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!

The horned gopher:

Show transcript:

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

This time we’re going to learn about some mammals with weird horns. Specifically, weird nose horns. Nose horns are properly called rostral horns, but that’s not as funny.

We’ll start with a family of extinct rodents called horned gophers, or more properly, mylagaulids. The horned gopher wasn’t a gopher, but it probably looked similar to ground squirrels like prairie dogs and marmots. It lived in what is now North America around twenty million years ago, and it had a pair of short, broad horns that pointed upwards between the nose and eyes, like a rhino’s horns but side by side and made of bone, not keratin. It was big for a rodent, about a foot long, or 30 cm, and ate plants.

So what did the horned gopher use its horns for? Both males and females had the horns and they’re too short and placed too far back for males to use them to fight each other. Horned gophers had poor eyesight so males probably weren’t trying to look and act flashy to attract females anyway.

At first researchers thought the horns helped in digging burrows. The horned gopher primarily used what’s called the head-lift method of digging, which means it pushed its nose into the dirt, then lifted its head with powerful neck muscles to remove a chunk of soil—basically using its nose as a shovel. But its horns pointed straight up and were set too far back on the nose to help with digging. Most researchers today think the horns were used for defense. If a predator tried to grab the animal by the neck, it could snap its head back and stab the predator right in the face.

The horned gopher had tiny eyes and front feet that resembled a mole’s, with long claws. Researchers think its ancestors probably spent most of the time underground, but that as it evolved to become larger, it also spent more time foraging above-ground. That led to more predators being able to attack it, so evolving horns as a defensive weapon helped it survive.

While the horned gopher was distantly related to modern squirrels, its family is completely extinct these days. But it’s still the smallest known horned mammal that ever lived.

The horned gopher is also the only horned mammal known that lived mostly underground in burrows. Almost. There was once a type of armadillo, naturally called the horned armadillo but more properly referred to as Peltephilus [pelta-FEElus], that had a pair of horns over its eyes but a little in front of them, close to where the horned gopher’s horns were. The horned armadillo’s horns developed from scutes on its head, and if you remember, scutes are bony plates embedded in the skin as armor. It might also have had a smaller pair of horns over its nostrils. It lived in what is now South America and went extinct around 11 million years ago.

The horned armadillo dug burrows liked the horned gopher did, but it was much bigger than the horned gopher, with some species as much as five feet long, or 1.5 meters. Despite its size, it probably resembled the pink fairy armadillo in overall shape rather than the more common nine-banded armadillo that lives in parts of North America. It had a short tail and its rump was squared off instead of rounded. It also had big sharp teeth. It may have eaten insects, possibly digging up ant nests, but more likely it mostly ate roots and other plant parts.

Arsinoitherium was another animal with nose horns, this one from Africa. It lived around 30 million years ago and was related to modern-day elephants, but it lived in swampy areas and tropical rainforests and ate plants. It probably looked a little like a rhinoceros and a little like a small elephant without a trunk. Different species were different sizes, but they were all pretty big, probably no smaller than about six feet tall at the shoulder, or 1.75 meters. And they had two pairs of horns, a little pair more like bumps over the eyes and two side-by-side forward-pointing giant nose horns that looked a lot like rhino horns but thicker. But they were real horns made of bone, not keratin, although they may have been covered in skin and hair like ossicones. You know, ossicones are those hornlike structures giraffes have.

Brontotherium looked a lot like a rhinoceros too, but that’s because it was distantly related to the rhino, although it was more closely related to the horse. It lived in North America around 35 million years ago and was enormous, standing around 8 feet tall at the shoulder, or 2.5 meters. It was a selective browser, probably preferring tender leaves to tough grass. It carried its massive head low like modern rhinos and buffalo do, and had a humped shoulder like both those animals where its massive neck muscles attached. And it had a pair of nose horns.

Both males and females had the nose horns, but the males’ horns were much larger. The horns were blunt and shaped sort of like a V, and researchers are pretty sure males used them to fight each other. We have fossilized brontotherium rib bones that show an injury shaped just like the nose horns. The horns were probably also useful to fight predators. Even though brontotherium was related to the rhino, its horns were bone, not keratin.

