Category Archives: sea monsters

Episode 015: Hammerhead shark and Megalodon!

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This week’s episode is all about some awesome sharks: the hammerhead shark, which used to scare the poop out of me when I was a kid, and the unbelievably huge but fortunately for all the whales extinct megalodon! Thanks to Zenger from Zeng This! for recommending such a great topic!

The great hammerhead, a huge and freaky-looking shark.

A ray leaping out of the water to escape a hammerhead. The article I pulled this from is here.

A guy with a teeny adorable bonnethead, a newly discovered species of hammerhead.

Hello there. I am a great white shark.

Show transcript:

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

This week’s episode was suggested by Zenger from the fun pop culture podcast Zeng This!, which I recommend if you don’t already subscribe. He suggested megalodon as a topic, so since I was already researching hammerhead sharks, I decided to put together a shark episode.

We’ll start with the hammerhead shark, because hammerheads scared the crap out of me as a kid. They just look so weird! You know what else scared me as a kid? Skeletons. It’s a good thing no one ever showed me the skeleton of a hammerhead shark.

There are a lot of species of hammerhead shark, some of them small like the new species of bonnethead discovered earlier this year that’s only about as long as your forearm, and some of them huge, like the great hammerhead, which can grow up to 20 feet long [6 meters]. One of the biggest sharks ever caught was a great hammerhead. At fourteen feet long [4.2 meters], it wasn’t the longest shark ever, but it weighed 1,280 pounds [580 kg]. It was caught in 2006 off the coast of Florida.

If it weren’t for its weird head shape, the hammerhead wouldn’t seem all that interesting. It’s mostly plain gray in color, hardly ever attack humans, and is common all over the world. But they’ve got that head! The shape is called cephalofoil, and not only are the shark’s eyes on the end of the stalks, the head is flattened.

Researchers think the shape serves two purposes. A hammerhead shark can see really well since its eyes are so far apart, and the shape actually provides a certain amount of lift when water flows over it, like an airplane’s wing, which helps the shark maneuver. Plus, of course, a wide head allows for even more electroreceptor cells so the shark can sense prey better.

Hammerheads have relatively small mouths compared to many other sharks. They do a lot of feeding on the ocean floor, snapping up rays, fish, crustaceans, octopus, even other sharks. Oh yeah, and a hammerhead will actually use its head as a weapon. Hammerheads like eating stingrays and will pin one to the ocean floor with its head to keep it from escaping until the shark can bite it. In February of 2017, tourists surfing near Panama saw a spotted eagle ray escape a hammerhead shark by leaping out of the water like a bird. The stingray actually beached itself on an island, too far up the beach for the shark to reach. After it gave up, the ray managed to catch a wave that carried it back out to sea. That’s pretty epic.

Hammerhead sharks are considered a delicacy in many countries, but since their fins are the most valuable part of the fish, fishermen sometimes catch a shark, cut its fins off, and toss the still-living shark back in the ocean. It always dies, because it can’t swim without fins. The practice is horrific and banned in many countries. Overfishing has also threatened many hammerhead species. Researchers estimate that the great hammerhead in particular has decreased in numbers some 80% in the last 25 years.

Ironically, recent studies have found repeatedly that shark fins and meat contain high levels of mercury and a neurotoxin called BMAA, which is linked to neurodegenerative diseases in humans. The frequent eating of shark fin soup and other dishes made of shark meat, and cartilage pills which some people take as a diet supplement, may increase the risk of developing diseases like Alzheimer’s and Lou Gehrig’s disease. (I ate shark once, a shark steak. It was terrible.)

You may think a 20-foot hammerhead is a really big shark, and it is. Great white sharks aren’t much bigger. But before the great white and the hammerhead, a 60 foot [18 meter] shark ruled the oceans. Megalodon is first found in the fossil record around 23 million years ago, and died out about 2 ½ million years ago. Because shark skeletons are made of cartilage instead of bone, they don’t fossilize well. We have a whole lot of megalodon teeth, but except for some vertebrae we don’t know much about the rest of the shark.

