Tag Archives: Greenland shark

Episode 364: Animals Who Will Outlive Us All

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Thanks to Oz from Las Vegas for suggesting this week’s topic!

Further reading:

Bobi, the supposed ‘world’s oldest dog’ at 31, is little more than a shaggy dog story

Greenland sharks live for hundreds of years

Scientists Identify Genetic Drivers of Extreme Longevity in Pacific Ocean Rockfishes

Scientists Sequence Chromosome-Level Genome of Aldabra Giant Tortoise

Giant deep-sea worms may live to be 1,000 years old or more

A Greenland shark [photo by Eric Couture, found at this site]:

The rougheye rockfish is cheerfully colored and also will outlive us all:

An Aldabra tortoise all dressed up for a night on the town:

Escarpia laminata can easily outlive every human. It doesn’t even know what a human is.

Show transcript:

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

This week we have a great suggestion by Oz from Las Vegas. Oz wanted to learn about some animals that will outlive us all, and gave some suggestions of really long-lived animals that we’ll talk about. We had a similar episode several years ago about the longest lived animals,where for some reason we talked a lot about plants, episode 168, but this is a little different.

But first, a quick correction! Last week we talked about the dodo and some of its relations, including the Nicobar pigeon. I said that the Nicobar pigeon lived in the South Pacific, but Pranav caught my mistake. The Nicobar pigeon lives in the Indian Ocean on the Nicobar Islands, which I should have figured out because of the name.

Anyway, back in the olden days when I was on Twitter all the time, I came across a tweet that’s still my absolute favorite. Occasionally I catch myself thinking about it. It’s by someone named Everett Byram who posted it in January 2018. It goes:

“DATE: so tell me something about yourself

“ME: I am older than every dog”

Not only is it funny, it also makes you thoughtful. People live a whole lot longer than dogs. The oldest living dog is a chihuahua named Spike, who is 23 years old right now. A dog who was supposed to be even older, 31 years old, died in October of 2023, but there’s some doubt about that particular dog’s actual age. Pictures of the dog taken in 1999 don’t actually look like the same dog who died in 2023.

The oldest cat who ever lived, or at least whose age is known for sure, died in 2005 at the age of 38 years. The oldest cat known who’s still alive is Flossie, who was born on December 29th, 1995. If your birthday is before that, you’re older than every cat and every dog.

The oldest human whose age we know for sure was Jeanne Calment, who died in 1997 at the age of 122 years. We talked about her in episode 168. The oldest human alive today, as far as we know, is Maria Branyas, who lives in Spain and will turn 117 years old on her next birthday in March 2024.

It’s not uncommon for ordinary people to live well into their 90s and even to age 100, although after you reach the century mark you’re very lucky and people will start asking you what your secret for a long life is. You might as well go ahead and make something up now to tell people, because it seems to mainly be genetics and luck that allow some people to live far beyond the lives of any dog or cat or most other humans. Staying physically active as you age also appears to be an important factor, so keep moving around.

But there are some animals who routinely outlive humans, animals who could post online and say “I am older than every human” and the others of its species would laugh and say, “Oh my gosh, it’s true! I’m older than every human too!” But they don’t have access to the internet because they are, for instance, a Greenland shark.

We talked about the Greenland shark in episode 163. It lives in the North Atlantic and Arctic Oceans where the water is barely warmer than the freezing point. It can grow up to 23 feet long, or 7 meters, with females being larger than males. Despite getting to such enormous sizes, it only grows one or two centimeters a year, and that was a clue for scientists to look into how old these sharks can get.

In 2016, a team of scientists published a study about how they determined the age of Greenland sharks that had been accidentally caught by fishing nets or that had otherwise been discovered already dead. The lenses inside vertebrate eyeballs don’t change throughout an animal’s life. They’re referred to as metabolically inactive tissue, which means they don’t grow or change as the animal grows. That means that if you can determine how old the lens is, you know when the animal was born, or hatched in the case of sharks.