Our last nose horn animal lived in North America up to about five million years ago. The various species of Protoceratidae [pro-TOSS-e-rated-die] were hoofed animals that looked sort of like deer, but were more closely related to a living ungulate called the chevrotain, or mouse deer. Protoceratid probably ate grass and other plants and may have lived in herds. Males had a pair of ordinary horns that looked a lot like cow horns, and in some species females had the horns too, although they were smaller. But males also had a horn on the nose. And it was weird.

Once again, the nose horn wasn’t like a rhino’s horn, which as we have established by now is made of keratin. And maybe I should have reminded you before now that keratin is the same protein that makes hair, fingernails, hooves, and things like that. Keratin also doesn’t fossilize. This nose horn was an actual horn made of bone, but researchers think it may have been covered with skin and fur like an ossicone.

Different Protoceratidae had different nose horns. Syndyoceras had a pair of nose horns that were fused at the base, then split apart to form a V shape. It may also have had large nasal passages that made its muzzle look much bigger than the skull would suggest at first glance. Synthetoceras had a long nose horn that grew up and slightly forward but split into a Y at the tip. Kyptoceras had a pair of nose horns that pointed forward. Researchers think the males used these nose horns to fight each other, much like deer fight with their antlers today.

One older Protoceratid that lived up to around 20 million years ago was called Protoceras, and males had three pairs of horns, although they probably resembled ossicones and were all covered in skin and hair. A small pair grew between the ears, another pair between the eyes and nose, and the largest pair grew on the nose. Females only had one smaller pair of horns between the ears, so the extra horns males had were probably for display.

Some Protoceratidae also had a pair of fanglike canine teeth that they may have used to root around in dead leaves for plant material. Male chevrotains have fangs like this too, but they use them to fight each other since they don’t have horns.

So basically, this is what we’ve learned from this episode: There used to be a lot more nose-horned animals than we have now, most of them lived in the Americas for some reason, and they were all awesome. Also, even though the first animal we think of when someone mentions nose horns is the rhino, the rhino’s keratin horns are actually unusual. Just be glad you’re not an intelligent birdlike creature from the far future trying to figure out what a rhinoceros actually looked like when it was alive.

Thanks for your support, and thanks for listening!

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 1,000th 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 19th 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....

This week we'll learn about a long-forgotten animal of folklore!

Further reading:

https://www.anomalist.com/

The Pictish Beast:

A dragonesque brooch:

Show transcript:

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

The Picts were a population of Celtic people who lived in what is now northern and eastern Scotland between around the third and tenth centuries. They had their own language, which is lost to time except for a handful of place-names, and made beautiful rock carvings and metal art, but we know very little about them even though their descendants still live in Scotland today. Vikings conquered the area, which led to upheavals among the many small kingdoms, so that by the 11th century, all the Picts had been absorbed into the greater Scottish population and had completely forgotten their heritage.

The carvings are what we’re interested in today. The Picts carved lots of different animals along with more abstract designs, and although the carvings are often stylized, we generally know what animals they represent. There are roe deer, red deer, dogs, boars, horses, cattle, salmon and other fish, otters, eagles, and more. But there’s one animal no one can identify, referred to as the Pictish Beast.

The Pictish Beast isn’t rare, either. One estimate is that 40% of all the animal carvings depict the Pictish beast, so it was obviously important. That makes it even more baffling that we don’t know what it is.

There are variations, but generally the Pictish Beast has a long snout or beak with a line showing that the mouth was long too. There’s a horn-like design that emerges from the top or rear of the head and bends backwards, with a little curl at the end. The body looks superficially doglike, with a little curled dog tail, but the legs don’t resemble any real animal’s legs. They appear stiff, not jointed, and often bend backwards slightly. The feet are simplified designs that curl backwards in a little spiral. The head is usually bent as though it’s staring downward. It has no ears or nostrils.

