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Episode 449: The Gloucester Sea Serpent

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This is a chapter of the Beyond Bigfoot and Nessie book, which you can buy or request at the library!

Further reading:

Debunking a Great New England Sea Serpent

A narwhal. I use this picture all the time:

The diseased black snake that was taken for a baby sea serpent:

Show transcript:

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

This week we’re going to have a sea monster episode! This is actually a chapter of the book that I published a few years ago now, Beyond Bigfoot and Nessie, and it’s called the Gloucester Sea Serpent. We had a Patreon episode recently that was about a different sea serpent, and while I was researching that, it was driving me completely nuts, because I kept trying to find the episode where I talked about the Gloucester sea serpent, and I finally remembered that that wasn’t an episode at all. It was just a chapter in the book. Maybe it’s time to record it.

While the Gloucester sea serpent was first mentioned in a traveler’s journal in 1638, it really came to prominence almost two centuries later. On August 6, 1817, two women said they’d seen a sea monster in the Cape Ann harbor. A fisherman said he’d seen it too, but neither the fisherman nor the women were believed. A 60-foot, or 18-meter, sea serpent in the harbor? Ridiculous!

Only a few days later, though, the monster started showing up in Gloucester Bay and attracted major attention—not because it was elusive, but because it was so commonly seen. Sailors, fishers, and even people on shore saw what was described as a huge serpent in the waters of Gloucester Bay, Massachusetts, in the northeastern United States. On one occasion more than two hundred people watched it for nearly four hours.

The creature’s length was described as anywhere up to 150 feet long, or 46 meters, and many people said it had a horse-sized head. Some people described its head as being about the same shape as a horse’s too, although with a shorter snout. The body was snake-like and about the thickness of a barrel.

Many people thought the sea monster had humps along the back, usually referred to as bunches or occasionally joints. Others said it undulated through the water in an up-and-down motion, which looked like humps. Others said it had no bunches or humps at all. Most people agreed that its back was dark brown.

One of the earlier witnesses, a man named Amos Story, watched the sea serpent from shore for an hour and a half. He was adamant that it had no bunches, that he only saw at most about 12 feet of its length at one time, or 3.6 meters, and that its head resembled that of a sea turtle. It was also fast, with Story claiming it covered a mile in only three minutes or so. That’s about 20 miles per hour, or 32 kilometers per hour—an incredible speed for an animal in the water.

As it happens, the leatherback sea turtle has been recorded as swimming that fast, and it can grow over 7 feet long, or 2.2 meters, and possibly much longer. It lives throughout the world’s oceans and is just as happy in cold waters as it is in tropical waters. In other words, it’s possible Story actually saw a huge leatherback turtle, which would explain why it had a turtle-like head that it held above the surface of the water at least part of the time. This is something leatherback turtles do. Then again, the leatherback has distinctive ridges and serrations on its back that Story didn’t mention.

So many people reported seeing the sea serpent that the Linnaean Society of New England decided it needed to investigate. The society had only formed a few years before, in 1814, to promote natural history. By 1822 it had disbanded, but in those eight years it accomplished quite a bit, including opening a small museum in Boston. Its most controversial endeavor was the sea serpent investigation.

Members of the Linnaean Society interviewed witnesses, making careful notes that were signed by the interviewees to indicate the details were accurate. These statements tell us a lot about what people saw, although it hasn’t helped us determine what the sea serpent actually was.

For instance, Captain Solomon Allen saw the creature more than once and gave a clear description of it. It was at least 90 feet long, or 27.5 meters, with as many as fifty joints, or bunches. Its head was snake-like—specifically rattlesnake-like, presumably meaning it was wider at the back and had a narrower snout—but the size of a horse’s head. It was dark brown, plain in color, and swam with an undulating side-to-side motion. It dived by sinking straight down, moved quickly, and sometimes seemed to play in the water by swimming in circles.

All this is great information, but it doesn’t resemble any known animal. It also doesn’t necessarily resemble the other witness statements. Let’s go over some of the more detailed sightings and see if we can come to some conclusions.

A man named William Foster reported bunches along the monster’s length, although he also described them as rings. When the animal’s head rose from the water, the first thing Foster saw was what he described as a prong or spear. It was about a foot long, or 30 centimeters, and tapered to a point. His interviewer asked if the spear might have been a tongue, but Foster didn’t think so.