In the past, scientists have been able to determine the age of dead whales using their eye lenses, but the Greenland shark was different. It turns out that the shark can live a whole lot longer than any whale studied, so the scientists had to use a type of carbon-14 dating ordinarily used by archaeologists.

The Greenland shark may be the oldest-living vertebrate known. Its life expectancy is at least 272 years, and probably closer to 500 years. Individual sharks can most likely live much longer than that. It’s not even mature enough to have babies until it’s about 16 feet long, or 5 meters, and scientists estimate it takes some 150 years to reach that length. Females may stay pregnant for at least 8 years, and maybe as long as 18 years. Babies hatch inside their mother and remain within her, growing slowly, until they’re ready to be born.

The Greenland shark is so big, so long-lived, and lives in such a remote part of the ocean that taking so long to reproduce isn’t a problem. Its body tissues contain chemical compounds that help keep it buoyant so it doesn’t have to use very much energy to swim, and which have a side effect of being toxic to most other animals. Nothing much wants to eat the Greenland shark. But it is caught by accident by commercial fishing boats, with an estimated 3,500 sharks killed that way every year. Scientists hope that by learning more about the Greenland shark, they can bring more attention to its plight and make sure it’s protected. There’s still a lot we don’t know about it.

At least one species of whale does live much longer than humans. In 2007, researchers studying a dead bowhead whale found a piece of harpoon embedded in its skin. It turned out to be a type of harpoon that was manufactured between 1879 and 1885. After that, scientists started testing other bowhead whales that were found dead. The oldest specimen studied was determined to be 211 years old when it died, and it’s estimated that the bowhead can probably live well past 250 years if no one harpoons it and it stays healthy. It may be the longest-lived mammal. It has a low metabolic rate compared to other whales, which may contribute to its longevity.

Most small fish don’t live very long even if nothing eats them. Rockfish, for instance, only live for about 10 years even if they’re really lucky. Well, most rockfish. There is one species, the rougheye rockfish, that lives much, much longer. Its lifespan is at least 200 years old.

The rougheye rockfish has a lot of other common names. Its scientific name is Sebastes aleutianus. It can grow over 3 feet long, or 97 cm, and is red or orangey-red. It lives in cold waters of the Pacific, where it usually stays near the sea floor. It eats other fish along with crustaceans.

Naturally, scientists are curious as to why the rougheye rockfish lives so long but its close relations don’t. In 2021 a team of scientists published results of a genetic study of the rougheye rockfish and 87 other species. They discovered a number of genes associated with longevity, along with genes controlling inflammation that may help the fish stay healthy for longer.

The rougheye rockfish only evolved as a separate species of rockfish about ten million years ago. Because the longest-living females lay the most eggs, the genes for longevity are more likely to be passed on to the next generation, which means that as time goes on, lifespans of the fish overall get longer and longer. The rougheye also isn’t the only species of rockfish that lives a long time, it’s just the one that lives longest. At least one other species can live over 150 years and quite a few live past 100 years.

Another animal that can easily outlive humans is the giant tortoise, which we talked about in episode 95. Giant tortoises are famous for their longevity, routinely living beyond age 100 and sometimes more than 200 years old. The oldest known tortoise is an Aldabra giant tortoise that may have been 255 years old when it died in 2006. The Aldabra giant tortoise is from the Aldabra Atoll in the Seychelles, a collection of 115 islands off the coast of East Africa.

Scientists studied the Aldabran tortoise’s genetic profile in 2018 and learned that in addition to genes controlling longevity, it also has genes that control DNA repair and other processes that keep it healthy for a long time.

Oz also suggested the infinite jellyfish, also called the immortal jellyfish. An adult immortal jelly that’s starving or injured can transform itself back into a polyp, its juvenile stage. We talked about it in episode 343 in some detail, which was recent enough that I won’t cover it again in this episode. Scientists are currently studying the jelly to learn more about how it accomplishes this transformation and how long it can really live.