Naturally there are lots of theories as to what the Pictish Beast represents. One theory is that it’s not a real animal at all but a type of dragon. Specifically, some experts consider it to be a version of a design called dragonesque brooches. These were pieces of jewelry made throughout southern Scotland and northern England during the first and second century. They were roughly S-shaped, made to look like a double-headed animal with a curly nose and distinctive round ears. Instead of dragons, though, the dragonesque brooch animals were probably actually stylized rabbits or hares. They were also popular at least 200 years before the Pictish Beast started being carved so often, so while there is a superficial resemblance, it’s not a perfect match by any means.

Then again, there is one stone, called the Mortlach 2 stone, that depicts both a Pictish Beast and what seems to be a simplified version of the dragonesque brooch design. Some researchers think the artist was depicting what was at the time the modern Pictish Beast and the old-timey dragonesque brooch that inspired it.

One suggestion is that the beast was inspired by the dragonesque brooch, but isn’t otherwise related. Remember that the brooches would have been considered super old at the time and were probably rare even then as a result. Think about how many pieces of jewelry you own that are several hundred years old. If an artist saw one of the brooches and thought it looked neat, but had no idea what it was supposed to represent, they might have recreated it with details that made sense to them, trying to imitate what they saw. But that doesn’t explain why the design became so incredibly popular.

There are other suggestions, of course. Sometimes the beast is depicted vertically, which makes it look superficially like a weird seahorse. Seahorses do live off the coast of Scotland, but that doesn’t explain why the Pictish Beast has large legs and such a little tail. Most of the time the beast is shown horizontally, legs down.

Sometimes the beast is referred to as an elephant, but knowledge of elephants in the British Isles over a thousand years ago was unlikely at best. And the beast has zero resemblance to an elephant so I don’t know who came up with that idea but let’s just set it aside and move on.

Because of the horn-like appendage on its head, some people suggest the beast might depict a stylized deer. That’s more likely than an elephant but Pictish carvings of deer exist and are obviously deer. That doesn’t mean the beast couldn’t have started out as a deer that took on more and more stylized and exaggerated components until no one remembered it was actually a deer, but that could be said about any animal, not just a deer.

Another suggestion is that it’s supposed to be a water animal of folklore, possibly a kelpie, or water horse, or a water bull. Both creatures were supposed to lure people into the water by posing as a lost pony or bull, but as soon as the person touched the animal, it would drag them under the water and drown them.

Other people suggest the Pictish Beast represents a dolphin or beaked whale, and that the horn-like appendage isn’t a horn at all but a representation of the dolphin spouting. When a dolphin or whale comes to the surface to take a breath, it first has to let out the last breath it took. It does so really fast, expelling the warm, moist air from its lungs so that it looks like a spray of mist or water. The beast’s long beak does look like a dolphin’s rostrum, and crucially, its mouth even curves upward slightly like a dolphin’s mouth.

The front legs could possibly be explained as stylized fins. But what about the hind legs? Dolphins don’t have rear fins. Even if you accept that the hind legs are supposed to represent the dolphin’s tail, it already has a little doglike tail.

That’s where some people have gotten frustrated and said, “Okay, fine. It’s the Loch Ness Monster.” But the Pictish Beast doesn’t fit the general description of Nessie either. Nessie is supposed to have a long neck and a very long body, often with humps or bumps that appear above the surface of the water, and a long tail. The beast doesn’t have a long neck or a long tail.

Personally, I like the idea that the Pictish Beast represents a mythical water creature like a kelpie, but that it was given dolphin characteristics to make it more frightening and exotic. Since we know so little about the Picts, it’s possible the beast stood for some important quality in their society, the same way we use a lion to represent courage or a dog to represent loyalty.

It’s one of those mysteries that we’ll probably never solve, unless someone invents a time machine and we can go back and ask some Picts. But frankly, if I had access to a time machine, I’d use it to go back and look at dinosaurs. So I guess we may never know what the Pictish Beast really is.

Thanks for your support, and thanks for listening!

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!

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!

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....

It's Albert the Albanerpetontid!

