Category Archives: sharks

Episode 137: The Orca, Jolly Terror of the Seas

Thanks to Pranav for this week’s topic, the orca or killer whale!

Further reading:

Save Our Seas Magazine (I took the Jaws art below from here too)

An orca:

Orcas got teeth:

Starboard and Port amiright:

Show transcript:

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

This week let’s return to the sea for a topic suggested by Pranav, the orca. That’s the same animal that’s sometimes called the killer whale. While it is a cetacean, it’s more closely related to dolphins than whales and is actually considered a dolphin although it’s much bigger than other dolphin species.

The orca grows up to 26 feet long, or 8 meters, and is mostly black with bright white patches. The male has a large dorsal fin that can be 6 feet tall, or 1.8 meters, while females have much shorter dorsal fins that tend to curve backwards more than males’ do. Some orcas have lighter coloring, gray instead of black or with gray patches within the black.

The orca lives throughout the world’s oceans although it especially likes cold water. It eats fish, penguins and other birds, sea turtles, seals and sea lions, and pretty much anything else it can catch.

Everything about the orca is designed for strength and predatory skill. It has good vision, hearing, sense of touch, and echolocation abilities. It’s also extremely social, living in pairs or groups and frequently hunting cooperatively.

Some populations of orca live in the same area their whole lives, traveling along the same coastline as they hunt fish. These are called resident orcas and they’re closely studied since researchers can tell individuals apart by their unique markings, so can keep track of what individuals are doing.

Other populations are called transient because they travel much more widely. Transient and resident orcas avoid each other, so they may be separate species or subspecies, although researchers haven’t determined whether this is the case yet. There’s even a newly discovered population of orcas found off the tip of South America that may be a new species. Researchers are analyzing DNA samples taken from the South American orcas with little darts. Fishers had reported seeing odd-looking small orcas in the area for over a decade, but recent photos taken by tourists gave researchers a better idea of what they were looking for. The new orcas have rounder heads and different spotting patterns than other orca populations.

Transient orcas eat more mammals than resident orcas do. Resident orcas mostly eat fish. They have clever ways of catching certain fish, too. A pod of orcas can herd herring and some other fish species by releasing bubbles from their blowholes, which frighten the fish away. A group of orcas releasing bubbles in tandem can make the school of fish form a big ball for protection. Then each orca slaps the ball with its tail. This stuns or even kills some of the fish, which the orca then eats easily. Pretty clever. An orca may also stun larger fish by smacking it with its powerful tail flukes.

But the orca is also good at catching seals and sea lions. Some orcas learn to beach themselves safely when chasing seals, since the seal will often try to escape onto land. Another hunting technique is called wave-hunting, where a group of orcas swim in a way that causes waves to slop over an ice floe. Any animal or bird resting on the ice floe is washed into the water.

Because transient orcas mostly hunt mammals that can hear the orcas’ echolocation clicks and other vocalizations, they tend to stay silent while hunting so they don’t alert their prey. Resident orcas don’t have to worry about noise as much, since most of the fish they eat either can’t hear or their calls or don’t react to them. Resident orcas are much more vocal than transient orcas as a result.

But all orcas have calls they use socially. These are calls that help members of the pod stay in contact, help them coordinate hunting activities, and identify themselves to members of other pods. A pod is usually made up of several family groups, usually ones that are related in some way. You know, like the orca equivalent of an extended family—you and your mom and siblings, maybe your dad, and your mom’s sister and her babies, and so on. Each pod has its own dialect, with their own calls not heard in other pods.

Orcas are also incredibly intelligent and show social traits that match those of humans and chimpanzees, like playfulness, cooperation, and protectiveness. Their social structure is also complex and similar in many ways to those of humans and other great apes. As you may remember from episode 134 about the magpie, complex social structures lead to intelligence in individuals. Individual orcas have what’s known as signature whistles, a unique vocalization that only applies to that one orca. In other words, orcas have names. Researchers have also identified signature whistles in other dolphin species.

Because orcas are so large, so social, so intelligent, and travel such enormous distances every day—up to 50 miles, or 80 km—it doesn’t make any sense to keep them in captivity. But there are a lot of orcas in captivity. In the last decade or so people have started to realize that maybe this is not good for the orcas. Captive orcas develop mental and physical problems that they don’t have in the wild, including bad teeth. A 2017 study of captive orcas found that all of them had tooth problems and more than 65% of them had teeth so worn that the tooth pulp was exposed. That’s the sensitive part of your tooth, so you can imagine the agony this must cause the orca. It’s so bad that over 61% of the orcas studied had had the pulp removed from some of their teeth, which at least stops the pain but which leaves the orca more prone to infection and disease, plus weakens the tooth and can lead to it cracking. Such awful tooth problems mostly result from the orca chewing on concrete and steel in its tank, and this kind of chewing is due to extreme anxiety and other mental problems due to captivity. It’s not seen in orcas in the wild at all. So no, there shouldn’t be any orcas in captivity, or any other cetaceans, unless it’s for rehabilitation purposes with the goal of releasing the orca back into the wild after it’s healthy again.

The orca can live to be at least 90 years old, possibly older. Females especially live much longer than males overall. Female orcas lose the ability to have babies after about age 40 and enter a stage of life called menopause. Humans do this too, and studies show that it’s for the same reasons. Older females help younger females care for their children, and they’re also group leaders who teach younger orcas where to find food and how to catch it.

The orca is an apex predator, meaning there is nothing in the wild that hunts and eats it. Even the great white shark. On average the orca is larger than the great white, and it has an advantage because it hunts cooperatively. Where there are orcas around, there are usually not any great white sharks. This is partly because the two species eat the same thing and the orca out-competes the shark, but it’s also because the orca can and will eat great white sharks.

Some orcas have figured out that they can turn a shark upside down and keep it there in order to hypnotize it. This is called tonic immobility and researchers aren’t entirely sure why it happens, but the shark remains immobile until it wears off after a few minutes. It doesn’t work in all shark species or for every shark, but it makes the shark a lot easier for the orca to kill since it can’t fight back. In 1997 witnesses saw an orca hold a great white upside down for 15 minutes, trying to hypnotize it. It didn’t work, but since sharks have to keep moving to breathe, since they can’t pump water through their gills otherwise, the shark in question actually suffocated and the orca ate it.

But a pair of orcas have taken predation of great white sharks to a whole new level.

The phenomenon was first spotted in 1997 off the coast of San Francisco in western North America. People in a whale-watching tour saw two orcas attack a great white shark and eat its liver. Just its liver. They knew exactly where the liver was and aimed for it during the attack. A great white’s liver is huge and full of yummy fat.

Later that year, researchers studying elephant seals in the area noticed that all the great white sharks that usually preyed on seal colonies had vanished. They’d actually moved out of the area instead of staying to eat the seals. Studies of tagged great whites determined that they avoided orcas to the point of migrating away from feeding sites entirely if orcas were around.

Twenty years later, a marine biologist in South Africa named Alison Kock studied a pair of orcas named Starboard and Port who were attacking sharks the same way and eating their livers. Initially they targeted sevengill sharks, which can grow up to ten feet long, or 3 meters. But all the sevengill sharks fled and in 2017 the carcasses of great white sharks started to wash ashore with their livers eaten. Dr. Kock was pretty sure Starboard and Port were the culprits. When she studied the dead sharks, she recognized tooth marks from orcas.

Remember how earlier I said there were two types of orcas known, the residential and the transient groups? Plus the newly discovered group? Well, there’s actually a fourth group called the offshore orca. These are populations of orcas that live farther away from shore than most other groups. They travel widely and are the only orcas known in the wild to have teeth that are worn down flat almost like the captive orcas. Researchers think the offshore orcas specialize in hunting sharks and their relatives, and that the tooth wear comes from the sharks’ rough skin. Unlike the captive sharks, the tooth wear doesn’t affect the orcas’ overall health. Studies of offshore orcas have determined that more than 93% of their diet is made up of sharks.

Starboard and Port are now mostly after the bronze whaler shark, which grows up to 11 feet long, or 3.3 meters. No shark is safe.

You can find Strange Animals Podcast online at That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at We also have a Patreon if you’d like to support us that way.

Thanks for listening!

Episode 130: Strangest Small Fish

This week we’re going to revisit a suggestion from Damian and follow up on episode 96, our strangest big fish episode. This time let’s find out about some weird small fish!

The teeny, newly-discovered American pocket shark:

The brownsnout spookfish wears its mirror sunglasses on the INSIDE:

The goblinfish with a dangerous head and basically a dangerous everything else too:

Two teeny pygmy seahorses. Can you spot them? Hint: they’re the ones with eyes.

The razorfish. Just another sea urchin spine, no fish to see here:

The much-maligned candiru:

The red-lipped batfish:

Gimme kiss:

Show transcript:

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

Ages ago, Damian suggested an episode about weird fish. We covered some weird big fish in episode 96, but now it’s time for some weird little fish.

So, think about sharks for a second. Big, scary, sharp teeth, fast swimmers, black eyes of a pitiless killer of the deep.

But have you perhaps considered that maybe the world needs a very small shark? One that actually kind of looks like a tiny whale? Like, a tiny shark, only about 5 ½ inches long, or 14 cm. Almost, you know, pocket sized. Oh, and it should glow in the dark.

That’s the American pocket shark, a real animal that was only discovered in 2010! It’s called a pocket shark not because it’s pocket sized, although it is, but because it has a sort of pocket on each side near its gills that produces luminous fluid. Researchers aren’t sure whether the shark uses the fluid for attracting prey or avoiding predators. Maybe both. Its head is bulbous and rounded, which kind of makes it look like a tiny whale.

The American pocket shark was discovered in the Gulf of Mexico while scientists were observing sperm whales and tracking them with sonar. When a whale surfaced from a dive, the research team dropped nets to the depth the whale had dived to, hoping to catch the same kind of prey the whales were eating. And one of the things they found in the net was a tiny shark new to science, found at a depth of 3,000 feet, or 914 meters.

In 2013 the tiny shark, which had been frozen for later study, was finally examined. The expert who looked at it had only seen one other shark like it before, a shark discovered in the eastern Pacific in 1979. But this tiny shark had some differences from that tiny shark, and after examining both specimens carefully, they’ve been classified as different species.

So that’s a cute start, but it’s still just a rare little shark that glows. Not really that unusual, right? Let’s look at a really weird fish next. Like, seriously weird.

It’s called the brownsnout spookfish, which is a really terrible name, but it’s not a terrible fish. I mean, it couldn’t hurt you. It grows about 7 inches long, or 18 cm, and eats copepods and other tiny crustaceans. Its snout is long and kind of pointy, its body is slender, and it has elongated pelvic fins. Because it lives in the deep sea, it has eyes that point upward, which help it see predators and prey that might be silhouetted against the far-distant surface of the ocean. But it also has something only one other fish is known to have, an extra structure to the side of the eyeball. It’s called a diverticulum and it does two things. First, it allows the fish to see downward in addition to upward, and second, it allows it to see across a really wide angle. The diverticulum does this because it contains a mirror that reflects light from the main eyeball onto the retina of the diverticulum. A MIRROR IN ITS EYEBALLS. The mirror is made up of tiny crystalline plates.

Some invertebrates like clams and crustaceans contain reflectors in their eyes, but except for the brownsnout spookfish, the only other vertebrate known to have mirrored eyeballs is the glasshead barreleye. Also a terrible name. The glasshead barreleye is a little smaller than the brownsnout spookfish, and not surprisingly, they’re related. But surprisingly, they’re not that closely related and the mirrored diverticulum appears to have evolved independently in each species.

Although the fish has been known to science for over a century, no one realized it had mirrors in its eyes until 2008 when a live one was caught by a deep-sea scientific expedition off the island of Tonga in the Pacific Ocean. Researchers took pictures of the brownsnout spookfish and got a shock when they looked at the photos. The upward-pointing parts of the eye reflected light normally, the typical eyeshine you get when you use a flash to photograph most animals. But the lower parts of the eyes reflected bright light. Researchers think the fish uses its downward-pointing eyes to see the faint bioluminescent flashes of its prey, while the upward-pointing eyes watch for predators approaching from above.