So far all the animals we’ve talked about, except the immortal jellyfish, are vertebrates. It’s when we get to the invertebrates that we find animals with the longest lifespans. The ocean quahog, a type of clam that lives in the North Atlantic Ocean, grows very slowly compared to other clams, and populations that live in cold water can live a long time. Sort of like tree rings, the age of a clam can be determined by counting the growth rings on its shell, and a particular clam dredged up from the coast of Iceland in 2006 was discovered to be 507 years old. Its age was double-checked by carbon-14 dating of the shell, which verified that it was indeed just over 500 years old when it was caught and died. Researchers aren’t sure how long the quahog can live, but it’s a safe bet that there are some alive today that are older than 507 years, possibly a lot older.

The real long-lived animals are very simple ones, especially sponges and corals. Some species of both can live for thousands of years. Various kinds of mollusks and at least one urchin can live for hundreds of years.

It’s probable that there are lots of other animals that routinely outlive humans, we just don’t know that they do. Scientists don’t always have a way to check an animal’s age, or they don’t think to do so while studying an organism. There are also plenty of animals that we just don’t know exist, especially ones that live in the ocean. For example, a species of tube worm named Escarpia laminata wasn’t even discovered until 1985, and it wasn’t until 2017 that scientists realized it lived for hundreds or even thousands of years.

The tube worm doesn’t have a common name, since it lives in the deepest parts of the Gulf of Mexico around what are called cold seeps, so no one ever needed to refer to it until it was discovered by scientists. A cold seep isn’t actually cold, it just isn’t as hot as a hydrothermal vent. In a cold seep, oil and methane are released into the ocean from fissures in the earth’s crust. Life forms live around these areas that live nowhere else in the world.

Many tube worms can grow quite long and can live over 250 years, with the giant tube worm growing almost 10 feet long, or 3 meters. Escarpia laminata is smaller, typically only growing about half that length. In a study published in 2017, a team of scientists estimated that it routinely lives for 250 to 300 years and potentially much, much longer. A tube worm doesn’t actually eat; instead, it forms a symbiotic relationship with bacteria that live in its body. The bacteria have a safe place to live and the tube worm receives energy from the bacteria as they oxidize sulfur released by the cold seeps. The tube worm, in other words, lives a stress-free life with a constant source of energy, and nothing much wants to eat it. The limit to its life may be the limit of the cold seeps where it lives. Cold seeps don’t last forever, although many of them remain active for thousands of years.

Humans are probably the longest-living terrestrial mammal. This may not seem too impressive compared to the animals we’ve talked about in this episode, but our lives are a whole lot more interesting than a tube worm’s.

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

Thanks for listening!

Episode 168: The Longest Lived

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This week let’s take a look at some animals (and other living organisms) that live the longest!

This isn’t Methuselah itself (scientists aren’t saying which tree it is, to keep it safe), but it’s a bristlecone pine:

The Jaya Sri Maha Bodhi, a sacred fig tree in Sri Lanka, planted in 288 BCE by a king:

Some trees of the quaking aspen colony called Pando:

Glass sponges (this one’s called the Venus Flower Basket):

Further reading:

Glass sponge as a living climate archive

Show transcript:

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

This week we’re going to look at the world’s longest lived animals and other organisms. We’re straying into plant territory a little bit here, but I think you’ll agree that this is some fascinating information.

The oldest human whose age we can verify was a French woman who lived to be 122 years old, plus 164 days. Her name was Jeanne Calment and she came from a long-lived family. Her brother lived to the age of 97. Jeanne was born in 1875 and didn’t die until 1997. But the sad thing is, she outlived her entire family. She had a daughter who died of a lung disease called pleurisy at only 36 years old—in fact, on her 36th birthday—and her only grandson died in a car wreck in his late 30s. Jeanne remained healthy physically and mentally until nearly the end of her life, although she had always had poor eyesight.

