, was incredibly well preserved—almost the entire skeleton, most of its body armor, and the contents of its stomach. Paleontologists can determine not just what kinds of plants it had eaten—which include ferns and seeds—but how it was processing its food. Most herbivorous dinosaurs swallowed leaves and other plant parts whole, then crushed the food in a powerful gizzard or gizzard-like organ along with rocks or grit. The rocks helped break up the plant material, and we have lots of these rocks associated with fossilized dinosaurs. The rocks are called gastroliths and are usually worn smooth. But Kunbarrasaurus didn’t have any gastroliths, and the plant material was so well preserved that researchers could see the cut ends of the plants where Kunbarrasaurus had bitten them. And all the pieces were small. Kunbarrasaurus therefore probably chewed its food, which meant it also probably had lips and cheeks of some kind to help keep the food in its mouth while it was chewing.

Another example of an animal with a consumulite that helped solve a mystery about its diet is Baryonyx. Baryonyx is a type of spinosaurid, a theropod dinosaur that grew at least 33 feet long, or 10 meters. It was discovered in 1983 in Surrey, England, and was described in 1986. It lived around 125 million years ago. It walked on its hind legs and probably used its arms to tear its prey into bite-sized pieces, because its first finger had a huge claw 12 inches long, or 31 cm.

But its skull was the real puzzle. Most theropods are meat-eaters, although a few evolved to eat plants. But Baryonyx had a long, relatively slender snout with a lot of close-growing teeth, and a sort of bulb at the end of its snout called a rosette. It looks more like the skull of a crocodilian called a gharial than a theropod. But as far as anyone knew when Baryonyx was discovered, there were no fish-eating theropods.

Until 1997, that is, when paleontologists studying Baryonyx spotted some overlooked details. In addition to a gastrolith in its belly area, they found some fish scales and teeth that showed evidence of being damaged by digestive acids. It probably hunted by wading through shallow water like a heron, catching fish and other animals with its long toothy snout.

It’s not just dinosaurs that are found with consumulites. Animals of all kinds eat all the time, so as long as the conditions are right to fossilize the remains of an animal, there’s a chance that whatever food was in the digestive tract might fossilize too. For instance, the same part of China that has yielded amazingly well preserved feathered dinosaurs has also produced other animals—including a carnivorous mammal called Repenomamus that grew more than three feet long, or one meter. I think we’ve talked about Repenomamus before, because we have evidence that it actually ate dinosaurs—at least baby ones, or it might have scavenged already dead dinosaurs. Either way, it lived around 125 million years ago and was shaped sort of like a badger with a long tail, although it wasn’t related at all to badgers or any other modern mammal. It probably laid eggs like monotremes still do. The reason we know what Repenomamus ate is because one specimen was found with pieces of a young Psittacosaurus in its stomach.

In at least one case it’s hard to tell which animal should be considered the eater and which should be considered the eaten. A fossil slab found in Southern Germany and described in 2012 contains a Rhamphorhynchus associated with two different fish.

Rhamphorhynchus lived around 150 million years ago and was a type of pterosaur with a long tail. Its wingspan was about six feet across, or 1.8 meters. It mostly ate fish, which it probably caught not by flying down to grab fish out of the water, like eagles do, but by floating like a goose and diving for fish. It had large feet and short legs, which would have helped it take off from the water just like a goose.

A fish that lived at the same time as Rhamphorhynchus was called Aspidorhynchus, and it grew up to two feet long, or 60 cm. It had long jaws filled with teeth, with the upper jaw, or rostrum, extending into a pointy spike.

In the fossil found in Germany, a Rhamphorhynchus has a small fish in its throat that it had probably just caught. While it was still swallowing it, an Aspidorhynchus fish attacked! But things obviously went wrong for everyone involved. Researchers suggest that the fish’s rostrum cut right through the flying membrane of Rhamphorhynchus’s left wing. The fish bit down but its teeth became tangled in the tissue. It started thrashing to free itself and Rhamphorhynchus was thrashing around too trying to get away, which only got them more tangled up together. The fish dived, drowning Rhamphorhynchus, and the weight of its body dragged Aspidorhynchus into deep water where there wasn’t enough oxygen for it to survive. It died too, and its heavier body lay partially across Rhamphorhynchus, holding it down so it wouldn’t drift away. The fossil shows Rhamphorynchus, Aspidorhynchus, and the tiny fish that Rhamphorhynchus never did get to finish swallowing.

Another fish, Cimolichthys, lived around 75 or 80 million years ago and grew a little over six feet long, or two meters. Its body was heavily armored by large scutes and it had several rows of teeth. It may have been related to modern salmon. It lived in what is now North America and Europe, and ate fish and squid. We know it ate fish and squid because, of course, we have the remains of various last meals found with preserved fossil Cimolichthys. For instance, one specimen was found with the internal shell of a cephalopod lodged in its throat. Researchers suspect the fish had tried to swallow a Tusoteuthis that was too big to fit down its throat. The Tusoteuthis got stuck and blocked the flow of water over the fish’s gills, basically drowning it. Tusoteuthis, by the way, could possibly grow up to 36 feet long, or 11 meters, although that depends on whether it had long feeding tentacles like modern squid or not. If it didn’t have long feeding tentacles, it was probably only about 19 feet long, or 6 meters, which is pretty darn big anyway. I wouldn’t want to have to swallow that thing whole. Not even if it was deep-fried first.

Another fish called Xiphactinus, which grew up to 20 feet long, or 6 meters, lived in the late Cretaceous period. It died out at the same time as the non-avian dinosaurs. It had massive fangs and was a terrifying predator, but sometimes that backfires. The fossil of a 13 foot, or 4 meter, Xiphactinus was found with a 6 foot long, or 1.8 meter, fish called Gillicus inside it. Paleontologists think Xiphactinus swallowed its prey whole, which thrashed around so much inside it that it ruptured an organ and killed the predator fish. Both fish sank to the bottom of the shallow Western Interior Seaway in North America until it was discovered in 1952.

Let’s finish with two even more incredible fossils. In 2008 paleontologists found a fossilized freshwater shark they dated to 250 million years ago. Right before it died, it had eaten two animals called temnospondyls. Temnospondyls were common animals, with many species found throughout the world, and researchers still aren’t sure if they were the ancestors of modern amphibians or a similar type of animal that died out without any descendants. One of the temnospondyls that the shark ate had the well digested remains of a spiny fish in its stomach.

But a few years later researchers in Germany found something even better. It’s a fossilized snake called a Palaeopython, related to boas. It was about three feet long, or one meter, and was still young. If it had lived to grow up, it would have doubled in size. It lived in trees but also hunted along the edges of rivers and lakes. About 48 million years ago, this particular snake caught a lizard that’s related to modern basilisk lizards. It swallowed the lizard headfirst. But then the snake died, possibly asphyxiated by a cloud of carbon dioxide from the volcanic lake nearby. We have a lot of incredibly detailed fossils from that lake, known as the Messel Pit.

Researchers aren’t sure how the snake made it into the lake. Maybe it was already in the shallow water when it died, or on the bank, and a wave washed it into the water. Maybe the wave was actually what killed the snake, washing it into the lake where it drowned. However it died, it sank into deep water and was covered in sediment that preserved it. Then, 48 million years later, paleontologists found it.

When the fossil was cleaned and prepared for study, researchers found that the lizard was preserved inside it. But there was another surprise inside the lizard! Right before it had been eaten by the snake, the lizard had eaten an insect. And the insect was so well preserved that researchers could tell it had an iridescent exoskeleton.

If I was fossilized right now, paleontologists from the far future would find a lot of chocolate in my stomach. Happy holidays to everyone, whatever your reason for celebrating at this time of year!

You can find Strange Animals Podcast online 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 if you’d like to support us and get twice-monthly bonus episodes.

Thanks for listening!

Episode 140: Rains of Fish and Frogs (and other things)

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We’re starting off October (you know, MONSTER MONTH) with accounts of animals that fall from the sky like rain, mostly fish and frogs! Is this a real thing that actually happens, and if so, what causes it?

Further reading:

Raining Frogs

Recent observations of “mystery star jelly” in Scotland appear to confirm one origin as spawn jelly from frogs or toads

Not a real photo of an octopus falling in a storm:

This photo is probably real, two shrimp/prawns on a windshield in the same storm as above (in 2018):

A photo of people picking up fish in the street but I have no idea where it was taken:

An arctic lamprey found in someone’s yard:

Some of the stuff called star jelly, star rot, or star snot:

A walking catfish:

Show transcript:

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

It’s finally October, and that means monsters and other spooky stuff! I have lots of fun episodes planned this month, but first, an important announcement!

A few weeks ago I got a message from someone on Podbean, and I feel terrible because I can’t reply or even see the whole message or who it’s from! Podbean does not like me. I get an email with the first couple of lines of the message but when I click through and log in to Podbean to see the whole message and respond, Podbean goes, “Message? What message? You don’t have any messages.” So please, person who messaged me with a suggestion I can’t see, I’d love it if you email me at strangeanimalspodcast@gmail.com! And if anyone else has ever messaged me somewhere but never received a reply, email is the best way to get hold of me. I always reply, so if you don’t get an answer it means I never saw your message and you should totally send it again. Thanks!

