Episode 249: Strange Seals

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Thanks to Richard from NC for his suggestion that leads us to learn about some interesting seals!

Further reading:

Mystery of Siberian freshwater seal food choice solved

Under Antarctica’s ice, Weddell seals produce ultrasonic vocalizations

Further listening/watching:

Rarely-heard Weddell Seal Sounds in Antarctica

The bearded seal Wikipedia page with audio so you can listen over and over and over

The Baikal seal, the world’s only fully fresh water seal species:

Baikal seal, round boi:

The Baikal seal’s teeth have teeth:

A Weddell seal mama with her pup who seems to be practicing singing:

Look ma, no ears!

The bearded seal. Can you tell where its name comes from? (Moustachioed seal might be more accurate.) (Also, note the ear opening with no external ear flap.)

Show transcript:

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

This week let’s learn about some interesting seals. Thanks to Richard from NC who suggested freshwater seals, which is where we’ll start.

Most seals live on the coast and spend most of the time in the ocean. But there’s one species of seal that lives exclusively in fresh water. That’s the Baikal [bay-CALL] seal, and the only place it lives is a big lake in Siberia called Lake Baikal.

Lake Baikal formed where two sections of the earth’s crust are being pulled apart by continental drift. That’s called a rift lake or rift valley lake. The lake gets bigger every year, but only by a tiny amount—just under an inch, or 2 cm. Since this has been going on for an estimated 25 to 30 million years, though, it’s an extremely big, deep lake. It is, in fact, the deepest lake on earth, and is also the oldest lake on earth. It’s more than twice as old as Lake Tanganyika in East Africa, which is also a large, deep rift lake but only about 12 million years old at the most.

Lake Baikal is almost 400 miles long, or 636 km, and nearly 50 miles wide, or 80 km. At its deepest point, it’s 3,893 feet deep, or 1,186.5 meters. That’s from the surface of the water to the muddy bottom. But that mud and sediment on the bottom has been building up for a very long time and there’s a lot of it—4.3 miles of it, in fact, or 7 km. The water is very clear and very oxygenated, but the surface freezes for several months out of the year. Then again, there are some hydrothermal vents, especially in the deepest areas, that heat the water around them to 122 degrees Fahrenheit, or 50 Celsius.

Because Lake Baikal is so deep, so big, so oxygenated, and so old, lots of species of animal live in and around it that live nowhere else in the world. That includes the Baikal seal.

The Baikal seal is related to the Arctic ringed seal but has lived in the lake exclusively for probably two million years. It only grows five and a half feet long at most, or 1.65 meters, and is usually closer to four feet long, or 1.2 meters. It’s gray in color and has no external ears, so that its head appears smooth. It can still hear, but because it doesn’t have ears sticking out of its head, it’s more streamlined than seals with external ears. It has large eyes, a pair of front flippers that it uses to maneuver in the water and on land, and a pair of hind flippers that act like a tail instead of legs.

That’s actually the main difference between earless and eared seals. Earless seals are more streamlined in general and more adapted for life in the water and for deep diving, but they’re awkward on land because they can’t use their hind limbs for walking. Eared seals have little flaps of external ears and while their hind flippers act as a tail in the water, the seal can turn its hind flippers over to walk on them on land.

The Baikal seal is quite small for a seal, which keeps it from needing as much food as a bigger animal. For a long time people thought the Baikal seal mostly ate fish, but a study published in late 2020 determined that it eats a whole lot of amphipods. Lake Baikal is home to a species of amphipod that grows up to about 10 millimeters long. Amphipods are a type of crustacean and all other freshwater amphipods known are bottom-dwellers. Only the Lake Baikal amphipod is free-floating.

The seal catches these tiny amphipods by sucking them up in a big mouthful of water, closing its teeth tightly, and using its tongue to force the water out through its teeth. The amphipods get caught against the teeth and the seal swallows them, yum. This is a type of filter feeding used by some other species of seal too, including the crabeater seal. Like the crabeater seal, it’s so well adapted to filter feeding that it has specialized teeth with curved projections all around their edges. These projections interlock closely when the seal closes its mouth. Because it doesn’t have to depend on eating fish, the Baikal seal isn’t threatened by commercial fishing. As long as it has plenty of amphipods to eat, it’s happy.