Three men on a schooner named the Laura, becalmed in the mouth of the harbor, witnessed the monster in late August. Sewall Toppan, master of the ship, reported that the monster’s head was the size of a 10-gallon keg, which would have been about 18 inches tall, or 46 centimeters, and 16 inches in diameter, or 40 centimeters. He said its head was held about 6 inches out of the water, or 15 centimeters, and that he could see 10 or 15 feet of its length disappearing into the water, or 3 to 4.5 meters. He didn’t see any kind of prong, but two of his sailors did.

One of the two sailors was Robert Bragg, who reported that the monster was swimming rapidly toward the ship with its head and about 15 feet of its body out of the water, or 4.5 meters. As it drew closer he saw its tongue, which he described as looking like a harpoon about 2 feet long, or 61 centimeters. He even reported that the animal raised its tongue almost straight up several times. He also said it was dark brown and smooth.

The third Laura witness, helmsman William Somerby, corroborated Bragg’s details, including the animal’s tongue, which he mentioned was light brown. As the monster passed within 40 feet of the ship, or 12 meters, Somerby even saw one of its eyes clearly. He said it was the size of an ox’s eye and was completely dark brown or possibly black. He and Bragg both noted that the animal had a bunch above its eyes, presumably meaning a bump or knob of some kind.

All three men said that they were familiar with whales and the animal was not a whale.

August 14 was a warm day and the water was calm. A man named Matthew Gaffney, a ship’s carpenter by trade but in his heart a monster hunter, borrowed a boat and took his brother and a friend with him to row. He also took a musket.

As the small boat approached cautiously, the monster was spiraling around in the water, as various people reported it doing on and off throughout the day. Gaffney waited until the boat was as close as it could safely approach without risking being capsized, then fired a shot at the monster’s head.

He was a good marksman and was certain he hit the animal, which sank immediately below the surface and vanished. Worried that the wounded monster would be enraged once its initial shock wore off, Gaffney and all the other boats on the harbor took off for shore. But when the sea monster resurfaced some distance off, it was obviously unbothered by being shot at. It continued its apparently playful circling around in the harbor.

Several witnesses who saw the monster on August 14, before and after Gaffney’s attempt to shoot it, gave statements. William H. Foster said it at first moved slowly, but then sped up and twisted and turned through the water. Sometimes its head would bend around toward its tail, and Foster specifically said that when that happened, parts of its body between the bunches would raise up as much as 8 inches out of the water, or 20 centimeters, showing that the animal was at least 40 feet long, or 12 meters.

Lonson Nash saw the sea serpent and reported that it moved quickly and left a long wake, and that while it swam underwater sometimes, it didn’t seem to be very far under. He could track its progress underwater by the disturbance it made on the surface. He also saw it double around so that its head was sometimes near its tail, but he mentioned that when it was swimming forward, it appeared perfectly straight.

Later that day, a shipmaster named Epes Ellery saw the monster’s head through a spyglass. He reported that it was flattened on top like a snake’s and that its mouth resembled a snake’s mouth—presumably meaning it had a thin lower jaw. He reported that its joints were the size of two-gallon kegs and rose about 6 inches above the surface, or 15 centimeters. He said the animal swam with a vertical motion, not a side-to-side motion.

An unnamed woman reported that the sea monster’s bunches looked like gallon kegs tied in a line. Another man said he saw the creature’s bunches at the surface as it lay still for a while, and that around 50 feet, or 15 meters, of its length was visible although he couldn’t see its head or tail. Other witnesses that same day reported much the same thing.

Captain Elkanah Finney saw the sea monster from shore later in August, after his son reported seeing something strange in the harbor. Finney first thought it was a bunch of seaweed, but when he looked at it through his spyglass he realized it was an animal moving quickly through the water. He said it might have been 100 feet long, or 30 meters, with 30 or 40 bunches down its length. In fact, he said it looked like a string of buoys and that each bunch was about the size of a barrel.

There are lots of other reports, all of them similar to these. The sea monster, whatever it was, spent a lot of time in and around Gloucester Bay that summer and even returned the following two summers. People were obviously seeing something. The question is what.

Let’s look at the sightings where the monster had a prong or that it stuck out a long, straight tongue. This sounds a lot like a narwhal. A narwhal can grow up to about 18 feet long, or 5.5 meters, and males, and some females, have a brown or brownish spiral tusk that can grow just over 10 feet long, or 3 meters. Many people think the narwhal’s tusk is a horn that sticks up from its forehead, but it’s actually an elongated tooth that grows through the upper lip. That would explain why some of the witnesses thought it was a tongue.