Further reading:

Earliest example of a rapid-fire tongue found in 'weird and wonderful' extinct amphibians

Amphibian skullllll:

Show transcript:

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

Let’s learn about a long-extinct amphibian that looked a lot like a reptile. It’s a family of animals called Albanerpetontidae. That’s a mouthful, so instead of talking about Albanerpetontids, I’ll talk about all the various species as though they were not only a single species, but a single individual named Albert.

Albert first appears in the middle Jurassic, around 165 million years ago, and disappears from the fossil record around 2 million years ago. That means it survived the extinction event that killed off the non-avian dinosaurs and many other animals, which is also true for many other amphibians. But Albert wasn’t like the amphibians we have around today. It belonged to its own order, Allocaudata.

There’s a lot of confusion in general as to how amphibians are related to each other and how closely related, for instance, the frogs and the salamanders actually are. The same is true for Albert. What we do know is that Albert was definitely an amphibian, but it was also really different in many respects from modern amphibians.

That’s weird, because only two million years ago Albert was still around and seems to have been fairly common. Albert fossils have been found in Europe, North America, northern Africa, and parts of Asia. Two million years isn’t all that long when you’re talking about big differences between related animal groups. But although Albert appears in the fossil record at about the same time as other amphibians, it seems to have evolved very differently in many ways.

Albert looked like a salamander and was originally classified as a salamander. It was small, its body was slender and elongated, its legs were short, and it had a long tail. It had tiny teeth and seemed to prefer wet environments, which makes sense when you’re talking about an amphibian. But Albert had a lot of traits not found in other amphibians, such as scales. The scales were more fish-like than reptilian and were embedded in Albert’s skin like osteoderms, especially concentrated on the head.

These scales have caused confusion for a whole lot of scientists. In 2016, for instance, scientists identified an unusual lizard found fossilized in amber as a 99-million-year-old chameleon. That’s because it had a weird bone in its jaw shaped like a little rod, which looked like a bone found in the modern chameleon’s tongue.

It turns out that the lizard was no lizard at all but our friend Albert, an amphibian. The chameleon is a reptile and not related to Albert, but they share the same type of elongated tongue bone. When the skull of a second amber specimen was discovered that was even better preserved, including a tongue pad and other soft tissue, scientists were able to evaluate whether Albert used its tongue the same way that a chameleon does.

One trait found in Albert skulls that scientists had long been confused about was how robust and large its skull was. Some scientists suggested that it used its big head to dig burrows, ramming its head into soft mud until it created a hole big enough to hide in. But it also had big eyes, which isn’t typical in an animal that burrows.

Scientists now think that Albert’s head was so strong because it needed to withstand the forces of its own tongue. It could probably shoot its tongue out incredibly fast like a chameleon, much faster even than a frog. It’s referred to as a projectile tongue, ballistic tongue, rapid-fire tongue, or boomerang tongue. The muscles that power a chameleon’s tongue are specialized to store energy when it contracts, then launch the tongue out like someone releasing a stretched-out rubber band. Albert’s similar ability evolved separately from the chameleon’s, and much earlier.

It’s also possible that Albert didn’t undergo a larval stage the way most other amphibians do. Juvenile specimens look like miniature adults, which is unusual in amphibians but ordinary in reptiles. Albert also had lizard-like claws. But we know Albert wasn’t a reptile, and in fact it may have demonstrated one of the most amphibian traits known, breathing through its skin. Many modern salamanders don’t have lungs or gills at all as adults, and instead absorb oxygen directly through the skin, called cutaneous respiration. The specialized bone in Albert’s jaw would have made it hard to breathe in the ordinary way, and we know it didn’t have gills.

The big question is why Albert went extinct when other amphibians are doing just fine. We don’t have an answer for that, or not yet. While Albert did seem to be quite successful, fossils of tiny, delicate animals like two-centimeter-long amphibians are rare, and that means we don’t have the full picture of what happened two million years ago that drove Albert to extinction.

For that matter, some scientists wonder if Albert might not actually be extinct. It might be alive and well in remote rain forests, spending most of its time hidden in damp leaf litter and using its mighty tongue to catch tiny insects. Maybe one day a scientist will turn over a log and make the find of a lifetime.

Thanks for your support, and thanks for listening!