Oh, and I forgot to mention. The brownsnout spookfish is mostly transparent. You can see right through it. Yeah.

After that, the goblinfish that lives around reefs off the southern coast of Australia seems practically normal. It grows up to 8 inches long, or 20 cm, and spends most of its time resting among rocks on the seabed. It hunts at night, eating small crustaceans, and instead of swimming it usually walks along the sea floor with its large pectoral fins.

The goblinfish gets its name from its appearance, which is frankly ugly unless you are another goblinfish. Its head looks sort of turtle-like, including a dip in its body behind its eyes and in front of its dorsal fin that looks like a turtle’s neck. Its eyes are large and orange in color. Its dorsal fin is spiny and runs most of the length of its back. It also has broad pectoral fins that it sometimes spreads like fans. It can change color to blend in with the rocks around it, which makes it hard for divers to see, which is too bad because it’s also venomous.

It’s a type of waspfish, related to scorpionfish and stonefish, all of which are venomous. Like many of those other fish, the goblinfish has venomous spines on its fins, but it also has a spine on each side of its head, underneath its eyes. Only these spines are hidden inside the fish’s head. The spine is called a lachrymal saber, and it acts like a switchblade that the fish can extend with its cheek muscles. The lachrymal saber isn’t venomous, but if you’ve just picked one up by the head and those switchblades come out, you probably aren’t going to be happy anyway. Also, why did you just pick that fish up by its head? What is wrong with you?

Next, let’s talk about the seahorse. It’s a fish although it doesn’t look like an ordinary fish. And in fact nothing about the seahorse is ordinary.

Unlike most fish, the seahorse has a flexible neck. Also unlike almost all other fish it swims vertically, with its head up and its tail down. It has a prehensile tail made up of 36 bony segments, and each segments is made of four pieces connected by tiny joints. The joints make the segments incredibly strong and able to withstand considerable pressure without breaking. The seahorse uses its tail to hold onto seaweed or other items to keep from being swept away in currents, since it isn’t a strong swimmer. It propels itself through the water by fluttering its dorsal fin, using its pectoral fins to steer. Males also fight each other by tail-wrestling and bopping their heads together. The seahorse’s body is protected with an external skeleton of bony plates, which take the place of ribs. The seahorse doesn’t have ribs. It also doesn’t have scales, just the bony plates with thin skin over them.

The seahorse lives in warm, shallow oceans throughout the world, especially in coral reefs and seagrass beds where there’s plenty of cover. The largest seahorse species grow to about 14 inches long, or 35 cm. The smallest species are barely more than half an inch long, or 15 mm. The smallest species are mostly new to science since they’re so hard to find and identify. Seahorses are well camouflaged to blend in with the plants and coral they live in.

The seahorse’s mouth is at the end of a long, tubelike snout, and it actually sucks its prey into its snout like a straw. It eats small crustaceans, larval fish, and other small animals. Oh, and its eyes can move independently of each other.

Seahorses don’t mate for life, but they do form bonds that last throughout the breeding season, and it has a long courtship period while the female develops her eggs. The pair participate in courtship dances and spend most of their time together. When the eggs are ready, the female deposits them in a special brood pouch in the male’s belly, where he fertilizes them. They then embed themselves in the spongy wall of the brood pouch and are nourished not only by the yolk sacs in the eggs, but by the male, who secretes nutrients in the brood pouch. So basically the male is pregnant. The female visits him every day to check on him, usually in the mornings. When the eggs hatch after a few weeks, the male expels the babies from his pouch and they swim away, because when they hatch they are perfectly formed teeny-tiny miniature seahorses.

If you’re wondering why I said the seahorse is almost the only fish that swims vertically, there’s some evidence that the oarfish does this too. We talked about the oarfish way back in episode 6, about sea monsters. But there’s another fish that swims vertically, the razorfish—but it swims with its head pointed down and its tail pointed up. It’s a slender fish that grows about six inches long, or 15 cm, with a pointy nose and tiny fins. Its back is protected by bony plates that extend past the tail fin in a spine. It eats tiny animals, including brine shrimp, AKA sea monkeys. When it feels threatened, the razorfish swims to the nearest sea urchin and hides among its spines, blending in with them. Schools of razorfish will swim around together, all of them head-down, because that’s just what they do.

Not all weird fish live in the ocean. A lot of freshwater fish are weird too. For instance, the candiru [kan-DEE-roo]. You’ve probably heard of this one although you may not know what it’s called. It’s native to the Amazon and Orinoco Rivers in South America and it’s actually a type of catfish. Some species grow over a foot long, or around 40 cm, but the species we’re talking about today, Vandellia cirrhosa, grows less than two inches long, or 5 cm. Like the brownsnout spookfish, it’s mostly translucent so it’s hard to see in the water. It has short spines on its gill covers that point backwards.

Unlike other catfish, the candiru eats blood, which gives it its other name of the vampire fish. It parasitizes other fish by lodging itself in their gills and sucking their blood. But the candiru is supposed to do something else, something that happens by accident. The story goes that if someone pees while in the water and a candiru is around, it’ll swim up the stream of urine, attracted by the smell, and lodge itself in the urethra of the person peeing. It’s supposed to do this thinking it’s entering the gills of a fish. Its spines keep it locked in place, causing intense pain to the person, followed by infection and, if the fish isn’t surgically removed, death.

At least, that’s the story. There’s even a 1997 video of a man who had to have a candiru removed from his penis after he peed while wading in a river in Brazil. The doctor filmed the surgery and even kept the fish he removed, preserved in formaldehyde. So it must be true, right?

Maybe not. One study determined that the candiru isn’t interested in the chemicals present in urine and in fact it hunts by sight, not smell. And a study of medical reports throughout South America only found a single instance of anyone reporting a candiru attack. That instance is the same one from 1997 where the surgery to remove the fish was filmed.

But a further study of the surgery, photos, and preserved candiru specimen tell a different story. The human urethra is extremely narrow and the preserved fish was much too large to enter without squishing itself to death, not to mention that the candiru is just not strong enough to muscle its way into anything but a larger fish’s gills. The doctor also said he’d had to cut off the candiru’s spines before removing it, but the specimen is fully intact, spines and all. It sounds like the video may be a hoax of some kind.

Reports of candiru attacks are common in parts of South America today and have been common as far back as recorded history, but they seem to be more of a legend than something that happens a lot or maybe even at all. Still, probably better not to pee into the Amazon River, just in case.

Let’s finish with the red-lipped batfish, a type of anglerfish only found around the Galapagos Islands in the Pacific Ocean. It lives on the ocean floor where the water is fairly shallow, and it grows about 8 inches long, or 20 cm. It’s usually a mottled brown, green, or grey with a white stomach, but its mouth is bright red. It looks like it’s wearing lipstick. It eats fish and other small animals, which it attracts using a lure on its head, a highly modified dorsal fin called an illicium.

The weirdest thing about the red-lipped batfish is actually its fins. It prefers to walk on the bottom of the ocean instead of swim, and it has modified pectoral fins called pseudolegs. The pseudolegs make it look a little bit like a weird frog with a tail, a unicorn horn, and lipstick. It’s like something out of a fever dream, honestly.

Researchers think the red lips may be a way to attract potential mates, presumably ones who are hoping for a big smooch.

You can find Strange Animals Podcast online at That’s blueberry without any E’s. We’re on Twitter at strangebeasties and have a facebook page at If you have questions, comments, or suggestions for future episodes, email us at We also have a Patreon if you’d like to support us that way.

Thanks for listening!

Episode 122: Strange Shark Ancestors

This week let’s learn about some ancestors of sharks and shark relatives that looked very strange compared to most sharks today!

Stethacanthus fossil and what the living fish might have looked like:

Two Falcatus fossils, female above, male below with his dorsal spine visible:

Xenacanthus looked more like an eel than a shark:

Ptychodus was really big, but not as big as the things that ate it:

A Helicoprion tooth whorl and what a living Helicoprion might have looked like:

Show transcript:

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

This week we’re going back in time again to learn about some animals that are long-extinct…but they’re not land animals. Yes, it’s a weird fish episode, but this one is about shark relatives!

The first shark ancestor is found in the fossil record around 420 million years ago, although since all we have are scales, we don’t know exactly what those fish looked like. The first true shark was called Cladoselache [clay-dough-sell-a-kee] and lived around 370 million years ago, at the same time as dunkleosteus and other massive armored fish. We covered dunkleosteus and other placoderms back in episode 33. Cladoselache grew up to four feet long, or 1.2 meters, and was a fast swimmer. We know Cladoselache ate fish because we have some fossils of Cladoselache with fish fossils in the digestive system—whole fish fossils, which suggests that cladoselache swallowed its prey whole. Cladoselache also had fin spines in front of its dorsal fins that made the fins stronger, but unlike its descendants, it didn’t have denticles in its skin. It didn’t have scales at all.

The denticles in shark skin aren’t just protection for the shark, they also strengthen the skin to allow for the attachment of stronger muscles. That’s why sharks are such fast swimmers.

[Jaws theme]

Stethacanthidae was a family of fish that went extinct around 300 million years ago. It was related to ratfish and their relatives, including sharks. Stethacanthus is the most well-known of the stethacanthidae. It grew a little over 2 feet long, or 70 cm, and was probably a bottom-dwelling fish that lived in shallow waters. It ate crustaceans, small fish, cephalopods, and other small animals.

We have some good fossils of various species of Stethacanthidae and they show one feature that didn’t get passed down to modern ratfish or sharks. That’s the shape of its first dorsal fin, the one that in shark movies cuts through the water just before something awful happens.

[Jaws theme again]

Stethacanthidae’s dorsal fin was really weird. It was shaped sort of like a scrub brush on a pedestal, with the bristles sticking upwards, which is sometimes referred to as a spine-brush complex. Researchers aren’t sure why its fin was shaped in such a way, but since it appears that only males had the oddly shaped fin, it was probably for display. It also had a patch of the same kind of short bristly denticles on its head. Males also had a long spine that grew from each pectoral fin that was probably also for display. Some researchers think the males fought each other by pushing head to head, possibly helped by the odd-shaped dorsal fin.

In the past, before researchers figured out that only the males had the strange dorsal fin, some people suggested that the fish may have used the fin as a sucker pad to attach to other, larger fish and hitch a ride. This is what remoras do. Remoras have a modified dorsal fin that is oval-shaped and acts like a sucker. The oval contains flexible membranes that the remora can raise or lower to create suction. The remora attaches to a larger animal like a shark, a whale, or a turtle and lets the animal carry it around. In return, the remora eats parasites from the host animal’s skin. But remoras aren’t related to sharks.

Other shark relatives had dorsal spines. Falcatus falcatus lived about the same time as Stethacanthus, around 325 million years ago. It grew up to a foot long, or 30 cm, and ate shrimp, fish, and other small animals. We have so many fossils of falcatus from the Bear Gulch Limestone deposits in Montana that we know quite a bit about it. It probably detected prey with electroreceptors on its snout like many modern sharks do, and it was probably a fast swimmer that could dive deeply. Its eyes are unusually large for a shark too. Females would have looked like a small, slender sharklike fish, but males had a spine that grew forward from just behind its head, sort of like a single bull’s horn. It’s called a dorsal spine and is actually a modified dorsal fin. It was probably for display, although males may have also used it to fight each other. We have a well preserved fossil of a pair of falcatus together, a male and female, where it looks like the female may be biting the male’s dorsal spine. Some researchers suggest the spine was used in a pre-mating ritual, but it’s probable that the fish just happened to die next to each other and no one was actually biting anyone.