A young narwhal is black or dark brown, although it grows lighter throughout its life so that old narwhals are almost white. A young animal would also have a short tusk. A narwhal often swims with its head out of the water and a male will sometimes lift his tusk up and down in the air. He can do this easily because, unlike most whales, the narwhal’s neck vertebrae aren’t fused and can bend the head around.

Most importantly, the narwhal is an Arctic animal and isn’t typically found as far south as Massachusetts, although it’s certainly been seen in that part of the ocean on rare occasions. Its rareness, together with its odd appearance compared to other whales, might lead witnesses to think it wasn’t a whale at all but some kind of monster.

That doesn’t explain the bunches, though. The witnesses on the schooner Laura didn’t report seeing any bunches on their sea monster (whose “tongue” reportedly looked like a harpoon), but William Foster’s pronged sea monster did have bunches.

Some researchers have dismissed the bunches, or humps, as a string of narwhals or other small whales traveling in a line. That’s definitely a possibility, but too many witnesses described the bunches as being always partially out of the water, not moving up and down. Not only that, the bunches were seen when the sea monster was lying quietly on the placid surface, not moving, often for long stretches.

Remember, though, that many witnesses described the bunches as resembling a line of buoys or kegs tied on a line. The animal often seemed to swim in circles until its head nearly touched its tail. William Foster reported that when it did this, its body between the bunches would rise several inches out of the water. Lonson Nash said when it was swimming forward, its body appeared perfectly straight.

Maybe witnesses weren’t seeing a long serpentine animal with bumps along its back. Maybe they were seeing a string of kegs used as buoys to keep fishing nets afloat, that had become tangled around a small whale’s tail.

Small kegs or large pieces of cork were sometimes used for this purpose at the time, including in Newfoundland and Norway. If a net tangled around a narwhal’s tail, the animal might have become used to dragging its burden around until the net eventually rotted away and freed the whale. This is something that still happens to whales today with nets and other fishing gear, although these days the nets are all plastic and won’t rot.

Narwhals mostly eat fish and squid, and often dive deeply to find food along the ocean floor. Our entangled narwhal chasing fish underwater might appear to be traveling in playful circles as the net dragged along behind and above it. Pulling all the buoys underwater would probably be difficult for the whale, which would explain why it mostly stayed near the surface.

It’s not a perfect match, of course, but the tangled-narwhal hypothesis fits a lot of the details reported for the Gloucester sea serpent. Narwhals also often travel in small groups, so if the entangled narwhal was with a few friends, that would explain why not every witness saw the bunches.

As for the Linnaean Society of New England, their investigation of the sea monster was excellent for the time. They took the sightings seriously and tried to remain impartial, although the members did seem to start from an assumption that the animal was an actual serpent of some kind.

Unfortunately, they made one fatal blunder. In late September 1817, someone found and killed a snake 3.5 feet long, or a little over a meter, that had bunches all down its spine. It was found only a few miles from Gloucester Harbor. The Linnaean Society decided it had to be a baby sea serpent.

They said so loudly and even proposed a scientific name for the sea serpent. But it wasn’t long before the “baby sea serpent” was identified as a common black snake. The body was dissected and the bunches turned out to be tumors from a diseased spine. The society’s investigation became a joke. But at least we still have the eyewitness accounts they gathered.

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

Thanks for listening!

Episode 406: Some Turtles and a Friend

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Thanks to Riley and Dean, Elizabeth, and Leo for their suggestions this week!

Further reading:

Groundbreaking study reveals extensive leatherback turtle activity along U.S. coastline

A bearded dragon:

The tiny bog turtle:

The massive leatherback sea turtle:

The beautiful hawksbill turtle [photo by U.S. Fish and Wildlife Service]:

Show transcript:

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

This week we’re going to learn about some reptiles suggested by four different listeners: Riley and Dean, Elizabeth, and Leo.

We’ll start with the brothers Riley and Dean. Dean wants to learn more about the bearded dragon, and that may have something to do with a certain pet bearded dragon named Kippley.

“Bearded dragon” is the name given to any of eight species of lizard in the genus Pogona, also referred to as beardies. They’re native to Australia and eat plants and small animals like worms and insects. They can grow about two feet long, or 60 cm, including the tail, but some species are half that length. Females are a little smaller than males on average.