So, back to the October fun! Let’s start off the month right with a strange phenomenon that’s been reported for untold centuries all over the world. Do fish and frogs and other animals actually sometimes fall from the sky like rain?

It seems pretty certain that while this is a rare event, and not all reports are of animals that actually fell from the sky, it does sometimes happen. In fact, lots of weird stuff falls from the sky from time to time. For instance, after a heavy rain over Punta Gorda, Florida at the end of August 1969, the streets were full of golf balls, dozens of them if not hundreds. But there wasn’t a golf course near the town.

Sometimes colored rain falls instead of ordinary clear water. This happens because raindrops form around tiny specks of dust or pollen in the air. When the dust is colored, the rain will be too. Red rains come from dust blown into the atmosphere from the Sahara while yellow rain results from dust from the Gobi Desert. Volcanic eruptions, soot, and other pollutants in the air can cause black rain. And a red rain that fell in Kerala, India in July 2001 was analyzed and the color found to be due to fungal spores. Snow is occasionally colored too, just like rain.

But sometimes frogs, fish, or other small animals do apparently fall from the sky, with or without rain. Here’s a typical report of a rain of frogs. It comes from the book The Unexplained by zoologist Karl Shuker, whose honesty and scholarship I trust. Not only that, it’s something that happened to his own grandmother, Gertrude Timmins. In 1902, Gertrude was only eight years old. She and her mother were walking across a field in the West Midlands in England when it started to rain. They opened their umbrellas, but a moment later Gertrude noticed that amid the regular pattering of rain on an umbrella there were some heavier thumps. Then she noticed that the thumps were caused by small frogs falling onto her umbrella and bouncing off onto the ground. Gertrude was frightened at first, naturally, because that’s just a weird thing to happen to anyone. But her mother told her not to be scared, it was just a rain of frogs.

Remember, Gertrude and her mother were walking across a field. There weren’t any trees or buildings around that the frogs might have fallen from. So where did they come from?

The main hypothesis is that the animals are picked up by a water spout or small tornado and carried on the wind until they’re dropped elsewhere, miles away. When I was a kid I thought this was a dumb suggestion. If a dissipating water spout dropped everything it had picked up out of a pond, why do people just report one kind of frog falling from the sky or one kind of fish? Where’s the algae, water plants, turtles, mud, and other stuff presumably also picked up and carried out of a pond?

The answer may be pretty simple. When the wind velocity is high, the tornado or water spout can carry heavy objects, but as the wind slows and loses energy, it starts to drop the heaviest items. But the wind is still moving, so as it moves across the land and slowly loses more and more energy, it drops the heaviest items first, then the next heaviest items, then the next heaviest, and so on.

It might not even be a tornado or water spout. A powerful updraft, which is often associated with storms, can lift light items like sticks, leaves, and pool toys and drop them miles away. Small frogs often weigh no more than a penny does and during breeding season can be incredibly common in a small area, hopping everywhere. It’s reasonable to assume that sometimes these little frogs get lifted from one area by a strong updraft and dropped elsewhere, astonishing anyone who happens to see it. If you doubt the strength of an updraft, keep in mind that storms can also generate downdrafts and they can be so powerful they destroy or uproot trees.

No one has witnessed frogs or other animals get sucked up into the air and dropped elsewhere, so we don’t know if it actually happens this way. But the animals are obviously getting into the air somehow.

Frogs aren’t the only animals witnessed to fall from the sky. Fish are actually probably the most common animals that fall with rain. It doesn’t even have to be raining.

On October 23, 1947 fish fell over Marksville, Louisiana in the United States. A biologist was having breakfast with his wife in a local restaurant when the server said that fish were falling from the sky. Naturally he went to look. He identified the fish as several different freshwater species common in the area, including two species of sunfish, a type of bass, and a few others, all ranging from 2 to 9 inches long, or 5 to 23 cm. It was a foggy but calm morning with no reports of tornados or strong winds in the area.

It’s possible that a small waterspout formed over one of the many nearby lakes, sucked up whatever fish happened to be in the wrong place at the wrong time, and deposited them a few miles away. Waterspouts form the same way tornados do except that it happens over water. The inside of a waterspout, like the inside of a tornado, is a low-pressure tunnel inside a high-pressure cone of air. It acts like a vacuum cleaner, sucking up water as it moves, and anything that’s in the water near the surface gets sucked up too.

There are two types of waterspouts. Tornadic waterspouts are tornados that happen to touch down over water instead of land. They can be dangerous and are usually reported in the local news and weather if they’re spotted. But fair-weather waterspouts aren’t associated with storms, although they do form ahead of developing storm systems. They’re typically smaller, much less dangerous, and much less likely to be reported to the news. So it’s possible that the 1947 fish fall was the result of a fair-weather waterspout.

This phenomenon isn’t something that used to happen in the olden days and doesn’t happen now. In June of 2009, there were tadpole rains in parts of Japan on two different days in slightly different areas. One man saw over a hundred dead tadpoles on car windshields in one parking lot after a rain shower.

On June 13, 2018, shrimp and possibly other sea creatures fell on the coastal city of Qingdao [zhing-daugh], China during a storm. The media reported it as a “seafood rain” since people posted photos of octopus, squid, starfish, mollusks, and shrimp that they claimed had fallen during the storm. Some of the photos are hoaxes, especially the ones of octopuses flying through the air, but at least some of them are real. Some people speculate that the source of the animals may have actually been a market stall, but since the city is on the coast of the Yellow Sea and the storm’s winds were measured at 77 mph, or 125 km per hour, it’s just as likely that the animals were lifted into the air from shallow water as from a market stall.

Sometimes we can figure out what the cause is of falling animals. In 2015 the Alaska Department of Fish and Game received four separate calls from people who’d found arctic lampreys on their property, including the parking lot of a store and someone’s front yard. If you remember from waaaaay back in episode 3, where we talked about the sea lamprey, lampreys are jawless fish with suckerlike mouths. They latch onto a fish and use their rasping teeth to parasitize it. The arctic lamprey grows to about a foot long on average, or 30 cm, but occasionally one will grow twice that long. It lives in cold freshwater lakes and rivers in the arctic, although it’s found as far south as Japan. An investigation revealed that all four lampreys found on land had cut marks and bruises in a specific pattern, which indicated that they’d been picked up in the beak of a seagull and then dropped, probably by accident when the lamprey wriggled too much. In 2015 there were an unusually high number of arctic lampreys in the Chera River, near where the four lampreys were reported on land.

A substance often referred to as star jelly or star rot has been seen in various parts of the world for centuries, usually connected in folklore with comets and shooting stars. In late 2008 through February 2009 the BBC’s Scotland Outdoors website collected photos and accounts of star jelly people had encountered in Scotland and other places. People reported finding lumps of the usually clear or white, jelly-like substance in their gardens, on walkways, on fence posts, stumps lawns, on the side of the road, in pastures, on rocks, and so on. One person found a lump of it on his tractor, another on a 3rd floor balcony.

Even hundreds of years ago some people suspected star jelly had something to do with frogs. At least some of it looks like the jelly-like matrix that surrounds the eggs of many frog and toad species. This is backed up by the presence of small black eggs in some star jelly that look like frog eggs. But it’s clearly not exactly frog spawn and is often found in places where a frog would never lay its eggs, even if it could for instance get up onto a third floor apartment balcony.

Many samples of star jelly have been examined by scientists and found to be the spawn jelly of frogs and toads, which is produced by the female to surround the eggs and keep them damp. As the female lays her eggs, each one is coated with a layer of spawn jelly, which absorbs water in the environment and increases in volume. Sometimes when a predator tears a frog or toad into pieces to eat it, the reproductive tract is torn open and its contents falls to the ground. When the spawn jelly is exposed to the air, it starts to absorb moisture from whatever it’s touching. This will make it swell up and become much more noticeable to people, especially if it’s rained and the spawn jelly has absorbed a lot of water.

Often an animal will eat a frog or toad, then later regurgitate the less digestible parts. This includes spawn jelly and some parts of the reproductive tract, specifically the oviducts since they contain the spawn jelly. Sometimes eggs are mixed in too. Star jelly has been examined and tested frequently, although most DNA testing has been inconclusive since samples are contaminated with bacteria. But a 2015 DNA test determined that the star jelly was from a frog. The test also found traces of magpie DNA, so we can probably guess what ate the frog.

Some star jelly doesn’t have anything to do with amphibians, though. Instead, some are slime molds or a type of freshwater algae-like bacteria known as nostoc. Neither slime molds nor nostoc fall from the sky but they can appear suddenly, so people may assume that’s what happened. Many birds that eat frogs and toads will eat them in midair, and may also regurgitate the indigestible portions while flying, so at least some star jelly does fall from the sky.