It’s not all that rare for humans to live past the age of 100, but it is rare for anyone to live to age 110 or beyond. But other animals have average lifespans that are much, much longer than that of humans.

In episode 163 we talked about the Greenland shark, which can live for hundreds of years. The oldest Greenland shark examined was possibly as old as 512 years old, and the sharks may live much longer than that. It’s actually the longest-lived vertebrate known.

No one’s sure which terrestrial vertebrate lives the longest, but it’s probably a tortoise. Giant tortoises are famous for their longevity, routinely living beyond age 100 and sometimes more than 200 years old. The difficulty of verifying a tortoise’s age is that to humans, tortoises all look pretty much alike and we don’t always know exactly when a particular tortoise was hatched. Plus, of course, we know even less about tortoises in the wild than we do ones kept in captivity. But probably the oldest known is an Aldabra giant tortoise that may have been 255 years old when it died in 2006. We talked about giant tortoises in episode 95.

But for the really long-lived creatures, we have to look at the plant world. The oldest individual tree whose age we know for certain is a Great Basin bristlecone pine called Methuselah. Methuselah lives in the Inyo National Forest in the White Mountains in California, which of course is on the west coast of North America. In 1957 a core sample was taken from it and other bristlecone pines that grow in what’s called the ancient bristlecone pine forest. Many trees show growth rings in the trunk that make a pattern that’s easy to count, so the tree’s age is easy to determine as long as you have someone who is patient enough to count all the rings. Well, Methuselah was 4,789 years old in 1957. It probably germinated in 2833 BCE. Other trees in the forest were nearly as old, with at least one possibly older, but the sample from that older tree is lost and no one’s sure where the tree the sample came from is.

Another bristlecone pine, called the Prometheus Tree, germinated even earlier than Methuselah, probably in 2880 BCE, but it’s now dead. A grad student cut it down in 1964, possibly by accident—stories vary and no one actually knows why he cut the tree down. The bristlecone pine is now a protected species.

There are other trees estimated to be as old as Methuselah. This includes a yew in North Wales that may be 5,000 years old and is probably at least 4,000 years old, and a cypress in Iran that’s at least 2,000 years old and possibly 5,000 years old. Sequoyahs from western North America, baobabs from Africa, and kauri trees from New Zealand are all documented to live over a thousand years and possibly many thousands of years.

In at least one case, a sacred fig tree in Sri Lanka, we know exactly when the tree was planted. A Buddhist nun brought a branch of the original sacred fig tree, the one that the Buddha was sitting under when he achieved enlightenment, to Sri Lanka and presented it to King Devanampiya Tissa. He planted the branch in the royal park in 288 BCE, where it grew into a tree which remains in the park to this day, more than 2,000 years later. It’s cared for by Buddhists monks and people come from all over Sri Lanka to visit the tree. If this sounds a little too good to be true, the easiest way to grow a sacred fig is to use a cutting from another tree. The cutting will root and grow into a new tree.

Not all trees are individuals. You may not know this and I didn’t either until recently. Some trees grow as colonies. The most well known tree colony is called Pando, made up of quaking aspens that live in Utah in North America. While the individual trees are only around 130 years old on average, Pando itself has been alive for an estimated 80,000 years. Each tree is a male clone and all the trees are connected by a root system that covers 106 acres, or 43 hectares. Because its root system is so huge and deep, Pando is able to survive forest fires that kill all other trees. Pando’s trees die, but afterwards the roots just send up shoots that grow into new trees. Researchers estimate that it’s been 10,000 years since Pando’s trees actually flowered. Unfortunately, Pando is currently threatened by humans stopping the forest fires that otherwise would kill off rival trees, and threatened by grazing livestock that kill off young trees before they can become established.