Another shark relative with a dorsal spine is Hybodus, which grew up to 6 ½ feet long, or 2 meters. Hybodus was a successful genus of cartilaginous fish that lived from around 260 million years ago up to 66 million years ago. Researchers think its dorsal spine was used for defense since both males and females had the spine. Hybodus would have looked like a shark but its mouth was relatively small. It probably ate small fish and squid, catching them with the sharp teeth in the front of its mouth, but it also probably ate a lot of crustaceans and shellfish, which it crushed with the flatter teeth in the rear of its mouth.

Xenacanthus had a dorsal spine too, but it was a much different shark ancestor from the ones we’ve talked about so far. It lived until about 208 million years ago in fresh water. It grew to about three feet long, or one meter, and would have looked more like an eel than a shark. It was slender with an elongated body, and its dorsal fin was short but extended along the back down to the pointed tail. This suggests it probably swam like an eel, since eels have a similar fin structure. It probably ate crustaceans and other small animals.

Xenacanthus’s spine grew from the back of the skull and, unusually for a shark relation, it was made of bone instead of cartilage. Both males and females had the spine and some researchers suggest that it may have been venomous like a sting ray’s tail spine.

Rays are closely related to sharks, and if you want to see a fish that makes every single weird extinct shark look normal, just look at a sawfish. The sawfish is a type of ray and it’s alive today, although it’s endangered. I’m going to do a whole episode on rays pretty soon so I won’t go into detail, but the sawfish isn’t the only fish alive today with a long snout with teeth that stick out on either side. The sawshark is related to the sawfish but is actually a shark, not a ray. And there’s a third type of fish with a saw, related to both sawfish and sawsharks, called the Sclerorhynchidae. Sclerorhynchids went extinct around 55 million years ago and are considered part of the ray family, although they’re not ancestors of living rays. Sclerorhynchids grew around three feet long, or about a meter, and probably looked a lot like modern sawfish although with a rostrum, or snout, that was more pointed and less broad than most sawfish rostrums. The teeth that stuck out to either side were also relatively small. Researchers think Sclerorhynchids used their saws the same way modern sawfish and sawsharks do, to find small animals living on or near the bottom in shallow water and slash them to death before eating the pieces.

[Jaws theme again]

Most of the shark relatives we’ve talked about so far were pretty small, certainly compared to sharks like the great white or megalodon, which by the way we covered in episode 15 along with the hammerhead shark. But a shark called Ptychodus grew up to 33 feet long, or ten meters. It went extinct about 85 million years ago. Its dorsal fin had serrated spines and its mouth had lots and lots of really big teeth–up to 550 teeth, but they weren’t sharp. Instead, they were flattened with riblike folds that helped Ptychodus crush the mollusks it ate. It probably also ate squid and crustaceans, along with any carrion it might come across. It lived at the bottom of the ocean, but in relatively shallow areas where there were plenty of mollusks but not too many mosasaurs or other sharks that might treat Ptychodus as a nice big meal.

In episode 33, the one about dunkleosteus, we also talked about helicoprion and some of its relations. Helicoprion looked like a shark but was actually less closely related to true sharks than to ratfish. Helicoprion lived until about 250 million years ago and some researchers estimate it could grow up to 24 feet long, or 7.5 meters.

Instead of a weird dorsal fin, helicoprion had weird teeth. Weird, weird teeth. It had a tooth whorl instead of the regular arrangement of teeth, where its teeth grew in a spiral that seems to have been situated in the lower jaw. It looked like the blade of a circular saw. Now, this is bizarre but it’s not really all that much more bizarre than sawfish teeth, which aren’t even inside the mouth and stick out sideways. But the frustrating thing for researchers is that we still don’t have any helicoprion fossils except for the teeth whorls and part of one skull. Like most sharks and shark relatives, almost all of helicoprion’s skeleton was made of cartilage, not bone, and cartilage doesn’t fossilize very well. So even though helicoprion was widespread and even survived the Permian-Triassic extinction event, we don’t know what it looked like or what it ate or how exactly its tooth whorl worked. But I think it’s safe to say that it would not be good to be bitten by helicoprion.

[stop playing the Jaws theme omg]

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

Thanks for listening!

[Jaws theme again]

Episode 114: The Depths of the Sea of Cortez

The Gulf of California, AKA the Sea of Cortez, is home to thousands upon thousands of animals, many of them not found anywhere else in the world. New research expeditions in its deep-sea fissures and trenches have turned up some amazing new animals too. Let’s take a look at a few of them!

Thanks to Hally for this week’s topic suggestion!

The lollipop catshark sounds cuter than it is:

The black brotula:

A super creepy grenadier fish. Look at those EYES:

A type of batfish. It uses its stiff fins to walk around on the bottom of the ocean:

Some beautiful hydrothermal chimneys:

Giant tube worms:

Show transcript:

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

It’s been a while since we did a deep-sea episode. This week let’s find out about some strange fish discovered in the Pacific Ocean off the coast of Mexico. Thanks to Hally for the suggestion!

The Gulf of California, also called the Sea of Cortez, is the stretch of water between mainland Mexico and the Baja peninsula. Researchers estimate it started forming over 5 million years ago when tectonic forces separated the strip of land now called Baja peninsula or Baja California from the mainland. It’s still attached to the mainland at its northern edge, where the Colorado River empties into the gulf. The sea is about 700 miles wide, or over 1100 km.

Because the gulf was formed by tectonic forces and undersea volcanos, parts of it are extremely deep—more than 12,500 feet deep in places, or 3,800 meters. It’s full of islands, nearly 1,000 of them, a few of them quite large and some just tiny, some of them volcanic and some not. And it’s rich in ocean life, with many animals found in the Gulf of California that live nowhere else in the world.

For instance, the lollipop catshark! What a cute name. It probably plays ukulele and its best friend plays the xylophone. They should start a band!

The lollipop catshark is actually not super cute, although it is pretty awesome. It’s a small shark, only about 11 inches long, or 28 cm, and it has pinkish gray skin that’s almost gelatinous in texture, although it also has tiny spiky denticles, especially on its back. It gets the name lollipop from its shape. It has a broad head with large gills, but its body tapers to a slender tail so that it’s sort of shaped like a tadpole. Not really lollipop shaped, frankly. Babies are born live instead of hatching from eggs, with a female giving birth to two babies at a time. It eats crustaceans and fish.

The reason the lollipop catshark has such big gills is that it lives at the bottom of the ocean where there’s not much oxygen. The Gulf of California is especially oxygen-poor in its deepest areas, so when a team of scientists sent a submersible to the deepest parts of the gulf in 2015, they didn’t expect to find that many fish or other animals. But not only were there a lot of lollipop catsharks, there were lots of other animals too.

The submersible found the most fish in a part of the gulf called the Carralvo Trough, which is nearly 3,300 feet deep, or 1,000 meters. A few years before, a submersible had discovered the bodies of dozens of dead squid in the trough, and researchers determined that the squid were all females that had laid eggs and then died and sunk to the bottom. The dead squid are usually eaten by scavengers within 24 hours of dying, including crabs and sea stars, brittle stars, and acorn worms, as well as small bottom-dwelling sharks like the lollipop catshark. So it was good timing that the submersible saw so many of them at once.

Another deep-sea animal found in the Gulf of California is the cusk eel. There are lots of species of cusk eel that live throughout the world’s oceans and even some fresh water, and despite the name, cusk eels are fish, not eels. They’re related to cod, although not closely. They live on the bottom of the ocean, usually in shallow water, where they burrow in the sediment and sand at the bottom.

But the cusk eel found in the Carralvo Trough is called the black brotula, and it’s so different from other cusk eels that it has its own genus. The black brotula grows up to 10 inches long, or about 25 cm, and only lives in the depths of the Gulf of California and in some deep areas along the western coast of Mexico and Chile. Not only can it tolerate low-oxygen water, it prefers it. It’s black or dark gray in color–even its intestines are black. And that’s pretty much all we know about it at this point. Cusk eels are generally not very well studied, and the black brotula is hard to study because it lives so deep in the gulf. Researchers don’t even know how it tolerates water with so little oxygen and what it eats down there. We do know that young black brotulas prefer shallower water.

Another deep-sea fish found in the Gulf of California is the grenadier [grin-a-deer]. Grenadiers are some of the most common deep-sea fish in the world, with lots of different species. Some researchers estimate that they may make up as much as 15% of all fish that live in the deep sea. All grendadiers have large heads with big eyes and mouths, slender bodies that taper to such a thin tail that some people call the fish rattail.

The grenadier has barbels under the chin with chemoreceptors on them, and more chemoreceptors on the mouth and head, so it can sense other fish nearby even if it can’t see them. It’s been found as deep as nearly 23,000 feet under the surface, or 7,000 meters, which is just ridiculous. That’s four and a third miles underwater, or seven km. The Gulf of California isn’t that deep, of course, but there are grenadiers swimming around in the deepest areas, eating anything they can catch.

Some grenadiers are eaten, but mostly they have a soft, unpleasant texture and are low in protein. The biggest grenadier, which is common throughout the deep areas of the Pacific Ocean, is the giant grenadier, which can grow to 6 ½ feet long, or 2 meters. It eats vampire squid and other cephalopods. The grenadier most commonly found in the Gulf of California is the smooth grenadier, which only grows to about a foot long, or 30 cm.

A type of batfish that’s common off the western coasts of North, Central, and South America is also found in the deep sea of the Gulf of California. It’s a small type of anglerfish, only about six inches long, or 15 cm, dark in color, with a broad flattened head tapering to a much thinner long tail. Like other anglerfish, it has strong, stiff fins that it uses to crawl around on the ocean floor, where it hunts small animals like polychaete worms and crustaceans as well as fish.

If you look at the pictures I have in the show notes, or if you’ve been paying attention to the descriptions of all these fish, you’ll notice that even though they’re not related, they all share similar features. Their heads are large and usually broad, while their bodies are relatively small with a slender tail. The large head allows the fish to have unusually large gills and eyes, with a broad mouth so it can gulp down any food it finds. You know what this points to? That’s right, convergent evolution, where the fish all share a similar habitat that has influenced certain aspects of the body shape!

Currently, researchers are exploring volcanic vents in the Gulf of California that are the deepest found in the area. The area contains hydrothermal vents, which can heat the water to over 660 degrees F, or 350 degrees Celcius, and cold seeps, which are only called cold because they’re not super heated.

The vents are surrounded by mineral towers called hydrothermal chimneys that are up to 120 feet high, or 37 meters. These deepest vents and chimneys were only discovered in 2015, with others nearby only discovered in 2012. There are two types of chimneys in the area, dark-colored ones that grow the biggest, which are made up of sulfide minerals, and smaller, more delicate ones made up of light-colored carbonate minerals. The only other carbonate chimneys ever found are in the Atlantic. They’re really pretty.

Between the super heated water, the high levels of sulfides and heavy metals from the vents, and the great depth, the area would kill most animal life. But hydrothermal ecosystems are home to extremophiles that thrive in places that are deadly to other animals. The dark-colored chimneys, often called black smokers since they give off plumes of superheated minerals that look like smoke, are home to giant tube worms that can grow nearly eight feet long, or 2.4 meters, although they’re only a little more than an inch and a half wide, or 4 cm.

Giant tube worms don’t have a digestive tract, just a sort of internal pouch to hold the chemosynthetic bacteria that provide nutrients to the worm. The worm gives the bacteria a safe place to live, and the bacteria convert the carbon dioxide, hydrogen sulfide, and other minerals into nutrients that the worm absorbs.

But how do giant tube worms find new hydrothermal vents? Old vents go cold and new ones open up all the time, and giant tube worms can’t move once they’ve attached themselves to a rock or other solid structure. It turns out that newly hatched giant tube worms are free-swimming larvae, and at first they don’t contain any of the symbiotic bacteria that they need later in life. They acquire the bacteria later, when bacteria in the water find the larva and burrow into its skin. The larva swims deeper into the ocean and finds a hydrothermal vent, if it’s lucky, and attaches itself to a rock or something nearby. It then develops rapidly from a larva into the juvenile stage, where its digestive system reforms into a place for the bacteria to live. Then it grows into an adult tube worm.

