Tag Archives: polychaete worms

Episode 342: Giant Snails and Giant Crabs

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Thanks to Tobey and Anbo for their suggestions this week! We’re going to learn about some giant invertebrates!

Further reading:

The Invasive Giant African Land Snail Has Been Spotted in Florida

A very big shell:

The giant African snail is pretty darn giant [photo from article linked above]:

The largest giant spider crab ever measured, and a person:

Show transcript:

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

This week we’re going to learn about some giant invertebrates, suggested by Tobey and Anbo. Maybe they’re not as big as dinosaurs or whales, but they’re surprisingly big compared to most invertebrates.

Let’s start with Tobey’s suggestion, about a big gastropod. Gastropods include slugs and snails, and while Tobey suggested the African trumpet snail specifically, I couldn’t figure out which species of snail it is. But it did lead me to learning a lot about some really big snails.

The very biggest snail known to be alive today is called the Australian trumpet snail, Syrinx aruanus. This isn’t the kind of snail you’d find in your garden, though. It’s a sea snail that lives in shallow water off the coast of northern Australia, around Papua New Guinea, and other nearby areas. It has a coiled shell that’s referred to as spindle-shaped, because the coils form a point like the spindle of a tower. It’s a pretty common shape for sea snails and you’ve undoubtedly seen this kind of seashell before if you’ve spent any time on the beach. But unless you live in the places where the Australian trumpet lives, you probably haven’t seen a seashell this size. The Australian trumpet’s shell can grow up to three feet long, or 91 cm. Not only is this a huge shell, the snail itself is really heavy. It can weigh as much as 31 lbs, or 14 kg, which is as heavy as a good-sized dog.

The snail eats worms, but not just any old worms. If you remember episode 289, you might remember that Australia is home to the giant beach worm, a polychaete worm that burrows in the sand between high and low tide marks. It can grow as much as 8 feet long, or 2.4 meters, and probably longer. Well, that’s the type of worm the Australian trumpet likes to eat, along with other worms. The snail extends a proboscis into the worm’s burrow to reach the worm, but although I’ve tried to find out how it actually captures the worm in order to eat it, this seems to be a mystery. Like other gastropods, the Australian trumpet eats by scraping pieces of food into its mouth using a radula. That’s a tongue-like structure studded with tiny sharp teeth, and the Australian trumpet has a formidable radula. Some other sea snails, especially cone snails, are able to paralyze or outright kill prey by injecting it with venom via a proboscis, so it’s possible the Australian trumpet does too. The Australian trumpet is related to cone snails, although not very closely.

Obviously, we know very little about the Australian trumpet, even though it’s not hard to find. The trouble is that its an edible snail to humans and humans also really like those big shells and will pay a lot for them. In some areas people have hunted the snail to extinction, but we don’t even know how common it is overall to know if it’s endangered or not.

Tobey may have been referring to the giant African snail, which is probably the largest living land snail known. There are several snails that share the name “giant African snail,” and they’re all big, but the biggest is Lissachatina fulica. It can grow more than 8 inches long, or 20 cm, and its conical shell is usually brown and white with pretty banding in some of the whorls. It looks more like the shell of a sea snail than a land snail, but the shell is incredibly tough.

The giant African snail is an invasive species in many areas. Not only will it eat plants down to nothing, it will also eat stucco and concrete for the minerals they contain. It even eats sand, cardboard, certain rocks, bones, and sometimes other African giant snails, presumably when it runs out of trees and houses to eat. It can spread diseases to plants, animals, and humans, which is a problem since it’s also edible.

Like many snails, the African giant snail is a simultaneous hermaphrodite, meaning it can produce both sperm and eggs. It can’t self-fertilize its own eggs, but after mating a snail can keep any unused sperm alive in its body for up to two years, using it to fertilize eggs during that whole time, and it can lay up to 200 eggs five or six times a year. In other words, it only takes a single snail to produce a wasteland of invasive snails in a very short amount of time.

In June 2023, some African giant snails were found near Miami, Florida and officials placed the whole area under agricultural quarantine. That means no one can move any soil or plants out of the area without permission, since that could cause the snails to spread to other places. Meanwhile, officials are working to eradicate the snails. Other parts of Florida are also under the same quarantine after the snails were found the year before. Sometimes when people go on vacation in the Caribbean they bring back garden plants, without realizing that the soil in the pot contains giant African snail eggs, because the giant African snail is also an invasive species throughout the Caribbean.

Next, Anbo wanted to learn about the giant spider crab, also called the Japanese spider crab because it lives in the Pacific Ocean around Japan. It is indeed a type of crab, which is a crustacean, which is an arthropod, and it has the largest legspan of any arthropod known. Its body can grow 16 inches across, or 40 cm, and it can weigh as much as 42 pounds, or 19 kg, which is almost as big as the biggest lobster. But its legs are really really really long. Really long! It can have a legspan of 12 feet across, or 3.7 meters! That includes the claws at the end of its front legs. Most individual crabs are much smaller, but since crustaceans continue to grow throughout their lives, and the giant spider crab can probably live to be 100 years old, there’s no reason why some crabs couldn’t be even bigger than 12 feet across. Its long legs are delicate, though, and it’s rare to find an old crab that hasn’t had an injury to at least one leg.