The bearded dragon gets its name because its throat is covered with pointy scales that most of the time aren’t very noticeable, but if the lizard is upset or just wants to impress another bearded dragon, it will suck air into its lungs so that its skin tightens and the spiky scales under its throat and on the rest of its body stick out. They’re not very sharp but they look impressive. Since the bearded dragon can also change color to some degree the same way a chameleon can, when it inflates its throat to show off its beard, the beard will often darken in color to be more noticeable. Both males and females have this pointy “beard.”

Bearded dragons that are sold as pets these days are more varied and brighter in color than their wild counterparts, although wild beardies can be brown, reddish-brown, yellow, orange, and even white. Australia made it illegal to catch and sell bearded dragons as pets in the late 20th century, but there were already lots of them outside of Australia by then. Pet bearded dragons are mainly descended from lizards exported during the 1970s, which means they’re quite domesticated these days and make good pets.

Like some other reptiles and amphibians, the bearded dragon has a third eye in the middle of its forehead. If you have a pet beardie and are about to say, “no way, there is definitely not a third eye anywhere, I would have noticed,” the eye doesn’t look like an eye. It’s tiny and is basically just a photoreceptor that can sense light and dark. Technically it’s called a parietal eye and researchers think it helps with thermoregulation.

Next, Riley wants to learn about turtles, AKA turbles, and especially wants everyone to know the difference between a tortoise and a turtle. It turns out that while many turtles are just fine living on land, they’re often more adapted to life in the water. Turtles have a more streamlined shell and often flipper-like legs or webbed toes. Tortoises only live on land and as a result they have shells that are more dome-shaped, and they have large, strong legs that resemble those of a tiny elephant.

You can’t always go by an animal’s common name to determine if it’s a tortoise or a turtle, but it’s also not always clear whether an animal is a tortoise or a turtle at first glance. Take the eastern box turtle, for instance, which is common in the eastern United States. It has a domed carapace, or shell, but it’s still a turtle, not a tortoise. And, I’m happy to say, it can swim quite well. This is a relief to find out because when I was about six years old, my mom visited someone who had kids a little older than me. I didn’t know them but they were nice and showed me the swampy area near their house. At one point one of the older boys found a box turtle, took it over to a little bridge over a pond, and dropped it in the water. I screamed, and he was absolutely shocked. He said he thought box turtles belonged in the water and he was helping it, but I thought they couldn’t swim and he’d just killed the poor turtle. I have continued to think he’d killed the poor turtle until just now, when I learned they can swim, and I can’t even tell you how relieved I am. Anyway, eastern box turtles have a domed shell, yes, and stumpy club-like front legs, but their hind legs are less like elephant legs than regular turtle legs. Since box turtles can live to be 100 years old, it’s possible that that one is alive and well even now.

Riley also wants everyone to know not to take a turtle from the woods, which is a very good rule to live by. In fact, it’s important not to take any wild animals from the woods no matter how cute they are. To continue our example, eastern box turtles have small territories that they defend from other box turtles. If you take the turtle out of its territory even for just a few days, when you return it to the woods, another turtle may have already taken over and will chase it away. Turtles don’t travel very fast and are vulnerable to being hit by cars and eaten by lots of different predators, so without a safe territory where it can hide and find food, it can die very quickly.

One of the turtles Leo suggested we learn about was the bog turtle. It’s the smallest turtle in North America, with a carapace barely four inches long, or 10 cm. It lives in a few parts of the eastern United States, and likes marshy areas with slightly acidic water. It spends a lot of time in the water, but also plenty of time on land. It eats worms, slugs, snails, water plants, berries, insects, and even small frogs when it can catch them.

The bog turtle is so small that pretty much anything big enough to swallow it will eat it. Its main defense is to bury itself in soft mud and hide. It’s almost completely black or dark gray in color, but it does have a bright orange spot on each side of its neck.

The bog turtle is critically endangered due to habitat loss, pollution, and poaching for the illegal pet trade. Conservationists are working to improve its habitat, and in the meantime some zoos and aquariums are helping with a captive breeding program. Since a bog turtle isn’t old enough to lay eggs until it’s at least 8 years old, the species as a whole reproduces slowly.

Leo also suggested hawksbill and leatherback turtles, and Elizabeth wants to learn about sea turtles in general. We talked about sea turtles way back in episode 75, so it’s definitely time to revisit the topic.