While the Baikal seal is the only truly freshwater seal species, a subspecies of ringed seal lives in a lake in Finland. Unlike the Baikal seal, though, which are numerous and doing just fine, the Saimaa ringed seal is endangered, with only around 400 individuals left in the wild. They’re strictly protected these days, fortunately, and the population is growing after it reached a low of only about 100 animals in 1983.

During the Pleistocene, the land mass that is now Finland was pressed down by the weight of glaciers. Once the glaciers melted, the land began to slowly rise back up until the lake where a population of ringed seals lived was cut off from the ocean.

Some other seals live in lakes that are cut off from the sea, including a population of harbor seals in Iliamna Lake in Alaska and a subspecies of harbor seal in northern Quebec, Canada, but let’s move on to seals that live in the ocean instead of fresh water.

Specifically, let’s discuss two earless seals that make interesting sounds. You may think you know what a typical seal sounds like, such as this kind of barking call:

[barking sound]

That’s actually not a seal but a closely related pinniped called a sea lion. Even though it’s not a seal, it is sort of technically a seal because it shares a family with fur seals and walruses, Otariidae, also called the eared seals that we talked about earlier. Some seals bark like sea lions and make lots of other noises, but it’s the earless seals that can really make weird sounds.

For instance, listen to this eerie sound:

[Weddell seal call]

That’s not a whale, it’s a seal. The Weddell seal lives around Antarctica and can grow quite large, up to 11 ½ feet long, or 3.5 meters. Males and females look alike although females tend to be slightly larger. It eats fish, squid, crustaceans, and pretty much anything else it can catch. It dives deeply and can stay underwater for up to 80 minutes, and while it has good eyesight, it doesn’t need to see to find food. The whiskers on its snout are incredibly sensitive and can sense tiny movements of water that indicate exactly where a fish or other animal is swimming.

Both male and female Weddell seals make various vocalizations, including some that can be described as songs, although the songs seem to be rare and researchers aren’t sure what the seals communicate with them. There’s still a lot we don’t know about these seals. Because Antarctica is so far away from most human activity, it’s extremely quiet most of the time. The seals can hear each other without having to compete with the noise from cars and boats and things like that. A seal sitting on the ice can hear other seals calling from deep in the water below the ice, and in fact the ice can amplify the sounds so well that scientists living in the Antarctic report being able to feel the sounds as well as hear them.

Here’s another clip of Weddell seals. These sounds are taken from an amazing youtube video I’ve linked to in the show notes. It’s short and has two scientists talking a little bit about their experiences hearing the seals, and then there’s about a minute of seal calls afterwards.

[Weddell seals calling]

Another seal with a loud, amazing vocalization is the bearded seal. It lives on the other side of the world from the Weddell seal, in the Arctic Ocean, and can grow almost nine feet long, or 2.7 meters. It eats fish and squid but mostly eats animals that live on the sea floor, including clams, polychaete worms, sea anemones, and many others. Like the Weddell seal and many other seals, its whiskers are incredibly sensitive. The bearded seal uses its long whiskers to feel around in the soft mud at the bottom of the ocean, looking for food.

In the spring, male bearded seals sing loudly and rhythmically, either to attract a mate or to defend a territory, or maybe both or something else—we don’t know. This is what the bearded seal sounds like underwater. I grabbed this audio off Wikipedia if you need to listen to it on repeat for a very long time. It’s an incredible sound.

[bearded seals singing]

This is what a bunch of bearded seals sound like when they’re singing together. This audio was taken on land although the seals sing underwater.

[more bearded seals singing]

These vocalizations sound so much like whale calls that I wondered if some seals can echolocate the way whales and dolphins can. There are quite a few studies into this topic, but right now most of the evidence points to no, seals don’t use echolocation to navigate underwater. Of course, studies in the future might discover something new about potential echolocation in seals. It’s only been very recently that sophisticated studies on bats have discovered that many species use different types of echolocation.

Conclusions of a two-year study published at the very end of 2020 show that a lot of Weddell seal vocalizations are ultrasonic, meaning they’re much higher than humans can hear. While the study doesn’t show any evidence of echolocation, they weren’t actually looking for it either. So you never know.

It’s possible, of course, that even if seals don’t echolocate right now, they might one day evolve the ability. Earless seals are well adapted to the water but still spend part of the time on ice or on land, especially to give birth. Many millions of years from now, the descendants of today’s seals might be completely aquatic the way whales and dolphins are. Because most scientists today think that seals can’t echolocate because their ears need to be useful on land as well in water, a fully aquatic seal that doesn’t need to hear well in the air might then develop echolocation to help it navigate underwater.

