Episode 498: Octopolis

Posted on August 17, 2026 by strangeanimalspodcast

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Further reading:

https://sharonahill.substack.com/

https://metazoan.net/109-octopolis-and-octlantis/

Scientists discover an underwater city full of gloomy octopuses

The gloomy octopus [photo by Niki Hubbard – https://www.inaturalist.org/photos/118664956, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=123044473]:

Show transcript:

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

As I’ve mentioned before, I really don’t like April Fools Day, which is April first. I especially don’t like it when someone makes an April fools day post online and just leaves it there afterwards. It’s too easy for other people to stumble across it and think it’s real. This goes double for strange animal and cryptid reports.

I subscribe to geologist Sharon Hill’s Pop Goes the Cryptid articles, and on March 31 she talked about a hoax called the North American Pine Squid. It got popular around Halloween of 2024. It’s said to be a black squid or octopus that lives in pine trees in remote, heavily forested places like the Pacific northwest and the Appalachian mountains. Most of the time it eats small animals like birds and squirrels, along with pine cones, but if someone walks underneath its tree, the pine squid grabs the person, pulls them up into the tree, and they’re never seen again.

But you don’t have to worry, because the pine squid isn’t a real animal. It’s also not even a new story. It’s based on another hoax called the Pacific Northwest tree octopus, which dates back to 1998. In the case of the tree octopus, it wasn’t created as a hoax or an April fool’s joke but as a study about whether children can tell if a website is reliable or not. The researchers made a page with information about a type of octopus that lived in the ocean but that also climbed trees. Then they asked several classrooms of children around age 11, from different schools in different countries, to read the page, look at the pictures provided, and answer some questions.

The study found that most of the children thought the page contained reliable information. Only a few figured out that the tree octopus wasn’t real. The study has been used repeatedly to argue that children need more lessons in how to evaluate a website to know if it contains reliable information, and of course that’s always a good thing. But it makes me a little angry too, because how were the kids supposed to know that octopuses can’t climb trees? There are so many amazing and strange animals out there, a tree octopus sounds perfectly normal if you don’t know very much about octopuses. So I argue that kids should be taught about everything, and taught in as interesting a way as possible so that they remember it better. The same goes for adults.

But this episode isn’t actually about April fools day, tree octopuses, or pine squids. It is about a type of octopus, and what I’m going to tell you is so weird that I have to reassure you that it’s actually true. It’s not a hoax or an April fools joke or anything like that. It’s about the gloomy octopus and the underwater cities some populations have created, referred to as Octopolis and Octlantis. I swear I’m not making this up!

The gloomy octopus lives off the eastern coast of Australia and the northern coast of New Zealand. It’s mainly brown and gray, but it has orange on the undersides of its arms, and it’s covered in little bumps that help camouflage it. Its eyes are white. On average, it has an armspan of about 6 ½ feet, or 2 meters, with females generally larger than males. Like many other octopuses, when the female lays her eggs, she stops eating completely and protects the eggs until they hatch. After they hatch, she dies.

The gloomy octopus lives in shallow warm water and especially likes places with lots of rocks, seagrass, reefs, and other places where it can hide. It spends a lot of time in a den it digs into the sea floor, only coming out at night to hunt. It especially likes scallops, but it will eat pretty much anything it can catch, including sea snails, crabs, seahorses, and even other gloomy octopuses. It usually brings its food back to its den to eat.

The gloomy octopus was thought to be a solitary animal until 2009. That’s when a biologist named Matt Lawrence was exploring Jervis Bay in New South Wales. In this particular part of the bay, the sand is silty and there are a lot of predators, so it’s not great for the gloomy octopus. But not only did Lawrence find a gloomy octopus there, he found 16 of them living in close proximity.

The octopuses’ dens were very close to each other, surrounding a human-made object that’s so encrusted with sea life that it can’t be identified. Scientists think it was a piece that fell off a boat at some point. Even more interesting, there are so many shells around, especially scallop shells, that instead of making dens in the sand, the octopuses are basically making dens in huge piles of scallop shells. The octopuses spend time moving the shells to improve their dens.

In other words, Lawrence had found an octopus city. Admittedly, it’s a very small city by human standards, with only 16 residents identified at any given time, but for a supposedly solitary animal, that’s pretty amazing.

The site was nicknamed Octopolis, and scientists think the presence of the piece of boat actually started the site. When it fell into the sand, it provided a great place for a gloomy octopus to hide. Since gloomy octopuses bring mollusks back to the den to eat, naturally they discard the shells near their dens. Once enough discarded shells had piled up, it provided better building material for another den. Another octopus moved in as the first one’s neighbor, which meant twice as many shells being discarded. Pretty soon another octopus joined the first ones, and eventually there were 16 separate dens in a little community.

Then, in 2017, another octopus city was discovered not far from Octopolis. Instead of a human-made object at its center, it has a few rocks sticking up in the middle of the city, which has been nicknamed Octlantis.

Observations of the octopuses living in these communities are surprising. The octopuses come out during the day even though ordinarily the gloomy octopus is most active at night, especially around dawn and dusk. They interact with each other in various ways, sometimes fighting, sometimes pairing off to mate, sometimes sneaking into another octopus’s den and trying to take it over. It might not be full of underwater skyscrapers and underwater scallop vendors on busy corners, but there’s a lot of hustle and bustle in these cities.

When biologists revisited Octopolis in 2023, they only found three octopuses. Octlantis had a little more activity and a few more octopuses, but nothing like its busy 2017 numbers. But this doesn’t mean that the cities are deserted. Low Octopolis populations were also discovered in 2010 and 2013, but a high population in between. The biologists also noted that the presence of sharks caused the octopuses to move, and in 2023 a shark was hanging around Octopolis.

Another reason for the changing population sizes at the sites is that gloomy octopuses don’t live very long. A three-year-old gloomy octopus is really old, since most die before they reach their first birthday. The octopuses spotted in Octopolis and Octlantis in 2023 might be as much as 14 generations removed from the ones seen in 2009. Young octopuses have to continually repopulate the cities as the older ones die off, and that might take longer some years than others.

Just because we know about Octopolis and Octlantis doesn’t mean those are the only two octopus cities in existence. There are probably a lot more. Scientists just haven’t noticed them yet. In years where sharks are spending too much time in Octopolis, the octopuses might just move to a city we don’t know about. Octopolis and Octlantis might even be really small in comparison to some cities. If you’re a diver around Australia or New Zealand, keep a sharp eye out for an octopus city. You might be the first human to visit New Octleans.

Thanks for your support, and thanks for listening!

Episode 497 Megarachne

Posted on August 10, 2026 by strangeanimalspodcast

Podcast: Play in new window | Download (Duration: 7:32 — 7.6MB)

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Megarachne as we know it now:

Show transcript:

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

Megarachne is only known from two specimens, neither of which is complete, which adds to the confusion. It lived around 300 million years ago in what is now South America. It was described in 1980 from the first specimen discovered and was named Megarachne, which means big spider. The scientist who described it thought it was a type of primitive spider related to modern tarantulas, but much bigger. He estimated its legspan was 20 inches, or 50 cm, with a body length of just over 13 inches, or 34 cm. That made it the largest spider ever known by a lot.

