Monthly Archives: February 2019

Episode 108: Strange Things Found in Amber

Thanks to Nicholas for suggesting this week’s episode topic! Lots of strange and fascinating insects and other animals are found trapped in amber. So what is amber, how does it preserve animal parts, and most importantly, what have scientists found in amber?

A millipede preserved in amber, one of 450 millipedes discovered in Myanmar amber. Somebody had to count them:

A newly described insect that got its own order because it’s so weird. Look at that triangular head with giant eyeballs!

A mushroom, a hair, and a tiny phasmid exoskeleton, all caught in amber:

Show transcript:

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

Last month I released an episode about trace fossils, and listener Nicholas wrote me to suggest I also do an episode about amber—specifically, the animals and other items that were trapped in amber and preserved inside it when the amber fossilized. Nicholas also sent me lots of links to really interesting articles!

Amber is the term for fossilized tree resin. If you’ve ever climbed a pine tree and ended up with pine sap all over your hands, which is impossible to get off by just washing your hands and is super sticky and picks up every bit of dirt, you’ll have an idea of what amber starts out as and why it sometimes has insects and other stuff in it. Despite the name pine sap, it’s not actually sap. Sap is the fluid that carries nutrients around to a plant’s cells, sort of like plant blood. Resin is secreted by certain trees and other plants for various reasons, including to protect it from insect damage, to kill fungus, to seal off a broken branch or other injury, and to taste bad so herbivores won’t eat it.

There are different types of amber, because there are different plants that produce resin. We don’t always know what species of plant a particular type of amber comes from, since many are now extinct and can’t be directly studied. Conifer trees evolved around 300 million years ago but became really successful during the Mesozoic around 250 million years ago, spreading throughout the world and dripping resin all over the place. Conifers include pine trees, fir trees, hemlocks, yews, larches, junipers, cedars, redwoods, spruces, and lots of other trees and shrubs that are still widespread today. Some flowering plants, mostly trees, also produce resins. But before conifers evolved and outcompeted them, plants called medullosales lived around the world and produced resin too. Medullosales first appear in the fossil record around 360 million years ago and mostly died out around 298 million years ago. They’re all extinct now.

If your name is Amber, by the way, you are named for fossilized tree resin. That sounds gross, but amber has been prized for millennia as a gemstone. When polished, it can be a gorgeous yellow, gold, or brown, often the color of honey. But some amber is other colors, including red, blue, or green. It all depends on what tree originally produced the resin, its chemical makeup, and how it was fossilized.

So how does the resin fossilize? Sometimes it would drip onto the ground, become buried, and fossilize along with the ground around it. Sometimes the resin-producing tree would fall, become buried, and the resin inside would fossilize along with the wood. Sometimes the resin would drip into water, float to a quiet area or sink to the bottom of the pool or lagoon, and fossilize along with the sand and other sediment that covered it. This is why so much amber is found in the ocean, by the way. Once fossilized, amber floats in salt water—just barely, but enough that on some beaches it’s commonly washed up with the tide. People collect the pieces of amber to polish and sell. Amber can also be burned and often gives off a musky, piney scent that has been used in religious ceremonies.

The reason we’re talking about fossilized plant material in an animal podcast is that amber sometimes has insects or other small animals or animal parts inside it. This happened when it was still resin, which is really sticky. If an ant or bee was in the wrong place at the wrong time, it could be covered with resin and die. Then, if that particular dollop of resin ended up getting protected by sediment at just the right time, instead of weathering away and decaying it might fossilize over millions of years with the ant or bee or whatever inside it. And because the ant or bee was protected from air, water, and bacteria by the resin, and kept in place, the things found in amber are usually mostly intact and include parts of the body that ordinarily never fossilize. It may even help preserve DNA, which ordinarily decays after a matter of thousands of years, although there’s still conflicting evidence about whether this is the case. All this helps researchers study animals that went extinct millions of years ago almost as though those animals were still around.

Substances inside amber are called inclusions, whether they’re something exciting like a spider or just a piece of dirt. Well preserved inclusions, especially pretty ones like flowers, can make the piece of amber extremely valuable. If you want to buy polished amber with an inclusion, though, keep in mind that there are a lot of fakes out there. Make sure to have an expert examine an expensive piece before you spend money on it.

So let’s learn about some insects and other things that have been discovered in amber. I’m going to mention Myanmar repeatedly because it’s a big amber-producing region and the subject of an intensive ongoing study of animals found in the amber. Myanmar is in southeast Asia and was once called Burma.

The oldest organism found in amber are two tiny mites and a fly dated to 230 million years ago. The amber in question is very small, droplets no more than about six millimeters across, found in the Italian Alps. The mites are two different species, both new to science although they have living relations that resemble the ancient mites closely. Both of them ate plants. The fly isn’t as well preserved so researchers aren’t sure what species it was.

A 3 millimeter beetle found in amber dated to 99 million years ago was found in Myanmar. It’s an ancient relative of the modern flat rove beetle that lives under tree bark. But the flat rove beetle lives in South America, with one species from southwestern North America. Comparing the modern beetles with their ancestor gives researchers a closer idea of when the supercontinent Gondwana started to split apart into smaller continents as the landmasses moved slowly across the Earth to their current positions.