Sometimes people assume an animal has fallen from the sky when it actually hasn’t. For instance, the walking catfish will wriggle across dry land to find water when its pond dries up. It can grow up to 1 ½ feet long, or half a meter, and is usually grayish-brown with little white spots. Its skin is covered with mucus that helps keep it from drying out when it’s out of water. It’s native to parts of Southeast Asia, but it’s been introduced to other places, including southern Florida. In places where it’s not native, people may not be familiar with its ability to breathe air and move around out of the water, so when they see the walking catfish on land they may assume it fell from the sky.

The walking catfish is an invasive species in many areas. It’s an omnivore and can tolerate all kinds of habitats, including stagnant water where other fish can’t survive, since it can breathe air. Fish farmers in areas where the walking catfish lives have to put fences up around their ponds to keep walking catfish out. And if you see one, don’t pick it up. Its fins have spines that help stiffen them so it can use them to move more effectively on land, but that make them sharp.

We obviously don’t know everything about animals that fall from the sky, so let’s finish with a real mystery. It’s called the Kentucky Meat Shower and it happened on March 3, 1876 in a tiny community called Olympia Springs, Kentucky.

Olympia Springs is east of Lexington, Kentucky, in the southeastern United States. These days it’s in the Daniel Boone National Forest and just outside of the Olympia State Forest, so there’s not much in the area except wilderness. This was probably also the case in 1876 except that in 1876 there probably wasn’t a Dairy Queen restaurant a ten minute drive away. Wikipedia says it happened in a community named Rankin in the same county, but most other sources say Olympia Springs. Either way, it was an isolated, remote area at the time.

On this particular day, a woman only identified as Mrs. Crouch was in the yard, making soap. It was a perfectly clear day, not a cloud in the sky, when suddenly it started raining meat. She said it fell like big snowflakes all around her, but presumably not as pretty as snow, and lasted for several minutes. It was fresh meat, looked like beef or other red meat, and the pieces were irregularly shaped and gristly. Some were as big as 4 inches across, or 10 cm, but most about half that size. The meat landed all around, including on fences, in an area estimated to be about 100 yards across and 50 yards wide, or 91 by 46 meters.

Mrs. Crouch and her husband were understandably shaken by this event, and records don’t report whether the soap got finished that day but I suspect not. The next morning, the meat was still lying around, but it had dried out overnight and was starting to spoil. A couple of men stopped by and actually tasted it—ugh, I hope they at least cooked it first—and said they thought it might be venison or mutton. That’s meat from deer and sheep, respectively.

Samples of the meat were sent to various experts who examined it. Keep in mind that this was 1876 so they couldn’t do much more than look at it under an old-timey microscope. Two samples were identified as lung tissue, two as cartilage, and three as muscle.

As soon as the story hit the newspapers, people were quick to offer solutions that didn’t actually fit the reported facts. One person suggested that it was just nostoc that hadn’t actually fallen from the sky, it had been on the ground all along but that rain had made it swell up, which is something nostoc does. Never mind that nostoc is a slimy bacteria that looks nothing like meat—remember, it’s sometimes identified as star jelly—and that it wasn’t raining at the time and that Mrs. Crouch actually saw it fall and that pieces of it were found draped over fences. Plus, nostoc doesn’t taste like venison or mutton. Plus, samples were identified as actual meat.

The main suggestion is that some vultures were flying overhead and had disgorged some meat they had eaten, which had been caught by the wind and fell across a wide area. But while even nowadays people claim that is what must have happened, it has one big flaw. Vultures don’t disgorge meat while they’re flying. They disgorge it as a way to deter predators approaching their nest, and they may disgorge if a predator approaches while they’re feeding so they can get into the air quickly, but not while flying. Not only that, but any meat disgorged by a vulture would smell and taste horrible, since it would have already been rotting before the vulture ate it, and it would then be coated with caustic vulture digestive juices.

So what might have caused the Kentucky Meat Shower? If it wasn’t a newspaper hoax, which were really common in the late 19th century, it might have been the result of some poor animal that was swept up by a tornado, torn apart, and the smallest pieces dropped over the Crouch’s farm after the winds had dissipated. Presumably the heavier pieces, like bones, fell earlier and probably landed in the forest where no one saw them fall. I looked for a weather report for Kentucky for that day, but couldn’t find one. Eastern Kentucky is not too far north from where I live in East Tennessee, so I can verify that March can be a very warm month with unsettled weather. It wouldn’t be at all unusual to have a storm strong enough to generate a small but powerful tornado in March, although this usually happens at night after a hot day.

I don’t know if I believe the Kentucky Meat Shower really happened or if it was a hoax. But either way, we can stop blaming vultures.

You can find Strange Animals Podcast online 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 if you’d like to support us that way.

Thanks for listening!

Episode 136: Smallest of the Small

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Last week we learned about the smallest species of animals not typically thought of as small, like snakes and cetaceans. This week let’s look at some of the tiniest animals in the world, the smallest of the small!

Further watching:

A short video about jerboas. Really interesting and well-made!

A button quail:

Baby button quails are the size of BEES:

Kinglets are teeny birds even when grown up. Left, the golden-crowned kinglet. Right, the goldcrest. These birds MAY BE RELATED, you think?

The pale-billed flowerpecker, also teeny and with a cute name:

Moving on from birds, the pygmy jerboa is one of the smallest rodents in the world:

The Etruscan pygmy shrew is even tinier, probably the smallest known mammal alive today. Shown here with friend/lunch:

The Western pygmy blue butterfly is probably the smallest butterfly known:

But the pygmy sorrel moth is even smaller. Right: red marks left behind on a sorrel leaf eaten by its larvae:

One of the world’s teeniest frogs:

Show transcript:

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

Last week we learned about the smallest species of animals that aren’t typically thought of as small. But this week let’s learn about the smallest of the small animals. It’s like saying they’re the cutest of the cute animals. We’ll start with the bigger ones and get smaller and smaller as we go.

Let’s start with a bird. The smallest bird is the bee hummingbird, which we’ve talked about before. But there’s another bird that’s really small, the button quail. It’s about the size of a sparrow.

The button quail isn’t actually a quail, but it looks like one due to convergent evolution. There are a number of species in parts of Asia and Africa and throughout Australia. It generally lives in grasslands and is actually more closely related to shore and ocean birds like sandpipers and gulls than to actual quails, but it’s not very closely related to any other living birds. It can fly but it mostly doesn’t. Instead it depends on its coloring to hide it in the grass where it lives. It’s mostly brown with darker and lighter speckled markings, relatively large feet, and a little stubby nothing of a tail. It mostly eats seeds and other plant parts as well as insects and other invertebrates.

The button quail is especially interesting because the female is more brightly colored than the male, although not by much. In some species the female may have bright white markings, in some their speckled markings are crisper than the males. The female is the one who calls to attract a male and who defends her territory from other females. The female even has a special bulb in her throat that she can inflate with air to make a loud booming call.

The male incubates the eggs and takes care of the chicks when they hatch. Baby button quails are fuzzy and active like domestic chicken babies but they’re only about the size of a bumblebee. In many species, as soon as the female has laid her eggs, she leaves them and the male and goes on to attract another male for her next clutch of eggs.

People sometimes keep button quails as pets, specifically a species called the painted buttonquail or the Chinese painted quail. It’s about five inches long, or 12 cm. The female has black and white stripes on her face and throat. The birds can become quite tame and can live several years.

Button quails make a lot of different noises. This is what a button quail sounds like:

[button quail calls]

One of the smallest birds in the world that isn’t a hummingbird is the kinglet, with several species that live in North America and Eurasia. The goldcrest is a type of kinglet and the smallest European bird. It’s only 3.3 inches long, or 8.5 cm, although some individuals are larger. It looks a lot like the North American bird the golden-crowned kinglet, which is just a shade smaller at 3.1 inches, or 8 cm. Both species have a golden patch on the top of the head. The male also has an orangey spot in the middle of the golden patch. Both live in coniferous forests and eat insects and spiders.

Because kinglets are so small and active, they can starve to death quickly—in only an hour in some cases. Females lay up to 12 eggs at a time. TWELVE EGGS. That is a lot of eggs. The nest is too small to hold a dozen eggs in one layer so they end up in a pile. The female keeps all of them warm by pushing her legs down into the pile of eggs. Since her legs have a lot of blood vessels near the surface, they’re much warmer than most birds’ legs.

When the babies hatch, they stay in a pile. The ones on the top of the pile get fed first, naturally, but then they burrow down into the pile and push their siblings up toward the top. They’re not just being nice, though, since birds in the bottom of the pile stay warmer.

This is what a golden-crowned kinglet sounds like:

[bird call]

The pale-billed flowerpecker is even smaller than the kinglets and are among the smallest birds in Asia. It lives in parts of India and nearby areas and mostly eats berries, although it also eats flower nectar. It grows to only 3 inches long, or 8 cm, and is plain brownish-green in color with a short tail and shiny black eyes. It lives in forests but often visits gardens. It doesn’t lay a dozen eggs at a time, just an ordinary two or three.

This is what a pale-billed flowerpecker sounds like. These are some teeny sounds from teeny birds:

[bird call]

There are several rodents that are considered the smallest rodent, but we’re only going to learn about one of them today, the pygmy jerboa. On average it’s only 1.7 inches long, or 4.4 cm, not counting its extremely long tail.