Other palaeontologists, especially arachnologists who specialize in spiders and their relations, weren’t convinced Megarachne was a spider. But it wasn’t until 2005 when a more complete specimen was discovered that anyone could say for sure what it was. The second specimen made it clear that it wasn’t a spider at all but a sea scorpion, or eurypterid, and not an especially large one compared to some. It probably grew to 21 inches long, or 54 cm.

But by then, Megarachne had gotten really popular as a giant spider. It was in the BBC documentary Walking with Monsters, although the producers changed its name to Mesothelae right before it aired, which was just after the new findings about Megarachne came out. Mesothelae is a suborder of big spiders from parts of Asia that retain many traits of ancestral spiders. It was a valiant attempt by the BBC to make the documentary less incorrect, but of course the spider they were talking about still wasn’t a spider and no spider known has ever grown that large.

But while Megarachne isn’t a giant spider, and isn’t even a very big eurypterid, it is important since not very many eurypterids are known from South America. It also appears to be closely related to Mycterops and Woodwardopterus, similar-looking euripterids from North America and Europe. But some researchers think it’s not as cut and dried as it sounds. Instead of three similar creatures living in different areas, they think there’s something else going on.

Eurypterids were arthropods, the phylum that includes insects, arachnids, and crustaceans, among others. Arthropods have an exoskeleton that they molt periodically as they grow, and many arthropods have complicated life stages compared to other animals. When a shark hatches, it looks like a miniature adult and just grows larger as it gets older, but when an arthropod hatches, it usually doesn’t look anything like its adult form. Some arthropods go through many stages of life before reaching the adult body plan. Crustaceans have numerous larval stages, for instance, that often look very different from the adult. Some researchers think that Megarachne, Mycterops, and Woodwardopterus were all the same animal, and that the differences are due to it being in three different stages of development when it died and was preserved.

We don’t have any way to know if this was correct, of course, not until we hopefully find more fossil remains. Other eurypterids did appear to go through some physical changes during maturation, as far as researchers can tell with the remains we have, but Megarachne, Mycterops, and Woodwardopterus belonged to a different family from other eurypterids and are much rarer. They might have been quite different developmentally.

We can also look at the living relations to see how likely it is that eurypterids had different larval stages where they looked different from the adult form. Eurypterids were probably most closely related to horseshoe crabs, although not everyone agrees. Horseshoe crabs have been around for 445 million years and are really neat animals that we’re lucky to still have in the world. The horseshoe crab hatches into a larva that looks a lot like a trilobite. It does indeed go through physical changes as it grows and molts over the course of three years, so it’s reasonable to assume that eurypterids did too.

On the other hand, some researchers think eurypterids were more closely related to modern scorpions. Scorpions actually give birth to live babies instead of laying eggs, and the female carries the babies on her back for several days up to several weeks, depending on the species. Once the babies have their first molt they look a lot more like miniature adults and pretty soon are able to leave their mother and hunt on their own. So again, it’s possible that eurypterids had a system more like this instead of like the horseshoe crab’s.

While we’re talking about scorpions, did you know that scorpions glow blue-green in ultraviolet light? The scorpion’s exoskeleton contains fluorescent chemicals, but we’re not sure why. Scorpions do have incredibly light sensitive eyes, and can navigate at night using only starlight. Their eyes can’t form sharp images like ours can, though. And scorpions have a lot of eyes. Spiders have four pairs of eyes, but some scorpions have more than that. All species have a pair on top of the cephalothorax, which corresponds to the head, and more on the sides of the cephalothorax. Some species have up to five pairs of eyes in addition to the ones on top of the head. Twelve eyes seems like overkill but it works for the scorpion. Eurypterids had both compound eyes and simple eyes.

That’s all we know about Megarachne right now, at least until we find more fossilized specimens. Let’s hope we do, and while we’re at it, let’s hope we find some more fossilized giant spiders because that would be cool.

Thanks for your support, and thanks for listening!

Episode 496 Two Mystery Invertebrates

Posted on August 3, 2026 by strangeanimalspodcast

Podcast: Play in new window | Download (Duration: 7:45 — 8.5MB)

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Further reading:

How did a tiny bee get to French Polynesia? Eight new species help solve a scientific mystery

Secrets in the canopy: Scientists discover 8 striking new bee species in the Pacific

Canopy specialist Hylaeus bees highlight sampling biases and resolve Michener’s mystery

Scientists discover endoparasitic marine tapeworm trapped in Cretaceous amber

Show transcript:

Welcome to the Patreon bonus episode of Strange Animals Podcast for August 2024!

It’s the start of Invertebrate August, so we have two invertebrate mysteries to discuss today, one mostly solved and one not.

Let’s start with the solved mystery, about a tiny bee. In 1934, three tiny bee specimens were collected in French Polynesia, specifically on a particular type of flower in the Tuamotu Archipelago. The bees really were tiny, only 4 mm long. They weren’t described until 1965, when they were placed in the genus Hylaeus. This is a really big genus with over 500 species that live throughout the world, but the species most closely related to the newly described Tuamotu’s masked bee lives in Australia, New Guinea, and New Zealand.

In case you’re kind of hazy on geography, like me, Australia, New Guinea, and New Zealand are part of what’s called Oceania, a giant chunk of the Pacific Ocean where there’s not a whole lot of land. I mean, except for Australia, which is big. The Tuamotu Archipelago is also part of Oceania, and part of French Polynesia, but it’s really remote. It consists of a spread-out collection of 78 low islands, many of them too tiny to support humans, none of them with a source of fresh water except for rain. They’re tropical and quite beautiful, with many unique animals and plants living on and around them. They’re also almost 2,500 miles, or 4,000 km away from the places where the tiny bee’s closest relatives live.

Even in 1965, scientists had questions about the tiny bee. How did 4mm bees get to such remote islands, and were they even still around? The bees hadn’t been seen in the wild since 1934. Since the Tuamotu Archipelago has suffered from European explorers and missionaries bringing invasive species to some islands, colonization by France, and nuclear weapons testing, scientists worried the bee had gone extinct and that they would never solve the mystery of how it got there in the first place.

Bees are attracted to flowers, and the three 1934 specimens were discovered on flowers, so naturally scientists had been looking for the bees on flowers. But it turns out that in the Polynesian islands, bees mostly hang out in the treetops. Once scientists figured this out, they began discovering new species of bee—eight of them in fact, collected between 2014 and 2019 from various islands in Fiji, Micronesia, and French Polynesia.

All eight species are closely related to Tuamotu’s masked bee, so scientists now have a pretty good idea of how it traveled thousands of miles to get to its French Polynesian home. Its ancestors island-hopped. There are more than 1,700 islands in the Pacific Ocean, many of them barely known to humans.

Researchers think there are probably a lot more species of bee to be discovered in the treetops of Pacific islands, now that they know where to look. With luck, they’ll be able to find Tuamotu’s masked bee too, quietly living out its bee life above the scientists’ heads.

Next, let’s discuss our unsolved mystery. Amber, which is fossilized tree resin, is the gift that just keeps on giving to the scientific world, and our mystery involves a flatworm found in amber.