The amber found in Myanmar has yielded a lot of interesting information during recent studies. For instance, 450 millipedes! Not all in one piece, of course. The research team used a new type of analysis called micro-CT, which scans the inclusion and creates a highly detailed 3D image which can then be studied without damaging or even touching the amber. This is helpful when the amber pieces are privately owned and only on loan to scientists. Some of the millipede specimens were newly hatched, some fully grown, and include many species new to science.

Another insect found in Myanmar amber dated to 99 million years ago is so unusual that researchers placed it in its own order. To illustrate how rare this is, there are over a million insects described by scientists but they all fit into 31 orders. But now there’s 32 orders. The insect had a triangular head with big bulging eyes, a long flat body, long legs, and no wings. It also had glands on its neck that secreted chemicals that probably helped repel predators. Because of its large eyes and the unusual head shape, it could see almost all the way around it without turning its head. Two specimens of the extinct insect have been found in amber. One of the researchers who described the insect, amber expert and entomologist George Poinar, Jr, said that he thought it looked like an alien’s head so he made a Halloween mask that looked like it. As you do. He said “when I wore the mask when trick-or-treaters came by, it scared the little kids so much I took it off.”

It’s not just insects that are found preserved in amber. One foot and part of a tail from a 100 million year old gecko were found in amber about a dozen years ago. Researchers think the rest of the gecko was probably eaten, possibly by a dinosaur. Even though there isn’t a lot of the gecko to study, there’s enough to determine that it was a genus and species new to science, and that it was probably a juvenile gecko that would have grown up to a foot long if it had lived, or 30 cm. It was only about an inch long when it died, or a bit over two cm. It was stripey and had the same type of toe pads that modern geckos have that allow them to walk up walls.

Another foot, this one from a frog, was discovered in more of the Myanmar amber that’s the subject of ongoing studies. It was a tiny juvenile frog that lived in a tropical forest around 100 million years ago. It’s only the third frog ever found in amber, and is by far the oldest in addition to being the best preserved. Its skull, forelegs, part of its backbone, and the partial hind leg and foot are all preserved, together with a beetle. The problem is, some of the details researchers need to determine what kind of frog it is are missing, like the pelvis. They have just enough information to tantalize them since what they can see indicates that it might be related to some species of toad that live in temperate climates today, but not enough to tell for sure. You know they have to be tearing their hair out in frustration. Hopefully they’ll find another frog with all the bits and pieces they need.

Another surprise from the Myanmar amber is a baby snake only about two inches long, or 5 cm. At first researchers thought it was yet another millipede—I mean, when you’ve found 450 millipedes in amber you probably start to think everything is a millipede—but a scan determined that it was way different. It’s well preserved and even shows some features that modern snakes no longer have, like V-shaped bone spurs on the tail vertebrae that probably helped with stability when snakes first evolved to be limbless. Unfortunately the specimen is missing its skull.

Only one salamander has been found in amber, and it came from a surprising place. The amber was mined from the mountains of the Dominican Republic, which is in the Caribbean near Haiti. But there are no salamanders in the Caribbean today. The salamander in amber dates to around 25 million years ago and proves that salamanders did once live in the Caribbean. Not only that, the amber itself comes from an extinct tree that’s related to a tree native to East Africa. The salamander was a tiny juvenile that fell into a glob of resin after a predator bit one of its legs off. So, you know, it was doomed either way. Poor little salamander.

One really exciting discovery is part of an actual dinosaur tail trapped in amber. It came from a juvenile dinosaur that a scientist found at a market in Myanmar in 2015. The seller thought the tail was a plant, because—you’ll like this—it’s covered in FEATHERS that looked like bits of leaf. It’s dated to 99 million years ago. The feathers were chestnut brown on the tail’s upper surface and white underneath. They’re also very different from modern bird feathers. Researchers aren’t sure which dinosaur species the tail is from, but they do note that the dinosaur died, probably because it couldn’t get free from the resin. It wasn’t like some modern lizards that can drop their tails to escape predators.

Lida Xing, the same researcher who acquired the dinosaur tail in amber also managed to buy a bird in amber in the same Myanmar amber market. Only a few birds have been found in amber and they sell for ridiculous amounts of money—like half a million dollars—to private collectors. As a result, they’re rarely studied. Fortunately, Lida Xing was able to buy the bird in amber and it’s been studied ever since. It’s a young bird that was partially weathered away and squished after it died. It’s about 2 ½ inches long, or 6 cm, and is a type of primitive bird that went extinct at the same time as the non-avian dinosaurs 66 million years ago. It was dark brown and had teeth and clawed fingers on its wings, although both the beak and the finger-wings are missing from the specimen.

Sometimes marine or freshwater organisms are found in amber. For a long time no one understood how this happened, but in 2007 a team of researchers conducted a simple study to find out how it worked. One of the researchers owned some swampy property in central Florida. The team went there and cut pieces out of some pine trees growing in the swamp. Resin flowed from the trees’ injuries, down the trunk, and into the water. The researchers then collected the resin from the water and took it to a lab to examine it. They found water beetles, nematodes, small freshwater crustaceans, mites, even bacteria found in swampy water, all stuck in the blobs of resin. In other words, it’s not a bit unusual for water animals to get caught in resin. The unusual part is when they’re preserved in the resin long enough for the resin to fossilize into amber, and then the really rare part is when they’re found by a human who understands what they’re looking at and realizes it’s important.