I’ll do a follow-up episode about seals and echolocation in a few million years when we can determine whether that’s happening.

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. If you like the podcast and want to help us out, leave us a rating and review on Apple Podcasts or just tell a friend. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us that way.

Thanks for listening!

Episode 046: The Other Loch Ness Monsters

There’s more in Loch Ness than one big mystery animal. This week we look at a few smaller mystery animals lurking in the cold depths of the lake.

Further reading:

Here’s Nessie: A Monstrous Compendium from Loch Ness by Karl P.N. Shuker

The goliath frog:

The Wels catfish (also, River Monsters is the best):

An amphipod:

Show transcript:

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

Back in episode 29, I dismissed Nessie, the Loch Ness monster, as probably not a real animal. But this week we’re heading back to Loch Ness to see what other monsters might lurk in its murky depths.

WHAAAAA? Other Loch Ness monsters???

Yes, really! See, ever since the first sightings of Nessie in the 1930s, Loch Ness has been studied and examined so closely that it would be more surprising if no one had ever spotted other mystery animals.

The source of most of the information in this episode is from zoologist Karl Shuker’s book Here’s Nessie! A Monstrous Compendium from Loch Ness. Check the show notes for a link if you’re interested in buying your own copy of the book.

Our first non-Nessie mystery dates from 1934, but it happened, supposedly, sometime in the 1880s. It appeared in the Northern Chronicle, an Inverness newspaper, on January 31, 1934. The article relates that a ship in Loch Ness hit a submerged reef called Johnnie’s Point and sank one night. Luckily no one died. The next day a local diving expert named Duncan Macdonald was hired to determine if the wreck could be raised, but he couldn’t spot the wreck during his dive.

Later that evening, some of the ship’s crew who had heard stories about strange creatures living in Loch Ness asked Macdonald whether he’d seen anything unusual. After some urging, Macdonald finally admitted that he had seen a frog-like creature the size of a good-sized goat sitting on a rock ledge some 30 feet, or 9 meters, underwater. It didn’t bother him so he didn’t bother it.

There are a lot of problems with this account, of course. For one thing, we don’t know who wrote it—the article has no byline. It’s also a secondhand account. In fact, the article ends with this line: quote “The story, exactly as given, was told by Mr Donald Fraser, lock-keeper, Fort Augustus, who often heard the diver (his own grand-uncle) tell it many years ago.” unquote

Plus, of course, frogs don’t grow as big as goats. The biggest frog is the goliath frog, which can grow over a foot, or 32 cm, in length nose to tail, or butt I guess since frogs don’t have tails, which is pretty darn big but not anywhere near as big as a goat. The goliath frog also only lives in fast-moving rivers in a few small parts of Africa, not cold, murky lakes in Scotland, and its tadpoles only feed one one type of plant. In other words, even if someone did release a goliath frog into Loch Ness in the 1880s—which is pretty farfetched—it wouldn’t have survived for long.

The biggest frog that ever lived, as far as we know, lived about 65 million years ago and wasn’t all that much bigger than the goliath frog, only 16 inches long, or 41 cm. It had little horns above its eyes, which gives it its name, devil frog. Its descendants, South American horned frogs, also have little horns but are much smaller.

So what might Mr. Macdonald have seen, assuming he didn’t just make it all up? Some species of catfish can grow really big, but catfish aren’t native to Scotland. It’s always possible that a few Wels catfish, native to parts of Europe, were introduced into Loch Ness as a sport fish but didn’t survive long enough to establish a breeding population in the cold waters. Catfish have wide mouths, although their eyes are small, and might be mistaken for a frog if seen head-on in poor light. Plus, the Wels catfish can grow to 16 feet long, or 5 meters.

Then again, since the article was published during the height of the first Loch Ness monster frenzy, it might all have been fabricated from beginning to end.

A 1972 search for Nessie by the same team that announced that famous underwater photograph of a flipper, which later turned out to be mostly painted on, filmed something in the loch that wasn’t just paint. They were small, pale blobs on the grainy film. The team called them bumblebees from their shape.

Then in July of 1981, a different company searching not for Nessie but for a shipwreck from 1952 filmed some strange white creatures at the bottom of the loch. One of the searchers described them as giant white tadpoles, two or three inches long, or about 5 to 7 cm. Another searcher described them as resembling white mice but moving jerkily.