The pygmy jerboa lives in the deserts of Pakistan and possibly in nearby areas too. It has very long hind legs and very short front legs so it hops like a tiny kangaroo, using its long tail as a way to balance and maneuver at high speeds. Its tail is twice as long as its body. Its large hind feet and the end of its tail are very furry to give it more surface area so it can easily maneuver through loose sand.

It mostly eats seeds and leaves, and it gets all the moisture it needs from the food it eats. It’s nocturnal and spends its days in the burrow it usually digs under bushes. Like many other tiny animals, when it rests it slows its metabolism drastically so it won’t starve to death while it’s asleep. Life is rough for tiny animals.

We don’t know a whole lot about the pygmy jerboa except that it’s endangered due to habitat loss, so let’s move on to an even smaller mammal.

The Etruscan shrew grows to about 1.6 inches long, or 4 cm, on average, not counting its short tail. The tail is about a third of the length of its body. It lives in southern Europe, parts of Asia, parts of the Arabian Peninsula, and northern Africa and prefers warm, moist climates. It’s the same size and weight as the bumblebee bat we talked about last week, so it’s one of the smallest mammals known.

The Etruscan pygmy shrew is pale brown with a lighter colored belly, a long nose, and short whiskers around its mouth that it uses to help it find its prey. It’s incredibly active and makes clicking noises almost constantly, as a way to alert other shrews that it’s there and is willing to defend its territory. It makes its nest among rocks and in the abandoned burrows of other animals.

Like the kinglets and other highly active, tiny animals, it has to eat a lot to keep its metabolism going—up to twice its own weight in food every day. It can also enter a torpid state where it reduces its body temperature and metabolism the same way the pygmy jerboa does, in order to not starve while it sleeps. But the Etruscan shrew doesn’t rest very often.

It mostly eats insects and other invertebrates like earthworms, but it will eat anything it can kill. This includes lizards, small rodents, and frogs. It especially likes grasshoppers and crickets, which are often as large as it is. In order to kill prey its own size, the shrew is incredibly fast. If you remember episode 82 where we talked about the star-nosed mole, the Etruscan shrew primarily hunts by touch and can react in barely 25 milliseconds when it touches something it wants to eat. It takes something like 300 milliseconds for a human to blink their eyes, if that gives you an idea of how fast the shrew is. It can touch a cricket and kill it in less time than it takes to blink.

So that’s as small as mammals get, as far as we know. What’s the smallest amphibian?

Well, it’s really, really small. The smallest known frog is only 7.7 mm long. Paedophryne amauensis isn’t just the smallest frog, it’s the smallest vertebrate known. It was only discovered in 2009 in Papua New Guinea.

It sounds like an insect and lives in the damp leaf litter on the forest floor, and it’s dark brown and black in color to blend in with dead leaves, so it was hard to find. Researchers only found it by using sensitive microphones to triangulate on its call, then quickly scooping up lots of leaf litter and stuffing it into plastic bags so anything living in the leaves couldn’t escape. Its eggs hatch into tiny froglets instead of tadpoles.

The tiniest frog is just about the same length as the tiniest fish, the stout infantfish that lives in a few coral reefs near Australia, including the Great Barrier Reef. It also grows 7.7 mm long on average, although females are typically longer and it can grow as much as 10 mm long. But the smallest known fish is the male of an anglerfish species that only grow 6.2 mm long. This doesn’t really count, though, since females grow up to two inches long, or 50 mm. Like other deep-sea anglerfish species, when a male of Photocorynus spiniceps finds a female, he bites her and stays there. Eventually his mouth actually fuses to her body and he lives the rest of his life as a sort of parasitic extension of the female. He supplies her with sperm to fertilize her eggs before she lays them, and she supplies him with nutrition and oxygen since he’s basically part of her body at that point. A female can have more than one male fused to her.

So, we seem to have reached the smallest vertebrates. What about the smallest insects and other invertebrates?

Butterflies are generally pretty small, but the smallest butterfly known is really, really small. The Western pygmy blue butterfly only has a wingspan of 20 mm at most but usually more like 12 mm across. That’s less than an inch. It lives in western North America and parts of the middle east, and has even been found on Hawaii. Its wings are a pretty coppery brown color with rows of black and white spots. It likes deserts and waste places where you wouldn’t expect to find anything as delicate as a tiny butterfly. Its caterpillars eat various types of weed plants.

That is pretty much it. There’s not much to this tiny butterfly. The real mystery is why it’s called the western pygmy blue when it’s not actually blue.

Compared to the smallest moth known, the western pygmy blue butterfly is a giant. The smallest moth is the pygmy sorrel moth and its wingspan is barely four millimeters. Its wings shade from silvery with a metallic bronze tint to purply with a white stripe, and gray along the ends. It’s really pretty but so tiny that it’s hard to spot. It lives in much of Europe and its larvae leave distinctive spiral shapes on sorrel leaves as it eats.

We’ll come back to insects in a minute or two, but let’s look at a few snails first. The smallest land snail is the Borneo snail. Its shell is only .7 of a mm high. It was only discovered in 2015. We don’t know a lot of about it yet, but it probably eats bacterial film growing on limestone in caves. So far researchers haven’t even found a living Borneo snail, though, just its shells.

The smallest water snail is even smaller than the Borneo snail. It’s from North America and its shell is only half a millimeter across at the most. Some individuals are only .3 mm across. Ammonicera minortalis lives in shallow water off the coast of southern Florida and around Cuba and other islands in that area. And that’s pretty much all we know about it. It’s a lot easier to study bigger animals just because they’re easier to find.

Small as that is, on average the smallest beetle is smaller than the smallest snail. It’s a type of featherwing beetle only described in 1999, and on average it’s .338 mm long. So far it’s only been found in Central America and it eats fungus. It’s yellowish-brown in color but that doesn’t really matter because it’s so small that you need a magnifying glass to really see it.

Once you start dividing millimeters, you’re getting into ridiculously tiny territory. But the smallest insect is a type of wasp known as a fairyfly. Kikiki huna is so small it’s measured in micrometers, sometimes called microns, and is smaller than some single-celled organisms. It’s only 150 micrometers long, which is shorter than an ordinary piece of printer paper is thick. It’s been found on Hawaii, Costa Rica, and Trinidad but it probably lives in other places but just hasn’t been found yet. Some researchers suspect that it’s as small as a flying animal can become without losing the ability to fly under its own power instead of just floating on the wind.

At this point anything smaller than Kikiki huna and its close relatives are made up largely of bacteria, which are frankly not as cute or as interesting as, say, button quail. So let’s finish with what may be the very smallest living organism ever found. Or it may not be. Because researchers are literally not even sure if the nanobe is even alive.

In 1996 researchers found what looked like filiments growing among rock samples collected from wells off the Australian coast. Some of them were only 20 nanometers in diameter. To put that into perspective, a nanometer is one billionth of a meter. That’s billion with a B. It’s one thousandth of a micrometer. A nanobe is a tenth of the size of the smallest known bacteria.

The researchers weren’t sure what they’d found so they did a lot of tests. They thought they might have discovered a new kind of crystal, but when they stained the nanobes with a type of dye that binds to DNA, the results indicated the nanobes might be living organisms. But no DNA has been successfully recovered from nanobes.

There’s still a lot of research to be done to determine what they are and if they’re actually alive, though. The main problem is that nanobes appear to be too small to contain all the things that living organisms need. But they do resemble fungi in some ways, just much, much smaller. If nanobes are alive, they’re extremely different from any living animal ever known and presumably live and reproduce in ways completely unlike all other life.

But here’s an interesting note. In 1996 researchers found structures inside a meteorite from Mars that look a lot like nanobes.

You can find Strange Animals Podcast online 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 if you’d like to support us that way.

Thanks for listening!

Episode 133: The mangrove killifish and the unicorn pig

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This week’s (short) episode is about two animals that should have been in the strangest small fish and weird pigs episodes, respectively. I left them out by accident but they’re so interesting that they deserve an episode all to themselves anyway. Thanks to Adam for suggesting the mangrove killifish!

Further reading:

25 Years in the Mud: How a Quirky Little Fish Changed My Life

The mangrove killifish just looks normal:

Not a unicorn pig (okay yes technically a unicorn pig):

Unicorn pig skull:

Show transcript:

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

A few weeks ago we had an episode about strange small fish. Shortly after that episode released, I was going through my disorganized ideas and suggestions file and realized I’d left out one of the best weird small fish ever, a suggestion by Adam. I also discovered I’d missed an extinct pig I’d planned to include in the recent weird pigs episode. So let’s play catch up in a short episode and learn about both this week.

The fish Adam suggests is called the mangrove killifish, also called the mangrove rivulus, which lives in parts of Florida and Mexico, down to Central and South America. It’s technically a marine fish, meaning it lives in salt-water, but it also likes brackish water, that’s less salty than the ocean, and occasionally it even lives in freshwater. It especially likes mangrove swamps. It grows up to 3 inches long, or 7.5 cm and is a mottled brown in color with an eye spot on its tail. It doesn’t look like anything special.