The carbonate chimneys have a different kind of tube worm that prefers a different range of minerals.

Giant tube worms were only discovered in 1977. No one back then dreamed that anything could live around hydrothermal vents so the team exploring some vents hadn’t even brought along a biologist, just geologists. I like to think that they freaked out when they saw tube worms and other animals living around the vents.

It just goes to show, like they say in Jurassic Park, life finds a way.

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

Thanks for listening!

Episode 087: Globsters

It’s October! Let the spooky monster episodes begin! This week we’re starting off with a bang–or maybe a squoosh–with an episode about globsters. What are they? Why do they look like that? Do they smell?

Yes, they smell. They smell so bad.

Trunko, a globster found in South Africa:

A whale shark:

The business end of a whale shark:

A globster found in Chile:

A globster found in North Carolina after a hurricane:

A globster that still contains bones:

Not precisely a globster but I was only a few weeks late in my 2012 visit to Folly Beach to see this thing:

Further reading:

Hunting Monsters by Darren Naish

Show transcript:

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

It’s October, and you know what that means! Monsters! …and have I got a creepy monster for you this week. Grab your Halloween candy and a flashlight while I tell you about something called a globster.

If you live near the seashore, or really if you’ve spent any time at all on the beach, you’ll know that stuff washes ashore all the time. You know, normal stuff like jellyfish that can sting you even though they’re dead, pieces of debris that look an awful lot like they’re from shipwrecks, and the occasional solitary shoe with a skeleton foot inside. But sometimes things wash ashore that are definitely weird. Things like globsters.

A globster is the term for a decayed animal carcass that can’t be identified without special study. Globsters often look like big hairy blobs, and are usually white or pale gray or pink in color. Some don’t have bones, but some do. Some still have flippers or other features, although they’re usually so decayed that it’s hard to tell what they really are. And they’re often really big.

Let’s start with three accounts of some of the most famous globsters, and then we’ll discuss what globsters might be and why they look the way they do.

The St. Augustine monster was found by two boys bicycling on Anastasia Island off the coast of Florida in November 1896. It was partially buried in sand, but after the boys reported their finding, people who came to examine it eventually dug the sand away from the carcass. It was 21 feet long, or almost 6.5 meters, 7 feet wide, or just over 2 meters, and at its tallest point, was 6 feet tall, or 1.8 meters. Basically, though, it was just a huge pale pink lump with stumpy protrusions along the sides.

A local doctor, DeWitt Webb, was one of the first people to examine the carcass. He thought it might be the rotten remains of a gigantic octopus and described the flesh as being rubbery and very difficult to cut. Another witness said that pieces of what he took to be parts of the tentacles were also strewn along the beach, separated from the carcass itself.

Dr. Webb sent photographs and notes to a cephalopod expert at Yale, Addison Verrill. He at first thought it might be a squid, but later changed his mind and decided it must be an octopus of enormous proportions—with arms up to 100 feet in length, or over 30 meters.

In January a storm washed the carcass out to sea, but the next tide pushed it back to shore two miles away. Webb sent samples to Verrill, who examined them and decided it was more likely the remains of a sperm whale than a cephalopod.

In 1924, off the coast of South Africa, witnesses saw a couple of orcas apparently fighting a huge white monster covered with long hair—far bigger than a polar bear. It had an appendage on the front that looked like a short elephant trunk. Witnesses said the animal slapped at the orcas with its tail and sometimes reared up out of the water. This went on for three hours.

The battle was evidently too much for the monster, and its corpse washed ashore the next day. It measured 47 feet long in all, or 14.3 meters, and the body was five feet high at its thickest, or 1.5 meters. Its tail was ten feet long, or over three meters, and its trunk was five feet long and over a foot thick, or about 35 cm. It had no legs or flippers. But the oddest thing was that it didn’t seem to have a head either, and there was no blood on the fur or signs of fresh wounds on the carcass.

The carcass was so heavy that a team of 32 oxen couldn’t move it. The reason someone tried to move it was because it stank, and the longer it lay on the beach the more it smelled.

Despite its extraordinary appearance, no scientists came to investigate. After ten days, the tide carried it back out to sea and no one saw it again. Zoologist Karl Shuker has dubbed it Trunko and has written about it in several of his books.

Another globster was discovered well above ordinary high tide on a Tasmanian beach in 1960 after a massive storm. It was 20 feet long, or 6 meters, 18 feet wide, or 5.5 meters, and about 4 ½ feet high at its thickest, or 1.4 meters. It stayed on the beach for at least two years without anyone being especially interested in it. It was in a fairly remote area, admittedly. It wasn’t until 1962 that a team of zoologists examined it. They reported that it was ivory-colored, incredibly tough, boneless, and without any visible eyes. The lump had four large lobes, but it also appeared to have gill slits. One of the zoologists suggested it might be an enormous stingray.

So what were these three globsters?

Let’s look at Trunko first. Shuker points out that when a shark decomposes, it can take on a hairy appearance due to exposed connective tissue fibers. But Trunko was fighting two orcas only hours before it washed ashore.


Here’s the thing. No one saw the fight from up close and orcas are well known to play with their food. There’s a very good chance that Trunko was already long dead and that the orcas came across it and batted it around in a monstrous game of water volleyball. That would also explain why there was no blood associated with the corpse.

In that case, was Trunko a dead shark? At nearly 50 feet long, it would have had to be the biggest shark alive…and as it happens, there is a shark that can reach that length. It’s called the whale shark, which tops out at around 46 feet, or 14 meters, although we do have unverified reports of individuals nearly 60 feet long, or 18 meters—or even longer.

Like the megamouth shark, the whale shark is a filter feeder and its mouth is enormous, some five feet wide, or 1.5 meters. But the interior of its throat is barely big enough to swallow a fish. Its teeth are tiny and useless. Instead, it has sieve-like filter pads that it uses to filter tiny plants and animals from the water, including krill, fish eggs and larvae, small fish, and copepods. The filter pads are black and are probably modified gill rakers. The whale shark either gulps in water or swims forward with its mouth open, and water flows over the filter pads before flowing out through the gills. Tiny animals are directed toward the throat so the shark can swallow them.

The whale shark is gray with light yellow or white spots and stripes, and three ridges along each side. Its sandpaper-like skin is up to four inches thick, or 10 cm. It has thick, rounded fins, especially its dorsal fin, and small eyes that point slightly downward. It usually stays near the surface but it can dive deeply too, and it’s a fast swimmer despite its size. Females give birth to live babies which are a couple of feet long at birth, or 60 cm. While no one has watched a whale shark give birth, researchers think a shark may be pregnant with hundreds of babies at a time, but they mature at different rates and only a few are born at once.

The whale shark isn’t dangerous to humans at all, but humans are dangerous to whale sharks. It’s a protected species, but poachers kill it for its fins, skin, and oil.

The whale shark usually lives in warm water, especially in the tropics, but occasionally one is spotted in cooler areas. They’re well known off the coast of South Africa. If the Trunko globster was a dead whale shark, the “trunk” was probably the tapered end of the tail, with the flukes torn or rotted off. Most likely the jaws had rotted off as well, leaving no sign that the animal had a head or even which end the head should be on.

But sharks aren’t the only big animals in the ocean, and the skin and blubber of a dead whale can also appear furry once it’s broken down sufficiently due to the collagen fibers within it. Collagen is a connective tissue and it’s incredibly tough. It can take years to decay. Tendons, ligaments, and cartilage are mostly collagen, as are bones and blubber.

While we don’t know what Trunko really was, many other globsters that have washed ashore in modern times have been DNA tested and found to be whales. In 1990 the Hebrides blob washed ashore in Scotland. It was 12 feet long, or 3.7 meters, and appeared furry, with a small head at one end and finlike shapes along its back. Despite its weird appearance, DNA analysis revealed it was a sperm whale, or at least part of one. Another sperm whale revealed by DNA testing was the Chilean blob, which washed ashore in Los Muermos, Chile in 2003. It was 39 feet long, or 12 meters.

As for the tissue samples of the St Augustine monster, they still exist, and they’ve been studied by a number of different people with conflicting results. In 1971, a cell biologist from the University of Florida reported that it might be from an octopus. Cryptozoologist Roy Mackal, who was also a biochemist, examined the samples in 1986 and also thought the animal was probably an octopus. A more sophisticated 1995 analysis published in the Biological Bulletin reported that the samples were collagen from a warm-blooded vertebrate—in other words, probably a whale. The same biologist who led the 1995 analysis, Sidney Pierce, followed up in 2004 with DNA and electron microscope analyses of all the globster samples he could find. Almost all of them turned out to be remains of whale carcasses, of various different species. This included the Tasmanian globster.

Sometimes a globster is pretty obviously a whale, but one with a bizarre and unsettling appearance. The Glacier Island globster of 1930, for instance, was found floating in Eagle Bay in Alaska, surrounded by icebergs from the nearby Columbia Glacier. The head and tail were skeletal, but the rest of the body still had flesh on it, although it appeared to be covered with white fur. Its head was flattish and triangular and the tail was long. The men who found the carcass thought it had been frozen in the glacier’s ice.

They hacked the remaining flesh off to use as fishing bait, but they saved the skeleton. A small expedition of foresters came to examine the skeleton, which they measured at 24 feet and one inch, or over 7.3 meters. They identified it as a minke whale. The skeleton was eventually mounted and put on display in a traveling show, advertised as a prehistoric monster found frozen in a glacier. In 1931 the skeleton was donated to the National Museum of Natural History in Washington DC, where it remains in storage. Modern examinations confirm that it’s a minke whale.

On March 22, 2012, a rotting corpse 15 feet long, or 4.6 meters, with armor-like scutes along the length of its body, washed ashore on Folly Beach in South Carolina. This isn’t exactly a globster, since it was still fish-shaped, but I’m including it because I was literally at Folly Beach a matter of weeks after this thing washed ashore. I wish I’d seen it. It turned out that it wasn’t a sea monster as people assumed, but a rare Atlantic sturgeon.

Many globsters have stumps that look like the remains of flippers, legs, or tentacles. The Four Mile Globster that washed ashore on Four Mile Beach, Tasmania in 1998 had protrusions along its sides that looked like stumpy legs. It was 15 feet long, or 4.6 meters, and 6 feet wide, or 1.8 meters, with white hair and flippers that were separate from the protrusions. We don’t actually know for sure what this globster was.

In 1988 a treasure hunter found a globster now called the Bermuda blob. It was about eight feet long, or almost 2.5 meters, pale and hairy with what seemed to be five legs. The discoverer took samples of the massively tough hide, which were examined by Sidney Pierce in his team’s 1995 study of globster remains. This was one of the few that turned out to be from a shark instead of a whale, although we don’t know what species.

But sharks don’t have five legs. And the Four Mile Globster had six stumps that were separate from the flippers still visible on the carcass. So what causes these leg-like protrusions? They’re probably flesh and blubber stiffened inside with a bone or part of a bone, such as a rib. As the carcass is washed around by the ocean, the flesh tears in between the bones, making them look like stumps of appendages.

There’s a good reason why so many globsters turn out to be sperm whale carcasses. A sperm whale’s massive forehead is filled with waxy spermaceti oil. The upper portion of the head contains up to 500 gallons of oil in a cavity surrounded by tough collagen walls. Researchers hypothesize that this oil is used both for buoyancy and to increase the whale’s echolocation abilities. The lower portion of the forehead contains cartilage compartments filled with more oil, which may act as a shock absorber since males in particular ram each other when they fight. So much of the head of a sperm whale, which can be as big as 1/3 of the length of the whale, is basically a big mass of cartilage and connective tissue. After a whale dies, this buoyant section of the body can separate from the much heavier skeleton and float away on its own.