The giant spider crab is orange with white spots, sort of like a koi fish but in crab form. Its carapace is also bumpy and spiky. You wouldn’t think a crab this size would need to worry about predators, but it’s actually eaten by large octopuses. The crab sticks small organisms like sponges and kelp to its carapace to help camouflage it.

The giant spider crab is considered a delicacy in some places, which has led to overfishing. It’s now protected in Japan, where people are only allowed to catch the crabs during part of the year. This allows the crabs to safely mate and lay eggs.

There’s another species called the European spider crab that has long legs, but it’s nowhere near the size of the giant spider crab. Its carapace width is barely 8 ½ inches across, or 22 cm, and its legs are about the same length. Remember that the giant spider crab’s legs can be up to six feet long each, or 1.8 meters. While the European spider crab does resemble the giant spider crab in many ways, it’s actually not closely related to it. They two species belong to separate families.

The giant spider crab spends most of its time in deep water, although in mating season it will come into shallower water. It uses its long legs to walk around on the sea floor, searching for food. It’s an omnivore that eats pretty much anything it can find, including plants, dead animals, and algae, but it will also use its claws to open mollusk shells and eat the animals inside. It prefers rocky areas of the sea floor, since its bumpy carapace blends in well among rocks.

Scientists report that the giant spider crab is mostly good-natured, even though it looks scary. Some big aquariums keep giant spider crabs, and the aquarium workers say the same thing. But it does have strong claws, and if it feels threatened it can seriously injure divers. I shouldn’t need to remind you not to pester a crab with a 12-foot legspan.

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 289: Weird Worms

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This week we learn about some weird worms!

Further reading:

Otherworldly Worms with Three Sexes Discovered in Mono Lake

Bizarre sea worm with regenerative butts named after Godzilla’s monstrous nemesis

Underground giant glows in the dark but is rarely seen

Giant Gippsland earthworm (you can listen to one gurgling through its burrow here too)

Further watching:

A giant Gippsland earthworm

Glowing earthworms (photo by Milton Cormier):

This sea worm’s head is on the left, its many “butts” on the right [photo from article linked to above]:

A North Auckland worm [photo from article linked to above]:

A giant beach worm:

Show transcript:

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

This week we continue Invertebrate August with a topic I almost saved for monster month in October. Let’s learn about some weird worms!

We’ll start with a newly discovered worm that’s very tiny, and we’ll work our way up to larger worms.

Mono Lake in California is a salty inland lake that probably started forming after a massive volcanic eruption about 760,000 years ago. The eruption left behind a crater called a caldera that slowly filled with water from rain and several creeks. But there’s no outlet from the lake—no river or even stream that carries water from the lake down to the ocean. As a result, the water stays where it is and over the centuries a lot of salts and other minerals have dissolved into the lake from the surrounding rocks. The water is three times as salty as the ocean and very alkaline.

No fish live in the lake, but some extremophiles do. There’s a type of algae that often turns the water bright green, brine shrimp that eat the algae, some unusual flies that dive into the water encased in bubbles, birds that visit the lake and eat the brine shrimp and flies, and eight species of worms that have only been discovered recently. All the worms are weird, but one of them is really weird. It hasn’t been described yet so at the moment is just going by the name Auanema, since the research team thinks it probably belongs in that genus.

Auanema is microscopic and lives throughout the lake, which is unusual because the lake contains high levels of arsenic. You know, a DEADLY POISON. But the arsenic and the salt and the other factors that make the lake inhospitable to most life don’t bother the worms.

Auanema produces offspring that can have one of three sexes: hermaphrodites that can self-fertilize, and males and females that need each other to fertilize eggs. Researchers think that the males and females of the species help maintain genetic diversity while the hermaphrodites are able to colonize new environments, since they don’t need a mate to reproduce.

When some of the worms were brought to the laboratory for further study, they did just fine in normal lab conditions, without extreme levels of arsenic and so forth. That’s unusual, because generally extremophiles are so well adapted for their extreme environments that they can’t live anywhere else. But Auanema is just fine in a non-harsh environment. Not only that, but the team tested other species in the Auanema genus that aren’t extremophiles and discovered that even though they don’t live in water high in arsenic, they tolerate arsenic just as well as the newly discovered species.

The team’s plan is to sequence Auanema’s genome to see if they can determine the genetic factors that confer such high resistance to arsenic.

Next, we go up in size from a teensy worm to another newly discovered worm, this one only about 4 inches long at most, or 10 cm. It’s a marine polychaete worm that lives inside sea sponges, although we don’t know yet if it’s parasitizing the sponge or if it confers some benefit to the sponge that makes this a symbiotic relationship. The worm was only discovered in 2019 near Japan and described in early 2022 as Ramisyllis kingghidorahi.