But the mangrove killifish has a lot in common with amphibians, especially the lungless salamanders. Many types of salamander absorb air through the skin instead of through lungs or gills. The mangrove killifish does this too. It often lives in abandoned crab holes, which may not have very high quality water. But that’s okay, because it can absorb air through its skin and can live out of the water for well over a month as long as its skin stays damp. It’s sometimes found in places where you wouldn’t expect to find a fish, like the inside of rotting logs or buried in damp dead leaves.

So how does the killifish get into the rotting logs or the leaf litter or the crab burrows that aren’t connected to waterways? It actually uses its tail to flip itself out of the water and onto land, and then it continues to flip here and there until it finds a place where it wants to live for a while. It can direct this jumping, not just flop around like most fish out of water, and can jump several times its own length.

A lot of times when the tide goes out, fish get trapped in crab holes, dimples in the sand or mud, and other shallow water. That’s okay if the tide comes back in far enough to re-submerge the holes, but if the water doesn’t quite reach, it’s not long before fish start to suffocate as all the oxygen in the water is used up. But the killifish doesn’t have that problem. It just flips itself out of the water. It can also leave the water if it gets too hot.

The killifish is also territorial in water, which requires a lot of energy. When it’s out of the water, or in a little temporary pool or a crab burrow where it doesn’t have to worry about other killifish, it can relax. On the other hand, it loses a lot of weight while it’s out of the water since it doesn’t eat as much. So there are trade-offs.

Even the killifish’s eggs can survive out of water. The fish usually lays its eggs in shallow water, sometimes even on land that’s just near water. The eggs continue to develop just fine, in or out of water, but they delay hatching until they’re submerged.

And that leads us to the most astonishing thing about the mangrove killifish. In most populations, almost all killifish are females, and most of the time they don’t need a male fish to fertilize their eggs. Females produce eggs but they also produce sperm that fertilize the eggs before they’re even laid. The eggs hatch into genetic duplicates of the parent—clones, basically. The term for an organism that produces both eggs and sperm is hermaphrodite, and while it’s common in some invertebrates, the killifish is the only known vertebrate hermaphrodite. Vertebrate, of course, is an animal with a backbone.

But while most killifish are females, there are occasionally males. Male killifish are orangey in color. When a male is around, females suppress their ability to self-fertilize eggs and they lay the eggs for the male to fertilize, just like any other fish. This helps keep the species genetically diverse and able to adapt to external pressures like increased numbers of parasites.

Next, let’s talk about the unicorn pig. Or pigicorn, if you like. It’s called Kubanochoerus [koo-ban-oh-ko-rus] and there were several species. It was related to modern pigs and lived throughout most of Eurasia and parts of Africa around 10 million years ago.

It was big, up to four feet tall at the shoulder, or 1.2 meters, and had tusks like other pigs. It probably looked a lot like a wild boar. But its skull is longer than modern pig skulls and it had horns. Three horns, specifically. Two of the horns were small and grew above the eyes, while a bigger horn grew forward from its forehead. The forehead horn wasn’t very long and was probably blunt. Researchers used to think males used these forehead horns to fight each other, but females had them too so they may also have been used for defense from predators.

That is literally all I can find out about this fascinating animal. I can’t even speculate about the horns since literally no other pig has horns, at least that I can find. Presumably the warty protrusions that many modern pig species have are similar to the horns that Kubanochoerus had. The eyebrow horns might have had the same purpose as the facial protrusions on warthogs and other pigs, as a way to protect the eyes when the pigs fight. The forehead horn, though…well, that’s just weird. It probably wasn’t covered with keratin, but we don’t know. My own guess is that it was something more like an ossicone and was covered with skin and hair. But again, we don’t know. Not until we invent a working time machine and go back to look at one.

That’s it, a very short episode. I’m actually in Dublin, Ireland right now attending WorldCon, so while I’m here I will keep an eye out for leprechauns, fairies, and pigicorns, just in case.

You can find Strange Animals Podcast online 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 if you’d like to support us that way.

Thanks for listening!

Episode 130: Strangest Small Fish

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This week we’re going to revisit a suggestion from Damian and follow up on episode 96, our strangest big fish episode. This time let’s find out about some weird small fish!

The teeny, newly-discovered American pocket shark:

The brownsnout spookfish wears its mirror sunglasses on the INSIDE:

The goblinfish with a dangerous head and basically a dangerous everything else too:

Two teeny pygmy seahorses. Can you spot them? Hint: they’re the ones with eyes.

The razorfish. Just another sea urchin spine, no fish to see here:

The much-maligned candiru:

The red-lipped batfish:

Gimme kiss:

Show transcript:

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

Ages ago, Damian suggested an episode about weird fish. We covered some weird big fish in episode 96, but now it’s time for some weird little fish.

So, think about sharks for a second. Big, scary, sharp teeth, fast swimmers, black eyes of a pitiless killer of the deep.

But have you perhaps considered that maybe the world needs a very small shark? One that actually kind of looks like a tiny whale? Like, a tiny shark, only about 5 ½ inches long, or 14 cm. Almost, you know, pocket sized. Oh, and it should glow in the dark.

That’s the American pocket shark, a real animal that was only discovered in 2010! It’s called a pocket shark not because it’s pocket sized, although it is, but because it has a sort of pocket on each side near its gills that produces luminous fluid. Researchers aren’t sure whether the shark uses the fluid for attracting prey or avoiding predators. Maybe both. Its head is bulbous and rounded, which kind of makes it look like a tiny whale.

The American pocket shark was discovered in the Gulf of Mexico while scientists were observing sperm whales and tracking them with sonar. When a whale surfaced from a dive, the research team dropped nets to the depth the whale had dived to, hoping to catch the same kind of prey the whales were eating. And one of the things they found in the net was a tiny shark new to science, found at a depth of 3,000 feet, or 914 meters.

In 2013 the tiny shark, which had been frozen for later study, was finally examined. The expert who looked at it had only seen one other shark like it before, a shark discovered in the eastern Pacific in 1979. But this tiny shark had some differences from that tiny shark, and after examining both specimens carefully, they’ve been classified as different species.

So that’s a cute start, but it’s still just a rare little shark that glows. Not really that unusual, right? Let’s look at a really weird fish next. Like, seriously weird.

It’s called the brownsnout spookfish, which is a really terrible name, but it’s not a terrible fish. I mean, it couldn’t hurt you. It grows about 7 inches long, or 18 cm, and eats copepods and other tiny crustaceans. Its snout is long and kind of pointy, its body is slender, and it has elongated pelvic fins. Because it lives in the deep sea, it has eyes that point upward, which help it see predators and prey that might be silhouetted against the far-distant surface of the ocean. But it also has something only one other fish is known to have, an extra structure to the side of the eyeball. It’s called a diverticulum and it does two things. First, it allows the fish to see downward in addition to upward, and second, it allows it to see across a really wide angle. The diverticulum does this because it contains a mirror that reflects light from the main eyeball onto the retina of the diverticulum. A MIRROR IN ITS EYEBALLS. The mirror is made up of tiny crystalline plates.

Some invertebrates like clams and crustaceans contain reflectors in their eyes, but except for the brownsnout spookfish, the only other vertebrate known to have mirrored eyeballs is the glasshead barreleye. Also a terrible name. The glasshead barreleye is a little smaller than the brownsnout spookfish, and not surprisingly, they’re related. But surprisingly, they’re not that closely related and the mirrored diverticulum appears to have evolved independently in each species.

Although the fish has been known to science for over a century, no one realized it had mirrors in its eyes until 2008 when a live one was caught by a deep-sea scientific expedition off the island of Tonga in the Pacific Ocean. Researchers took pictures of the brownsnout spookfish and got a shock when they looked at the photos. The upward-pointing parts of the eye reflected light normally, the typical eyeshine you get when you use a flash to photograph most animals. But the lower parts of the eyes reflected bright light. Researchers think the fish uses its downward-pointing eyes to see the faint bioluminescent flashes of its prey, while the upward-pointing eyes watch for predators approaching from above.

Oh, and I forgot to mention. The brownsnout spookfish is mostly transparent. You can see right through it. Yeah.

After that, the goblinfish that lives around reefs off the southern coast of Australia seems practically normal. It grows up to 8 inches long, or 20 cm, and spends most of its time resting among rocks on the seabed. It hunts at night, eating small crustaceans, and instead of swimming it usually walks along the sea floor with its large pectoral fins.

The goblinfish gets its name from its appearance, which is frankly ugly unless you are another goblinfish. Its head looks sort of turtle-like, including a dip in its body behind its eyes and in front of its dorsal fin that looks like a turtle’s neck. Its eyes are large and orange in color. Its dorsal fin is spiny and runs most of the length of its back. It also has broad pectoral fins that it sometimes spreads like fans. It can change color to blend in with the rocks around it, which makes it hard for divers to see, which is too bad because it’s also venomous.