Seven species of sea turtle are alive today, and you can tell they’re turtles and not tortoises because they have streamlined shells and flippers instead of feet. They migrate long distances to lay eggs, thousands of miles for some species and populations, and usually return to the same beach where they were hatched. Female sea turtles come ashore to lay their eggs in sand, but the males of most species never come ashore. The exception is the green sea turtle, which sometimes comes ashore just to bask in the sun. Once the babies hatch, they head to the sea and take off, swimming far past the continental shelf where there are fewer predators. They live around rafts of floating seaweed call sargassum, which protects them and attracts the tiny prey they eat.

Six of the extant sea turtles are relatively small. Not small compared to regular turtles, small compared to the seventh living sea turtle, the leatherback. It’s much bigger than the others and not very closely related to them. It can grow some nine feet long, or 3 meters, and instead of having a hard shell like other sea turtles, its carapace is covered with tough, leathery skin studded with tiny osteoderms. Seven raised ridges on the carapace run from head to tail and make the turtle more stable in the water, a good thing because leatherbacks migrate thousands of miles every year. Not only is the leatherback the biggest and heaviest turtle alive today by far, it’s the heaviest living reptile that isn’t a crocodile. It has huge front flippers, is much more streamlined even than other sea turtles, and has a number of adaptations to life in the open ocean.

The leatherback lives throughout the world, from warm tropical oceans up into the Arctic Circle. It mostly eats jellyfish, so it goes where the jellyfish go, which is everywhere. It also eats other soft-bodied animals like squid. To help it swallow slippery, soft food when it doesn’t have the crushing plates that other sea turtles have, the leatherback’s throat is full of backwards-pointing spines. What goes down will not come back up, which is great when the turtle swallows a jellyfish, not so great when it swallows a plastic bag. It’s endangered due to pollution, accidental drowning when it gets caught in fishing nets, and habitat loss of its nesting beaches.

The hawksbill, or hawkbill sea turtle grows to a much more reasonable size, around three feet long, or 90 cm, and mostly lives around tropical reefs. It has a more pointed, hooked beak than other sea turtles, sort of like a hawk, which gives it its name. You might think it eats fish with a beak like that, but it mostly eats jellyfish and sea sponges. It especially likes the sea sponges, some of which are lethally toxic to most other animals. It also doesn’t have a problem eating even extremely stingy jellies and jelly-like animals like the Portuguese man-o-war. The hawkbill’s head is armored so the stings don’t bother it, although it does close its eyes while it chomps down on jellies. Its meat can be toxic due to the toxins it ingests. People used to kill hawksbill sea turtles for their multicolored shells, but these days it’s a protected species like all sea turtles.

The hawksbill is also biofluorescent! Researchers only found this out by accident in 2015, when a team studying biofluorescent animals in the Solomon Islands saw and filmed a hawksbill glowing like a UFO with neon green and red light. So you never know what other secrets sea turtles might be hiding.

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

Thanks for listening!

Episode 075: Archelon and Other Giant Sea Turtles

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This week we’re going to find out about the biggest turtles that ever lived! Spoiler: one of them is alive right now, swimming around eating jellyfish.

A green sea turtle. These guys are adorable:

A hawkbill glowing like a neon sign!

The majestic and enormous leatherback:

Bebe leatherback. LET ME GOW

Seriously, how are baby sea turtles so darn cute?

Archelon was a big tortle:

Further reading:

This is a link to a pdf of that “Historicity of Sea Turtles Misidentified as Sea Monsters” article

Show transcript:

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

This week we’re back in the sea, but not the deep sea this time, because we’re looking at marine turtles!

The oldest known turtle ancestor lived around 220 million years ago, but it wouldn’t have looked a whole lot like a modern turtle. For one thing, it had teeth instead of a bill. It resembled a lizard with wide ribs that protected its belly. It lived in the ocean, probably in shallow inlets and bays, but it may have also spent part of its time on land. Some researchers think it may have had at least a partial shell formed from extensions of its backbone, but that this didn’t fossilize in the three specimens we have.

The oldest sea turtle fossil found so far has been dated to 120 million years old. It was seven feet long, or 2 meters, and already showed a lot of the adaptations that modern sea turtles have. Researchers think it was closely related to the green sea turtle and the hawksbill sea turtle.