Researchers generally compare megalodon with the great white, since while they’re not necessarily closely related, they occupy the same ecological niche. We do know how the teeth were arranged, since associated teeth in formation as they had been in the jaw, although the jaw itself wasn’t preserved, have been discovered in North Carolina and Japan.

At a rough estimate, megalodon probably grew 60 or even 70 feet long [18 to 21 m]. Its jaws were over six feet across [1.8 meters] with some 276 teeth in five rows. Due to the size of its teeth and jaws, it probably mostly preyed on large whales, and was probably a lot blockier looking than the great white. If the great white is a racecar, megalodon was that bus from Speed.

Some researchers want to classify megalodon as a close relative of the great white shark, which has serrated teeth like megalodon’s. But others argue the great white is more closely related to the mako shark, which does not have serrated teeth. For a long time the megalodon hypothesis was more accepted, but a study published in the March 12, 2009 issue of Journal of Vertebrate Paleontology concluded that mako sharks and great whites probably share a recently discovered fossilized ancestor some 4 to 5 million years old. Its teeth have coarse serrations, which researchers think are a transitional point between no serrations and the serrations in modern great white shark teeth. The similarities between the great white and megalodon are due to convergent evolution.

This points to something many people don’t understand about science. It’s messy. It’s incomplete. Our collective body of knowledge is being added to, adjusted, reinterpreted, and hopefully corrected all the time. From the outside it can look like people arguing over ridiculous minutiae, or a bunch of eggheads who can’t make up their minds. In reality, as new information is added to what we know, what we used to think was true has to be changed to fit new facts. It’s exciting!

For a long time researchers though megalodon died out around the beginning of the Pleistocene because the world grew colder as the world entered into the ice ages. New findings suggest that climate change didn’t push the megalodon into extinction, other sharks did. Newcomers like the great white and the orca, which of course isn’t a shark but a whale, starting expanding into new territory, out-competing megalodon around the same time that a lot of marine mammals were also going extinct. Megalodon needed a lot of food to survive—more than the much smaller upstarts.

Back when megalodon was king, though, there was plenty of food to go around. It wasn’t even the only mega-predator hunting the oceans. In 2008, fossils of an ancestor of today’s sperm whale were discovered in Miocene beds dated to around 12 or 13 million years ago. The whale has been dubbed Livyatan melvillei and estimates of its length, from the partial skull, lower jaw, and teeth that were found is around 57 feet [17 meters]. Since modern sperm whales are frequently some 60 feet long [18 m] and 80-foot [24 m] monster males were reported in the past, it’s possible the newly discovered Leviathan could attain similar lengths. Its biggest teeth were two feet long [61 cm] compared to modern sperm whales’ 8-inch teeth [20.5 cm]. It also apparently had teeth in its upper jaw as well as its lower. The sperm whale only has teeth in its lower jaw, and since it mostly eats squid, it doesn’t really need teeth at all. Individuals who have lost their teeth survive just fine.

The Leviathan, though, used its teeth. Like megalodon, it may have preyed on baleen whales. Megalodon teeth were found in the same fossil deposits where the Leviathan was discovered. I bet they battled sometimes.

So how do we know Megalodon isn’t still around, cruising the oceans in search of whales? After all the megamouth shark was only discovered in 1976 and it’s almost 20 feet long [6 m]. Well, we have two big clues that there isn’t a population of Megalodon sharks still living. Both involve its teeth.

Sharks have a lot of teeth, and they lose them all the time as new teeth grow in. Shark teeth are among the most common fossils around, and any dedicated beachcomber can find shark teeth washed up on shore. If megalodon still lived, we’d be finding its teeth. We’d also probably be finding whales and other large marine animals with scars from shark attacks, the way we find scars on sperm whales from giant squid suckers.