Globsters aren’t a modern phenomenon, either. We have written accounts of what were probably globsters dating back to the 16th century, and older oral traditions from folklore around the world. The main problem with globsters is that they’re not usually studied. They smell bad, they look gross, and they may not stay on the beach for long before the tide washes them back out to sea. For instance, after Hurricane Fran passed through North Carolina in 1996, a group of young men found a globster washed up on a beach on Cape Hatteras. They took pictures and estimated its length as twenty feet long, or six meters, six feet wide, or 1.8 meters, and four feet high at its thickest, or 1.2 meters. From the pictures it’s pretty disgusting, like a lump of meat with intestines or tentacles hanging from it. But the men weren’t supposed to be on the beach, which was part of the Cape Hatteras National Park and closed due to hurricane damage. They didn’t mention their find to anyone until the following year, when one of the men learned about the St Augustine Monster in his college biology class. By then, of course, the Cape Hatteras globster was long gone. While it might have been a rotting blob of whale blubber or a piece of dead shark, we don’t know for sure. So if you happen to find a globster on a beach, make sure to tell a biologist or park ranger so they can examine it…before it’s lost to science forever.

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

Thanks for listening!

Episode 074: Colossal Squid and the Things That Eat Them

We’re going to learn about the colossal squid in this episode, with bonus info about the giant squid…and then we’re going to learn about the massive things that eat this massive squid!

A giant squid, looking slightly guilty for eating another squid:

A colossal squid, looking less than impressive tbh:


A sperm whale looking baddass:

A southern sleeper shark, looking kind of boring:

Show transcript:

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

This week we’re going to learn first about the colossal squid, and then we’re going to learn about what eats the colossal squid.

You’ve probably heard of the giant squid, but maybe you haven’t. Let’s start with it, because the giant squid and the colossal squid are both massive, amazing deep-sea animals.

Stories of huge squid go back to ancient times. Aristotle and Pliny wrote about it, the legend of the kraken may be at least partially inspired by it, and sailors have told stories about it for time out of mind. Naturalists of the mid-19th century knew it must exist because whalers had found enormously long tentacles and huge beaks in sperm whale stomachs. But except for the occasional badly damaged specimen washed up on shore, no one had seen a giant squid. Certainly no one had seen a living giant squid.

It wasn’t until 2001 that a live giant squid was caught on film, and then it was only a larval squid. In 2002 a live adult giant squid was caught off the coast of Japan. It wasn’t especially big, just 13 feet long, or 4 meters, but up until then an adult giant squid had never been captured or even photographed. Its body is now on display at the National Science Museum of Japan. It wasn’t until 2004 that a research team got photographs of a live giant squid in its natural habitat, also off the coast of Japan. Since then researchers have taken more photographs and footage of giant squid, and we’re starting to learn more about it.

Squids in general have a body called a mantle, with small fins at the rear and eyes near the base above the arms, eight arms, and two long tentacles. The arms and tentacles are lined with suction cups that contain rings of serrated chitin, which allows the squid to hang on to its prey. Chitin is the same stuff lobster shells and fish scales are made of. It’s the invertebrate version of keratin. In the middle of the arms, at the base of the mantle, is the squid’s mouth, which looks for all the world like a gigantic parrot beak, also made of chitin. Instead of actual teeth, the squid has a radula, which is basically a tongue studded with chitinous teeth that it uses to shred its prey into pieces small enough to swallow.

Most of the length of a giant squid comes from its tentacles. Researchers estimate that the longest giant squid’s mantle is about 7 ½ feet long, or 2.25 meters. The longest giant squid’s mantle and arms together reach around 16 feet long, or 5 meters. That’s still pretty huge, but it’s not until you add in the tentacles that the length just gets ridiculous. The longest giant squid known—and this is an estimate based on the size of the biggest beak ever found—was 43 feet, or 13 meters. Females are typically much bigger than males and can weigh twice as much.

The giant squid is a deep-sea animal, probably solitary, and eats fish and smaller squid, including other giant squid. It’s an active hunter and catches prey by grabbing it with its super-long tentacles, reeling it in to hold it more securely with its arms, then biting it with its beak and shredding it into pieces with its radula.

The giant squid has the largest eye of any living animal, as big as 11 inches in diameter, or 27 cm. Since it mostly lives in the deep sea, it probably needs such big eyes to see bioluminescent light given off by the animals it eats and to detect predators. Only ichthyosaurs had larger eyes. Well…except for the colossal squid, which may have eyes even bigger than the giant squid’s.

So if the giant squid can grow to some 43 feet long, is the colossal squid even longer? Only a little. Researchers estimate the colossal squid can grow to around 46 feet long, or 14 meters, but it has shorter tentacles and a much longer mantle than the giant squid so is an overall much bigger and heavier animal.

But that size estimate is only that, an estimate. We know very little about the colossal squid. It was first described from parts of two arms found in the stomach of a sperm whale in 1925, and for more than 50 years that was pretty much all we had. Then a Russian trawler caught an immature specimen in 1981 off the coast of Antarctica. Since then researchers have been able to study a few other specimens caught or found dead, mostly from the Antarctic seas.

As far as we know, the colossal squid is an ambush predator rather than an active hunter like the giant squid. It lives in the deep seas in the Southern Ocean, especially around Antarctica, as far down as 7,200 feet or 2.2 km beneath the surface of the ocean, and it mostly eats fish. While its tentacles are much shorter than the giant squid’s, they have something the giant squid does not. Its suckers have hooks, some of them triple-pointed and some of which swivel. When it grabs onto something, it is not going to let go until somebody gets eaten.

The largest colossal squid ever found was caught in 2007 in the Antarctic. It was caught by a trawler when they hauled in a fishing line. The squid was eating an Antarctic toothfish caught on the line and wouldn’t let go, so the fishermen hauled it aboard in a net and froze it. It was 33 feet long, or ten meters, and by the time it was thawed out for study, its tentacles had shrunk so that it was even shorter. Its eye was 11 inches across, or 27 cm, but when the squid was alive its eye was probably bigger, maybe as much as 16 inches across, or 40 cm—in which case, it wins the biggest eye category and deserves a trophy. With an eyeball on it.

So if the biggest colossal squid we’ve ever seen is only 33 feet long, how do we know it can grow to 46 feet long? Because whalers have found colossal squid beaks in the stomachs of sperm whales that are much larger than the 33-foot squid’s beak.

And that brings us to the first predator of the colossal squid, the sperm whale. Lots of things eat young colossal squids, from fish and albatrosses to seals and bigger squids, but today we’re talking about predators of full-grown colossal squid. There aren’t many. In fact, there are only two that we know of.

The sperm whale eats pretty much anything it wants, frankly, but mostly what it wants is squid. It eats both giant and colossal squid, and we know because squid beaks aren’t digestible. They stay in the whale’s stomach for a long time. Specifically they stay in the whale’s second stomach chamber, because sperm whales have a four-chambered stomach like cows and other ruminants do. Sometimes a whale will puke up squid beaks, but often they just stay in the stomach. Some whales have been found with as many as 18,000 squid beaks in their stomachs. 18,000! Can you imagine having 18,000 of anything riding around in your stomach? I wouldn’t even want 18,000 Cap’n Crunches in my stomach and I really like Cap’n Crunch cereal.

Sometimes squid beaks do make it deeper into the whale’s digestive system, and when that happens, researchers think it stimulates the body to secrete a greasy substance called ambergris to coat the beak so it won’t poke into the sides of the intestines. Small lumps of ambergris are sometimes found washed up on shore after the whale poops them out, and it can be valuable. Once it’s been out of the whale for a while it starts to smell really good so has been traditionally used to make perfume, but these days most perfume companies use a synthetic version of ambergris.

The sperm whale can grow to at least 67 feet long, or 20.5 meters, and may possibly grow much longer. It’s an active hunter and a deep diver, with the biggest whales routinely diving to almost 7,400 feet or 2,250 meters to catch that tasty, tasty squid. It can stay underwater for over an hour. It has teeth only in the lower jaw, which is long and thin. The upper jaw has holes in the gum called sockets where its lower teeth fit into, which is kind of neat. But because male sperm whales sometimes fight by ramming each other, occasionally a whale’s jaw will become broken, dislocated, or otherwise injured so that it can’t use it to bite squid. But that actually doesn’t seem to stop the whale from eating squid successfully. They just slurp them up.

Sperm whales use echolocation to find squid, but researchers also think the whale can use its vision to see the squid silhouetted against the far-off water’s surface. Sperm whales have big eyes, although not nearly as big as squid eyes, and a whale can retract its eyeballs into its eye sockets to reduce drag as it swims. It can also protrude its eyes when it wants to see better. Researchers have tagged sperm whales with radio transmitters that tell exactly where the whale is and what it’s doing, at least until the tag falls off. The tags occasionally show that a sperm whale will hunt while swimming upside down, which researchers think means the whale is looking up to see squid silhouettes.

You’ll often hear people talk about sperm whales and giant squids battling. Sperm whales do often have sucker marks and scars from giant and colossal squid arms, but that doesn’t mean the squid was trying to drown the whale. Squid have no real defense against getting eaten by sperm whales. All a squid can do is hang on to the whale in hopes that it won’t actually end up in the whale’s belly, which is not going to happen, squid. Some researchers even theorize that the sperm whale can stun prey with a massive burst of powerful sonar impulses, but so far there’s no evidence for this frankly pretty awesome hypothesis.

The other main predator of full-grown colossal squid are a few species of sharks called sleeper sharks. They’re slow-moving deep-sea sharks that mostly live in cold waters around the Arctic and Antarctic. We don’t know much about a lot of sleeper sharks species. Many of them were only discovered recently, and some are only known from one or a few specimens. Sleeper sharks are generally not much to look at. They don’t have great big mouths full of huge teeth like great whites, they don’t have weird-shaped heads like hammerheads, and they’re just plain grayish all over, maybe with some speckles.

The Greenland shark is one type of sleeper shark. It’s the one with the longest known lifespan of any vertebrate, as much as 500 years old. The Greenland shark is also one of the largest sharks alive, up to 24 feet long, or 7.3 meters, and possibly longer. But the Greenland shark isn’t one of the sleeper sharks that eat colossal squid, since it lives around the Arctic and the colossal squid lives around the Antarctic. But the Southern sleeper shark lives around the Antarctic and is so closely related to the Greenland shark that for a long time many researchers thought it was the same species. The Southern sleeper shark is overall shorter, only around 14 feet long, or 4.4 meters, although since we don’t know a lot about it, we don’t really know how big it can get. It’s probably an ambush predator and it definitely eats colossal squid because colossal squid beaks are sometimes found in its stomach.

In 2004 a team of researchers examined the stomach contents of 36 sleeper sharks that had been accidentally killed by fishing trawlers around and near Antarctica. They found remains of at least 49 colossal squid, bigger on average than the squid sperm whales typically eat.

Just going by what we know about the Greenland shark, it’s safe to say that the southern sleeper shark is an extremely slow swimmer, barely exceeding more than two miles an hour, or 3.5 km per hour. That’s about the speed you walk if you’re not in any particular hurry. It may also be prey to the same parasitic copepod, which is a type of crustacean, that infests a lot of Greenland sharks. The parasite attaches itself to the shark’s EYEBALL. But some researchers think the parasite actually gives something back to the shark, by glowing with a bioluminescence that attracts prey, which the shark then eats. Greenland sharks don’t appear to need to see in order to find prey anyway. That doesn’t make it any less gross.

I’m very sorry to end this episode with an eyeball parasite, so here’s one last thing to take your mind off it. As long as there have been reports of gigantic squid, there have been reports of gigantic octopuses. The largest octopus currently known is the giant Pacific octopus with a 20 foot legspan, or 6 meters. But there may be a gigantic octopus much larger than that. In 1928, six octopuses were sighted off the coast of Oahu in Hawaii by a sailor in the US Navy, who estimated their legs spanned 40 feet across, or 12.5 meters. In 1950, a diver in the same area reported seeing an octopus with a body the size of a car, and with tentacles estimated as 30 feet long each, or 9.3 meters.