Some of the most useful information preserved in amber concerns animal behavior. For instance, the recent discovery of a tick wrapped in spider silk. Spiders don’t usually eat ticks, but occasionally they do, and this tick in amber had been wrapped up in spider silk to immobilize it. Researchers aren’t sure whether the spider planned to eat the tick or was just stopping it from tearing up its web. Either way, it fell out of the web and plopped right into resin, which fossilized and was then found around 100 million years later. From this little piece of amber, we have direct evidence of a spider wrapping up its prey the same way they do today.

Another example is dated to 130 million years ago, when some green lacewing eggs hatched and the larvae and eggs were trapped in resin almost immediately. The green lacewing is a type of flying insect that’s still around today, although the ones found in resin are a species new to science. Since the babies were covered in resin during the act of hatching, researchers have learned a lot about how they emerged from the eggs.

There’s even a piece of amber dated to around 100 million years ago, also found in Myanmar, that shows a dragonfly with a missing head, together with the foot and tail of a tiny lizard. Researchers think the lizard may have caught the dragonfly and decapitated it to kill it, but before it could eat it, both predator and prey were trapped in resin. It’s too bad we don’t have the lizard’s head, because it would be really awesome if it had the dragonfly’s head in its mouth.

Some pieces of amber tell a story like this, like a photograph from millions of years ago. About 50 million years ago near what is now the Baltic Sea, a small mammal, possibly a rodent, bit a mushroom off at its base. A tiny insect, specifically a phasmid, or walking stick, was feeding on the mushroom and jumped away. All this happened just as a blob of resin dropped on the scene. The mammal fled, leaving behind a hair. The insect was trapped but was able to wriggle out of its exoskeleton in an early molt and escape, leaving its exoskeleton behind. The mushroom did nothing, because it was a mushroom. That particular phasmid species is now extinct, as is the mushroom species. Researchers don’t know much about the mammal. They know that the exoskeleton was literally shed moments before it was enveloped in resin because it still shows tiny filaments that would have crumbled away otherwise.

Even more dramatically, another piece of amber, again from Myanmar and about 100 million years old, shows a spider in the act of attacking a wasp. Both the spider, a bristly orb-weaver, and the parasitic wasp are still around today.

Other things are also preserved in amber, from pollen and plant spores to feathers and spiderwebs. It’s mined and gathered in various parts of the world for jewelry, so new amazing specimens could be discovered any day.

I could literally just keep going with this episode for hours talking about what’s been found so far, but I have to stop somewhere so I’ll leave you with one last amber inclusion.

It’s another strange insect new to science, also found in Myanmar amber dated to about 100 million years ago. It was tiny but really weird-looking. Researchers have been referring to it as a unicorn fly because it had a sort of horn sticking up from the top of its head that had three eyes at its tip. Researchers think its specialized horn with eyes on it gave it an advantage when flowers were tiny, as they were back in the early Cretaceous when it lived. Flowering plants had only recently emerged and were diversifying rapidly. It probably ate pollen and nectar. But when flowers evolved to be larger, it lost its evolutionary advantage and went extinct. It also had tiny mandibles that meant it could only eat very small particles of food, long legs, and weirdly shaped antennae.

The unicorn fly was described by our friend George Poinar, who described the weird insect with the triangular head too. And true to form, Dr. Poinar is up to his same tricks. He’s reported as saying that he was “thinking of making some masks based on it for Halloween.”

George, no! The children are frightened! Stop making Halloween masks!

One note about listener suggestions. I’ve been getting a lot of them lately, which is awesome, but I don’t necessarily use the suggestions in order. Which one I pick out for the next episode depends on a lot of things, including how much time I have for research, what strikes me as neat on any given day, and whether I can work a suggestion in to a planned episode about a larger topic. But I promise I do keep all suggestions in a list, and I will eventually get to them all! I’m always delighted to get more, too, so don’t feel like I’m telling you not to send any. Some of the best episodes I’ve done have been from listener suggestions, about animals I’d never heard of before.

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

Thanks for listening!


Episode 107: Ankylosaurus and Stegosaurus

This week we’re going to learn about some armored dinosaurs, a suggestion by Damian!

I love that there’s a stock picture of an ankylosaurus:

Stegosaurus displaying its thagomizer:

Thagomizer explained:

Show transcript:

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

This week’s episode is another suggestion, this one from Damian, who wants to learn about armored dinosaurs like stegosaurus. It turns out that stegosaurus and its relatives are really interesting, so thanks to Damian for the suggestion!

We’ll start with ankylosaurus, which lived near the end of the Cretaceous period, right before all the non-avian dinosaurs went extinct, about 65 million years ago. A lot of paleontologists pronounce it ANKillosaurus, but it’s properly pronounced anKYlosaurus and for once, I’m finding the correct pronunciation easier, probably because it has the name Kylo right in the middle, like Kylo Ren of Star Wars.

There are a lot of species in the ankylosauridae family, but ankylosaurus was the biggest and is probably the one you would recognize since it’s a popular dinosaur. It’s the one with a big club on the end of its tail, but its leathery skin was studded with armored plates called osteoderms or scutes that made it look something like a modern crocodile. It also had spikes along its sides, although they weren’t as long or as impressive as some of the other ankylosaurids’ spikes.