Seven species of sea turtle are alive today. They all have streamlined shells and flippers instead of feet. They all breathe air, but they have big lungs and can stay underwater for a long time, up to about an hour while hunting, several hours when asleep or resting. Like whales, they surface and empty their lungs, then take one huge breath. They can see well underwater but can probably only hear low-frequency sounds.

Sea turtles have a special tear gland that produces tears with high salt concentration, to release excess salt from the body that comes from swallowing sea water. They migrate long distances to lay eggs, thousands of miles for some species and populations, and usually return to the same beach where they were hatched. Female sea turtles come ashore to lay their eggs in sand, but the males of most species never come ashore. The exception is the green sea turtle, which sometimes comes ashore just to bask in the sun. Once the babies hatch, they head to the sea and take off, swimming far past the continental shelf where there are fewer predators. They live around rafts of floating seaweed call sargassum, which protects them and attracts the tiny prey they eat.

Six of the extant sea turtles are relatively small. Not small compared to regular turtles, small compared to the seventh living sea turtle, the leatherback. More about that one in a minute. The other six are the green, loggerhead, hawksbill, Kemp’s ridley and Olive ridley, and the flatback.

Let’s start with the green sea turtle, since I just mentioned it. Its shell is not always green. It can be brown or even black depending on where it spends most of its life. Green turtles that live in colder areas of the Pacific have darker shells, which probably helps them stay warm by absorbing more heat from sunlight. Young turtles have darker shells than old turtles for the same reason.

The green sea turtle can grow up to five feet long, or 1.5 meters, can live some 80 years, and mostly eats plants, especially seagrass, although babies eat small animals like worms, jellyfish, and fish eggs. A recent satellite tracking study of green sea turtles in the Indian Ocean tracked the turtles to a huge underwater seagrass meadow that no human realized existed until then. The meadows were farther underwater than the ones researchers knew about, up to 95 feet deep, or 29 meters. Researchers think the seagrass can grow at these depths because the water is so clear in the area, which means more light for the plants.

Unlike the green sea turtle, which lives throughout much of the world’s oceans, the flatback sea turtle is only found around Australia. It’s greenish or grayish and only grows around 3 feet long, or 95 cm, and eats invertebrates of various kinds, including jellyfish, shrimp, and sea cucumbers. It stays near shore in shallow water and doesn’t migrate, so it’s mostly safe from getting tangled in commercial fishing nets that kill a lot of other sea turtle species.

The smallest sea turtle is the olive ridley, which only grows around two feet long, or 60 cm. Its shell is roughly heart-shaped and is usually olive green. It mostly lives in tropical waters and is the most common sea turtle of all the living species, but getting rarer. It likes warm, shallow water and eats small animals like snails, jellyfish, and sea urchins.

Kemp’s ridley sea turtle is closely related to the olive ridley, and is not much larger. It grows to around 28 inches long, or 70 cm, and eats the same things as the olive ridley. It also likes the same warm, shallow waters, but it nests exclusively along the Gulf Coast of North America. Oil spills in the Gulf have killed so many turtles that the species is now listed as critically endangered. Conservationists sometimes remove eggs to safer, cleaner beaches where babies are more likely to hatch and survive. Besides oil spills and other types of pollution, Kemp’s ridley sea turtles are often killed when they get tangled in shrimp nets and drown. Fortunately, shrimp trawlers in the Gulf now use turtle excluders, which help keep turtles from getting tangled.

The hawksbill sea turtle grows to around three feet long, or 1 meter, and lives around tropical reefs. It has a more pointed, hooked beak than other sea turtles, which gives it its name. You might think it eats fish or something with a beak like that, but mostly it eats jellyfish and sea sponges. It especially likes the sea sponges, some of which are lethally toxic to most other animals. It also doesn’t have a problem eating even extremely stingy jellies and jelly-like animals like the Portuguese man-o-war. The hawkbill’s head is armored so the stings don’t bother it, although it does close its eyes while it chomps down on jellies. People used to kill hawksbill sea turtles for their multicolored shells, but don’t eat them. Its meat can be toxic due to the toxins it ingests.

The hawksbill is also biofluorescent! Researchers only found this out by accident in 2015, when a team studying biofluorescent animals in the Solomon Islands saw and filmed a hawksbill glowing like a UFO with neon green and red light. Researchers still don’t know why and how the hawksbill glows. They think the red color may be emitted by certain algae that grow on hawksbill shells, but the green appears to be emitted by the turtle itself. Since the hawksbill lives mostly around coral reefs, where many animals biofluoresce, researchers hypothesize it might be a way for the turtle to blend in. If everyone’s glowing, the big turtle-shaped spot that isn’t glowing would give it away. Then again, since male turtles glow more brightly than females, researchers also think it may be a way to attract mates.