Remember the study I mentioned earlier, about researchers finding lots of colossal squid remains in sleeper shark stomachs? They found something else in one of the sharks, remains of a huge octopus. Species unknown.

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

Thanks for listening!

Episode 033: Dunkleosteus, Helicoprion, and their weird-toothed friends

This week we’ll learn about some terrifying extinct fish, the armored dunkleosteus and the spiral-toothed helicoprion, plus a few friends of theirs who could TEAR YOU UP.

Dunkleosteus did not even need teeth:

Helicoprion had teeth like crazy in a buzzsaw-like tooth whorl:

Helicoprion’s living relatives, chimaeras (or ghost sharks) are a lot less impressive than they sound:

Helicoprion probably looked something like this:

But helicoprion has been described in all sorts of wacky ways over the years:

So what are the odds this rendition of edestus is correct? hmm

Show transcript:

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

This week we’ve got a listener suggestion! Will B. suggested placoderms, which were armored fish that lived hundreds of millions of years ago. He especially recommended Dunkleosteus. I looked it up and went, “Oh holy crap,” so you bet we’re going to learn about it today. I’m also pairing that terrifying fish with a really weird shark relation called Helicoprion. And we might even take a look at a few other fishes while we’re at it. Creepy extinct fish for everyone! Oh, and Will asked that I include more metric conversions. [heavy sigh] okay I guess

If you had happened to live around 350 million years ago when Dunkleosteus was alive, you would be a fish. Well, you would probably be a fish. I don’t know for sure. That was during the Late Devonian period, and the Devonian is remembered as the “age of fish” by undergraduate geology and palaeo students everywhere. While land plants were evolving like crazy, developing true roots and seeds, fish were even crazier. Ray-finned fish evolved during the Devonian and so did lobe-finned fish like coelacanths. The first amphibious critters developed in shallow lakes and started to spend time on land, and in the ocean there were early sharks, lots of trilobites, and a whole lot of armored fish. Including, eventually, dunkleosteus.

Dunkleosteus terrelli was the biggest species of placoderm. It probably grew over 30 feet long OR TEN METERS, WILL, which made it bigger than a great white shark. But dunkleosteus didn’t have teeth. And before you think, oh, it must have been a filter feeder or something, oh no. It didn’t need teeth. Instead it had bony plates like a gigantic beak. It could open and close its jaws incredibly fast—something like one 50th of a second—and could bite through armor and bone no problem. One article referred to its jaws as sheet-metal cutters. Scientists think its bite was as powerful as that of a T rex, although it didn’t quite match that of megalodon, but since T rex and megalodon both lived many millions of years later than Dunkleosteus, it’s useless to speculate who would win in a fight. But my money’s on Dunkleosteus.

Dunkleosteus wasn’t a fast swimmer. Its head was covered in heavy armor that probably served two main purposes. One, the armor plates gave its massive jaw muscles something substantial to attach to, and two, it kept its head safe from the bites of other placoderms. That’s right. Dunkleosteus was a cannibal.

We actually don’t know exactly how long Dunkleosteus was or what most of its body looked like. The only fossils we’ve found were of the head armor. We do have complete fossils and body impressions of other, much smaller placoderms, so since all placoderms seemed to have the same body plan we can make good guesses as to what Dunkleosteus looked like.

One surprising thing we do have associated with Dunkleosteus fossils are some remains of its meals. These are called fish boluses, and they’re basically just wads of partially-digested pieces of fish that either get horked up by whatever ate them or pass through the digestive tract without being fully digested. From the fish boluses, we know that Dunkleosteus probably preferred the soft parts of its prey and didn’t digest bones very well.

In 2013, a fossil fish over 400 million years old was described that combines features of a placoderm skeleton with the jaw structure that most bony fishes and four-footed animals share. Some other early bony fishes discovered recently also show some features of placoderm skeletons. What does that mean? Well, until these discoveries, researchers had thought bony fishes weren’t very closely related to placoderms. Now it looks like they were. And that means that placoderm jaws, those fearsome cutting machines, were actually the basis of our own jaws and those of most animals alive today. Only, in our case they’re no longer designed to shear through armor and bone. Maybe through Nutter Butters and ham sandwiches instead.

So what happened to dunkleosteus? Around 375 million years ago something happened in the oceans—not precisely an extinction event, but from our perspective it looks like one. Even without human help species do go extinct naturally every so often, and when that happens other species evolve to fill their ecological niches. But during the late Devonian, when species went extinct in the ocean… nothing took their place.

We don’t know what exactly was going on, but researchers have theories. One suggestion is that, since sea levels were rising, marine environments that were once separated by land got joined together. Species that had evolved in one area suddenly had access to a much bigger area. They acted like invasive species do today, driving native species to extinction and breeding prolifically. They kept new species from developing, and caused a breakdown in the biodiversity of their new territories. This only happened in the oceans, not on land, which adds credence to the theory.

It took a long, long time for the oceans to fully recover. For example, coral reefs disappeared from the fossil record for 100 million years as corals almost died out completely. But the animals that had already started evolving to take advantage of life on land survived and thrived—and that led to us, eventually. Us and our little unarmored jaws.

From Dunkleosteus and its sheet-metal cutter beak let’s go to another fish that looked like a shark but had teeth that are so bizarre I can’t even understand it. Helicoprion and its tooth whorl have baffled scientists for over a century.

The various species of Helicoprion lived around 290 million years ago. Like sharks, only its teeth are bony. The rest of its skeleton is made of cartilage, which doesn’t preserve very well.

So what’s a tooth whorl? It resembles a spiral shell, like a snail’s, only made of teeth. I’m not even making this up. Originally people actually thought they were some kind of weird spiky ammonite shell, in fact. Then someone pointed out that they were made of teeth, but no one could figure out what earthly use a circular saw would be if you were a fish and just wanted to eat other fish. Where would you even keep a circular saw of teeth?

Various suggestions included putting the tooth whorl at the very end of the lower jaw, just sort of stuck out there doing nothing; putting the tooth whorl way in the back of the throat where I guess it would cut up fish as they went down; on the snout, on the back, or even on the tail, which are not places where teeth typically do much good. Originally researchers thought the tooth whorl was probably a defensive trait, but now it’s accepted that it was used the way the rest of us use our teeth, which is to eat things with.

The smallest teeth in a tooth whorl are on the inside curls and the biggest are on the outside. Eventually researchers realized the small teeth were from when the individual was a baby fish and had little teeth. Like sharks, helicoprion kept growing teeth throughout its life. Unlike sharks, it didn’t lose its old teeth when the new ones grew in. The older, smaller teeth were just pushed forward along the curve of the whorl and eventually were buried within the animal’s jaw, with only the biggest, newest teeth actually being used.

In 1950 a crushed tooth whorl was found with some cranial cartilage, so scientists knew that the whorl was associated with the head and wasn’t, for instance, on the dorsal fin. That fossil was found in Idaho and consisted of 117 teeth. The whorl was 23 cm in diameter, or about 9 inches across, although slightly larger ones have been found. In 2011 the fossil was examined with a state-of-the-art CT scanner and a 3D computer model generated of the animal’s skull.

Researchers think they have a pretty good idea of what a living helicoprion’s head and jaws looked like. The tooth whorl was fused with and extended the full length of the lower jaw. It grew inside the mouth roughly where the tongue would be if it had a tongue, which it did not. Helicoprion didn’t have teeth in its upper jaw, so the tooth whorl acted less like chompers than like a meat slicing machine. When it closed its mouth, the tooth whorl was pushed back a little and would therefore slice through any soft-bodied prey in the mouth and also force its prey deeper into its mouth. Helicoprion probably ate small fish, cephalopods, and other soft-bodied organisms.

Since we don’t have any fossils or impressions of helicoprion’s body, we don’t know for sure what it looked like, but researchers estimate it probably grew to around 13 feet or 4 meters, but may have possibly exceeded 24 feet or 7.5 meters.

For a long time researchers thought helicoprion was a shark, but it’s now classified as a type of chimaera, which are small weird-looking shark-like fish known also as ghost sharks, spookfish, ratfish, and rabbit fish. I’m going to call them ghost sharks because that’s awesome. They’re not that closely related to sharks although they do have cartilaginous skeletons, and most species like the ocean depths. Ghost sharks have been spotted at depths of 8,500 feet, or 2,600 meters. The longest any species grows is around 5 feet, or 150 cm. Unlike helicoprion, they don’t have exciting teeth. They don’t really have teeth at all, just three pairs of tooth plates that grind together. Some species have a venomous spine in front of the dorsal fin.

While we’re talking about shark-like fish with weird teeth, let’s discuss Edestus, a genus of shark-like fish with weird teeth that lived around 300 million years ago, around the same time as dunkleosteus. It was related to helicoprion but it didn’t have a tooth whorl. Instead it had one curved bracket of teeth on the lower jaw and one on the upper jaw that meshed together like pinking shears. You know what pinking shears are even if you don’t recognize the name. Pinking shears are scissors that have a zigzag pattern instead of a straight edge, so you can cut a zigzag into cloth but not paper because do not dare use my pinking shears for anything but cloth. It dulls them.

Anyway, like helicoprion Edestus didn’t shed its teeth but it did grow new ones throughout its life, so like helicoprion it had a bunch of teeth it no longer needed. In Edestus’s case we don’t have any bits of skull or jaw cartilage to give us a clue as to how its teeth sat in its jaw. A lot of scientific art of Edestus shows a shark with a pointy mouth, where the upper point curves upward and the lower point curves downward with teeth sticking out from the middle. Sort of like an open zipper, if the zipper part was teeth and the non-zipper side was a shark’s mouth. To me that looks sort of ridiculous, and I suspect in reality Edestus looked a lot more like helicoprion. The downward and upward curved parts of the tooth arc was probably buried within its jaw, not sticking out. But that’s just a guess based on about 30 minutes of research.

Researchers estimate that the largest species of Edestus probably grew to about 20 feet long, or 6 meters. No one’s sure how or what it ate, but one suggestion is that if its teeth did project out of its mouth, it might have slashed at prey with its teeth sort of like a swordfish slashes prey with its elongated beak. Hopefully scientists will find a well preserved specimen one day that will give us some clues as to what Edestus looked like, at which point I bet the drawings we have now will look as silly as helicoprion with a tooth whorl perched on its nose.

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

Thanks for listening!

Episode 016: Jellyfish

If you look at this episode and think, “Oh, ho hum, think I’ll skip this one because snore, jellyfish,” you are so wrong! Jellies are fascinating, creepy, and often beautiful. Come learn all about our squishy friends in the sea!

A Portuguese man o’war. Creepy as heck:

A lion’s mane jelly. You do not want this guy on your ship. Incidentally, a lot of the photos you find of divers with enormous lion’s mane jellies are fakes that make the jellies look gigantic.

The cosmic jelly, a deep-sea creature:

The creepy Stygiomedusa gigantea, guardian of the underworld:

A newly discovered golden jelly.

Further reading:

Jelly Biologist (I’ve been enjoying browsing this site)

Show transcript:

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

This week’s episode is about jellyfish—also called jellies, which is more accurate since they’re not fish at all.

Originally, I was going to focus on the Portuguese man o’war, another in the ongoing feature of “animals that scared me as a kid” and technically not even a jelly. But there’s so much to learn about jellies that we’re going to cover a whole lot more than that.

Jellies are interesting animals, to say the least. Their bodies have radial symmetry, meaning they’re the same in all directions. While the body shape varies, most jellies have a bell-like shape. The bell is generally rather thin, made up of an external covering, an internal covering, and an elastic gel-like material in between. Inside, the jelly has a digestive cavity with four to eight oral arms surrounding the mouth and long tentacles hanging beneath. The jelly also has a simple nerve net that can detect light and react to other stimuli, and which takes the place of a brain.