It’s a type of waspfish, related to scorpionfish and stonefish, all of which are venomous. Like many of those other fish, the goblinfish has venomous spines on its fins, but it also has a spine on each side of its head, underneath its eyes. Only these spines are hidden inside the fish’s head. The spine is called a lachrymal saber, and it acts like a switchblade that the fish can extend with its cheek muscles. The lachrymal saber isn’t venomous, but if you’ve just picked one up by the head and those switchblades come out, you probably aren’t going to be happy anyway. Also, why did you just pick that fish up by its head? What is wrong with you?

Next, let’s talk about the seahorse. It’s a fish although it doesn’t look like an ordinary fish. And in fact nothing about the seahorse is ordinary.

Unlike most fish, the seahorse has a flexible neck. Also unlike almost all other fish it swims vertically, with its head up and its tail down. It has a prehensile tail made up of 36 bony segments, and each segments is made of four pieces connected by tiny joints. The joints make the segments incredibly strong and able to withstand considerable pressure without breaking. The seahorse uses its tail to hold onto seaweed or other items to keep from being swept away in currents, since it isn’t a strong swimmer. It propels itself through the water by fluttering its dorsal fin, using its pectoral fins to steer. Males also fight each other by tail-wrestling and bopping their heads together. The seahorse’s body is protected with an external skeleton of bony plates, which take the place of ribs. The seahorse doesn’t have ribs. It also doesn’t have scales, just the bony plates with thin skin over them.

The seahorse lives in warm, shallow oceans throughout the world, especially in coral reefs and seagrass beds where there’s plenty of cover. The largest seahorse species grow to about 14 inches long, or 35 cm. The smallest species are barely more than half an inch long, or 15 mm. The smallest species are mostly new to science since they’re so hard to find and identify. Seahorses are well camouflaged to blend in with the plants and coral they live in.

The seahorse’s mouth is at the end of a long, tubelike snout, and it actually sucks its prey into its snout like a straw. It eats small crustaceans, larval fish, and other small animals. Oh, and its eyes can move independently of each other.

Seahorses don’t mate for life, but they do form bonds that last throughout the breeding season, and it has a long courtship period while the female develops her eggs. The pair participate in courtship dances and spend most of their time together. When the eggs are ready, the female deposits them in a special brood pouch in the male’s belly, where he fertilizes them. They then embed themselves in the spongy wall of the brood pouch and are nourished not only by the yolk sacs in the eggs, but by the male, who secretes nutrients in the brood pouch. So basically the male is pregnant. The female visits him every day to check on him, usually in the mornings. When the eggs hatch after a few weeks, the male expels the babies from his pouch and they swim away, because when they hatch they are perfectly formed teeny-tiny miniature seahorses.

If you’re wondering why I said the seahorse is almost the only fish that swims vertically, there’s some evidence that the oarfish does this too. We talked about the oarfish way back in episode 6, about sea monsters. But there’s another fish that swims vertically, the razorfish—but it swims with its head pointed down and its tail pointed up. It’s a slender fish that grows about six inches long, or 15 cm, with a pointy nose and tiny fins. Its back is protected by bony plates that extend past the tail fin in a spine. It eats tiny animals, including brine shrimp, AKA sea monkeys. When it feels threatened, the razorfish swims to the nearest sea urchin and hides among its spines, blending in with them. Schools of razorfish will swim around together, all of them head-down, because that’s just what they do.

Not all weird fish live in the ocean. A lot of freshwater fish are weird too. For instance, the candiru [kan-DEE-roo]. You’ve probably heard of this one although you may not know what it’s called. It’s native to the Amazon and Orinoco Rivers in South America and it’s actually a type of catfish. Some species grow over a foot long, or around 40 cm, but the species we’re talking about today, Vandellia cirrhosa, grows less than two inches long, or 5 cm. Like the brownsnout spookfish, it’s mostly translucent so it’s hard to see in the water. It has short spines on its gill covers that point backwards.

Unlike other catfish, the candiru eats blood, which gives it its other name of the vampire fish. It parasitizes other fish by lodging itself in their gills and sucking their blood. But the candiru is supposed to do something else, something that happens by accident. The story goes that if someone pees while in the water and a candiru is around, it’ll swim up the stream of urine, attracted by the smell, and lodge itself in the urethra of the person peeing. It’s supposed to do this thinking it’s entering the gills of a fish. Its spines keep it locked in place, causing intense pain to the person, followed by infection and, if the fish isn’t surgically removed, death.

At least, that’s the story. There’s even a 1997 video of a man who had to have a candiru removed from his penis after he peed while wading in a river in Brazil. The doctor filmed the surgery and even kept the fish he removed, preserved in formaldehyde. So it must be true, right?

Maybe not. One study determined that the candiru isn’t interested in the chemicals present in urine and in fact it hunts by sight, not smell. And a study of medical reports throughout South America only found a single instance of anyone reporting a candiru attack. That instance is the same one from 1997 where the surgery to remove the fish was filmed.

But a further study of the surgery, photos, and preserved candiru specimen tell a different story. The human urethra is extremely narrow and the preserved fish was much too large to enter without squishing itself to death, not to mention that the candiru is just not strong enough to muscle its way into anything but a larger fish’s gills. The doctor also said he’d had to cut off the candiru’s spines before removing it, but the specimen is fully intact, spines and all. It sounds like the video may be a hoax of some kind.

Reports of candiru attacks are common in parts of South America today and have been common as far back as recorded history, but they seem to be more of a legend than something that happens a lot or maybe even at all. Still, probably better not to pee into the Amazon River, just in case.

Let’s finish with the red-lipped batfish, a type of anglerfish only found around the Galapagos Islands in the Pacific Ocean. It lives on the ocean floor where the water is fairly shallow, and it grows about 8 inches long, or 20 cm. It’s usually a mottled brown, green, or grey with a white stomach, but its mouth is bright red. It looks like it’s wearing lipstick. It eats fish and other small animals, which it attracts using a lure on its head, a highly modified dorsal fin called an illicium.

The weirdest thing about the red-lipped batfish is actually its fins. It prefers to walk on the bottom of the ocean instead of swim, and it has modified pectoral fins called pseudolegs. The pseudolegs make it look a little bit like a weird frog with a tail, a unicorn horn, and lipstick. It’s like something out of a fever dream, honestly.

Researchers think the red lips may be a way to attract potential mates, presumably ones who are hoping for a big smooch.

You can find Strange Animals Podcast online at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. We’re on Twitter at strangebeasties and have a facebook page at facebook.com/strangeanimalspodcast. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. We also have a Patreon if you’d like to support us that way.

Thanks for listening!

Episode 122: Strange Shark Ancestors

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This week let’s learn about some ancestors of sharks and shark relatives that looked very strange compared to most sharks today!

Stethacanthus fossil and what the living fish might have looked like:

Two Falcatus fossils, female above, male below with his dorsal spine visible:

Xenacanthus looked more like an eel than a shark:

Ptychodus was really big, but not as big as the things that ate it:

A Helicoprion tooth whorl and what a living Helicoprion might have looked like:

Show transcript:

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

This week we’re going back in time again to learn about some animals that are long-extinct…but they’re not land animals. Yes, it’s a weird fish episode, but this one is about shark relatives!

The first shark ancestor is found in the fossil record around 420 million years ago, although since all we have are scales, we don’t know exactly what those fish looked like. The first true shark was called Cladoselache [clay-dough-sell-a-kee] and lived around 370 million years ago, at the same time as dunkleosteus and other massive armored fish. We covered dunkleosteus and other placoderms back in episode 33. Cladoselache grew up to four feet long, or 1.2 meters, and was a fast swimmer. We know Cladoselache ate fish because we have some fossils of Cladoselache with fish fossils in the digestive system—whole fish fossils, which suggests that cladoselache swallowed its prey whole. Cladoselache also had fin spines in front of its dorsal fins that made the fins stronger, but unlike its descendants, it didn’t have denticles in its skin. It didn’t have scales at all.

The denticles in shark skin aren’t just protection for the shark, they also strengthen the skin to allow for the attachment of stronger muscles. That’s why sharks are such fast swimmers.

[Jaws theme]

Stethacanthidae was a family of fish that went extinct around 300 million years ago. It was related to ratfish and their relatives, including sharks. Stethacanthus is the most well-known of the stethacanthidae. It grew a little over 2 feet long, or 70 cm, and was probably a bottom-dwelling fish that lived in shallow waters. It ate crustaceans, small fish, cephalopods, and other small animals.

We have some good fossils of various species of Stethacanthidae and they show one feature that didn’t get passed down to modern ratfish or sharks. That’s the shape of its first dorsal fin, the one that in shark movies cuts through the water just before something awful happens.

[Jaws theme again]

Stethacanthidae’s dorsal fin was really weird. It was shaped sort of like a scrub brush on a pedestal, with the bristles sticking upwards, which is sometimes referred to as a spine-brush complex. Researchers aren’t sure why its fin was shaped in such a way, but since it appears that only males had the oddly shaped fin, it was probably for display. It also had a patch of the same kind of short bristly denticles on its head. Males also had a long spine that grew from each pectoral fin that was probably also for display. Some researchers think the males fought each other by pushing head to head, possibly helped by the odd-shaped dorsal fin.