We don’t know exactly how big ankylosaurus could get because we’re still missing some key bones like the pelvis, but paleontologists estimate it could grow around 33 feet long, or ten meters. Is legs were relatively short and its body wide, something like a turtle. When it felt threatened, it may have just dropped to the ground to protect its unarmored belly and laid there like a huge spiky tank.

Because we only have a few fossil specimens of ankylosaurus, there’s actually a lot we don’t know about it. Much of what we do know is actually mostly from ankylosaurus relatives. Researchers think ankylosaurus actually may not have been a typical ankylosaurid. They aren’t sure if the few fossils found mean it was a rare animal or if it just lived inland, away from water, since fossilization is much more common when water is involved. It lived in what is now North America, although it had relatives that lived throughout much of the world.

Ankylosaurus had a beak something like a turtle’s but it also had teeth that it probably used to strip leaves from stems before swallowing them whole. It probably ate ferns and low-growing shrubs. It had a massive gut where plant material would have been fermented and broken down in what was probably a long digestive process. But some researchers think it may have mostly eaten grubs, worms, and roots that it dug up with its powerful forelegs or its beak, sort of like a rooting hog. Its nostrils are smaller and higher on its nose than in other ankylosaurids, which could be an adaptation to keep dirt out. This might also explain why ankylosaurus appears different from other ankylosaurids, which definitely ate plants.

Ankylosaurus had a remarkably small brain for its size. Paleontologists think it may have used its massive tail club as a defensive weapon, but they don’t know for sure. The tail might just have been for display, or maybe males used their tail clubs to fight during mating season. It probably couldn’t walk very fast and was probably cold-blooded, which allowed it to survive after other dinosaurs went extinct after the big meteor struck. Eventually the plants it ate started going extinct, and since it was a big animal that needed a lot of food, it finally went extinct too. Researchers think bird ancestors survived because they were small and could live by eating plant seeds.

One interesting thing about ankylosaurs of all kinds is how they kept from overheating. Large bodies retain heat better than small bodies, which is why polar bears and mammoths are such chonks. Ankylosaurs were massive animals that lived in warm climates. New research published in late 2018 shows that they kept their brains cool by having extremely convoluted nasal passages with blood vessels alongside them. This helped cool the blood before it reached the brain, keeping it from overheating.

Ankylosaurus was related to stegosaurus. Stegasaurus lived in North America around 150 million years ago, during the Jurassic, but its ancestors were found in many other parts of the world. Like its cousin, stegosaurus had a small brain but grew to enormous size, as much as 30 feet long, or 9 meters. You definitely know what a stegosaurus looks like, since next to T rex it’s probably the most recognizable dinosaur. It had big dermal plates that stood up in rows along its spine and four spikes on the end of its tail, called a thagomizer. I’m not even making that name up, it really is called a thagomizer and the term really is from the Far Side cartoon. Its forelegs were shorter than its hind legs, and researchers think it probably stood with its head down to browse on low-growing vegetation, with its tail sticking up as a warning to any predator foolish enough to get too close.

The thagomizer spikes were probably used for defense. Not only do a lot of the spikes show injuries, we have a fossilized tail vertebra from an Allosaurus with a hole punched right through it. The hole matches the size and shape of a stegosaurus’s tail spike.

Paleontologists aren’t as sure about what the plates were for. They were made of bone covered with a keratin sheath that might have been brightly colored or patterned. There are signs that the plates contained a lot of blood vessels for their size, which suggests they helped with thermoregulation—that is, they might have helped the animal absorb and shed heat. Then again, new studies also suggest that the males had larger, broader plates while females had smaller, sharper ones. This argues that the plates might have been for display. Of course, they could be for both display and for thermoregulation.

Sometimes you’ll hear that stegosaurus had such a small brain that it had a second brain in the hip to help it control its tail. This isn’t the case, though. There is a canal in the stegosaurus’s hip near the spinal cord, but this is something found in other dinosaurs and in modern birds. In birds it’s where a structure called the glycogen body is, but researchers don’t actually know what the glycogen body is for. That’s right, something present in all birds, even chickens and pigeons, is more or less still a mystery to scientists. But whatever it is, it’s not a second brain.

There are other mysteries associated with the stegosaurus, like how it ate. It had a tiny head for its size, about the size of a dog’s head, with peglike teeth that seem to have been used for chewing or shearing plant material. But because the head was so small, and the teeth weren’t shaped for grinding, it probably couldn’t have chewed its food up like modern grazing mammals do. But it also doesn’t seem to have ingested gastroliths, small stones used for grinding up food in the stomach.

There were lots of other armored dinosaurs, generally related to stegosaurus and ankylosaurus. I was going to talk about triceratops too, but technically it didn’t have armor, just head frills and horns. Besides, I think triceratops and its relations need their own episode pretty soon. So we’ll finish up with another ankylosaurid, Akainacephalus.

The only fossil we have of akainacephalus was discovered in 2008 in Utah. It’s a remarkably complete fossil, including the skull and jaws, and has been dated to around 76 million years old. It had a spiky ridge over its eyes and short triangular horns on its cheeks that pointed downward. It also had a tail club that ankylosaurids are known for.

Akainacephalus was formally described in 2018 as not just a new species of ankylosaurid, but one in its own genus. Even though it was found in North America, researchers have determined that it’s more closely related to the ankylosaurids that lived in Asia.