Wait, you may be saying, no one was talking about megamouth shark teeth found on beaches before it was discovered. Well, megamouth sharks have tiny, tiny teeth that they don’t even use. They gather food with gill rakes that filter krill from the water. Megalodon teeth can be seven inches long [18 cm]. Great white teeth are only two inches long [5 cm]. Occasionally a fossilized megalodon tooth washes up on shore, and when it does, it makes the news.

So okay, you might be saying, you fractious person you, what if megalodon survived into modern times but has died out now. Well, we’d probably still know. Not only would the non-fossilized teeth still be found, since nothing is going to eat them and they don’t decay readily, but a lot of cultures have incorporated shark teeth into weapons over the centuries. A seven-inch serrated tooth is a weapon worth having.

Consider the Gilbert Islands in the Pacific. Sharks were important in the Kiribati culture there, and the people crafted amazing weapons with shark teeth. Anthropologists studying the weapons discovered that some of the teeth used in older weapons come from sharks that are now extinct in the area.

So no, I’m going to insist that whatever you saw on Shark Week, megalodon is not out there and hasn’t been for a couple of million years. But what about other mystery sharks?

There aren’t very many reports, surprisingly. Even Karl Shuker comes up empty, with just one mention of a reportedly hundred-foot [30 m] shark called the Lord of the Deep by Polynesian fishermen, but I can’t find any additional information about it.

That doesn’t mean there aren’t mystery sharks out there, of course, just that they’re probably not gigantic or radically different from known shark species. In fact, new sharks are discovered all the time. In just the last few months, a three-foot [1 m] ghost shark with rabbit-like teeth, and a tiny hammerhead called a bonnethead have been described. And yeah, I’d love to be wrong about the megalodon’s existence.

Researchers are studying the genetics of sharks’ rapid healing, which could have important medical applications for humans. A recent study published in the January 2017 BMC Genomics Journal provides evidence that the genes linked to the immune system in sharks and rays have evolved in ways that their counterparts in humans have not. One gene is involved in killing cells after a certain amount of time, which is something cancer cells manage to avoid. It’s possible that as researchers learn more, new therapies for treating cancer in humans could be developed.

So maybe we should stop eating so many sharks. Shark meat isn’t good for you anyway.

You can find Strange Animals Podcast online at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us and get twice-monthly bonus episodes for as little as one dollar a month.

Thanks for listening!

Episode 011: The Vampire Squid and the Vampire Bat

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This week we’re going all goth in April for the vampire squid and the vampire bat. They’re so awesome I want to die.

The vampire squid looking all menacing even though it’s barely a foot long.

“I love you, vampire bat!!” “I love you too, Kate.”

Thanks for listening! We now have a Patreon if you’d like to subscribe! Rewards include patron-only episodes and stickers!

Show transcript:

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

I thought about waiting to run this episode in October, but that’s a really long way away. So we’ll have Halloween in April and talk about the vampire squid and the vampire bat.

The vampire squid has one of the coolest Latin names going, Vampyroteuthis infernalis, which means “vampire squid from hell.” It’s a deep-sea squid and until recently, not a lot was known about it. It was discovered in 1903 and originally classified as an octopus. Its body is about six inches long [15 cm], with another six inches or so of tentacles, which are connected with webbing called a cloak. Actually I’m not sure if scientists refer to this as a cloak, but if you’ve called your animal the vampire squid from hell, you can’t complain if podcasters, for instance, refer to web-connected octopus legs as a cloak.

So is it an octopus or a squid? It’s both, in a way. The vampire squid is the last surviving member of its own order, Vampyromorphida, which shares similarities with both.

The vampire squid’s color varies from deep red to velvety black. The inside of its cloak is black and the parts of its legs inside the cloak are studded with spines. Its beak is white. Basically the only thing this little guy needs to be the world’s ultimate goth is a collection of Morrissey albums.

It lives in the lightless depths of the ocean below 3,000 feet [914 meters]. There’s not a lot of oxygen down there so there aren’t very many predators. The vampire squid doesn’t need oxygen because it’s a vampire—or at least it can live and breathe just fine with oxygen saturations as little as 3%. Its metabolic rate is the lowest of any cephalopod.