Finally, the loggerhead sea turtle grows to a little longer than three feet, or 95 cm, and its shell is usually reddish-brown. It lives throughout the world’s oceans and while it nests in a lot of places, many loggerheads lay their eggs on Florida beaches. It eats invertebrates like bivalves and sponges, barnacles and jellyfish, starfish, plants, and lots of other things, including baby turtles. Its jaws are powerful and it has scales on its front flippers that stick out a little, called pseudoclaws, which allow it to manipulate its food or tear it into smaller pieces.

All sea turtles are endangered and are protected worldwide, although some countries enforce the protection more than others. Some people still eat sea turtles and their eggs, even though both can contain bacteria and toxic metals that make people sick. But mostly it’s habitat loss, pollution, and fishing nets and longlines that kill turtles.

People want to build houses on the beach, or drive their cars on the beach, and that destroys the habitat female turtles need to lay their eggs. Turtles also get stuck in fishing equipment and drown. And there’s so much plastic floating around in the sea that all sorts of animals are affected, not just turtles. A floating plastic bag or popped balloon looks like a jellyfish to a sea turtle that doesn’t know what plastic is. A turtle can eat so much plastic that its digestive system becomes clogged and it dies. One easy way you can help is to remember your reusable bag when you go shopping. The fewer plastic bags that are made and used, the fewer will find their way into the ocean. Some countries have banned plastic shopping bags completely.

Now let’s talk about the leatherback turtle. It’s much bigger than the others and not very closely related to them. It can grow some nine feet long, or 3 meters, and instead of having a hard shell like other sea turtles, its carapace is covered with tough, leathery skin studded with tiny osteoderms. Seven raised ridges on the carapace run from head to tail and make the turtle more stable in the water, a good thing because leatherbacks migrate thousands of miles every year. Not only is the leatherback the biggest and heaviest turtle alive today by far, it’s the heaviest living reptile that isn’t a crocodile. It has huge front flippers, is much more streamlined even than other sea turtles, and has a number of interesting adaptations to life in the open ocean.

The leatherback lives throughout the world, from warm tropical oceans up into the Arctic Circle. It mostly eats jellyfish, so it goes where the jellyfish go, which is everywhere. It also eats other soft-bodied animals like squid. To help it swallow slippery, soft food when it doesn’t have the crushing plates that other sea turtles have, the leatherback’s throat is full of backwards-pointing spines. What goes down, will not come back up, which is great when the turtle swallows a jellyfish, not so great when it swallows a plastic bag.

The leatherback can dive as deep as 4,200 feet, or almost 1,300 meters. Even most whales don’t dive that deep. But it’s a reptile, so how does it manage to survive in such cold water, whether in the Arctic Ocean or nearly a mile below the water’s surface?

The leatherback’s metabolic rate is high to start with, and it swims almost constantly. Its muscles generate heat as they work, which keeps the turtle’s body warmer than the surrounding water, as much as 30 degrees Fahrenheit warmer, or 18 degrees Celsius. Its flippers and throat also use a system called countercurrent heat exchange, where blood that has been chilled by outside temperatures returns to the heart in veins that surround arteries containing warm blood flowing from the heart. By the time the cool blood reaches the heart, it’s been warmed by the arterial blood. This keeps heat inside the body’s core.

Unlike other sea turtle species, leatherbacks don’t necessarily return to the same beach where they were hatched to lay their eggs. Females usually nest every two or three years and lay about 100 eggs per nest. No one is sure how long leatherbacks live, but it may be a very long time. Most turtles have long lifespans, and many sea turtle species don’t even reach maturity until they’re a couple of decades old.

One interesting thing about sea turtles, which is also true of many other reptiles, is that the temperature of the egg determines whether the baby turtle will develop into a male or female. Cooler temperatures produce mostly male babies, warmer temperatures produce mostly female babies. This is pretty neat, until you remember that the global temperature is creeping up. A new study of sea turtles around Australia’s northern Great Barrier Reef found that almost all baby turtles hatching there are now female—up to 99.1% of all babies hatched. Another study found the same results in sea turtle nests in Florida, where 97 to 100% of all babies are female. The studies also found that the amount of water in the nest’s sand also contributes to whether babies are male or female, with drier nests producing more females. Researchers are considering incubating some nests in climate-controlled rookeries to ensure that enough males hatch and survive to produce the next generation.