The amber comes from Myanmar and dates to about 99 million years ago. In addition to bits of inorganic matter like tiny pebbles and sand grains, most organisms found in amber from this site are insects and roundworms, animals you’d expect to find on and around trees. The team examining this particular piece of amber found lots of interesting things, but then they discovered this one.

The flatworm is about 10mm long and it’s beautifully preserved, which means the scientists were able to compare it to modern flatworms to see what it might be most closely related to. It’s most similar to a parasitic flatworm found in shark intestines. You know, an animal not typically found in trees. (I stole that joke from paleontologist Kenneth De Baets, by the way. Credit where credit’s due.) It isn’t a complete worm but a partial one, basically a tentacle with little hooks to keep it in place in the host animal’s digestive system.

The modern worm is classified as a type of tapeworm, and tapeworms are distressingly common parasites. If you’ve ever adopted a rescue cat or dog, you’ve probably had to have it treated for a tapeworm infestation. Luckily, tapeworms are also very specific about which species they parasitize, so you can’t get tapeworms from a pet. (It’s still icky.) Fish get tapeworms too, after eating marine invertebrates carrying various kinds of tapeworm larvae.

The question is, how did a parasitic worm found in fish end up in amber? Occasionally there is rare amber found that fell into water and trapped water organisms, but this particular amber wasn’t associated with water. Other items found in the same piece of amber included sand grains, tiny hairlike structures found on some ferns, and the nymph of a scale insect. The team suggests that the tree where the amber came from grew near a beach and that a dead shark washed ashore. While scavengers were picking through the carcass, a piece of worm somehow got separated from the body and ended up in a tree. Possibly a scavenger grabbed a big yummy mouthful of rotting shark guts and either climbed or flew up into a tree to eat it, and part of the worm fell out and landed in a blob of amber.

Because tapeworms are endoparasites, meaning they live inside their hosts, and because they’re soft-bodied and fragile, it’s very rare that one is preserved. Pretty much the only other preserved tapeworm specimen we have isn’t a tapeworm itself but some eggs found in fossilized shark dung, dated to 270 million year ago. Scientists aren’t even completely sure the eggs are from a flatworm since they’re not that well preserved. So it’s fantastic that this particular specimen was so well preserved, and that it made its way into the hands of scientists!

Thanks for your support, and thanks for listening!

Episode 493: NEW The Mystery of Esconichthys and Friends

Posted on July 13, 2026 by strangeanimalspodcast

Podcast: Play in new window | Download (Duration: 16:26 — 18.4MB)

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

Find the Backerkit campaign here!

Further reading:

Nix Illlustration: Esconichthys

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

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

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

Two halves of an esconichthys fossil:

Show transcript:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Thanks for listening!

Episode 487: Animals and the Sense of Taste

Posted on June 1, 2026 by strangeanimalspodcast

Podcast: Play in new window | Download (Duration: 8:53 — 10.0MB)

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Further reading:

What gives bees their sweet tooth?

Show transcript:

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

Right before I left on my trip to Belize a few months ago, my aunt Janice gave me a magazine to read on the plane, the Autumn 2021 copy of LivingBird. It’s about birds and birdwatching. I actually forgot to take it with me and it was in my car the whole time I was gone, but when I got home I took it in to read.

One article caught my eye, titled “Investigating the Sweet Tooth of Songbirds.” Literally the same day that I read that article, I stumbled across another article on ScienceDaily titled “What gives bees their sweet tooth?” And a podcast episode idea was born!

You may have heard that domestic cats can’t taste sweetness, and that’s true. When your pet cat wants to drink the milk in a bowl of sugary cereal, it’s not the sugar they care about because they can’t taste it. Also, milk isn’t good for cats and even if they can’t taste the sugar, it can end up giving them cavities.

The question is, why don’t cats taste sweetness? And what other animals can’t taste it either?

Carnivores like cats don’t need to taste sweet flavors because it’s just not present in meat, which is what carnivores eat. You can test this easily if you put two saucers on the floor for your cat, one with a small amount of unseasoned chicken and a sugar cube in the other. I guarantee you the cat will eat the chicken and play with the sugar cube, which will get sugar all over the floor so maybe don’t do that after all. This is where I share with you, for no reason, that when I was in elementary school I used to eat sugar cubes while pretending I was a horse.

Horses can taste sweet flavors like sugar because they’re herbivores. Herbivores eat plants, and in fact herbivores have a whole lot of taste buds so that they can easily tell what kind of plants they’re eating. Bitter tasting plants might be toxic while sweet ones provide lots of energy. Herbivores are also keenly attuned to the taste of salt since their diet is typically low in salt and they need to seek it out.

Humans are omnivores, and omnivores eat pretty much anything. Like our great ape cousins, we also evolved to eat a lot of fruit. Ripe fruit tastes sweet so we really like our sweet foods. Omnivores like dogs, pigs, and bears also like sweet foods because they’re high in calories and therefore provide a lot of energy.

But how does an animal lose an entire sense of taste? It’s not like all tigers woke up one day and boom, the ability to taste sweetness was gone. It happens gradually as the genes responsible for an animal’s sense of taste mutate over many generations.

Let’s take as our example the bottlenose dolphin. The ancestors of the dolphin and other cetaceans were terrestrial animals related to the ancestors of modern even-toed ungulates like hippos, camels, deer, and pigs, and were probably either herbivores or omnivores. But as the dolphin’s ancestors evolved over millions of years, they shifted to a fully marine lifestyle and a fully carnivorous diet. Over the thousands and thousands of generations, the genes that control the ability to taste sweetness mutated so much that they’re now useless, but since the dolphin doesn’t need to taste sweetness the mutations don’t matter.

In the case of the bottlenose dolphin and other cetaceans, in fact, they also can’t taste bitterness or umami. Umami is what helps you taste the difference between chicken and turkey, steak and pork, tuna and trout. Basically it’s the flavor of meat or savory foods, including cheeses. You can taste the difference between cheddar and Swiss because of the umami receptors in your taste buds, which are determined by genes.

But the dolphin eats nothing but meat! Why would it lose the ability to taste meat? Researchers think it’s because the dolphin swallows fish and other animals whole, without chewing. Cetaceans and other marine carnivores like sea lions that swallow their food whole actually have almost no taste buds at all.

If you’re wondering what happens when an animal that can’t taste sweetness has to adapt to a diet where tasting sweet foods is important, that’s exactly what happened with songbirds. The ancestors of birds lost the ability to taste sweetness millions of years ago when they were dinosaurs. Then, well, you know what happened to the non-avian dinosaurs. Suddenly the ancestors of modern birds had a lot of available ecological niches to take advantage of and they evolved rapidly to fill them. This included small birds who eat berries and nectar.

Genetic studies suggest that the ancestors of songbirds regained the ability to taste sweetness around 30 million years ago in Australia. The same thing happened in hummingbirds at about the same time. In both cases, the genes that control the ability to taste umami evolved to taste sweetness instead—but songbirds and hummingbirds adapted different umami genes. That’s what you call a subtle case of convergent evolution.