Before Akainacephalus evolved, Asia and North America were connected with a land bridge due to low sea levels. This land bridge is called Beringia, and while it’s currently underwater, at different times in the past it’s been exposed and allowed animals to cross from Asia to North America and from North America to Asia. Beringia is about 600 miles wide, or around 1,000 km, when it’s above water. At the moment, it’s represented by a couple of little islands in the shallow Bering Strait, since it’s been underwater for the last 11,000 years.

Previously researchers thought this land bridge had only been open once during the Cretaceous, but that was before paleontologists examined akainacephalus. Since akainacephalus is related to ankylosaurids that lived in Asia after the land bridge was submerged, it’s possible there was a second opening of Beringia that allowed akainacephalus’s ancestor to migrate from Asia to North America.

That’s one of the really neat things about science. You start by looking at a cool spiky fossil skull, and you end up learning something new about how deep the oceans were 80-some million years ago.

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

Thanks for listening!

Episode 106: Domestication with and without foxes

Thanks to M Is for Awesome, who suggested the topic of domestication! This week we look mainly at foxes and how they relate to the domestication of dogs. Also, chickens.

Unlocked Patreon episode about chicken development and domestication:

A red fox:

Domestic foxes want pets and cuddles also coffee:

The fennec fox with toy I JUST DIED:

The raccoon dog is actually a species of fox:

Show transcript:

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

Back in episode 80, about mystery dogs and other canids, I said I was going to leave foxes for another episode. And here it is! But as I researched, it turned out that while there are lots of interesting foxes, they’re all pretty similar overall. So while we will learn about some of the more unusual foxes this week, I’m mostly going to talk about how animals are domesticated by humans. This is a suggestion from M Is for Awesome, who suggested domestication “and how it changes domesticated creatures from their wild cousins.” You may not know how this relates to foxes, in which case, I’m about to blow your mind.

But first, we should learn about how scientists think other canids became domesticated. You know, how dogs became dogs instead of wolves.

Domestication of wolves took place possibly as much as 40,000 years ago, but certainly at least 14,000 years ago. Gray wolves are the closest living relative of the domestic dog, but the gray wolf isn’t the dog’s ancestor. Another species of wolf lived throughout Europe and Asia, possibly two species, and domestication of these wolves occurred at least four different times in different places, according to DNA studies of ancient dog remains.

One of the oldest dog remains ever found dates to 33,000 years ago, found in a cave in Russia. Researchers think it wasn’t fully domesticated, but was probably connected with the people who had been using the cave as shelter. A 2017 study concluded that it isn’t related to any modern dogs and apparently was related to a species of wolf that has since gone extinct.

Many researchers think that wolves actually started the domestication process. Wolves hunt but they also scavenge, so they may have gotten into the habit of following bands of humans around to find scraps of food. Back in the hunter-gatherer days before we started growing crops, humans were nomadic, moving from place to place to find food. Wolves would have been attracted to the bones and other parts of dead animals humans left behind. If a wolf got too close to a campfire where humans were sitting around eating, two things might happen. If it was an aggressive wolf, the humans would chase it away or even kill it. But if it wasn’t aggressive, maybe because it was scared or young, a human might have tossed it a little bit of meat or a bone. That wolf would definitely hang around more, hoping for more food. If the humans grew used to it, it might even have started to consider itself part of the human’s pack. And if another predator approached, the wolf might growl at it and warn the humans, who would reward the wolf with more food. Over the generations, the wolves who got along best with humans would receive the most food and therefore be more likely to have babies that also got along with humans. It’s a lot easier to act as a camp guard and be given food and pets than it is to go out and try to kill ice age megafauna with your teeth.

Remains of a puppy dated to 14,000 years ago was found recently in a prehistoric grave in Germany. A test of its DNA indicates that it is related to modern dogs. The puppy was fully domesticated, well cared for, and had been buried with a man and a woman. Researchers can even tell that the puppy died of distemper, which leaves telltale marks on the teeth. The puppy had survived until the disease was well advanced, and it could only have done so with special care from humans. Even today distemper is a terrible disease among dogs. I had a puppy that died of it when I was little. Obviously, even 14,000 years ago dogs were already more than working animals or camp scavengers. Someone loved that puppy and tried to help it get better.

An interesting thing happens with domestication. Certain physical traits come along with the behavioral traits of reduced aggression and willingness to treat humans as surrogate parents. In the case of dogs, these often include a puppy-like appearance, including floppy ears, curled tail, smaller adult size, and a rounder head with smaller jaws. This isn’t the case with all dog breeds, of course, but the changes seem to be genetically linked to behavior. It’s called domestication syndrome.

So this is interesting, but how does it apply to foxes? Foxes are canids, but they aren’t all that closely related to dogs.

Well, in 1959 a Russian zoologist named Dmitry Belyaev decided to see if he could domesticate foxes. Taming and domestication are different things. A wild animal that has become used to certain humans can be considered tame, but a domesticated animal is one that is genetically predisposed to treat humans as caregivers. Belyaev didn’t just want to tame a few foxes, he wanted to try actually domesticating them.

He started his project by going to a fur farm that bred foxes to kill for their furs, which were then made into coats and other clothing. These were red foxes, which are common throughout much of the world, but because they were bred for their fur, they weren’t red. They were a darker color called silver, a color mutation, but other than that they were regular foxes. Belyaev chose foxes by how well they tolerated people, the ones that were less likely to bite.