So those are the seven types of sea turtle alive today. Now let’s talk about an extinct sea turtle, a relative of the leatherback. This is archelon, and it was huge.

Archelon was the biggest turtle that has ever lived, as far as we know. The first fossil archelon was discovered in 1895 in South Dakota, in rocks that were around 75 million years old. The biggest archelon fossil ever found came from the same area, and measures 13 feet long, or 4 meters. It’s even broader from flipper to flipper, some 16 feet wide, or 5 meters. It lived in the shallow sea that covered central North America during the Cretaceous, called the Western Interior Seaway. I like that name. Its shell was leathery and probably flexible like the leatherback’s, but unlike the leatherback, it wasn’t teardrop shaped. In fact, it was very round. Since it lived at the same time as mosasaurs, its wide shell may have kept it from being swallowed by predators. It probably ate squid and jellyfish like the leatherback, and researchers think it was probably a slow swimmer. It went extinct at the same time as the dinosaurs, but fortunately its smaller relations survived.

We don’t know if that 13-foot-long archelon was an unusually large specimen, an average specimen, or a small specimen. It was probably on the large size, but it’s a good bet that there were larger individuals swimming around 75 million years ago. We don’t know if leatherbacks occasionally get bigger than nine feet long, for that matter. But we do have reports of sea turtles that are much, much bigger than any sea turtles known.

In August of 2008, a 14-year-old boy snorkeling in Hawaii reported swimming above a sea turtle that was resting on the bottom of a lagoon. He estimated the turtle was eight to ten feet across with a round shell. At the time he didn’t realize that was unusual. He also reported seeing a geometric pattern on the shell, which is not a feature of the leatherback or archelon but is present in other sea turtles. So if his estimation of size is correct, he saw a sea turtle far bigger than any living today.

In 1833, a schooner off the coast of Newfoundland came across what they thought was an overturned boat. When the crew investigated, they discovered it wasn’t a boat at all but an enormous leatherback turtle, which they reported was 40 feet long, or 12 meters.

Many sea serpent sightings may actually be misidentifications of sea turtles. Sea turtles do have relatively long necks which they can and do raise out of the water. A long neck with a small head sticking out of the water, with a hump behind it, describes a lot of sea serpent reports. It’s also possible that some sea serpent reports are actually sightings of sea turtles entangled with fishing nets and other debris that the turtle drags with it as it swims, which may look like a long snake-like tail behind a humped body.

For instance, in 1934 some fishermen off the coast of Queensland, Australia spotted what they thought was a sea serpent. I’ll quote the description, which is from an article with the lengthy title of “Historicity of Sea Turtles Misidentified as Sea Monsters: A Case for the Early Entanglement of Marine Chelonians in Pre-plastic Fishing Nets and Maritime Debris” by Robert France. I’ll put a link in the show notes in case you want to read the article, if I can find it again. I printed it out so I could keep it.

Anyway, the fishermen reported that the sea serpent looked like this:

“The head rose about eight feet out of the water, and resembled a huge turtle’s head…the colour was greyish-green. The eye…was small in comparison to the rest of the monster. The other part in view was three curved humps about 20 feet apart, and each one rose from six feet in the front to a little less in the rear. They were covered with huge scales about the size of saucers, and also covered in barnacles. We could not get a glimpse of the tail, as it was under the water.”

Robert France suggests that this was a sea turtle entangled with a string of fishing gear, specifically fishing floats. He also gives a number of other examples dating back hundreds of years. Fortunately for sea turtles and other animals in the olden days, most fishing nets were made from rope, usually hemp and sometimes cotton, which eventually rotted and freed the animal, if it survived being entangled for months on end.

So if you live around the ocean, or any kind of water for that matter, make sure to pick up any litter you find, especially plastic bags. You could save a lot of lives. Who knows, maybe the sea turtle you save from eating that one fatal plastic bag will grow up to become the biggest sea turtle alive.

As a companion piece to this episode, Patreon subscribers got an episode about the Soay Island Sea Monster sighted in 1959, which was probably a sea turtle of some kind. Just saying.

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

Thanks for listening!