Songbirds and hummingbirds adapted to a diet high in sugar because it’s a good source of energy and easily found in flowers. In turn, flowers needed to be pollinated and have their seeds spread around, so they evolved to provide even more sugars in nectar and berries. But birds aren’t the only animals that pollinate flowers and are attracted to nectar. Insects can all detect sweetness. However, bees are exceptionally attuned to sweetness and have two taste neurons instead of one per taste bud.

Insects don’t have taste buds the same way we do, of course. In mammals, reptiles, and birds, taste buds are located on the tongue, in a few parts of the mouth, and at the top of the throat. In insects, taste receptors can be in any number of places. They’re on an insect’s mouthparts but often also on their feet, legs, and antennae.

Some amphibians have taste receptors on the body as well as concentrated in the mouth, and many fish have taste receptors all over their body. Catfish in particular have the most taste buds known, up to 175,000. Humans have about 10,000. Cats only have about 500.

Before you start feeling sorry for your cat for not being able to taste sweet foods and not having a great sense of taste in general, cats have a taste receptor we don’t. It’s the water sense. To us, a nice cold glass of water tastes refreshing but doesn’t really have a flavor. A cat or dog, and many other animals whose diet is mostly meat even if they aren’t specifically carnivores, have the ability to taste water in a way we can’t even imagine. Because meat is high in salt content, having taste buds attuned to water helps the animal drink enough water to process all that salt.

If you gave me the choice, I’d choose sweetness over the ability to taste water. But my cats would probably disagree.

Thanks for your support, and thanks for listening!

Episode 484: The Sewellel and the Superflea

Posted on May 11, 2026 by strangeanimalspodcast

Podcast: Play in new window | Download (Duration: 7:54 — 8.0MB)

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The sewellel is a little rodent:

The superflea is a big flea (left, compared to a regular flea, right):

Show transcript:

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

Let’s learn about a rodent you may never have heard of, unless you live where it does, and a parasite that makes that rodent its host. It’s not an ordinary parasite, but don’t worry, it’s not icky. You can continue to snack.

The rodent is called the sewellel, Aplodontia rufa. It’s also called the mountain beaver even though it doesn’t always live in the mountains and it isn’t a beaver. It doesn’t even look like a beaver. For one thing, it only has a little nub of a tail and it only grows around 20 inches long, or 50 cm. It has small eyes and ears, short legs, a chunky body, and long claws. This body shape should give you a hint about its lifestyle: the sewellel is a digger, although it can also swim just fine and can even climb small trees to eat young twigs and leaves.

The sewellel is an aplodont, a large group of rodents that have been common in Europe, Asia, and North America for 40 million years. But it’s the only one left. All the other aplodonts went extinct several million years ago at least. We’ve actually talked before about one of the sewellel’s extinct relations, the horned gopher (which was not a gopher), in the Patreon episode about animals with nose horns.

The sewellel itself hasn’t been around all that long, only appearing in the fossil record a few million years ago. It lives in a small area of northwestern North America, in parts of British Columbia, Washington state, Oregon, and a few parts of California. It lives in forests where it doesn’t get too cold in the winter, since it doesn’t hibernate and isn’t as good at keeping itself warm as other rodents are. It also needs to drink more water than other rodents and prefers to live in wet climates as a result.

In fact, the sewellel is sometimes referred to as a living fossil since it lacks many features that all other living rodents have. Its teeth resemble a simpler version of squirrel teeth, so some researchers think it may be most closely related to squirrels, but even if that’s the case, it isn’t very closely related. The sewellel’s ancestors were more adapted to live in trees and a study published in 2018 determined that it had a larger brain than the sewellel. Since the sewellel is nocturnal and spends most of its life underground, it doesn’t need to see very well, and the part of the brain that processes vision is much smaller than in its ancestors.

The sewellel mostly eats ferns, although it also eats other plants, and some of its favorite plants are toxic to other animals. It’s a solitary, mostly nocturnal animal that digs deep, complex burrows, and it stays as close as possible to the burrow entrance so it can hide easily if it needs to. Everything eats the sewellel, from owls to coyotes to bobcats to eagles.

And that brings us to the parasite associated with the sewellel. Many animals have parasites that are specific to that particular species. The Patreon episode about whale lice has some information about how specific this can get. The male sperm whale has a different species of louse than the species that lives on female sperm whales, for instance. Also, the whale louse isn’t a louse, it’s a type of crustacean.

The sewellel’s parasite is a type of flea. Big deal, you say, fleas are all about the same.

Are they, though? Because the sewellel’s flea is actually kind of a big deal. It is, in fact, the largest flea known, called the superflea. It can grow up to 8 mm long (and possibly longer, reports vary). I just measured, and that’s the length of my little fingernail, from the base to the quick. Most species of flea are 3 mm long at most.

The superflea is only found on the sewellel. It looks like an ordinary flea except for its size, meaning it’s laterally flattened with legs that allow it to jump long distances. So why is it so big compared to other fleas, especially considering that it lives on an animal that’s about the size of a chonky cat? No one knows. No one has even the slightest idea why this flea is so big.

There used to be even bigger fleas, some up to two cm long. That’s 20 mm, or just a little more than twice the length of the superflea. Of course, those 20 mm fleas lived 165 million years ago and probably lived on dinosaurs. Also, they couldn’t jump and instead of being flattened laterally, or side to side, like modern fleas, they were flattened dorsoventrally, or top to bottom. So they weren’t very much like modern fleas.

That’s all we know about the superflea, but let’s have one last sewellel fact before we go. With all this talk of the sewellel being a primitive rodent whose closest relations are all extinct, you might think there’s nothing really special about it beyond its giant fleas. You would be wrong, though, because the sewellel’s front paws have opposable thumbs. It’s not as mobile as our opposable thumbs, but it allows the sewellel to manipulate food more easily. It will sometimes sit up on its big round bottom to eat, just like a really weird squirrel.

Thanks for your support, and thanks for listening!

Episode 482: Smoky Mountain Mystery Animals

Posted on April 27, 2026 by strangeanimalspodcast

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I took this episode from an article I wrote for Flying Snake magazine, which was published in December 2020 (Vol. 6, #18).

Show transcript:

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

The Great Smoky Mountains is a subrange of the Appalachian Mountains, which stretches from the middle of Alabama in the United States north into southeastern Canada. The Appalachians formed when the world’s continents crunched together to form the supercontinent Pangaea. The southern Appalachians formed separately and later than the northern Appalachians, around 270 million years ago.

The Appalachians were once as high as the Rockies or Himalayas, but by the time the dinosaurs went extinct, they had eroded down to the mountain cores. Sediment weathered from the peaks and filled in valleys. But during the Pleistocene, when massive glaciers covered the northern parts of North America, the weight of the ice pushed the North American plate down, causing the southern part of the plate to rise. Eventually the ancient mountains’ roots were a thousand feet (300 m) above sea level again. Rivers that once flowed east into the Atlantic Ocean or west into the remains of the shallow Western Interior Seaway shifted their courses to flow northward. Streams that once meandered across the land now plunged down steep slopes and dug gorges into the rock. And over thousands of years, animals and plants retreating from the ice migrated southward along the mountain range.