Jellies don’t have brains. They don’t have hearts, specialized sensory organs, or much of anything else. But they’ve been around for some 650 million years, possibly much longer, so clearly it all works.

The jelly’s life cycle is pretty weird. Most start out as polyps that stick to rocks or shells and use their little tentacles to catch microscopic organisms. A polyp can bud, producing new polyps that are clones of the original. Eventually, a polyp will constrict its body and develop into a stack of larvae. Each larva develops into a tiny jelly, which separates from the stack and swims away.

Once it’s grown, a jelly reproduces by releasing sperm, if it’s male, which the water carries to the female to fertilize her eggs. Some female jellies have brood pouches on the oral arms, some just carry the fertilized eggs inside the body while they develop. The embryos develop into swimming larvae called planula, which leave the female and attack themselves to something firm, where they transform into polyps.

This seems needlessly complicated, but again, it works for the jelly.

Polyps can live for years, while adult jellies, which I’m delighted to report are called medusas, usually only live a few months. The immortal jellyfish throws another step into this process. It can transform back into a polyp from any stage of its life if it needs to. As a polyp, the immortal jellyfish is tiny, only about a millimeter long. As a full-grown medusa it’s not all that much bigger, less than four millimeters in diameter. Because it can transform back into a polyp as many times as it needs to, apparently without any kind of degradation or injury, the immortal jellyfish is effectively, well, immortal.

Before you get too excited, though, keep in mind that there’s not a whole lot of research into the immortal jellyfish yet. It’s not even known if they will transform back into polyps in the wild, since it’s only ever been observed in captivity.

Almost all jellies have stinging cells, usually concentrated on the tentacles or oral arms, which they use to stun and kill prey. The stinging cells contain venom-filled nematocysts, which are coiled structures that uncoil and sting when touched. Humans are not jelly prey, but jelly stings can still be uncomfortable—and sometimes fatal—to humans.

You’ve probably heard of the infamous box jellyfish, the most dangerous species of which is common around Australia. Unlike most jellies, box jellyfish have true eyes and a relatively well-developed nervous system. They’re active, hard for humans to detect while swimming since they’re nearly transparent, and in the case of Chironex fleckeri, their venom can kill a human in as little as two minutes. Most fatalities occur in children, but most stings don’t result in death.

Another vicious and occasionally fatal stinger is the Portuguese man o’war, although it isn’t actually a jelly. It’s not even a single animal, it’s a colony. One member is the float, another the feeding polyps, and so forth. The man o’war takes its name from a type of ship, which the float somewhat resembles. The float is bluish or purplish, generally under a foot long [30 cm], and filled with gas. Underneath the float are feeding polyps from which hang purple tentacles, typically around 30 feet long [9 m] but sometimes up to 200 feet long [61 m]. If something attacks the man o’war, it can vent some of the gas in its bladder and submerge temporarily.

When I was a kid, my family occasionally went to the beach in North Carolina. Man o’wars are tropical animals but they do occasionally drift farther north. I was fully aware of this as a kid and did not want to get in the water farther than my waist. My grandfather and one of my aunts reassured me that they’d both been stung by a man o’war once, and it wasn’t any more painful than a wasp sting.

That did not make me feel any better. In fact, it made me even more scared because then I KNEW there were man o’wars out there. I wasn’t afraid of being stung, I was afraid of touching those creepy tentacles.

As it happens, my grandfather and Aunt Barbara probably had not encountered a Portuguese man o’war but a smaller animal called a by-the-wind sailor, which is now my favorite name of anything. It has a blue bladder float like the man o’war, but its sting is much milder, A man o’war sting is incredibly painful, more of a shock, that can lead to intense muscle and joint pain, open wounds on the skin at the sting site, headache, chills and fever, nausea, and can cause victims to faint and drown. Occasionally the venom travels to the lymph nodes and causes even more serious symptoms, including swelling of the larynx, an inability to breathe, and cardiac distress. Even a dead man o’war can sting if you touch its tentacles. Why would you touch its tentacles.

I’m not the only one who feels this way about man o’wars, clearly, because one of its other names if the floating terror. That sounds like the title of a pulp science fiction novel.

The bluebottle is a smaller related species found in the Indian and Pacific Oceans. The man o’war is found in those oceans and the Atlantic. A few weeks ago, in early May 2017, hundreds of man o’wars washed ashore in Georgia and South Carolina. Man o’wars are pretty common around Florida, especially in winter, and occasionally they wash ashore in the thousands.

The man o’war eats fish and other organisms that get caught in the stinging tentacles, but there are some fish that live among the tentacles, even feeding on them, like the man o’war fish and the clownfish. Not a lot of things eat Portuguese man o’wars, but the loggerhead turtle and ocean sunfish do. I like them both. The blanket octopus is immune to the man o’war’s venom and may carry broken-off tentacles to deter predators.

If you’re stung by a man o’war, treat the sting the same way you’d treat other jelly stings. Rinse with vinegar to remove any remaining bits of tentacle or nematocysts, then apply heat for 45 minutes, either with a hot pack or by immersing in hot water. Don’t rinse with urine or vodka; it can make the stings worse—and definitely don’t rinse with fresh water. If you don’t have vinegar, rinse with sea water, but keep in mind that you may be pouring nematocysts back onto the patient with the water. This treatment is from a very recent study conducted by researchers at the University of Hawaii at Manoa, released only a few weeks ago as this episode goes live, so if you’ve heard differing advice for jelly stings, it may be out of date.

Jellies are related to some surprising things: coral, sea anemones, a rare parasitic worm, the freshwater hydra—a ten mm long tubular animal with stinging tentacles at one end that it can stretch four or five times the length of the body to catch its tiny prey. Like jellies, the hydra can regenerate parts of its body if they’re injured or bitten off. And the hydra doesn’t appear to age, making it biologically immortal, although in a different way than the immortal jellyfish.

So what’s the largest jelly known, not counting ridiculously long tentacles like the man o’war’s? That would be the lion’s mane jellyfish. Its bell can have a diameter of over seven feet [2 m] and it has pretty darn long tentacles, too—sometimes over 120 feet long [36.5 m]. It likes cold water and the biggest individuals live where it’s coldest. While small individuals are brown or tan in color, the big ones are usually red or purple. The sting of a lion’s mane jellyfish isn’t usually that bad, but it has a lot of tentacles, so it can inflict thousands of stings upon contact.

In 1973, the Australian ship Kuranda collided with a huge jelly in the South Pacific while traveling through a storm on her way to the Fiji Islands. The jelly was so enormous that the deck was covered in jellyfish goo and tentacles up to two feet deep [61 cm]. One crew member died after getting stung. The weight of the jelly was so great, an estimated 20 tons [18 metric tons] that it started to push the ship nose-down and the captain, Langley Smith, sent out an SOS. The salvage tug Hercules arrived and sprayed the Kuranda’s deck with a high-pressure hose, dislodging the jelly. Samples were sent to Sydney and tentatively identified as a lion’s mane jelly.

But remember, lion’s mane jellies don’t live in the warm waters near Fiji and Australia. There are other reports of lion’s mane jellies seen in the area, though, so it’s possible there’s a gargantuan warm-water variety that hasn’t been discovered yet.

Most jellies live near the surface of the ocean, but there are some deep-sea species known, with more being discovered every year. A gorgeous jelly, dubbed the cosmic jellyfish by the press, was spotted 9,800 feet [2987 m] below the surface near American Samoa this February. It has an umbrella-like bell with short tentacles that point both downward and upward. You may have seen it in the news described as looking like a flying saucer, which it does. A similar jelly was discovered in the Mariana Trench in 2016, almost two and a half miles underwater [4 km]. These are lovely jellies with translucent bells and glowing red and yellow innards, but there are less lovely ones down there.

The big red jellyfish discovered in 2002 is an ugly cuss. It lives in waters up to 4900 feet deep [1493 m] and is over a foot in diameter [30 cm]. It’s dull red in color and doesn’t have tentacles, just thick oral arms.

Stygiomedusa gigantea, also known as the guardian of the underworld by at least one website, and now by me, isn’t so much ugly as horrifying. Its bell is some three feet across [1 m], and while it doesn’t have tentacles or even stinging cells, it does have four 30-foot-long [9 m] oral arms that resemble dark brown or reddish strips of cloth that drift in the ocean currents.

Some deep-sea jellies don’t have tentacles or oral arms. Deepstaria enigmatica, a rare jelly described in 1967, basically just looks like a big mesh bag. Its close relative, Deepstaria reticulum, is very similar, but it’s reddish instead of whitish. The Deepstaria hangs motionless in the deep with its three-foot-wide [1 m] bell open, waiting for something to swim into it. When it does, the bell contracts like a bag, the fish or other organism is stung by nematocysts lining the bell, and the jelly pushes its stunned prey into its mouth with tiny cilia inside the bell.

Isopods, which are small crustaceans, frequently hitch rides inside Deepstaria bells. It’s not known if they’re parasites or confer some benefits to the jellies, but they don’t seem to be affected by the stings.

There are plenty of mysteries associated with enormous jellies, although the two most famous ones I dug into started to seem less and less likely once I got closer to the primary sources. According to Eric Frank Russell in his 1957 book Great World Mysteries, in 1953 a diver testing a new type of deep-sea diving suit in the South Pacific saw an enormous jelly-like monster kill a shark. The diver had been testing how deep he could dive in the suit and noticed a fifteen-foot [4.6 m] shark following him down. I’m going to quote the relevant section instead of paraphrasing, because it’s pretty amazing.

“The shark was still hanging around some 30 feet [9 m] from me and about 20 feet [6 m] higher, when I reached a ledge below which was a great black chasm of enormous depth. It being dangerous to venture farther, I stood looking into the chasm while the shark waited for my next move. Suddenly the water became distinctly colder. While the temperature continued to drop with surprising rapidity, I saw a black mass rising from the darkness of the chasm. It floated upwards very slowly. As at last light reached it I could see that it was of a dull brown color and tremendous size, a flat ragged-edged thing about one acre in extent. It pulsated sluggishly and I knew that it was alive despite its lack of visible limbs or eyes. Still pulsating, this frightful vision floated past my level, by which time the coldness had become most intense. The shark now hung completely motionless, paralyzed either by cold or fear. While I watched fascinated, the enormous brown thing reached the shark, contacted it with its upper surface. The shark gave a convulsive shiver and was drawn unresisting into the substance of the monster. I stood perfectly still, not daring to move while the brown thing sank back into the chasm as slowly as it had emerged. Darkness swallowed it and the water started to regain some warmth.”

I am skeptical, I admit. Eric Frank Russell was primarily a science fiction writer and this sounds like something from a novel, probably one called The Floating Terror. If he described the monster as 20 feet across or even 30 or 40 [6, 9, 12 m], I’d be going, “Hmm, but hey, the deep sea is full of amazing things.” But an acre? That’s 208 feet 9 inches across. 43,450 square feet. A lot of meters [4,046 square meters]. It’s three times the size of my yard, which takes me like an hour to mow. It’s just too big to believe, not without corroborating details—like a first-hand account of the actual diver. We don’t even know his name. And what about the diver’s buddy? Divers don’t go down alone, although maybe they did back in 1953. The whole story is just too thin, too fantastical to be believed.

The other promising mystery I looked into is a supposed legend from Chile, a sea monster that resembles a cow hide stretched flat but with eyes all around the edges and four big eyes in the middle. It rises to the ocean’s surface and swallows animals it encounters.