Further reading:

Identifying the beasts in Caesar’s forest

Reindeer:

Show transcript:

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

After the glaciers retreated from Europe at the end of the last ice age, around 11,000 years ago, forests grew wherever there was enough soil to support a tree. As these new forests spread, they joined forests that had survived the glaciations. By the time ancient Romans were writing about the things they encountered while exploring western Europe, around 2,000 years ago, the forest stretched across much of the continent and was considered a wild, dangerous place. They called it the Hercynian [her-SIN-ian] forest and it was supposed to be full of peculiar animals.

An account of the forest appears in the book Commentarii del Bello Gallico, the first edition of which was published just over 2,000 years ago in 49 BCE. It was written by Julius Caesar, or at least he was involved in it even if he didn’t actually write it personally, since it was about his military campaigns. In one section of the book he discusses the Hercynian forest and three remarkable animals that lived in it.

The first was called the uri, which were supposed to look like bulls but were almost the size of elephants, and were incredibly aggressive. This is probably the same animal often called the aurochs, which we talked about in episode 58. The aurochs was probably the wild ancestor of the domesticated cow and could stand almost six feet tall at the shoulder, or 1.8 meters. It had already gone extinct in most places 500 years before Caesar wrote his book, but it still lived in parts of Europe.

The second animal is a lot harder to identify. The alces looked like a big goat that either didn’t have horns or had very short ones, but its legs didn’t have joints. If an alces fell over, it couldn’t get up again. Caesar explained that hunters used this to their advantage. Because the alces couldn’t lie down at night, it would sleep by propping itself against a tree. The hunters would note which tree an alces preferred, and during the day they’d cut a notch in the trunk. When the alces leaned against it at night to sleep, the tree would topple over, taking the animal with it. The waiting hunters would then be able to just stroll up and kill the alces.

Naturally, this story doesn’t make any sense. All tetrapods have jointed legs. But the story of an animal without joints in its legs crops up in various stories from around this time, including the part where hunters cut a notch in a tree trunk to knock the animal over. It’s a story once told about the elephant and the Eurasian elk, among others, and the alces was probably based on the Eurasian elk. That’s the Eurasian population of the animal called the moose in North America. Because the story specifies that the alces either didn’t have horns or had very small ones, it’s possible that Caesar based his story on the female elk, which doesn’t have antlers.

Incidentally, we’re so certain that the alces was the same animal as the Eurasian elk that its scientific name is actually Alces alces.

Finally, the Hercynian deer was likewise large and had a single horn. A translation of the passage states: “There is an ox with the shape of a deer; projecting out of its forehead, in the middle, between the ears, is a single horn, which is both longer and more upright than those horns we are used to seeing.” Other sources that talk about this animal also say that the horn branched at the end, and Caesar notes that both males and females had these horns.

This gives us a big clue as to what animal might have inspired the account. Unlike most deer, both male and female reindeer have antlers. Unlike caribou, the North American reindeer species, the European reindeer often has relatively long and straight main shafts on its antlers that then enlarge at the end in what’s called a palmate structure. That basically means it’s shaped like a hand.

But reindeer have two antlers, not one. It’s possible that the story of the Hercynian deer was inspired by the unicorn legend, which was based on the rhinoceros. It might also have been inspired by Caesar sighting a reindeer that had dropped one antler but hadn’t yet lost the other one, since like other deer, reindeer shed their antlers and regrow them every year.

The reason Caesar wrote about the animals of the Hercynian forest in the first place was to underline how strange and uncivilized the people living in the area were. The people in question are what today we would call Germans. Caesar stresses that all these animals are ones never seen anywhere else, and he might easily have added exotic details from other fabulous animals to make these animals seem extra weird.

These days most of the Hercynian forest is long gone, chopped down for people to turn into farmland and towns. While the Eurasian elk and the reindeer are still around, they no longer live as far south as Germany. The last aurochs went extinct in 1627 in Poland. But the German people are doing just fine, and they’re a lot more civilized than Caesar gave them credit for 2,000 years ago.

Thanks for your support, and thanks for listening!

This week let's look at the work of a really astonishing number of spiders!