Pando isn’t the only quaking aspen colony known, though. There are a number of smaller colonies in western North America. Researchers think it’s an adaptation to frequent forest fires and a semi-arid climate that makes it harder for seedlings to grow. Quaking aspens that live in northeastern North America, where the climate is much wetter, grow from seeds instead of forming colonies.

Other species of tree form colonies too, including a spruce tree in Sweden whose root system dates to nearly 10,000 years ago and a pine colony in Tasmania that is about the same age but with individual trees that are themselves 3,000 years old. Not all long-lived plant colonies are trees, though. A colony of sea grass in the Mediterranean may be as much as 200,000 years old although it may be only 12,000 years old, researchers aren’t sure.

I could go on and on about long-lived plants, but let’s get back to the animals. If the Greenland shark is the longest lived vertebrate known, what’s the longest lived invertebrate? Here’s your reminder that a vertebrate is an animal with some form of spine, while an invertebrate has no spine.

Many invertebrates that live in the ocean have long lifespans. Corals of various kinds can live for thousands of years, for instance. The ocean quahog, a type of clam that lives in the North Atlantic Ocean, grows very slowly compared to other clams. It isn’t fully mature until it’s nearly six years old, and populations that live in cold water can live a long time. Sort of like tree rings, the age of a clam can be determined by counting the growth rings on its shell, and a particular clam dredged up from the coast of Iceland in 2006 was discovered to be 507 years old. Its age was double-checked by carbon-14 dating of the shell, which verified that it was indeed just over 500 years old when it was caught and died. Researchers aren’t sure how long the quahog can live, but it’s a safe bet that there are some alive today that are older than 507 years, possibly a lot older.

But the invertebrate that probably lives the longest is the glass sponge. It’s found throughout the world’s oceans, but is especially common in cold waters of the Northern Pacific and Antarctic. It usually grows up to about a foot tall, or 30 cm, although some species grow larger, and is roughly shaped like a vase. Most species are white or pale in color. In some places the sponges fuse together to form reefs, with the largest found so far 65 feet tall, or 20 meters, and nearly four and a half miles long, or 7 km.

The glass sponge is a simple creature with a lattice-like skeleton made of silica covered with porous tissue. It anchors itself to a rock or the ocean floor, frequently in deep water, and as water flows through the openings in its body, it filters microscopic food out. So it basically lives a very slow, very plant-like existence.

One glass sponge, Monorhaphis chuni, anchors itself to the sea floor with a long basal spicule that looks like a stem. This stem can be over nine feet long, or 3 m. It needs to be long because it lives in deep water where there’s a lot of soft sediment at the bottom. In 1986 the skeleton of a dead Monorhaphis was collected from the East China Sea so it could be studied. Since a glass sponge adds layers of skeleton to its basal spicule every year as it grows, you guessed it, the layers can be counted just like tree rings—although it requires an electron microscope to count since the layers are very small. The sponge was determined to be about 11,000 years old when it died. Researchers are able to determine local ocean temperature changes from year to year by studying the rings, just as tree rings give us information about local climate.

Let’s finish with something called an endolith. An endolith isn’t a particular animal or even a group of related animals. An endolith is an organism that lives inside a rock or other rock-like substance, such as coral. Some are fungi, some lichens, some amoebas, some bacteria, and various other organisms, many of them single-celled and all of them very small if not microscopic. Some live in tiny cracks in a rock, some live in porous rocks that have space between grains of mineral, some bore into the rock. Many are considered extremophiles, living in rocks inside Antarctic permafrost, at the tops of the highest mountains, in the abyssal depths of the oceans, and at least two miles, or 3 km, below the earth’s surface.

Various endoliths live on different minerals, including potassium, sulfur, and iron. Some endoliths even eat other endoliths. We don’t know a whole lot about them, but studies of endoliths found in soil deep beneath the ocean’s floor suggest that they grow extremely slowly. Like, from one generation to the next could be as long as 10,000 years, with the oldest endoliths potentially being millions of years old—even as old as the sediment itself, which dates to 100 million years old.