When the climate warmed some 11,000 years ago and the ice age glaciers melted, many cold-adapted species were trapped in the peaks of the southern Appalachians. One of the highest peaks is Mount LeConte, with its highest point, High Top, measured at 6,593 ft, or 2,010 meters. I hiked Mount LeConte on 7 May, 2016 when the weather in nearby Knoxville, Tennessee was a warm 82 Fahrenheit, or 27.8 Celcius, but there was snow on the mountain that morning. I wrote my name in it. A spruce-fir forest grows on the upper slopes, a remnant of forest that grew throughout the mountains during the last ice age. The climate at the peak of Mount LeConte is more like that of southern Canada than the warm, humid southeastern United States.

The Great Smoky Mountains National Park was established in 1934 to protect the mountains along the Tennessee/North Carolina border. No one lives in the park’s 800 square miles (2,072 square km), which receives up to 90 inches [2.29 m] of rain a year, some of it from hurricanes that sweep up from the southern Atlantic or the Gulf of Mexico. Large tracts of old-growth forest still remain in the park too.

So as you can see, the Smokies are a biodiversity hotspot. In 2018, the park announced its 1,000^th species discovered that is new to science, which by July 2020 had grown to 1,025. Overall, 20,000 known species live in the park as of 2019 and scientists estimate that up to 100,000 more are yet to be discovered.

The Smokies are heavily forested, of course, but some mountain summits and crests have no trees. Instead, native grasses and shrubs grow. They’re called grassy balds and no one is sure why they exist. The prevailing theory is that Pleistocene megaherbivores opened the forests for grazing, and after their extinction, the balds remained open due to bison, elk (wapiti), and deer. When white settlers moved into the area, they used the balds to graze cattle and other livestock. Remains of mammoth and mastodon, musk ox, ground sloth, and other megaherbivores have been excavated from various balds throughout the park.

Amphibian enthusiasts call the Smokies the Salamander Capital of the World, with 30 known species. Largest of these is the hellbender, which we talked about in episode 14, a giant salamander that can grow nearly 2 ½ feet long, or 74 cm, and which lives in swift-moving mountain streams. It’s most closely related to the Chinese and Japanese giant salamanders, which can grow over twice as long as the hellbender. Twenty-seven of the salamanders found in the Smokies are lungless, in the family Plethodontidae. Instead of breathing with lungs or gills, the lungless salamanders absorb oxygen through their skin. Of these, the red-cheeked salamander is endemic to the Smokies—that is, it’s found nowhere else in the world.

The red-cheeked salamander lives in forests in high elevations. It can grow up to seven inches long, or 18 cm, and is gray or black with bright red patches on its face. It spends the day in a burrow, then comes out at night to find insects in the leaf litter. But it’s hard to tell apart from the imitator salamander, although the imitator only grows a little over four inches long, or 11 cm. The imitator has red cheeks but its body is patterned black and brown instead of solid gray or black. Sometimes its cheeks are yellow, too, while the red-cheeked salamander only ever has red cheeks.

Another animal found only in the Smoky Mountains, although it may also be present in mountains outside of the park, is a species of jeweled spider fly called Mary-Alice’s emerald (Eulonchus marialiciae). Mary-Alice’s emerald has a metallic-green body and yellow legs, and the adults eat nectar. But the larvae eat spiders. Specifically, they parasitize spiders. After hatching, the larva goes in search of a spider, especially trapdoor spiders that live in burrows. When it finds one, it works its way into the spider’s body and eats it from the inside out, eventually killing it. Then it pupates in the burrow and emerges as an adult spider fly. It prefers high elevations that are cool and moist.

A less horrific animal found in the Smokies is the Carolina northern flying squirrel. It was one of the species whose ancestors migrated south along the Appalachians during the Pleistocene. Then, after temperatures started to warm, the cold-adapted flying squirrel migrated north again. Some populations remained on mountaintops in the Smoky Mountains and have been isolated for thousands of years, evolving into a subspecies of flying squirrel found only in high elevations of the Smokies. It’s much rarer than the southern flying squirrel that lives throughout the southeastern United States, and prefers spruce forests instead of the hardwood forests that southern flying squirrels like. But the spruce forests are threatened by climate change, the introduced woolly adelgid insect that kills fir trees, and pollution in the form of acid rain and pesticides that travel to the mountains from other states and even other countries.

The Carolina northern flying squirrel has a patagium of furry skin that connects its front and back legs. When it jumps from a branch, it stretches its legs out and uses the patagia to glide to a new perch. It’s clumsy on the ground, though, and spends most of its time in trees. It mostly eats fungi, mushrooms, and lichens, but will also eat nuts, insects, bird eggs and even baby birds, and other plant material like tree sap and buds.

Bobcats still live in the Smokies, but the cougar, or mountain lion, was supposedly killed off in the area by the end of the 19^th century. The U.S. Fish and Wildlife Service removed the eastern cougar subspecies from the endangered species list in 2018, since it is supposed to be extinct. The last cougar in what is now the park was supposedly killed in 1920. But sightings continue in the Smokies, close to a dozen a year, and some sightings are compelling, like the 2002 report of a cougar crossing a road in the park, spotted by a veterinarian who treated captive cougars in his practice. Considering how seldom seen the bobcat is despite it being relatively abundant, it’s possible that a small number of cougars still live in the park—either animals that have moved back into the mountains from elsewhere, or a relict population.

The red wolf is native to the eastern United States and was once common in the Smoky Mountains, but was killed off by white settlers throughout most of its range. Where it remained in the wild, it interbred with closely related coyotes, until it was declared extinct in the wild in 1980. Fortunately, by then a captive breeding program was in place. Starting in 1991, 37 red wolves were released in the Great Smoky Mountains National Park in Tennessee, following the release of 63 red wolves into the Alligator River Natural Area in North Carolina a few years earlier. But the release didn’t go well in the Smokies. Wolves are shy and need enormous territories with lots of game. Before long some wolves were leaving the park and attacking livestock. Others died of parvo virus, especially wolf pups.

Worse, this was about the same time that coyotes moved into the area from the west. The wolves started interbreeding with the coyotes, and the coyotes also competed with the wolves for food. In 1998, the Fish and Wildlife Service ended the program and recaptured all but one of the wolves originally released into the park.

The North Carolina release went better, with a population peak in 2006 estimated at nearly 130 wolves. But that program was suspended in 2015, and without management of the wild population, the number has dwindled. As of 2019, only 14 wolves remain in North Carolina—and that’s the entire population of red wolves in the wild.

But sightings of red wolves continue in the Smokies. The trouble is that the red wolf looks very similar to the coyote. It’s taller and larger, with a more pronounced reddish shade to its coat, but even experts can have trouble telling the two species apart if they can’t get a good look at the animal. Most likely people are seeing coyotes, possibly ones descended from red wolf/coyote hybrids born during the reintroduction program.

The biggest mystery in the park is the occasional sighting of a Bigfoot-type creature. Most sightings are probably bears, though. An estimated 1,500 American black bears live in the Smokies, and while some bears get used to hikers and tourists, most are shy and seldom seen. A black bear keeping an eye on hikers or cars will sometimes stand on its hind legs for a better view, and would naturally look like a hulking humanoid if glimpsed. But other sightings aren’t so easy to explain.