He bred these foxes and when the babies grew up, he chose the least aggressive ones to breed. Then he chose the least aggressive babies from those parents, and so on. And after only six generations, he started to see results. Some of the foxes in the sixth generation actively sought out humans. They licked their hands, whined for attention, and even wagged their tails.

Something else happened too. The foxes started showing physical differences. Some had fur with white patches or various other color variations, some had floppy ears, some carried their tails so that the tip pointed up. All these traits are common in dogs, but pretty much never seen in wild foxes. Recent research shows that the changes are genetic and linked to lower adrenaline production. One color of fox, called Georgian white, has never been seen except in Belyaev’s domesticated foxes. It’s a lovely white all over with black ears and black or gray markings on the face and paws.

In case you’re wondering how much of the behavioral differences are due to increased human contact, the study also breeds the least tame foxes. They continue to look and act like wild foxes.

The breeding project has continued even though Belyaev died in 1985. These days almost all the foxes are as tame as dogs. Belyaev also conducted domestication projects with rats and American mink, both of which succeeded as well as the fox project. But if you want a pet fox, you’re out of luck. The foxes are occasionally for sale, but they’re extremely expensive and some parts of the world don’t allow foxes to be kept as pets at all, even these domesticated foxes. Occasionally someone will pop up online claiming to have some of the domesticated foxes for sale, but they always disappear after taking people’s money and never deliver any foxes.

Besides, even though Belyaev’s foxes are domesticated, they aren’t dogs. They don’t always behave in ways that make sense to humans. Humans and dogs have been buddies for untold thousands of years and we’ve basically evolved together, while foxes have only been domesticated for basically one human lifetime. One zoologist whose institute has several of the domesticated foxes for study and outreach says that she has to watch her coffee cup because if she doesn’t, one of the foxes might pee in her coffee. As soon as I read that, my desire to own a pet fox diminished. They’re really cute, but so are dogs, and while I have had a dog that would steal and eat sticks of butter off the counter, I never had to worry about him peeing in my coffee. Besides, the domestic foxes are also hard to house-train and still retain a wild fox’s musky odor.

The fennec fox is the smallest canid, and it’s sometimes kept as a pet, but it’s not domesticated. If the babies are taken from their mother very early, they grow up fairly tame, but they’re still wild animals and can be aggressive.

I have seen a fennec fox at the Helsinki Zoo! It was adorable. I definitely can see why people want one as a pet, but honestly, cats are about the same size and shape but are a lot less likely to bite. Also, cats purr. The fennec fox lives in northern Africa and parts of Asia and its fur is a pale sandy color with a black tip to the tail. Its eyes are dark and its ears are large. It stands only about 8 inches tall at the shoulder, or 20 cm, but its ears can be six inches long, or 15 cm. It eats rodents, birds and their eggs, insects, and other small animals, as well as fruit. It can jump really far, some four feet in one bound, or 120 cm. Because it lives in desert areas, it rarely needs to drink water. It gets most of its water through the food it eats, and researchers think it may also lap dew that gathers in the burrow where it spends the day.

The most common species of fox is the red fox. Foxes are canids related to dogs and wolves, and just to be confusing, male foxes are sometimes called dogs. Female foxes are vixens and baby foxes are cubs or kits. But the red fox isn’t the only species out there, not by a long shot.

For instance, the grey fox lives throughout North and Central America. It can look a lot like a red fox but its legs are always reddish or tan, unlike the red fox, which always has black legs. Instead of a white tip to its tail like red foxes have, the grey fox has a black tipped tail. It’s also not that closely related to the red fox or any other foxes, for that matter. Its pupils are rounded like a dog’s instead of slit like other foxes, which have eyes that resemble cats’ eyes.

The grey fox also has hooked claws that allow it to climb trees. That’s right. I said it can and does climb trees just like a cat. It’s nocturnal and omnivorous, which means it eats pretty much anything. It especially likes rabbits and rodents, but it also eats lots of fruit and insects.

The only other canid that can climb trees is the raccoon dog, which is neither a raccoon nor a dog. It’s actually a type of fox, but it does look a lot like a raccoon at first glance. It has grizzled brown-gray fur, a black mask over the eyes and cheeks, and a short muzzle and rounded ears. And, of course, it also climbs trees like a raccoon. But it’s larger and bulkier than a raccoon with much longer legs, and its tail isn’t ringed like a raccoon’s tail.

The raccoon dog is native to parts of Asia, but it was introduced to parts of western Russia in the early 20th century as a fur animal and is now widespread throughout much of Europe. It’s an omnivore too; pretty much all foxes are omnivores. It eats rodents, frogs and toads, birds, fish, fruit and plant bulbs, some grains, and insects. You know, pretty much anything. It even eats toads that are toxic to other animals, diluting the toxins with massive amounts of saliva. And in cold areas, the raccoon dog hibernates. It’s the only canid that does.

Several months ago, I released a Patreon episode about chicken teeth that also talked about the domestication of chickens. It wasn’t my best episode but it’s relevant here so I went ahead and unlocked it for anyone to listen to. There’s a link in the show notes so you can click through and listen in your browser without needing a Patreon login or anything. Anyway, let’s finish up today with some information I just learned about the domestication of chickens. Specifically, a breeding project similar to the Belyaev foxes but with the wild birds that are the ancestors of domesticated chickens.