In the past, before researchers figured out that only the males had the strange dorsal fin, some people suggested that the fish may have used the fin as a sucker pad to attach to other, larger fish and hitch a ride. This is what remoras do. Remoras have a modified dorsal fin that is oval-shaped and acts like a sucker. The oval contains flexible membranes that the remora can raise or lower to create suction. The remora attaches to a larger animal like a shark, a whale, or a turtle and lets the animal carry it around. In return, the remora eats parasites from the host animal’s skin. But remoras aren’t related to sharks.

Other shark relatives had dorsal spines. Falcatus falcatus lived about the same time as Stethacanthus, around 325 million years ago. It grew up to a foot long, or 30 cm, and ate shrimp, fish, and other small animals. We have so many fossils of falcatus from the Bear Gulch Limestone deposits in Montana that we know quite a bit about it. It probably detected prey with electroreceptors on its snout like many modern sharks do, and it was probably a fast swimmer that could dive deeply. Its eyes are unusually large for a shark too. Females would have looked like a small, slender sharklike fish, but males had a spine that grew forward from just behind its head, sort of like a single bull’s horn. It’s called a dorsal spine and is actually a modified dorsal fin. It was probably for display, although males may have also used it to fight each other. We have a well preserved fossil of a pair of falcatus together, a male and female, where it looks like the female may be biting the male’s dorsal spine. Some researchers suggest the spine was used in a pre-mating ritual, but it’s probable that the fish just happened to die next to each other and no one was actually biting anyone.

Another shark relative with a dorsal spine is Hybodus, which grew up to 6 ½ feet long, or 2 meters. Hybodus was a successful genus of cartilaginous fish that lived from around 260 million years ago up to 66 million years ago. Researchers think its dorsal spine was used for defense since both males and females had the spine. Hybodus would have looked like a shark but its mouth was relatively small. It probably ate small fish and squid, catching them with the sharp teeth in the front of its mouth, but it also probably ate a lot of crustaceans and shellfish, which it crushed with the flatter teeth in the rear of its mouth.

Xenacanthus had a dorsal spine too, but it was a much different shark ancestor from the ones we’ve talked about so far. It lived until about 208 million years ago in fresh water. It grew to about three feet long, or one meter, and would have looked more like an eel than a shark. It was slender with an elongated body, and its dorsal fin was short but extended along the back down to the pointed tail. This suggests it probably swam like an eel, since eels have a similar fin structure. It probably ate crustaceans and other small animals.

Xenacanthus’s spine grew from the back of the skull and, unusually for a shark relation, it was made of bone instead of cartilage. Both males and females had the spine and some researchers suggest that it may have been venomous like a sting ray’s tail spine.

Rays are closely related to sharks, and if you want to see a fish that makes every single weird extinct shark look normal, just look at a sawfish. The sawfish is a type of ray and it’s alive today, although it’s endangered. I’m going to do a whole episode on rays pretty soon so I won’t go into detail, but the sawfish isn’t the only fish alive today with a long snout with teeth that stick out on either side. The sawshark is related to the sawfish but is actually a shark, not a ray. And there’s a third type of fish with a saw, related to both sawfish and sawsharks, called the Sclerorhynchidae. Sclerorhynchids went extinct around 55 million years ago and are considered part of the ray family, although they’re not ancestors of living rays. Sclerorhynchids grew around three feet long, or about a meter, and probably looked a lot like modern sawfish although with a rostrum, or snout, that was more pointed and less broad than most sawfish rostrums. The teeth that stuck out to either side were also relatively small. Researchers think Sclerorhynchids used their saws the same way modern sawfish and sawsharks do, to find small animals living on or near the bottom in shallow water and slash them to death before eating the pieces.

[Jaws theme again]

Most of the shark relatives we’ve talked about so far were pretty small, certainly compared to sharks like the great white or megalodon, which by the way we covered in episode 15 along with the hammerhead shark. But a shark called Ptychodus grew up to 33 feet long, or ten meters. It went extinct about 85 million years ago. Its dorsal fin had serrated spines and its mouth had lots and lots of really big teeth–up to 550 teeth, but they weren’t sharp. Instead, they were flattened with riblike folds that helped Ptychodus crush the mollusks it ate. It probably also ate squid and crustaceans, along with any carrion it might come across. It lived at the bottom of the ocean, but in relatively shallow areas where there were plenty of mollusks but not too many mosasaurs or other sharks that might treat Ptychodus as a nice big meal.

In episode 33, the one about dunkleosteus, we also talked about helicoprion and some of its relations. Helicoprion looked like a shark but was actually less closely related to true sharks than to ratfish. Helicoprion lived until about 250 million years ago and some researchers estimate it could grow up to 24 feet long, or 7.5 meters.

Instead of a weird dorsal fin, helicoprion had weird teeth. Weird, weird teeth. It had a tooth whorl instead of the regular arrangement of teeth, where its teeth grew in a spiral that seems to have been situated in the lower jaw. It looked like the blade of a circular saw. Now, this is bizarre but it’s not really all that much more bizarre than sawfish teeth, which aren’t even inside the mouth and stick out sideways. But the frustrating thing for researchers is that we still don’t have any helicoprion fossils except for the teeth whorls and part of one skull. Like most sharks and shark relatives, almost all of helicoprion’s skeleton was made of cartilage, not bone, and cartilage doesn’t fossilize very well. So even though helicoprion was widespread and even survived the Permian-Triassic extinction event, we don’t know what it looked like or what it ate or how exactly its tooth whorl worked. But I think it’s safe to say that it would not be good to be bitten by helicoprion.

[stop playing the Jaws theme omg]

You can find Strange Animals Podcast online at strangeanimalspodcast.com. We’re on Twitter at strangebeasties and have a facebook page at facebook.com/strangeanimalspodcast. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. We also have a Patreon if you’d like to support us that way.

Thanks for listening!

[Jaws theme again]

Episode 121: Cave Dwelling Animals

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This week let’s learn about some animals that live in caves!

The dipluran Haplocampa:

Oilbirds and their big black eyes:

A swiftlet:

The angel cave fish that can walk on its fins like a salamander walks on its feet:

Leptodirus, carrying around some air in its abdomen in case it needs some air:

The cave robber spider and its teeny hooked feet:

The devils hole pupfish:

Show transcript:

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

Way back in episode 27 we learned about some animals that live deep in caves. Cave dwelling animals are always interesting because of the way they’ve adapted to an unusual environment, so let’s learn about some of them!

We’ll start with an invertebrate. Diplurans are common animals that are related to insects but aren’t insects. They live all over the world, with hundreds of species known to science, but most people have never seen one because of where they live. They like moist, dark areas like soil, dead leaves, and caves. They’re also small, usually only a few millimeters long, although a few species grow larger, up to two inches long, or five cm.

Diplurans have long bodies with a number of segments, six legs, long antennae, and a pair of tail appendages called cerci. Depending on the species, the cerci may just be a pair of straight filaments like an extra pair of antennae, or they may look like pincers. Diplurans with pincer-like cerci use them to help capture prey, while ones with antennae-like cerci eat fungi and plant material.

Diplurans also don’t have eyes. They don’t need eyes because they live underground where there’s little or no light. A lot of species are pale in color or lack pigment completely.

Diplurans have been around for something like 350 million years, although we don’t have very many fossil diplurans. But recently, a new species of dipluran was discovered in North America that has raised some interesting questions.

Vancouver Island is a large island on the west coast of Canada, near the city of Vancouver. It’s prone to earthquakes and contains a lot of caves, and last summer, in June of 2018, a party of cavers and scientists explored two of the caves and found a new dipluran, which has been named Haplocampa wagnelli. This dipluran is chunkier than most other known diplurans, with shorter antennae, which researchers think points to a more primitive body plan. Since the dipluran is so different from most other diplurans known, and because the caves where it was found were under a thick ice sheet until around 18,000 years ago, researchers are trying to figure out if it found its way into the caves after the ice sheet melted or if it survived in the caves while they were buried under ice.

Haplocampa seems to be most closely related to a few diplurans found in Asia. Asia was connected to western North America during the Pleistocene when sea levels were much lower, since so much of the world’s water was frozen, so it’s possible the ancestors of Haplocampa migrated from Asia after the ice sheets started to melt but before the Bering Land Bridge was completely submerged. Possibly its eggs were accidentally transported by birds who foraged in leaf litter where its ancestor lived.

A lot of animals that live in caves are only found in one particular cave system. This happens when a species of animal that lives near a cave moves into the cave, either full-time or part-time. As its descendants grow up, they become more and more adapted to cave life, until eventually they couldn’t live outside of the cave. Since there’s no way for them to travel from one cave system to another, they are confined to that single cave. And since caves are largely difficult for humans to explore, that means there are lots and lots and lots of animals unknown to science living out their quiet lives deep within caves where humans have never visited. Every so often a group of adventurous and brave scientists explore a cave and discover new animals, usually with the help of experienced cavers.