In February of 2009, a photographer named Deb Campbell was hiking the Middle Prong Trail in the snow. The Middle Prong Trail passes three major waterfalls and many smaller ones as it follows along a tributary of the Little River. She had the trail almost completely to herself—she says she only saw one person the whole time. Later she reported, “[A]t some point I am photographing along the stream and I start to smell a gawd awful stench. Not really like anything I had ever smelled before. I look around, see nothing, listen intently…nothing. So I finish up at that spot and go further up the trail.” The smell receded behind her but the snow increased, so finally she turned around to hike out. Around the area where she smelled the stink earlier, she started feeling watched. She stopped long enough to secure her camera gear for much faster hiking in slick conditions, when she heard a deep growl that she described as “very low, not like a cat, almost guttural.” Needless to say, she got off the mountain as quickly as possible.

The black bear doesn’t truly hibernate since its body temperature remains normal instead of dropping, but it does find a den in cold weather and will sleep for long stretches. It may emerge from its den occasionally during the winter during warm spells, but for the most part it’s asleep in its den from around November through March in the Smoky Mountains. But Campbell was hiking in February during a snowfall, with snow already on the ground. A bear would most likely not be out of its den in that weather unless it had been disturbed.

And bears don’t actually smell bad. During the winter hibernation most bears don’t defecate at all. Any feces left in a bear’s digestive tract harden to form a fecal plug. If it does feel the need to defecate near the end of the winter, it will do so just outside its den, but the fecal plug has very little odor. Even under ordinary conditions, unless a bear has been eating carrion, it will smell no worse than a dog that needs a bath.

Not only that, black bears don’t actually growl. They make grunty, huffing noises when warning people away or when males fight in the summer, and a frightened bear will moan, but they don’t growl like a dog.

It’s possible that Campbell hiked past a bear that had emerged from its den early and had found and eaten carrion, possibly roadkill, and that she was so close to the bear without seeing it that she smelled its breath. That’s almost more frightening than the thought of passing near a Bigfoot. The growl might have come from a different animal, a coyote or who knows, maybe even a red wolf. Or Campbell might have encountered a creature sometimes called a skunk ape due to its foul odor.

The skunk ape is most commonly reported in Florida swamps, but sightings—or smellings—have come from many other states. The smell is sometimes described as that of rotting food and roadkill on a hot day. A bear or other animal that has been rooting around in garbage bins can pick up this odor, especially in hot weather, but it’s hard to believe that a bear would be actively foraging so much in winter that it would smell like trash. January and February are the depths of winter in East Tennessee. The bears are hibernating, not foraging.

Thanks for your support, and thanks for listening! This is what a couple of fighting bears sound like:

[bear sounds]

Episode 480: Old, Old Life

Posted on April 13, 2026 by strangeanimalspodcast

Podcast: Play in new window | Download (Duration: 7:36 — 8.3MB)

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Let’s learn about some of the oldest life ever discovered!

Further reading:

Microbiologists Find Living Microbes in 2-Billion-Year-Old Rock

Chart of life extended by nearly 1.5 billion years

Show transcript:

Back in episode 168 we talked about the longest-lived organisms known, and finished the episode by discussing endoliths. I’ll quote from that episode as a refresher.

An endolith isn’t a particular animal or even a group of related animals. An endolith is an organism that lives inside a rock or other rock-like substance, such as coral. Some are fungi, some lichens, some amoebas, some bacteria, and various other organisms, many of them single-celled and all of them very small if not microscopic. Some live in tiny cracks in a rock, some live in porous rocks that have space between grains of mineral, some bore into the rock. Many are considered extremophiles, living in rocks inside Antarctic permafrost, at the tops of the highest mountains, in the abyssal depths of the oceans, and at least two miles, or 3 km, below the earth’s surface.

Various endoliths eat different minerals, including potassium, sulfur, and iron. Some endoliths even eat other endoliths. We don’t know a whole lot about them, but studies of endoliths found in soil deep beneath the ocean’s floor suggest that they grow extremely slowly. Like, from one generation to the next could be as long as 10,000 years, with the oldest endoliths potentially being millions of years old—even as old as the sediment itself, which dates to 100 million years old.

That episode was almost five years ago, and in October of 2024 some new information was published. The study mentions the 100-million-year-old limit known so far, where living microorganisms were indeed discovered in geological layers below the ocean floor. But what they found was even older.

The scientific team analyzed rock samples from northeastern South Africa, specifically rock that formed when magma cooled below the surface of the earth. It’s called the Bushveld Igneous Complex and is very large, very old, and very stable.

The team drilled core samples of the rock from 50 feet down, or 15 meters, and cut it into thin slices to examine. To their surprise, they discovered microbial life in the rock’s cracks, which were sealed tightly with clay so that nothing should be able to get in or out of the rocks. To be sure the microbes hadn’t been introduced during the drilling or preparing process, they used infrared spectroscopy to compare the proteins in the microbes with the proteins caught in the clay. They matched, meaning the microbes had been there as long as the clay had been there, which was basically almost as long as the rocks had been in place. They were also able to verify that yes, the microbes were definitely alive.

So, how old are the rocks? TWO BILLION YEARS OLD. Billion with a B! While the individual microbes probably aren’t actually that old, the population of microbes has been living in those cracks far within the rock for two billion years. Scientists are excited to learn more about them, because by studying organisms that have been separated from all other life for that long, they can learn about how early life on earth evolved.

Even more exciting, at least if you’re me, NASA’s Perseverance rover on Mars is going to be bringing some rocks back to earth that are about 2 billion years old. Scientists are really excited to see if there is any evidence for microbial life inside the Martian rocks!

I know I won’t live long enough to see the first macrobial life from another planet, but I really hope I’m alive when we discover the first microbial life. I don’t think life is rare on other planets, it’s just that the distances are so enormous that getting to another planet and sending information back home is an almost insurmountable problem right now. The closest planets to us are Mars and Venus, and these days Mars just doesn’t seem like it would be very habitable for anything but microbes. But microbes can live just about anywhere!

Also in 2024, a team from Virginia Tech has put together a chart marking when various life forms started appearing in the fossil record and when they also stopped appearing in the fossil record. Versions of this chart of life have been made before, but they typically only go back to about half a billion years ago, around the time of the Cambrian. Before that, life was much less likely to fossilize, or the rocks containing the fossils have been worn away.

The team gathered fossil data from scientists and institutions around the world and compiled it into a chart of life that extends back two billion years. The farther back you look, the less changes there are among the type and differences in species. There’s even a huge stretch of time called the boring billion where things really weren’t changing much at all, at least not according to the fossil record we have available. It wasn’t until the earth’s climate became much cooler and then warmed again, between 720 and 635 million years ago, that things really began to change.

The team is considering factors that contributed to the stability of the boring billion, and why it all changed so radically. It’s a good thing it did from our perspective, since if the boring billion had continued over the next billion years until today, we’d all be single-celled organisms. I wonder if the microbes in those two billion year old rocks even noticed the changes. Probably not. They were in rocks.

Thanks for your support, and thanks for listening!

Episode 479: Metal Animals

Posted on April 6, 2026 by strangeanimalspodcast

Podcast: Play in new window | Download (Duration: 7:50 — 7.9MB)

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Further reading:

Beavers Have Metal Teeth

Show transcript:

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

Let’s find out about some animals that incorporate metal into their bodies in more than just trace amounts.