The bird is called the red jungle fowl, which lives in Asia and looks like a chicken, but is smaller than domesticated chickens. It was domesticated as long as 8,000 years ago but the wild bird still exists. A Swedish research team tried replicating Belyaev’s domesticated fox experiment with some of the wild birds. Like the foxes, the researchers bred a population of birds that were just ordinary wild jungle fowl and not selected for tameness, and a population of birds that were chosen because they tolerated humans a little more than usual. As each of the baby birds grew up, they were tested by having a human walk into the pen and try to touch it. The human wasn’t told whether the bird was from the tame group or the wild group. But after a couple of generations, it was obvious which was which. The tame birds became so tame that they didn’t mind the human at all.

And like the foxes, although the only trait the researchers selected for was tameness, the chickens began to change in other ways too. They became bigger and the hens laid more and larger eggs. This happened within only a few generations, which suggests that domestication is a much faster process than researchers once assumed.

And thanks to recent study, we’re pretty sure we know why these physical changes happen along with the behavioral changes. Selecting for tameness alters the genes that controls what are called the neural crest cells. When the embryo is developing, the neural crest cells migrate to different parts of the body. They affect the coat or feather coloring and some other physical developments, but they also affect the development of many other traits, including the fight-or-flight response. In other words, if you select for an animal that tends to be calm instead of fighty or flighty, you’re also accidentally selecting for differences in physical traits. Follow-up studies confirm that neural crest cells migrate differently in domestic animals than they do in their wild counterparts.

Research into domestication is a hot area of study right now, now that DNA and molecular genetics studies are more sophisticated. You know, in case anyone out there is considering a career in science.

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

Thanks for listening!

Episode 105: The Hagfish and the Sea Spider

This week’s episode is about two strange animals of the sea: the hagfish, which isn’t a fish, and the sea spider, which isn’t a spider.

A curled-up hagfish:

The sea spider is actually quite pretty as long as I don’t have to touch it:

Show transcript:

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

A long long long time ago, and I can’t even remember which episode it was, I mentioned that one day I would do an episode about the hagfish because it’s such a weird animal.

Well, that day is today.

The hagfish isn’t a fish. It looks more like an eel and is sometimes called a slime eel. But it’s not an eel either. In fact, it’s so weird that scientists are still trying to figure out exactly where the hagfish fits in the animal world.

The only living animal that is similar to the hagfish is the lamprey, and current research suggests that they are fairly closely related. We talked about the sea lamprey way back in episode three.

There are a number of hagfish species. The biggest is the goliath hagfish (Eptatretus goliath), which can grow more than four feet long, or 127 cm, but most species are much smaller. As mentioned, it looks sort of like an eel, with a tail that’s flattened like a paddle. It doesn’t have true fins, it doesn’t have a jaw, and it only has a single nostril. It usually breathes by swallowing water, which runs through gill pouches inside the body, but some researchers think it can also absorb oxygen through its skin. It can survive for hours without oxygen.

The hagfish is considered a vertebrate because it has a rudimentary spine, called a notochord. It has eyespots instead of true eyes, which can only detect light, but fossilized ancestors of living hagfish seem to have had more complex eyes. I guess they just didn’t need them.

The hagfish has a lot of blood for its size. Its skin is loose and only attached to the rest of the body along its back and at its slime glands. Since its skin is thick and contains about a third of the body’s blood, the hagfish actually looks kind of like a fluid-filled sock with a tail. If you’ve ever bought an eelskin wallet or other item, it was probably actually made from hagfish skin. Because the hagfish has such low blood pressure, the lowest recorded in any animal, and because its skin is so loose and it only has a few bones, it can squeeze through incredibly small openings. When it does, the blood in its skin is pushed into the rear of its body. This would kill an ordinary animal, but it doesn’t affect the hagfish at all.

There’s so much weirdness about the hagfish that it’s hard to know where to start. Its mouth, for instance. Instead of jaws, its skull has a piece of cartilage that can move forward and backward, with two pairs of comb-shaped teeth attached to the plate. This sounds like it would be an awkward way to bite into food, but it works so well for the hagfish that it hasn’t changed in some 300 million years. It’s more like a toothed tongue or a radula than anything resembling vertebrate jaws. The hagfish also has short tentacles around its mouth.

The hagfish eats anything, but the main part of its diet is probably marine worms that live on the sea floor. It also scavenges carcasses that sink to the bottom of the sea. If you’ve seen that amazing time-lapse video of a blue whale carcass, you’ve seen hagfish. They’re the ones that burrow into the carcass to bite pieces of meat off from the inside, and the ones that will actually tie their body into a knot to help yank food off the carcass. Since the hagfish lives on or near the sea floor, trawlers who drag nets along the sea floor to fish often catch hagfish by accident. Sometimes they catch so many hagfish that by the time they haul the net up, the hagfish have eaten all the fish in the net.

But the hagfish also hunts fish actively, especially the red bandfish that lives off the coast of New Zealand. The red bandfish digs a burrow, and the hagfish will slither into the burrow and drag the fish out to eat it. It may actually suffocate the fish first by smothering its gills with slime.