The vampire squid doesn’t move a lot. It drifts gently, aided in buoyance because its gelatinous tissues are roughly the same density as seawater. Adults have two small fins sticking out from their mantle, which they flap to propel them through the water.

If something threatens a vampire squid, it brings its legs up to expose the spiny insides of its cloak and hide its body. If something really threatens a vampire squid, even though it doesn’t have ink sacs, it can eject a cloud of bioluminescent mucus, and can flash its photophores in a dazzling display of lights. These photophores are concentrated on the outside tips of its arms. If the end of an arm is bitten off, the vampire squid can regenerate it.

So we have a creepy-looking, if small, cephalopod that lives in the deep, deep sea called a vampire squid. WHAT. DOES. IT. EAT?

I hate to disappoint you, but the vampire squid eats crap. In fact, it eats the crap of animals that eat crap. There’s not a lot of food in the ocean depths. Mostly there’s just a constant rain of fish poop, algae, bits of scales and jellyfish, and other waste. Lots of little creatures live on this stuff and their poop joins the rain of barely-food that makes it down to the abyssal depths where the vampire squid waits.

The squid had two retractable filaments—not the same thing as the two feeding tentacles true squids have, but used for feeding. The filaments are extremely long, much longer than the vampire squid itself. It extends the filaments, organic detritus falls from above and sticks to them, and the vampire squid rolls the detritus up with mucus from its arm tentacles into little sticky balls and pops the balls into its mouth.

That’s not very goth. Or it might be incredibly goth, actually.

Most cephalopods only spawn once before they die. A 2015 paper in Current Biology reports that the vampire squid appears to go through multiple spawning phases throughout its life. It may live for a long time too, but we don’t know for sure. There’s still a lot we don’t know about the vampire squid.

Because squids and octopuses are soft bodied, we rarely find them in the fossil record. In 1982, though, a beautifully preserved octopus body impression was found in France in rocks dating to 165 million years ago. And guess what kind of octopus it turned out to be! Yes, it’s related to the vampire squid.

If the vampire squid is the kind of pensive goth who listens to The Smiths and reads Poe in cemeteries, the vampire bat is out clubbing with its friends, blasting Combichrist, and spending its allowance in thrift shops. There are three species of vampire bat, but they’re different enough from each other that each belongs to its own genus. They’re native to the Americas, especially tropical and subtropical environments, although they haven’t been found any further north than Mexico. And yes, vampire bats do actually feed on blood. It’s all they eat.

Vampire bats are small, active, and lightweight. They’re only about 3 ½ inches long [9cm] with a 7-inch wingspan [18 cm], and weigh less than two ounces [57 grams]. They live in colonies that consist of big family groups: a small number of males and many more females and their babies. Males without a colony hang out together and probably never clean up their apartments.

Vampire bats belong to the leaf-nosed bat family, and like other leaf-nosed bats they sleep during the day and hunt at night. But the vampire bat doesn’t actually have a nose leaf. That’s a structure that aids with echolocation, and vampire bats don’t need the high level echolocation ability that insect-eating bats do. They get by with a reduced ability to echolocate, but they have another highly developed sense that no other mammal has: thermoreception. They use it to determine the best place to bite their prey. The warmer, the better. That’s where the blood is.

The vampire bat also has good eyesight, a good sense of smell, and hearing that’s attuned to the sound of breathing. A bat frequently remembers the sound of an individual animal’s breathing, and returns to it to feed night after night. What vampire bats don’t have is a very good sense of taste. They don’t really need it. In fact, they don’t have the kind of bad food avoidance that every other mammal has. In a study where vampire bats were given blood with a compound that tasted bad and made them throw up, the next time they were offered the bad-tasting blood, they ate it anyway.

Most bats are clumsy on the ground. They’re built for flying and for hanging from perches. But vampire bats are agile. They crawl around and even run and jump with no problems.