The search for the wreck lasted three weeks and the white mystery animals were spotted more than once, but not frequently. Afterwards, the company sent video of them to Dr. P Humphrey Greenwood, an ichthyologist at the Natural History Museum in London. Since this was the 1980s, of course, the film was videotape, not digital, but Dr. Greenwood got some of the frames computer enhanced. Probably on a computer that had less actual computing power than my phone. Anyway, the enhancement showed that the animals seemed to have three pairs of limbs. Dr. Greenwood tentatively identified them as bottom-dwelling crustaceans, but not ones native to Loch Ness.

Over the years many people have made suggestions as to what these mystery crustaceans might be. I’m going out on a limb here and declaring that they are not baby Loch Ness monsters. Karl Shuker suggests the white mice footage, at least, might be some kind of amphipod.

We’ve met amphipods before in a couple of episodes, mostly because some species exhibit deep-sea gigantism. Amphipods are shrimp-like crustaceans that live throughout the world in both the ocean and fresh water, and most species are quite small. While they do have more than three pairs of legs—eight pairs, in fact, plus two pairs of antennae—the 1981 videotape wasn’t of high quality and details might easily have been lost. Some of the almost 10,000 known species of amphipod are white or pale in color and grow to the right size to be the ones filmed in Loch Ness. But no amphipods of that description have ever been caught in Loch Ness.

New amphipods are discovered all the time, of course. They’re simply everywhere, and the smallest species are only a millimeter long. But because they’re so common, it’s also easy to transport them from one body of water to another. A rare amphipod discovered in Alpine lakes only a few years ago is already threatened by a different, more common species of amphipod introduced to one of the lakes by accident. So it’s possible that the white mice crustaceans in Loch Ness traveled there on someone’s boat.

That’s certainly the case with another creature found in Loch Ness in 1981, but we know exactly what this one is. It’s a flatworm native to North America, a bit over an inch long, or 3 cm, and only about 5 millimeters wide. It attaches its cocoons to boat bottoms, and in this case it was brought to Loch Ness by equipment used to hunt for Nessie. Spoiler alert: they didn’t find her.

You can find Strange Animals Podcast online at strangeanimalspodcast.com. We’re on Twitter at strangebeasties and have a facebook page at facebook.com/strangeanimalspodcast. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. If you like the podcast and want to help us out, leave us a rating and review on Apple Podcasts or whatever platform you listen on. We also have a Patreon if you’d like to support us that way.

Thanks for listening!

Episode 027: Creatures of the Deeps

This week is our six-month anniversary! To celebrate, we’ll learn about some of the creatures that live at the bottom of the Mariana Trench’s deepest section, Challenger Deep, as well as other animals who live in deep caves on land. We also learn what I will and will not do for a million dollars (hint: I will not implode in a bathysphere).

A xenophyophore IN THE GRIP OF A ROBOT

A snailfish from five miles down in the Mariana trench:

The Hades centipede. It’s not as big as it looks, honest.

The tiny but marvelous olm.

Show transcript:

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

For this week’s episode, we’re going to find out what lives in the deepest, darkest places of the earth—places humans have barely glimpsed. We’re not just talking deep sea, we’re talking the abyssal depths.

Like onions and parfaits, the earth is made up of many layers. The core of the earth is a ball of nickel and iron surrounded by more nickel and iron. The outer core is molten metal, but the inner core, even though it’s even hotter than the outer core—as hot as the surface of the sun—has gone through the other side of liquid and is solid again. Surrounding the core, the earth’s mantle is a thick layer of rocks and minerals some 1900 miles deep, and on top of that is the crust of the earth, which doesn’t actually sound very appealing but that’s where we live and we know it’s really pretty, with trees and oceans and stuff on top of it. The upper part of the mantle is broken up into tectonic plates, which move around very slowly as the molten metals and rocks beneath them swirl around and get pushed up through cracks in the mantle.

Under the oceans, the crust of the earth is only around 3 miles thick. And in a few places, there are crevices that actually break entirely through the crust into the mantle below. The deepest crack in the sea floor is the Mariana Trench in the western Pacific. At its deepest part, a narrow valley called Challenger Deep, the crack extends seven miles into the earth.

The pressure at that depth is immense, over 1,000 times that at sea level. Animals down there can’t have calcium carbonate shells because the pressure dissolves the mineral. It’s almost completely dark except for bioluminescent animals, and the water is very cold, just above freezing.