Further reading:

Megaweb!

Some of the webs:

Show transcript:

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

Baltimore, Maryland is a city in the northeastern United States, in North America, with a population of 2.8 million people. In 1993 a new wastewater treatment plant was built called the Back River Wastewater Treatment Plant, which filters water through big sand beds to trap any particles remaining in it after it’s been filtered and treated in other facilities. The plant consists of 48 big sand beds with a corridor down the middle, and in order to keep the sand beds as clean as possible, the whole area has a big metal roof over it held up with steel columns. It doesn’t have walls, though, just a roof. The whole thing covers four acres, or 1.6 hectares, which I think is a metric term. It’s just over 16,000 square meters. It’s big, in other words, and the roof is pretty tall, up to 24 feet high over the walkway, or 7.5 meters.

Obviously, I’m telling you about this place in detail because of an animal that got into the water treatment plant and caused a lot of alarm. It wasn’t a big animal like a bear, though. It wasn’t even a dangerous animal. It was, in fact, a really small animal that’s mostly harmless to humans, various species of orbweaver spider. The problem wasn’t the spider itself but just how many spiders were in the water treatment plant.

The plant had always had problems with lots of orbweavers, but in 2009 there were so many spiders that the workers were worried for their safety. In late October 2009, the managers called for help about “an extreme spider situation.” The problem was way beyond anything that an ordinary pest control business could deal with, so the city put together a team of arachnologists, entomologists, and experts in urban pest control to figure out the best course of action.

The team didn’t just charge in, say, “Wow, that’s a lot of spiders, let’s hose the whole place down.” They were scientists and studied the situation methodically. They consulted the architectural plans of the plant to determine just how much volume was available under the roof, they took samples of the webs and stored them for study, they took over 300 photos, and basically they got as much data as they could.

There were so many spiders that their webs blended together into thick mats that filled almost every space the spiders could reach. These cobweb mats were attached to the rafters, the walkways, everywhere, with the older mats starting to detach and fray. Light fixtures hung down from the tallest point of the roof that were 8 feet long, or 2.44 meters, and there were so many webs attached to them that they were pulled out of alignment. And all the webs were filled with spiders.

The spiders in the web samples were removed and preserved, then examined to see what species they belonged to. The team identified specimens from nine genera in six families, but most of the spiders caught were the species Tetragnatha guatemalensis. This is a type of long-jawed orbweaver native to North and Central America. Females are much larger than males, with a legspan up to 2 inches across, or about 5 cm. Long-jawed orbweavers have long, thin bodies, and one of the ways it hides is by stretching out on a blade of grass or a twig with its legs out straight. It especially likes marshy areas, such as in the rafters above 48 giant sand beds full of water.

A conservative estimate of the number of spiders in the Back River Wastewater Treatment Plant in the first week of November, 2009 was 107 million. 107 million spiders! Since a big percentage of the spiders were newly hatched, there were probably a lot more in the facility than the scientists estimated from the samples they took, so there might easily have been several hundred million spiders total. The sheets of webbing in the ceiling covered an estimated 2 acres total, or about 8,000 square meters, while the cloud-like masses of webbing in other areas was about half that size and would have filled 23 railroad boxcars.

The really interesting thing is that orbweaver spiders are usually solitary. Spiders may build webs near each other, but not usually like this. But these orbweavers lived in a place protected from wind and weather, and close to water, which attracted lots of midges and other small insects, and the presence of humans probably kept a lot of potential spider predators away, like birds. Life was good for these spiders and the scientists observed that they weren’t acting aggressively to each other, even when they were of different species.

After studying the water treatment plant and its spiders, the team came to several conclusions. Since the spiders are harmless to humans, and are doing a really good job controlling the midge population, the scientists decided that pest control was not necessary and would even be a bad idea since the pesticides would inevitably get into the water. Instead, they recommended that web removal be implemented as a normal course of action when the webs started building up too much. They even suggested that the workers should be proud of their record-breaking webs, and that the plant was an ideal site for scientists to study the spiders in detail.

Thanks for your support, and thanks for listening!