And that brings us to another weird thing about the hagfish, its slime. The hagfish is famous for its slime. It has something like a hundred slime glands along its sides, and if it feels threatened it will release massive amounts of slime through the glands. It only takes a fraction of a second to release slime. This doesn’t just make it slippery, the slime actually absorbs water and increases in volume, and it’s sticky. If a fish grabs a hagfish, suddenly the hagfish has secreted more than five gallons of slime—that’s 20 liters—which contains thin fibers that help clog the fish’s gills. Meanwhile, the hagfish will tie itself into a knot and push the knot from its head to its tail, which pushes the slime off of its own body and leaves it behind. The hagfish swims away, leaving the predator dealing with copious amounts of slime sticking to its gills. Basically, almost nothing eats the hagfish, not even sharks. But exuding so much slime does cost the hagfish energy. It can take weeks to recover.

One really interesting thing about hagfish slime is those fibers that make up part of its volume. When dried out, the fibers look like silk and are almost as strong and thin as spider silk. They’re also produced from cells that are genetically smaller than those in spiders. Researchers are trying to figure out how to take the DNA for hagfish fiber production and implant it into bacteria that would then produce quantities of silk. Because it’s so strong and lightweight, the silk could then be used to make cloth that could take the place of petroleum-based fibers like nylon. This is so exciting. My guess is it’ll be marketed as eel silk, because that sounds way better than hagfish slime fibers.

We don’t have many hagfish fossils since the hagfish only has a few bones and the rest of its body is rarely preserved in the fossil record. But we do have one really good fossil dated to 100 million years old. Recently, it was imaged using a method called synchrotron scanning, which identifies chemical traces of soft tissues left in the stone. The scan revealed the chemical signature of keratin along the fossil’s sides, and since the slime fibers are made of keratin, researchers think that 100 million years ago the hagfish was already producing slime.

An interesting side note about the synchrotron scanning is that it can be used to detect glue or paint used to make a fossil look more complete than it really is. Fossil forgers beware.

Researchers still don’t know a lot about how hagfish reproduce. We do know that hagfish eggs take a long time to hatch, something like eleven months. The eggs have hooked hair-like structures at the ends and usually stick together in bunches. Hagfish don’t hatch into larvae like lampreys do, but instead hatch into little hagfish. Some hagfish species appear to be hermaphroditic, which means an individual contains both eggs and sperm, but they probably don’t lay eggs until they’re older.

The hagfish also has three hearts. Happy Valentine’s Day.

Another weird and fascinating ocean creature is the sea spider. Honestly, despite its name, after the hagfish, the sea spider seems positively normal.

The sea spider isn’t actually a spider, but it’s also not a crab. Like the hagfish, researchers aren’t sure where the sea spider belongs taxonomically. Traditionally it’s been grouped with the group of arthropods known as chelicerata [kelisserate-a], which includes true spiders, scorpions, ticks, and their relatives, and horseshoe crabs. But some researchers think the sea spider is more closely related to our old friend Anomalocaris, a stem arthropod that lived during the Cambrian. Recent genetic studies so far indicate that the traditional chelicerata classification is probably correct.

The sea spider has four pairs of legs, although a few species have five or six pairs of legs instead. Some species have one or two pairs of simple eyes, but other species have no eyes at all. The body is quite small in relation to the legs, which are extremely long, which means the digestive tract is actually partly in the legs, because the body is too small for it. It walks along the bottom of the ocean or may swim by pulsing its long legs like a jellyfish with legs instead of a bell. In species that swim, the legs may be lined with long bristles. Males take care of the eggs until they hatch, so male sea spiders have a pair or two of small legs called ovigers that are used to carry eggs.

Like true spiders, the sea spider doesn’t breathe in a way we think of breathing. It absorbs oxygen through pores in its exoskeleton, and the oxygen is then absorbed into a substance called hemolymph. This is basically invertebrate blood. The hemolymph is moved around its body to the cells that need it—not by its heart, which is relatively weak and only moves hemolymph around the small body, but by the digestive system. Since the digestive system goes all the way down into the legs and already moves digestive fluids around, that makes sense.

Some species have mouthparts, but most eat using a proboscis that it uses to suck hemolymph and other fluids out of its prey. Some species have spines at the tip of the proboscis. It sticks its proboscis into a sponge, worm, jelly, sea anemone, or other invertebrate, injects digestive fluids that liquefy the surrounding tissues, and slurp the fluids up. Sometimes this kills the prey animal, sometimes it doesn’t.

Sea spiders live throughout the world’s oceans and there are well over a thousand known species. Most are small and live in shallow water, but a few live in water up to 23,000 feet deep, or 7,000 meters. The biggest species live in the cold waters around Antarctica, with the very largest individual ever found having a legspan of about 27 inches, or 70 cm. So no, they’re not dangerous to humans at all and while they may look scary because those legs are so long, they’re harmless unless you happen to be a soft-bodied invertebrate that can’t run away.

That doesn’t mean there aren’t actual spiders that live in the ocean. Marine spiders are actual spiders, and they’re intertidal, which means they live in the typically small area between high tide and low tide. During high tide they hide underwater in shells, coral, or plants, and they can breathe because they build air chambers from silk. When the tide goes out, the spiders run onto the sand and hunt small insects and other invertebrates. A new species of marine spider was discovered in Queensland, Australia in 2009 that grows to almost 9 mm in size. That’s almost a centimeter long, or half an inch! Males are smaller, though. It was named Desis bobmarleyi after the Bob Marley song “High Tide or Low Tide.”

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

Thanks for listening!