That is way older than Jeanne Calment and all those trees.

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

Thanks for listening!

Episode 163: Three Weird Fish

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Thanks to Nathan for his suggestions! This week we’re going to learn about three strange and interesting fish!

A northern snakehead:

A giant snakehead:

A Greenland shark, fish of mystery:

The upside-down catfish is indeed upside down a lot of the time (this is actually a picture of Synodontis nigriventris, closely related to the upside-down catfish we talk about in the episode):

An ancient Egyptian upside-down catfish pendant that ladies wore in their hair:

Show transcript:

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

We haven’t done a fish episode in a while, so this week let’s learn about three weird fish. Thanks to Nathan for suggesting the first two fish, the snakehead and the Greenland shark.

The snakehead is a freshwater fish that gets its name because while it’s an ordinary-looking fish for the most part, it has a flattened head that looks a little bit like a snake’s. Different species of snakehead look different in other ways, of course, so let’s examine a couple of typical species.

The northern snakehead is native to Asia, but it’s been introduced into other parts of the world by accident or as a food fish. It’s one of the largest species, with reports of some specimens growing up to five feet long, or 1.5 meters. It’s usually no more than three feet long, though, or 1 meter. It’s brown with darker blotches and has sharp teeth that it uses to catch fish, frogs, and other small animals.

Like other snakeheads, the northern snakehead can breathe air and survive out of water for several days as long as it stays damp. Young snakeheads can even wriggle considerable distances on land to find water. It likes stagnant or slow-moving water.

Because it’s a fierce predator that can find its way to new waterways, introduced snakeheads are invasive species that can cause havoc to populations of native fish. The northern snakehead has been introduced into many waterways in the United States in the last twenty years, as a result of people releasing unwanted aquarium fish and accidental release of snakeheads in fish-farming operations. Since snakeheads reach mature age quickly and females can lay thousands of eggs at a time, snakeheads are illegal to own in many places now and release snakeheads into the wild is even more against the law.

The giant snakehead also grows up to five feet long, or 1.5 m, and is from parts of southeast Asia. Young giant snakeheads are red, but when they grow up they’re black and white with a thick black stripe down each side. It’s also been introduced into a lot of places as a food fish and a game fish, but since it’s a tropical species it can’t survive colder weather and isn’t as invasive as a result, at least not outside of tropical and subtropical areas.

The giant snakehead can be aggressive, though, especially when it’s guarding its nest. Both parents act as guards of the eggs and the newly hatched babies, which follow their mother around wherever she goes. That’s actually really cute.

Next let’s talk about the Greenland shark. We covered it briefly in episode 74, about colossal squid and the things that eat them, but mostly we talked about its close relative the sleeper shark. The Greenland shark is similar in some ways but it’s much bigger than the sleeper shark. It lives in the North Atlantic and Arctic Oceans where the water is barely warmer than the freezing point and it grows up to 24 feet long, or 7.3 meters, with females being larger than males.

But despite how enormous it is, it’s not a shark you need to worry about. First of all, what are you doing swimming in water that cold? Second, the Greenland shark is a slow swimmer, no more than about 1 ½ miles per hour, or 2.6 km/h. You can walk faster than that without even trying. You can probably dog-paddle faster than that.

And yet, the Greenland shark manages to eat seals and fish and other animals that move quickly. Since no one’s actually observed a Greenland shark hunting, no one knows how they catch prey. Some researchers speculate that it sneaks up on sleeping seals and grabs them. It also eats a lot of carrion, including dead moose and reindeer and polar bears that fall into the water and drown. One shark was found with an entire reindeer in its stomach.