The trench is crescent shaped and sits roughly between Japan to the north and Papua New Guinea to the south, and the Philippines to the west. It’s caused by the huge Pacific plate, which is pushing its way underneath the smaller Mariana plate, a process called subduction. But near that activity, another small plate, the Caroline plate, is subducting beneath the Pacific plate. Subduction around the edges of the Pacific plate is the source of the earthquakes, tsunamis, and active volcanos known as the Ring of Fire. Some researchers think there’s a more complicated reason for Mariana Trench and other especially deep trenches nearby, though. There seems to be a tear in the Caroline plate, which is deforming the Pacific Plate above it.

Challenger Deep is such a deep part of the ocean that we’ve barely seen any of it. The first expedition that got all the way down was in 1960, when the bathyscape Trieste reached the bottom of Challenger Deep. This wasn’t an unmanned probe, either. There were two guys in that thing, Jacque Piccard and Don Walsh, almost ten years before the moon landing, on a trip that was nearly as dangerous. They could see out through one tiny thick window with a light outside. The trip down took almost five hours, and when they were nearly at the bottom, one of the outer window panes cracked. They stayed on the bottom only about 20 minutes before releasing the weights and rising back to the surface.

The next expedition didn’t take place until 1995 and it was unmanned. The Kaiko could collect samples as well as record what was around it, and it made repeated descents into Challenger Deep until it was lost at sea in 2003. But it not only filmed and collected lots of fascinating deep-sea creatures, it also located a couple of wrecks and some new hydrothermal vents in shallower areas.

Another unmanned expedition, this one using a remotely operated vehicle called the Nereus, was designed specifically to explore Challenger Deep. It made its first descent in 2009, but in 2014 it imploded while diving in the Kermadec Trench off New Zealand. It imploded. It imploded. This thing that was built to withstand immense pressures imploded.

In 2012, rich movie-maker James Cameron reached the bottom of the Mariana Trench in the Deepsea Challenger. He spent nearly three hours on the bottom. Admittedly this was before the Nereus imploded but you could not get me into a bathysphere if you paid me a million dollars okay well maybe a million but I wouldn’t do it for a thousand. Maybe ten thousand. Anyway, the Deepsea Challenger is currently undergoing repairs after being damaged in a fire that broke out while it was being transported in a truck, which is just the most ridiculous thing to happen it’s almost sad. But it’s still better than imploding.

In addition to these expeditions, tethered cameras and microphones have been dropped into the trench over the years too. So what’s down there that deep? What have these expeditions found?

The first expedition didn’t see much, as it happens. As the bathyscape settled into the ooze at the bottom of the trench, sediment swirled up and just hung in the water around them, unmoving. The guys had to have been bitterly disappointed. But they did report seeing a foot-long flatfish and some shrimp, although the flatfish was more likely a sea cucumber.

There’s actually a lot of life down there in the depths, including amphipods a foot long, sea cucumbers, jellyfish, various kinds of worms, and bacterial mats that look like carpets. Mostly, though, there are Xenophyophores. They make big delicate shells on the ocean bottom, called tests, made from glued-together sand grains, minerals like lead and uranium, and anything else they can find, including their own poops. We don’t know a lot about them although they’re common in the deep sea all over the world. While they’re unicellular, they also appear to have multiple nuclei.

For the most part, organisms living at the bottom of the Challenger Deep are small, no more than a few inches long. This makes sense considering the immense water pressure and the nutrient-poor environment. There aren’t any fish living that deep, either. In 2014 a new species of snailfish was spotted swimming about five miles below the surface, a new record; it was white with broad fins and an eel-like tail. Snailfish are shaped sort of like tadpoles and depending on species, can be as small as two inches long or as long as two and a half feet. A shoal of Hadal snailfish were seen at nearly that depth in 2008 in the Japan Trench.

While there are a number of trenches in the Pacific, there aren’t very many deeps like Mariana Trench’s Challenger Deep—at least, not that we know of. The Sirena Deep was only discovered in 1997. It’s not far from Challenger Deep and is not much shallower. There are other deeps and trenches in the Pacific too. But like Challenger Deep, there aren’t any big animals found in the abyssal depths, although the other deeps haven’t been explored as much yet.