We’ll start with the scaly-foot gastropod, a deep-sea snail. It lives around hydrothermal vents in the Indian Ocean, about 1 and ¾ miles below the surface, or about 2800 meters. The water around these vents, referred to as black smokers, can be more than 350 degrees Celsius. That’s 660 degrees F, if you even need to know that that’s too hot to live.

The scaly-foot gastropod was discovered in 2001 but not formally described until 2015. The color of its shell varies from almost black to golden, depending on which population it’s from, and it grows to almost 2 inches long, or nearly 5 cm. It doesn’t have eyes, and while it does have a small mouth, it doesn’t use it for eating. Instead, the snail contains symbiotic bacteria in a gland in its esophagus. The bacteria convert toxic hydrogen sulfide from the water around the hydrothermal vents into energy the snail uses to live. It’s a process called chemosynthesis.

In return, the bacteria get a safe place to live.

The snail’s shell contains an outer layer made of iron sulfides. Not only that, the bottom of the snail’s foot is covered with sclerites, or spiky scales, that are also mineralized with iron sulfides. While the snail can’t pull itself entirely into its shell, if something attacks it, the bottom of its foot is heavily armored and its shell is similarly tough.

Researchers are studying the scaly-foot gastropod’s shell to possibly make a similar composite material for protective gear and other items. The inner layer of the shell is made of a type of calcium carbonate, common in mollusk shells and some corals. The middle layer of the shell is regular snail shell material, organic periostracum, which helps dissipate heat as well as pressure from squeezing attacks, like from crab claws. And the outer layer, of course, is iron sulfides like pyrite and greigite. Oh, and since greigite is magnetic, the snails stick to magnets.

The scaly-foot gastropod is the only animal known that incorporates iron sulfide into its skeleton, but other animals use metals in their teeth. Some spiders have tiny amounts of zinc in the tips of their fangs. Some mollusks have small amounts of iron in the teeth of their radulas—you know, the tongue-like structure used to scrape food off rocks. The teeth of the limpet, a type of mollusk, may be one of the strongest structures in the world. It contains goethite nanofibers, and goethite is a type of iron.

The teeth of beavers and some other rodents contain iron in the enamel coating. This makes the teeth much harder, although the amount of iron is quite small and unstructured. Most other mammals, including humans, have magnesium in tooth enamel instead of iron. The iron content makes the teeth look orange because of rust.

Bloodworms are disgusting horrible worms that my uncle used to fish with when we visited the beach when I was a kid. I was scared of the bloodworms, which irritated my uncle, because I was very vocal about hating the worms and he wasn’t catching any fish with them. Bloodworms live in the sand or silt of shallow water, usually in the ocean but since they can tolerate low salt levels, they may also live farther inland in canals and inlets. Some species can grow nearly 15 inches long, or 37 cm. They’re usually pink or reddish in color with bristles along the body and four little antennae on the head. But the reason I’m talking about them here is that their teeth are reinforced with copper that makes them nearly as hard as teeth coated with enamel. Its jaw also contains copper ions.

Copper is toxic to most animals, which may be the source of the bloodworm’s venom. That’s right: horrible worms are also venomous.

Another invertebrate that incorporates metal in its body is the parasitic fig wasp. Fig wasps are interesting and there are a lot of them. Figs are pollinated by fig wasps that are not parasitic. The fig flower has a bulb at its base containing a tiny hole. The pollinating fig wasp crawls into the hole, pollinating the flower at the same time, and lays her eggs inside the bulb. She then dies. As the fig developes, the wasp eggs hatch into larvae and then develop into adult wasps. Males mate with females, then chew a hole out of the fig, but only the female wasps have wings, so the males remain and die. As the fig ripens, it actually digests the dead wasps, and—and this is important to those of us who really like figs—leaves no bits of dead wasp inside the fig. So that’s how the pollinating fig wasps work. It’s a symbiotic relationship between the fig tree and the wasp.

But the parasitic fig wasp is different. The female has a long ovipositor, which it uses to drill into developing figs and into the pollinating fig wasp larvae. When its eggs hatch, they eat the larva alive. This is yet another reminder that nature is disgusting! But the really interesting thing is that at least one parasitic fig wasp species, Apocrypta westwoodi, has an ovipositor that resembles a drill bit, and it’s hardened with zinc. The ovipositor is basically a syringe with a drill bit, but since it’s so strong while being much thinner than a human hair, researchers are studying its structure to help develop minimally invasive medical syringes.

One interesting note. You’d think that iron and other metals would be more common in animal bodies as armor. Animals use some metals for various purposes as it is, like the iron containing hemoglobin in our blood. But incorporating iron and other metals into the body has a high metabolic cost and frequently biological materials are stronger than metal in the ways that count. Plus, they don’t rust.

Thanks for your support, and thanks for listening!

Episode 478: Life in Ice

Posted on March 30, 2026 by strangeanimalspodcast

Podcast: Play in new window | Download (Duration: 13:12 — 14.6MB)

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Is there life on Europa? We take a look at Greenland and Antarctica to find out more about life on Jupiter’s icy moon.

Further reading:

Life on Venus claim faces strongest challenge yet

Stanford researchers’ explanation for formation of abundant features on Europa bodes well for search for extraterrestrial life

Show transcript:

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

Today we’re going to learn about the potential of life on Europa, a moon of Jupiter! To do that we’ll need to look at some extreme life on Earth too.

Back in September 2020, we talked about potential signs of life in the atmosphere of Venus, which excited me a whole lot. As a follow-up to that episode, further studies suggest that signs of phosphine detected in Venus’s atmosphere, which might be produced by life, may actually just be sulfur dioxide (not a sign of life). But while it’s not looking likely that phosphine is actually found in Venus’s atmosphere, so far no studies can completely rule it out. So, maybe.

Venus isn’t the only part of our solar system where life might exist outside of Earth, though. Astronomers have been speculating about Europa for a long time. The planet Jupiter is a gas giant that has at least 80 moons, but Europa is the one that’s closest to the planet. It’s only a little bit smaller than our own moon.

Europa has an atmosphere, mostly made up of oxygen but so thin that if you could magically appear on the moon, you wouldn’t be able to breathe. Also, you would freeze to death almost immediately. It’s a dense moon, so astronomers think it’s probably mostly made up of silicate rock, which is what Earth is mostly made up of, along with Mars, Venus, Mercury, and a lot of moons.

If you’ve ever looked at our moon through a telescope or binoculars, you know it has lots of impact craters on its surface caused by asteroid strikes in the past. Europa doesn’t have very many craters—in fact, its surface is incredibly smooth except for what look like cracks all over it. It’s mostly pale in color, but the cracks are reddish-orange or brown.

The cause of the cracks has been a mystery ever since astronomers got the first good look at Europa. Many astronomers think these cracks are where warm material from below the surface erupted through the crust, sort of like what happens where lava oozes up on Earth and forms oceanic ridges. But on Europa, the material breaking through the crust isn’t lava, it’s ice—but ice that isn’t as cold as the surface ice. You know you’re on a cold, cold moon when ice that’s close to freezing instead of way below freezing can act like lava. The surface of Europa is about 110 kelvin at the equator and even colder at the poles. That’s -260 F or -160 C.