Two species of vampire bat prey mainly on birds, while the third—the common vampire bat—feeds on mammals. Bird blood has a much higher fat content than mammal blood, which is higher in protein. But results of a study released in January 2017 found that hairy-legged vampire bats, which usually prey on large wild birds, had started feeding on domestic chickens as their wild prey became scarcer—and then they started feeding on human blood.

A vampire bat doesn’t suck blood. It makes a small incision with extremely sharp fangs and laps up the blood with its grooved tongue. It may even trim hair from the bite site first with its teeth. Its saliva contains an anti-coagulate called draculin that keeps the blood flowing. The bat doesn’t eat much, because let’s face it, it’s just a little guy. In order to hold more blood, as soon as it starts to feed its digestion goes into overdrive. Within some two minutes after it starts to eat, the bat is ready to urinate in order to get rid of the extra fluid so it can hold more blood. A feeding session may last about 20 minutes if the bat isn’t disturbed, and the bat may drink about an ounce of blood in all.

A vampire bat needs to eat at least every two days or it will starve. A bat that hasn’t found prey in two nights will beg for food from its colony mates, which often regurgitate a little blood for the hungry bat to eat. New mother bats may be fed this way by her colony for as much as two weeks after she’s given birth so that she doesn’t have to hunt. Baby vampire bats drink their mother’s milk just like any other mammal.

If a mother bat doesn’t return from hunting, other colony members will take care of her baby so it won’t die. Colony members groom each other and are generally very social. Even the male bats that aren’t part of the colony are allowed to roost nearby. Nobody fights over territory. These are nice little guys.

Vampire bats do sometimes carry rabies, but it’s pretty rare compared to infection rates in dogs. They are more dangerous to livestock than to humans. Attempts to kill off vampire bat colonies to stop the spread of rabies actually has the opposite effect, since bats from a disturbed colony will seek out another colony to join.

Vampire bats have considerable resistance to rabies and frequently recover from the disease, after which they’re immune to reinfection, and there’s some preliminary evidence to suggest that native human populations in areas where vampire bats are common may also have developed some resistance to rabies. Researchers hope that this finding will lead to better treatment of rabies in the same way that the draculin anticoagulant in vampire bat saliva led to advances in blood-thinning medications.

I like to imagine a vampire bat hanging out with a vampire squid. The bat would sip blood from a tiny wineglass and fidget with its jewelry while it tries to conversation. The squid would just stare at the bat. Then it would eat a globule of crap. The bat would pee on itself and the whole evening would just be a bust. Also, one of them would drown but if I can imagine a tiny wineglass I can imagine a tiny bat-sized bathysphere or something. Never mind.

You can find Strange Animals Podcast online at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us and get twice-monthly bonus episodes for as little as one dollar a month.

Thanks for listening!

Episode 006: Sea Monsters

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This week’s episode is all about sea monsters: mysterious sightings, possible solutions, and definitely discovered monsters of the world’s oceans!

The giant oarfish! Try to convince me that’s not a sea serpent, I dare you.

The megamouth shark. Watch out, krill and jellyfish!

The frilled shark. Watch out, everything else including other sharks!

A giant isopod. Why are you touching it? Stop touching it!

Sorry, it’s just a rotting basking shark:

Recommended reading:

In the Wake of Bernard Heuvelmans by Michael A. Woodley

In the Wake of the Sea-Serpents by Bernard Heuvelmans

The Search for the Last Undiscovered Animals by Karl P.N. Shuker

Episode 003: The Tuatara and the Sea Lamprey

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In this week’s episode, we look at a couple of so-called living fossils: the tuatara and the lamprey. One of them hasn’t changed appreciably in almost 400 million years. Tune in to find out which one and learn about how gross it is and how cute the other one is! (I may be biased.) (re-recorded audio)

The adorable tuatara! It eats anything, including baby tuataras. Not cool, lizardy guy:

A face not even a mother could love. The sea lamprey:

A recently discovered fossil lamprey, complete with impression of its body:

Show transcript:

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

This week’s episode is about my favorite reptile and a revolting sea creature, and just to be clear, those are two different animals.