In 2016 and early 2017, NOAA, the U.S. Coast Guard, and Oregon State University dropped a titanium-encased ceramic hydrophone into Challenger Deep. To their surprise, it was noisy as heck down there. The hydrophone picked up the sounds of earthquakes, a typhoon passing over, ships, and whalesong—including the call of a whale researchers can’t identify. They think it’s a type of minke whale, but no one knows yet if it’s a known species we just haven’t heard before or a species completely new to science. For now the call is referred to as the biotwang, and this is what it sounds like.

[biotwang whale call]

But what about animals that live in deep places that aren’t underwater? It’s actually harder to explore land fissures than ocean trenches. Cave systems are hard to navigate, frequently extremely dangerous, and we don’t always know how deep the big ones go. The deepest cave in the world is Krubera Cave, also called Voronya Cave, in Georgia—and I mean the country of Georgia, not the American state. Georgia is a small country on the black sea between Turkey and Russia. So far it’s been measured as a mile and a third deep, but it’s certainly not fully explored. Cave divers keep pushing the explored depth farther and farther, although I do hope they’re careful.

We’ve found some interesting animals living far beneath the earth in caves. The deepest living animal ever found is a primitive insect called a springtail, which lives in Krubera cave and which was discovered in 2010. It’s pale, with no wings, six legs, long antennae, and no eyes. There are a whole lot of springtail species, from snow fleas to those tee-tiny gray bouncy bugs that live around the sink in my bathroom no matter how carefully I clean. All springtails like damp places, so it makes sense that Krubera cave has four different species including the deepest living one. They eat fungi and decomposing organic matter of all kinds. Other creatures new to science have been discovered in Krubera cave, including a new cave beetle and a transparent fish.

A new species of centipede was described in 2015 after it was discovered three-fourths of a mile deep in three different caves in Croatia. It’s called the Hades centipede. It has long antennae, leg claws, and a poisonous bite, but it’s only about an inch long so don’t panic. Also it lives its entire life in the depths of Croatian caves so you’re probably safe. There are only two centipedes that live exclusively in caves and the other one is named after Persephone, Hades’ bride. It was discovered in 1999.

A cave salamander called an olm, which in local folklore was once considered a baby dragon, was recently discovered 370 feet below ground in a subterranean lake, also in Croatia. It’s a fully aquatic salamander that only grows a few inches long. Its body is pale with pink gills. It has eyes, but they’re not fully developed and as it grows, they become covered with layers of skin. It can sense light but can’t otherwise see, but it does have well-developed electroreceptor skills, hearing, smell, and can also sense magnetic fields. It eats snails, insects, and small crustaceans and has very few natural predators.

In 1952 researchers created an artificial riverbed in a cave in France that recreates the olm’s natural habitat as closely as possible. The olms are fed and protected but not otherwise interacted with by humans. There are now over 400 olms in the cave, which is a good thing because in the wild, olms are increasingly threatened by pollution, habitat loss, and unscrupulous collectors who sell them on the pet trade black market.

Olms live a long, long time—probably 100 years or longer. Some individuals in the artificial riverbed are 60 years old and show no signs of old age. Researchers aren’t sure why the olm lives so long. We don’t really know a whole lot about the olm in general, really. They and the caves where they live are protected in Croatia.

There are a few places in the world where people have drilled down into the earth, usually by geologists checking for pockets of gas or water before mining operations start. In several South African gold mines, researchers found four new species of tiny bacteria-eating worms, called nematodes, living in water in boreholes a mile or more deep. After carefully checking to make sure the nematodes hadn’t been introduced into the water from mining operations, the researchers theorized the nematodes already lived in the rocks but that the boreholes created a perfect environment for them. Nematodes are well-known extremophiles, living everywhere from hot springs to the bellies of whales. They can withstand drought, freezing, and other extreme conditions by reverting to what’s called the dauer stage, where they basically put themselves in suspended animation until conditions improve.

The boreholes also turned up some other interesting creatures, including flatworms, segmented worms, and a type of crustacean. They’re all impossibly tiny, nearly microscopic.

If you go any deeper, though, the only living creatures you’ll find are bacteria and other microbes. In a way, though, that’s reassuring. The last thing we want to find when we’re poking around in the world’s deepest cracks is something huge that wants to eat us.

You can find Strange Animals Podcast online at strangeanimalspodcast.com. We’re on Twitter at strangebeasties and have a facebook page at facebook.com/strangeanimalspodcast. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. If you like the podcast and want to help us out, leave us a rating and review on iTunes or whatever platform you listen on. We also have a Patreon if you’d like to support us that way. Rewards include stickers and twice-monthly bonus episodes.

Thanks for listening!