The Greenland shark spends winter in shallow water where it’s warmer, but in summer it spends more time in deep water. At least one submersible observed a Greenland shark 7,200 feet below the surface of the ocean, or 2,200 meters. Occasionally a Greenland shark travels more widely, usually in deep water where the water is cold. In 2013 one was caught by researchers in the Gulf of Mexico, which is way far away from the Arctic. It was swimming at over 5,700 feet deep, or 1,750 meters.

The Greenland shark is adapted to the cold and pressure of the deep sea in many ways. Its blood contains three types of hemoglobin, which help it absorb as much oxygen as possible from water that’s poorly oxygenated to start with. Its muscles and other tissues contain high levels of urea and other compounds that increase its buoyancy, so that it doesn’t need to work as hard to stay in one place. But the presence of urea in its muscles means that the Greenland shark not only tastes horrible, it’s toxic. In Iceland Greenland sharks are considered a delicacy, but only after the toxins have been removed from the meat by long treatment. This includes burying it in the ground for weeks, partially fermenting it, and drying it for several months afterwards. Most people don’t bother and any commercial fishing boats that catch Greenland sharks just toss them back overboard.

The Greenland shark has a very slow metabolism and grows extremely slowly too. That’s okay, though, because it lives a very long time. A VERY long time. The biggest Greenland sharks may be as much as 600 years old. Researchers examine the crystals in dead Greenland shark eyeballs to determine when they were hatched.

And speaking of Greenland shark eyeballs…some of you know where this is going. I hope you’re not eating grapes or anything right now. There’s a type of copepod, a crustacean, that acts as a parasite of the Greenland shark and the Pacific sleeper shark, its close relative. The copepod grows to about an inch long, or 28 mm, and attaches itself to the shark’s cornea, which is part of the eyeball. This impairs the shark’s vision but it doesn’t seem to care and it doesn’t seem to have any trouble finding food.

Okay let’s stop talking about that. Our third and final weird fish for this episode is a type of catfish that’s sometimes kept in aquariums. It’s called the upside-down catfish.

There are actually a number of closely-related catfish known as upside-down catfish, but the one we’ll talk about today is Synodontis batensoda. It lives in parts of Africa in marshy areas and slow-moving water. It grows to a little over a foot and a half long, or 50 cm, and eats plankton, algae, mollusks, insects and larvae, and crustaceans.

But the upside-down catfish gets its name from its habit of swimming upside down. Because it’s kept as an aquarium fish so often, many people assume that the upside-down swimming is something it developed because it’s kept in an enclosed aquarium habitat. But that’s actually not the case.

The catfish used to be well-known in Egypt, and there’s even an Egyptian tomb carving depicting a catfish swimming upside down, dating to the Middle Kingdom around 4,000 years ago. The upside-down catfish was often depicted in jewelry, too, including hair ornaments so beautifully made that the species of catfish can be determined. Young women in Egypt traditionally wore fish ornaments to decorate their braids. There’s a story about one young woman who was helping row a king across a lake when her fish pendant fell into the water. She stopped rowing, naturally, which messed up the other rowers. The king wanted to know why the boat had stopped, and when the woman explained, he offered to give her a new fish pendant. But no, she said, she wanted that one, the one that was now at the bottom of the lake. But the king had a magician who said no problem, and caused the water to fold back like a blanket, exposing the lake’s bottom so the pendant could be retrieved. I didn’t make that story up, either. It’s from the Westcar Papyrus that dates to around the 17th century BCE.

So why does the upside-down catfish swim upside down? Like other catfish, its mouth is angled downward so it can find food in the mud at the bottom of the water. So when it wants to grab an insect on the water’s surface, or eat algae off the bottom of a submerged leaf, it can only do so by turning upside down.

So that’s it for this week’s episode. I don’t know what else to say because I’m just sitting here trying to imagine how I’d manage if someone told me I had to swim upside down. But then, I can barely swim right side up. Good job, upside-down catfish!

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

Thanks for listening!

Episode 074: Colossal Squid and the Things That Eat Them

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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:

THAT EYEBALL:

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.

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Thanks for listening!