The exciting thing is that researchers are pretty sure the surface of Europa is icy but that the crust lies over a deep saltwater ocean that covers the entire moon. Yes, an ocean! As Europa orbits Jupiter, the planet’s gravity pulls at the moon, while the smaller gravity fields of the other nearest moons also pull on Europa in other directions. This push and pull causes tides that help warm the ocean and keep it from freezing solid. The brown coloration in the moon’s cracks may be due to mineral salts from the water that get leached up through the cracks after warm ice breaks through, assuming that’s what is actually happening to cause the cracks. Astronomers even have images of Europa taken by space probes that show what look like water plumes erupting through the surface and shooting up an estimated 120 miles high, or 200 km.

But new studies suggest that the water plumes might not be from the ocean. They might be from pockets of water that form within the crust itself, which grow larger until they burst out through the crust. This is even more exciting when it comes to potential life on the moon, because it suggests that the crust isn’t just a big block of ice. It’s a dynamic system that might harbor life instead of all potential life on Europa being restricted to the ocean. But to learn more about Europa, we have to come back to Earth and examine the island of Greenland.

Most of Greenland is covered with a permanent ice sheet like the ones found in Antarctica, but it’s a lot easier to study than Antarctica. One feature seen in the ice sheet is something called a double ridge, shaped sort of like a capital letter M. It’s caused when the ice fractures around pressurized water that forms inside the ice sheet and refreezes. This is caused when water from streams and lakes on the surface finds its way into the ice. The double ridge can look like a crack. New pictures of the cracks on Europa’s surface look just like Greenland’s double ridges, but much bigger.

My explanation of all this is extremely clumsy, because this is a really complex mechanism. Researchers only figured it out because some of the team had been studying Greenland’s double ridges for a completely different project, and noticed the similarities. There’s a link in the show notes to an article about this phenomenon if you want to learn more.

The Greenland ice sheet is over a mile thick. In 1966, the U.S. Army drilled into the ice to see what was under it, and the answer is dirt, as you might have expected. They took a 15-foot, or 4.5 meter, core sample and stuck it in a freezer, where everyone promptly forgot about it for 51 years. At some point it ended up in Denmark, where someone noticed it in 2017.

In 2019, the frozen core sample was finally studied by scientists. They expected to find mostly sand and rock. Instead, it was full of beautifully fossilized leaves and other plant material.

The main reason scientists were so surprised to find leaves and soil instead of just rock is that ice is really heavy, and it moves—slowly, but a mile-thick sheet of ice cannot be stopped. If you listened to the recent episode in the main feed about the rewilding of Scotland, you may remember that Scotland doesn’t have a lot of fossils from the Pleistocene because it was covered in glaciers that scoured the soil and everything in it down to bedrock, destroying everything in its path. But this hasn’t happened in Greenland, even though the sample was taken from an area only about 800 miles, or 1,290 km, from the North Pole.

Where the ice sheet now is, there used to be a forest. Obviously, the ice sheet hasn’t always covered Greenland. Research is ongoing, but a study of the sediment published in 2021 indicates that Greenland was ice free within the last million years, and possibly as recently as a few hundred thousand years.

All this is interesting, but it’s very different from Europa, whose ice sheets have probably been in place almost from the moon’s formation. What kind of life can live on, in, or under ice sheets?

On Earth, at least, a lot of organisms live on glaciers. Most are tiny or microscopic, including a type of algae that grows on top of ice, bacteria that live pretty much everywhere, including inside ice crystals, and microbes of various kinds. But there are some larger organisms, including glacial copepods, snow fleas, glacial midges, and the ice worms we talked about in episode 185 that live on glaciers in the Pacific Northwest.

Most likely, life on Europa will be tiny too. Researchers hypothesize that there could be microbial life living deep within the ice or in the pockets of melted water that develop inside it. There might be microbial mats or algae-type organisms that live on the underside of the ice, anchored there but able to extract nutrients from the ocean water.

But obviously, Europa’s ocean is where most life will probably be found, assuming it’s there. While there’s no environment quite like Europa’s to be found on Earth, since Earth is so close to the sun and nice and warm in comparison, parts of the deep sea are somewhat similar. Lots of animals live around hydrothermal vents, where volcanic activity breaks through the ocean floor and superheats water in small areas. Invertebrates of all kinds have adapted to live between boiling hot water and frigid deep-sea water, where absolutely no sunlight has ever reached. Animals like giant tube worms can grow nearly 10 feet long, or 3 meters, and don’t actually eat anything. Instead, they have symbiotic bacteria that provide them with all the nutrients they need while in turn, the bacteria get a safe place to live.

When the intensely heated, mineral-rich water of a hydrothermal vent comes in contact with cold water, it causes all sorts of chemical reactions. That’s what fuels most of the life around the vents. There are even some fish that live around hydrothermal vents, including the cutthroat eel that can grow over 5 feet long, or 1.6 meters. They’re bottom-dwelling deep-sea eels that live worldwide, but they spend time around hydrothermal vents to eat some of the other animals that live there exclusively. There’s even a type of bacteria found at one vent off the coast of Mexico that uses the faint light emitted by lava deep within the vent for photosynthesis. All other known photosynthesizing organisms use the sun as a light source.

Scientists think that Europa has hydrothermal vents similar to the ones on Earth. Since at least some researchers think life on Earth got its start around hydrothermal vents, it wouldn’t be surprising if life forms also live around Europa’s vents. But that doesn’t mean that life could only live around the vents.

In 2018, a team of scientists in Antarctica bored through the ice sheet and took a sample from the sea floor far below the ice to see if anything lived there. Since this was in the middle of the ice sheet with absolutely no sunlight or open ocean within a million square kilometers, they didn’t expect to find much. When they gave the sample to marine biologist David Barnes to examine, and he got a first look at it, initially he actually thought they’d pulled a practical joke on him. There was no way this one small sample could contain evidence of so much life in such an extreme environment.

He counted 77 different species of organism in the sample. There were worms, bryozoans, sponges, even fragments of jellyfish, and of course there were lots and lots of microorganisms. All the animals were small, which isn’t surprising. That they were there at all was the truly surprising thing.

We don’t know yet if life exists anywhere outside of Earth. Odds are good that it does, just because there are so many planets and moons around so many stars throughout our galaxy and all the other galaxies in the universe. Whether we’ll ever find it is another thing. Until we do, though, we will just have to appreciate all the amazing diversity of life on our own planet, and keep watching the night skies and wondering.

Thanks for your support, and thanks for listening!

Strange Animals Podcast

A podcast about living, extinct, and imaginary animals!

Category Archives: invertebrates

Episode 498: Octopolis

Episode 497 Megarachne

Episode 496 Two Mystery Invertebrates

Episode 493: NEW The Mystery of Esconichthys and Friends

Episode 487: Animals and the Sense of Taste

Episode 484: The Sewellel and the Superflea

Episode 482: Smoky Mountain Mystery Animals

Episode 480: Old, Old Life

Episode 479: Metal Animals

Episode 478: Life in Ice