If you look at a tuatara, it appears pretty ordinary. It’s a brownish-grayish-green lizard with lighter-colored spines along its back, and it can grow to about two feet long, or 61 cm. It’s a hefty lizard, sure, but you’d probably think it was nothing special. But dang, is it special.

First of all, it’s not strictly a lizard. It’s the only surviving member of its own order, Rhynchocephalia. It also has many physical traits not shared by lizards—or any other living reptile. Or mammal. Or bird. Or anything else.

Its teeth, for instance. The tuatara has two rows of teeth in the upper jaw, one in the lower, with the lower jaw’s teeth fitting neatly between the two upper rows. Some snakes have two upper rows of teeth and one lower row, but not arranged like the tuatara’s. Not to mention that the tuatara’s teeth aren’t even teeth at all. They’re just pointy projections of the jaw bone.

The tuatara also chews in a literally unique way. When the lower teeth mesh between the upper rows of teeth, the animal moves its jaw forward and back. This slices its food against the sharp tooth edges.

The tuatara also has a third eye. I’m not making this up. It legit has a photoreceptor on top of its head called the parietal (pahRAYetal) eye with a lens, cornea, retina, and so forth. Hatchling tuataras have a translucent patch of skin above the eye, but as the hatchling grows and molts its skin, the patch darkens until the third eye is no longer visible. Researchers think it may help with thermoregulation and hormone production. The tuatara isn’t the only creature with a third eye, but it has the most well developed one.

Like the turtle, the tuatara has a primitive auditory system. It has no external ears and no eardrum, although it can hear. Its skeleton has some features apparently retained from its fish ancestry, such as its spine and some aspects of its ribs. Males don’t have a penis—but a lot of birds don’t either and we still have lots of birds, so obviously they make it work.

Because it has such a slow metabolism—the lowest body temperature of any other reptile—the tuatara grows slowly. It won’t reach breeding age until it’s ten to twenty years old, and females only lay eggs about once every four years. The average lifespan of a tuatara is 60 years. Researchers believe it could live to 200 years in captivity.

Baby tuataras are active in the daytime, probably so their parents won’t eat them. Tuataras eat pretty much anything they can catch. Adult tuataras are active at night, and sleep during the day in dens. Sometimes a tuatara digs its own den, sometimes it shares a den with burrowing seabirds. The birds leave in the morning and the tuatara comes home to sleep until night, when the birds return.

The Tuatara is native to New Zealand, and in an all-too-common situation, when people showed up, the tuatara promptly went extinct on the mainland. It was restricted to 35 islands where it was mostly safe from introduced rats, until its reintroduction in the fenced Karori Sanctuary in 2005. Tuataras have begun to breed in the sanctuary.

One thing I didn’t know about New Zealand—one of many many things, since pretty much all of my New Zealand knowledge comes from watching the Lord of the Rings movies, is that it was underwater for millions of years. Some 82 million years ago, New Zealand separated from Gondwana, the chunk of land that eventually separated into the southern continents we know today. The entire continent containing New Zealand was partially drowned some 25 million years ago, and for a long time scientists thought New Zealand was completely underwater. In the late 2000s, though, a fossil tuatara was found in New Zealand that was dated to about 18 million years ago. If New Zealand was underwater for a few million years, how did the tuatara recolonize it after the sea receded? Tuataras are not good swimmers, and it’s a long distance to float on driftwood without water.

Researchers now think that the highest elevations of New Zealand remained above sea level, allowing tuataras and some other species of plants and animals to survive the inundation.

You’ll see the tuatara referred to as a living fossil in a lot of articles. The media loves to call things living fossils. The tuatara has been around for 225 million years, but so have crocodiles and alligators. In fact, crocs and gators are found in the fossil record even earlier, 250 million years ago. The tuatara in particular has a lot of modern adaptations, including a number of cold-weather adaptations. A 2008 study discovered that the tuatara has the highest molecular evolution rate of any animal ever measured.