At first glance this sounds ridiculous, until you realize that many jellies have semi- or fully transparent bells and their internal organs, such as they are, may resemble eye-like blobs in the center of their bodies. Some jellies do have light-sensitive eye spots near their edges too. But the research I did to follow up this story, which I took from Karl Shuker’s blog, but which is originally from Jorge Luis Borges’ 1969 book called The Book of Imaginary Beings, indicated that the actual legend is much different and much less jelly-like.

El Cuero is a cowhide monster called Threquelhuecuvu among the Mapuche of Patagonia. It lives in rivers, lakes, and the ocean. It’s nearly circular, has claws around its edges, and one pair of red eyes. It also has tentacles on its head and a mouth in its middle, which it uses to suck bodily fluids from its prey. It’s supposed to come out of the water and come on land, and when an animal steps on it, it wraps its body around the animal and suffocates it. Then it drags its prey into the water to eat it. The only way to kill it is to throw cacti into the water. When the monster grabs the cacti, it’s pierced through with spines and dies.

It’s generally supposed that the monster is based on freshwater stingrays, although they’re not known to live in Patagonia. But in 1976, after a bus full of tourists ended up on the bottom of Lake Moreno, divers who retrieved the drowned victims reported enormous rays in the depths.

There is a freshwater stingray species in South America which has thorn-like denticles on its body and a closely related species, also with denticles, sometimes travels upriver from the ocean off the Chilean Patagonian coast. That might be the source of the cowhide monster.

So those two mysteries are almost certainly bust. But don’t feel discouraged. Not only was that 20-ton ship-sinking 1973 lion’s mane jelly a real, documented thing that happened [note from episode 248: sorry, it turns out it wasn’t real], there are lots of jelly species being discovered all the time.

Not all are deep-sea species. In 2013, a fisherman in northeast Italy hauled up a net full of golden jellies he’d never seen before. He contacted the local university, and a researcher came out and determined that the lovely golden jellies were completely unknown to science. In 2015, a 9-year-old boy caught a new species of box jelly that’s only around an inch long [3 cm].

There are freshwater jellies too, but not a lot is known about them. To add to the confusing and complex life cycle of marine jellies, many freshwater jellies also have a dormant stage where they basically turn into tiny jelly seeds, tough and capable of surviving even if dried out.

And back in the Cambrian era, some 500 million years ago, some jellies actually had skeletons. Fossil impressions show plates, spines, and spokes from comb jellies, which today are completely soft-bodied. Comb jellies are different from the kind of jellies I’ve mostly talked about in this episode, and not even closely related to them. I’d dig into them next, but we’re already pushing 20 minutes and there’s a limit to how much jellyfish information I can expect my listeners to tolerate in one sitting. We’ll save the comb jellies for another episode.

You can find Strange Animals Podcast online at That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at We also have a Patreon if you’d like to support us that way.

Thanks for listening!

Episode 015: Hammerhead shark and Megalodon!

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 That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at We also have a Patreon at 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 010: Electric Animals

This week’s episode is about electric animals! There are so many of them that I could only touch on the highlights.

We start with the electric eel. It’s not actually an eel but it is most definitely electric. This one has just read some disturbing fanfic:

The oriental hornet is a living solar panel:

The platypus’s bill is packed with electricity sensors. I couldn’t make this stuff up if I tried:

Amphisbaenids are not electric AS FAR AS WE KNOW. Bzzt.

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.

This week we’re looking at electric animals! You’ve probably heard of the electric eel, but you may not know there are a lot of fish, insects, and even a few mammals that can sense or generate electric impulses. This is a re-record of the original episode with some updated information.

All animals generate electric fields in their nerves and the contracting of muscles. Animals that can sense these fields are called electroreceptive. An electroreceptive animal can find hidden prey without using its other senses.

To take that a step further, many electroreceptive animals can also generate weak electrical fields, usually less than a single volt—small electrical pulses or a sort of wave, depending on the species, that can give them information about their environment. Like a dolphin using echolocation, a fish using electro-location can sense where potential prey is, where predators, plants, and rocks are, and can even communicate with other fish of its same species. Of course, those same electric pulses can also attract electroreceptive predators. It’s hard being a fish.

But in some cases, the animal can generate an electric shock so strong it can stun or kill other animals. The most famous is the electric eel, so let’s start with that one.

The electric eel isn’t actually an eel. It’s a type of knife-fish related to carp and catfish. Some other species of knife-fish generate electric fields, but the electric eel is the only one that uses it as a weapon.

The electric eel is a weird fish even without the electric part. It can grow over eight feet long, or 2.5 m, lives in freshwater in South America, and gets most of its oxygen by breathing air at the surface of the water instead of through its gills. It has to surface for air about every ten minutes or it will drown. That’s a weird habit for a fish, but it makes sense when you consider that many electric eels live in shallow streams or floodplains with a tendency to dry up between rains. Oh, and electric eels frequently swim backwards.

A male electric eel makes a foam nest for females with his spit, and the female lays her eggs in it—as many as 17,000 eggs, although 1,200 is more common. The male defends the nest and hatchlings until the rainy season starts and the young electric eels can swim off on their own.

The electric eel has rows of some 6,000 specialized cells, called electrocytes, that act like batteries to store energy. When all the electrocytes discharge at the same time, the resulting shock can be as much as 860 volts, although it’s only delivered at about one amp. I have no idea what that means because I don’t understand electricity.

Since the electrocytes are all found in the animal’s tail, and electric eels are mostly tail, the fish will sometimes curl up and hold its prey against its tail to increase the shock it receives. This honestly sounds like something a villain from a superhero movie would do. The electric eel will also sometimes leap out of the water to shock an animal it perceives as a threat.

You do not want to be in the water when an electric eel discharges. It probably won’t kill you unless you have a heart problem, but it could stun you long enough that you drown. And if more than one electric eel discharges at the same time, the danger increases. There’s a River Monsters episode about electric eels that shows a whole bunch of them in water so shallow that they’re barely covered. Walking through that pond would probably be deadly. I also really love that show.

How does the electric eel not shock itself? Well, it probably does. All of its vital organs are in the front fifth of its body, and well insulated by thick skin and a layer of fat. But its discharges are extremely fast. Think taser, not sticking a fork in a wall socket, which by the way is something you should not do. The charge naturally travels away from its tail and into the nearest object, usually its prey.

There are three known species of electric eel, all of which live in the Amazon basin in South America. Two of the three species were only identified in 2019 after DNA studies of 107 specimens. One of the new species, Electrophorus voltai, can discharge up to 860 volts of electricity, higher than the well-known E. electricus. Researchers think E. voltai has evolved to generate higher jolts because it lives in the highlands of the Brazilian Shield, where the water is clear and doesn’t conduct electricity as well as the mineral-rich water in other electric eel habitats.

One last thing about the electric eel. It can shock people who touch it up to eight hours after it dies.

Most electric animals are fish since water conducts electricity well. Some other notable electric fish are the stargazer, a venomous bottom-dwelling ocean fish that generates shocks from modified eye muscles; the paddlefish; the electric catfish; and of course sharks.

Sharks are the kings of electroreceptive animals. Some sharks can sense voltage fluctuations of ten millionths of a volt. Sharks only sense electricity; they can’t generate it. But some of their cousins, the electric rays, can generate an electric shock equivalent to dropping a toaster in a bathtub, which by the way is another thing you shouldn’t do although why would you even have a toaster in the bathroom?

Scientists are only just discovering electric use in insects. It’s probably more widely spread than we suspect, and it’s used in ways that are very different from fish. The oriental hornet, for instance, converts sunlight into energy like a tiny flying solar panel. Researchers think the hornet uses that extra energy for digging its underground nests.

Flying insects generate a positive charge from the movement of air molecules, which is basically what static electricity is. It also happens to moving vehicles, and which is why you should touch the metal of your car to discharge any static electricity before pumping gasoline so you don’t spark a fire. This episode is full of safety tips. In the case of bees, this static charge helps pollen adhere to their bodies. You know, like tiny yellow socks stuck to a shirt you’ve just taken out of the dryer. When a bee lands on a flower, its charge also temporarily changes the electrical status of the flower. Other bees can sense this change and don’t visit the flower since its nectar has already been taken.

Spiderwebs are statoelectrically charged too, which actually draws insects into the web, along with pollen and other tiny air particles. This helps clean the air really effectively, in fact, so if you have allergies you should thank spiders for helping keep the pollen levels down. The webs only become electrically charged because the spider combs and pulls at the thread during the spinning process.

Only three living mammals are known to be electroreceptive. The South American Guiana dolphin has a row of electroreceptors along its beak, visible dots called vibrissal crypts. They’re basically pores where whiskers would have grown, except that marine mammals no longer grow whiskers. The vibrissal crypts are surrounded by nerve endings and contain some specialized cells and proteins. Researchers think the dolphins use electroreception to find fish and other prey animals in murky water when the animals are so close that echolocation isn’t very effective. A lot of toothed whales, including other dolphins, show these dots, and it’s possible that the Guiana dolphin isn’t the only species that is electroreceptive.

The platypus and its cousin the echidna are the other two electric-sensing mammals. These two are both such odd animals that they’re getting their own episode one day—and that episode is # 45! They are weird way beyond being the mammals that lay eggs deal. So I’ll just mention that their bills are packed with electroreceptors. The platypus in particular uses electroreception as its primary means of finding prey in the mud at the bottom of ponds.

There are undoubtedly more animals out there that make use of electrical fields in one way or another. One possible addition to the list, if it exists at all, is called the Mongolian death worm.

Nomadic tribes in the Gobi Desert describe a sausage-like worm over a foot long, or 30 cm, and the thickness of a man’s arm. Its smooth skin is dark red and it has no visible features, not even a mouth, which makes it hard to tell which end is the head and which is the tail. It squirms or rolls to move. It spends most of its life hidden in the sand, but in June and July it emerges, usually after rain, and can kill people and animals at a distance.

In his book The Search for the Last Undiscovered Animals, zoologist Karl Shuker discusses the death worm at length, including the possibility that it might be able to give electric shocks under the right conditions. Among the reports he recounts are some that sound very interesting in this regard, including that of a visiting geologist poking an iron rod into the sand, who dropped dead with no warning. A death worm emerged from the place where the geologist had been prodding the sand. I’m going to add “don’t poke an iron rod into the sand of the Gobi Desert” to my list of warnings.

The Gobi is a cold desert and has bitter winters, but it’s still a desert, which means it’s arid, which means the death worm probably isn’t a type of earthworm or amphibian—nothing that needs a lot of moisture to stay alive. On the other hand, two types of earthworms have recently been discovered in the Gobi, and there are a few amphibians, especially frogs, that have evolved to live in areas that don’t receive much rain. In episode 156, about some animals of Mongolia, we talk about the Mongolian death worm again if you want to know a little more. Some parts of the Gobi get more moisture than others and may be where the death worm lives.

Shuker suggests it might be a kind of amphisbaenid. Amphisbaenids are legless lizards that look more like worms than snakes. They move more like worms than snakes too, and spend a lot of their lives burrowing in search of worms or insects. No known species of amphisbaenid can generate electric shocks, but then again, only one of the over 2,000 known species of catfish generates electricity.

It’s not completely out of the realm of possibility that electrogenesis might develop in a reptile, assuming that’s what the death worm is. Sand isn’t a good conductor of electricity, but wet sand is. The death worm might ordinarily use weak electrical pulses to stun its small prey, but if it emerges after rain because its tunnels are temporarily flooded, it might feel vulnerable above ground and be more likely to discharge electrically as a warning when approached.

Of course, as always, until we have a body—until we know for sure that the Mongolian death worm is a real animal and not a folktale, we can’t do more than speculate. But it is interesting to think about.

As far as I can find, no living reptiles or birds show any electrical abilities akin to those in fish and other aquatic animals. But electroreceptors in fish were only discovered in the 1950s. There’s a lot we still don’t know. Always another mystery to solve!

You can find Strange Animals Podcast online at That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at We also have a Patreon at if you’d like to support us and get twice-monthly bonus episodes.

Thanks for listening!