Animals that are endemic to a specific cave system are rare to start with and vulnerable to any changes in the cave environment. The Tumbling Creek cave snail is only found in a single stream in Tumbling Creek Cave in Missouri, in the United States. It lives its whole life in the water and is only about 2 millimeters in size, with a pale yellowish shell. When it was first discovered in 1971 it was common. Thirty years later, researchers could only find about forty of the snails due to water pollution.

Caves aren’t very friendly environments. Most of the animals that live in caves are very small as a result. Lots of insects and spiders live in caves, some snails, lots of fish, lots of crustaceans that live in fresh water, like crawdads and amphipods, and some salamanders. But the only mammals and birds that live in caves leave the cave to hunt or forage outside of it, like bats. There just isn’t enough food inside a typical cave to sustain a population of larger animals.

So what do cave animals eat? Obviously they eat each other, but without plants a cave system is definitely lacking in organic matter that can sustain populations of animals. Nutrients enter a cave primarily in two ways. Water flowing into a cave brings nutrients from outside, and animals that mainly live outside but sleep in caves also bring nutrients in. In the case of animals, their poop is a major source of organic material, with dead animals also contributing to the cave’s ecosystem. Bats in particular support a lot of cave animals with their poop, which is called guano, but bears, hyenas, and various other animals, birds, and insects also spend time in caves, either to sleep or to hibernate, and bring nutrients in from outside in one way or another.

There are two birds that spend time in caves, and I’m going to talk about both of them briefly even though technically they don’t live in caves, because they’re so interesting. Both birds are nocturnal and can echolocate like bats. The oilbird lives in parts of northern South America and is related to nightjars. I have a whole episode planned about nightjars and their relatives, but the oilbird is the only one that echolocates (as far as we know). The other bird that echolocates is the swiftlet.

The oilbird nests in caves and also roosts in caves during the day, then flies out at night and eats fruit. Some oilbirds roost in trees during the day instead. Its wings have evolved to allow it to hover and to navigate through tight areas, which helps it fly through caves. It sees well in darkness, with eyes that are arranged more like those of deep-sea fish rather than typical bird eyes.

Several species of swiflet echolocate. These are the birds that make their nests from saliva, and which humans gather to make bird’s nest soup from. They mostly live in Asia. They nest in caves and roost in caves at night, then fly out during the day to catch insects.

Researchers don’t know a lot yet about either bird’s echolocation. It’s audible to human ears, unlike most bat echolocating, and some researchers think it’s less sophisticated than bats’. It’s always possible there are other birds that echolocate, but we don’t know about them yet because maybe we can’t hear their echolocating.

This is what oilbirds sound like. The clicking noises are the echolocation calls.

[oilbird calls]

Cave fish are especially interesting. There isn’t one kind of cave fish but hundreds, mostly evolved from ordinary fish species that ended up in a cave’s water system and stayed. Sometimes the species of fish that gave rise to cave fish are still around, living outside the cave, but most cave fish species have evolved so much that they’re no longer very closely related to their outside ancestors.

Cave fish are considered extremophiles and they tend to have similar characteristics. They usually have no pigment, no scales, and often have no eyes at all, or tiny eyes that no longer function. They’re usually only a few inches long, or maybe 10 cm, and have low metabolic rates. They typically eat anything they can find.

Some cave fish have evolved in unusual ways to better fit their specific habitats. The cave angel fish lives in a single large cave system in Thailand, in fast-moving water. It’s about an inch long, or not quite 3 cm, and gets its name from its four broad fins, which look feathery like angel wings.

It was discovered in 1985 but it wasn’t until 2016 that researchers verified a persistent rumor about the fish, which is that it can WALK on its fins. It has a robust pelvis and vertebral column, and strong fin muscles that allow it to climb rocks to navigate waterfalls.

Other fish navigate waterfalls and other obstacles by squirming and wriggling, using their fins to push them along. But the cave angel fish walks like a salamander. Scientists are studying the way it walks to learn more about how the ancestors of four-legged animals evolved.

The largest cave dwelling animal is the blind cave eel, which grows up to 16 inches long, or 40 cm, although it’s very slender. Since it appears pink due to a lack of pigment in its skin and it has no eyes or fins, it looks a lot like a really long worm. But it’s actually a fish. Not much is known about it, but it’s widespread throughout western Australia and is sometimes found in wells. It lives in caves or underground waterways that are connected to the ocean.

The first insect that was recognized as living only in caves is a beetle called Leptodirus hochenwartii. It was discovered in 1831 deep in a cave in Slovenia, and researchers of the time found it so intriguing that they invented a whole new discipline to study it and other cave animals, known as biospeleology.

Leptodirus has some interesting adaptations to cave living. It has no wings and no eyes, its antennae and legs are long, but the real surprise is its body. Its head is small and the thorax, the middle section of an insect, is slender. But the abdomen is relatively large and round, and the insect uses it to store moist air. Caves tend to be humid environments and Leptodirus has evolved to need plenty of moisture in the air it breathes. But some parts of a cave can be dry, so not only does Leptodirus keep a supply of breathable air in its abdomen, its antennae can sense humidity levels with a receptor called the Hamann organ.

Some spiders live in caves and like other cave dwellers, they’ve evolved to look strange compared to ordinary spiders. The cave robber spider was only discovered in 2010 in a few caves in Oregon. Researchers suspect there are more species of cave robber spider in other cave systems that haven’t been explored yet by scientists.

The cave robber spider is so different from other spiders that it’s been placed in its own family, Trogloraptoridae, which means cave robber. It has hook-like claws on the ends of its legs which it probably uses to capture prey. It spins small, simple webs on the roofs of caves and researchers think it probably hangs upside down from its web and grabs its prey as it passes by. But since no one knows what the cave robber spider eats, it’s anyone’s guess. Researchers have even tried raising the spider in captivity to learn more about it, but it wouldn’t eat any of the insects or other small invertebrates it was offered as food. It starved to death without ever eating anything, so it’s possible it only eats specific prey. It’s a yellowish-brown spider with two rows of teeth, called serrula in spiders, which researchers say is unique among spiders.

It’s also pretty big for a cave dweller. Its body is up to 10 millimeters long, or about a third of an inch, and it has a legspan of about 3 inches, or 7.6 cm. But it’s very shy and rare, and of course it’s not going to hurt you. It literally wouldn’t even hurt a fly to keep itself from starving.

One of the scientists who discovered the spider and is studying it, Charles Griswold, points out that there are stories in the area of giant spiders living in caves. He suggests the cave robber spider might be the source of the stories, since a three inch spider looks much bigger when it’s hanging down from the roof of a cave right in your face, with hooked claws.

Let’s finish with a remarkable cave fish known as the devil’s hole pupfish. Devil’s hole is a geothermal pool inside a cavern in the Amargosa Desert in Nevada, which is in the southwestern United States. It’s not far from Death Valley. The cavern is more than 500 feet deep, or 150 meters, with water that stays at about 92 degrees Fahrenheit, or 33 degrees Celsius. There’s a single small opening into the cavern at the surface, which geologists estimate opened about 60,000 years ago. The cavern and cave system are more than half a million years old.

The geothermal pool is home to the devils hole pupfish, which is barely an inch long, or 25 millimeters, and looks pretty ordinary. It mostly stays around the opening to the surface, where there’s a limestone shelf just below the water’s surface that measures about 6 ½ by 13 feet, or 2 by 4 meters. While the pupfish does swim deeper into the cavern at times, it mostly eats algae that live on and around the shelf, and tiny animals that live within the algae. It also depends on the shelf for laying eggs and spawning.

So the shelf is really important. But it’s also really small and close to the surface. It can only support so many pupfish, so the average devil’s hole pupfish population is about 200 or 300 fish, although this fluctuates naturally depending on many factors. In the 1960s, a farming corporation drilled wells in the area and pumped water out for irrigation, and the water in devil’s hole started to drop and drop. Devil’s hole is part of Death Valley National Monument, and conservationists were well aware of how fragile the pupfish’s environment was. As the water level dropped, threatening to expose the limestone shelf that the pupfish depended on for their entire lives, conservation groups sued to stop the pumping of groundwater in the area. After a series of court cases that went all the way up to the Supreme Court, the water rights were acknowledged to be part of the national monument status. Pumping of groundwater was limited and the pupfish was saved.

The water level in devil’s hole is monitored daily, which has led to a lot of information about how the water is affected by seismic events. Earthquakes as far away as Alaska, Japan, and South America have all affected the water level.

Researchers aren’t sure how long the pupfish have lived in devil’s hole. Some researchers think they’ve been there for 20,000 years, others think it’s more like a few hundred. Researchers aren’t sure how such a small population of fish has stayed healthy for so long, since such a restricted number of individuals should be so inbred they’re no longer viable. The most recent genetic analysis of the pupfish suggests they became isolated from other pupfish species in the area less than a thousand years ago. But if that’s the case, no one’s sure how they got into devil’s hole in the first place. Flooding of the area hasn’t happened in the last thousand years.

Because the pupfish’s habitat is so fragile, the U.S. Fish and Wildlife Service has moved some of the fish into captive populations that mimic the fish’s original habitat. It’s nice to think that these tiny silvery-blue fish with big eyes have so many people working to keep them safe.

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