Basically, you can’t keep the tuatara down. Drown its entire continent? No problem. Run a couple of ice ages through there? It’ll adapt. And now we realize that this isn’t even its final form.

I take you now from a chunky little lizardy thing eating crickets in New Zealand to a two-foot-long monstrosity that drills into living creatures to drink the blood and bodily fluids it rasps from their tissues, the sea lamprey.

What does the tuatara have to do with the sea lamprey? I mean beyond the fact that the tuatara would happily slurp up any lampreys it could get into its mouth? Well, if the tuatara is the most rapidly evolving creature ever studied, the lamprey has remained basically unchanged for at least 360 million years.

Lampreys are eel-like parasites that lack jaws. Instead, they have a circular mouth rimmed with rows and rows of rasping teeth, for lack of a better word. I saw this described in one paper as a feeding apparatus, and it’s as good a description as any although it doesn’t convey the utter, utter horror that is the lamprey’s mouth. I may be showing my prejudices here.

Those aren’t teeth, by the way, they’re made of cartilage. The lamprey doesn’t have any bones at all, but it does have a cartilage tooth-studded tongue used to drill into its prey once it’s clamped on with its sucker-like mouth. Dear God.

Not all lampreys are parasitic. Some are filter feeders as larva and don’t eat at all once they grow up, just live on their bodily reserves until they breed and die, but I’m just talking about parasitic lampreys today because they’re gross. The most common parasitic lamprey is the sea lamprey, which lives in the Atlantic Ocean, parts of the Mediterranean and Black Seas, and in the Great Lakes as an introduced pest. The sea lamprey can grow up to four feet long, or 120 cm.

Because of their lack of bone, lampreys don’t fossilize well, but one fossil found in South Africa has revealed a lot about the lamprey. In a 2006 paper in Nature, researchers describe a beautifully preserved lamprey dated to 360 million years ago. Not only are the gills and mouth perfectly visible, so is an impression of its body. It was the oldest lamprey fossil found at the time, and it shows that the lamprey basically hasn’t changed ever since. If anything deserves to be called a living fossil, it’s the lamprey.

Back when the lamprey first evolved, it wasn’t preying on true fish. There weren’t any yet. The lamprey has held fast through at least four major extinction events. It’s a vertebrate, but has never evolved those things other vertebrates—except the hagfish, which is just weird—have developed: jaws, scales, paired fins. On the other hand, some lampreys do have a third eye.

Because lampreys are so primitive from an evolutionary standpoint, scientists can study them to learn how other vertebrates evolved. For instance, the lamprey has seven pairs of gill arches. In other vertebrates, the interior pair of gill arches evolved into upper and lower jaws and middle ear bones. That includes us.

Lampreys today prefer fresh water that’s not too warm, although the sea lamprey spends most of its adult life in the ocean, although it will also be fine in fresh water. The sea lamprey migrates upriver to spawn. After the female lays her eggs, she and the male both die. When the eggs hatch, the larvae migrate downstream to quiet water where they feed on plankton until they metamorphose into adult lampreys. Then they continue their migration downstream to the ocean or lake. They live about a year before returning upstream to spawn and die.

Lamprey larvae live as filter feeders, and until about 2014 scientists didn’t know if this was a recent development or not. Then some fossilized lamprey larvae were discovered in inner Mongolia rocks dating back 125 million years, and they look identical to modern larvae.

Old and “primitive” as it is, the lamprey is able to tolerate all sorts of environments. Most water animals can either live in saltwater or freshwater, not both, but the sea lamprey does just fine in either. In the Great Lakes, sea lampreys are so damaging to the native fish that researchers have been trying for decades to get rid of them. The sea lamprey can also feed on fish that are toxic to pretty much any other predator.

In many cultures, lamprey is considered a delicacy, and it’s supposed to taste quite good, but make sure you clean those things well. Their mucus is a toxin. You will not catch me eating lamprey if I can possibly avoid it.

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

Thanks for listening!