Almost all worms known are shaped, well, like worms. They have a mouth at one end, an anus at the other, and in between they’re basically just a tube. Ramisyllis is one of only three worms known that have branched bodies, which is why they’re called branching sea worms. In this case, Ramisyllis has a single head, which stays in the sponge, but its other end branches into multiple tail ends that occasionally break off and swim away. The tails are specialized structures called stolons. When a stolon breaks off, it swims away and releases the eggs or sperm it contains into the water before dying. The worm then regenerates another stolon in its place.

Ramisyllis’s branches are asymmetrical and the worms found so far can have dozens of branches. Its close relation, a species that lives in sponges off the coast of northern Australia, can have up to 100 branches. Researchers suspect that there are a lot more species of branching sea worms that haven’t been discovered yet.

Next, let’s head back to land to learn about a regular-sized earthworm. There are quite a few species across three different earthworm families that exhibit a particular trait, found in North and South America, Australia and New Zealand, and parts of Africa. A few species have been introduced to parts of Europe too. What’s the trait that links all these earthworms? THEY CAN GLOW IN THE DARK.

Bioluminescent earthworms don’t glow all the time. Most of the time they’re just regular earthworms of various sizes, depending on the species. But if they feel threatened, they exude a special slime that glows blue or green in the dark, or sometimes yellowish like firefly light. The glow is caused by proteins and enzymes in the slime that react chemically with oxygen.

Researchers think that the light may startle predators or even scare them away, since predators that live and hunt underground tend to avoid light. The glow may also signal to predators that the worm could taste bad or contain toxins. The light usually looks dim to human eyes but to an animal with eyes adapted for very low light, it would appear incredibly bright.

One bioluminescent earthworm is called the New Zealand earthworm. It can grow up to a foot long, or 30 cm, although it’s only about 10 mm thick at most, and while it’s mostly pink, it has a purplish streak along the top of its body (like a racing stripe).

Like other earthworms, the New Zealand earthworm spends most of its time burrowing through the soil to find decaying organic matter, mostly plant material, and it burrows quite deep, over 16 feet deep, or 5 meters. If a person tried to dig a hole that deep, without special materials to keep the hole from collapsing, it would fall in and squish the person. Dirt and sand are really heavy. The earthworm has the same problem, which it solves by exuding mucus from its body that sticks to the dirt and hardens, forming a lining that keeps the burrow from collapsing. This is a different kind of mucus than the bioluminescent kind, and all earthworms do this. Not only does the burrow lining keep the worm safe from being squished by cave-ins, it also contains a toxin that kills bacteria in the soil that could harm the worm.

Worms that burrow as deep as the New Zealand earthworm does are called subsoil worms, as opposed to topsoil worms that live closer to the surface. Topsoil contains a lot more organic material than subsoil, but it’s also easier for surface predators to reach. That’s why topsoil worms tend to move pretty fast compared to subsoil worms.

The New Zealand earthworm glows bright orange-yellow if it feels threatened, so bright that the Maori people used the worm as bait when fishing since it’s basically the best fish lure ever.

Another New Zealand earthworm is called the North Auckland worm, and while it looks like a regular earthworm that’s mostly pink or greenish, it’s also extremely large. Like, at least four and a half feet long, or 1.4 meters, and potentially much longer. It typically lives deep underground in undisturbed forests, so there aren’t usually very many people around on the rare occasion when heavy rain forces it to the surface. Since earthworms of all kinds absorb oxygen through the skin, instead of having lungs or gills, they can’t survive for long in water and have to surface if their burrow completely floods.

We don’t actually know that much about the North Auckland worm. Like the New Zealand earthworm, it’s a subsoil worm that mostly eats dead plant roots. Some people report that it glows bright yellow, although this hasn’t been studied and it’s not clear if this is a defensive reaction like in the New Zealand earthworm. It’s possible that people get large individual New Zealand earthworms confused with smaller North Auckland worm individuals. Then again, there’s no reason why both worms can’t bioluminesce.

An even bigger worm is the giant beach worm. It’s a polychaete worm, not an earthworm, and like other polychaete worms, including the branching sea worm we talked about earlier, it has a segmented body with setae that look a little like legs, although they’re just bristles. The giant beach worm’s setae help it move around through and over the sand. It hides in a burrow it digs in the sand between the high and low tide marks, but it comes out to eat dead fish and other animals, seaweed, and anything else it can find. It has strong jaws and usually will poke its head out of its burrow just far enough to grab a piece of food. It has a really good sense of smell but can’t see at all.

There are two species of giant beach worm that live in parts of Australia, especially the eastern and southeastern coasts, where people dig them up to use as fish bait. The largest species can grow up to 8 feet long, or 2.4 meters, and possibly even longer. There are also two species that live in Central and South America, although we don’t know much about them.

Another huge Australian worm is the endangered Giant Gippsland earthworm that lives in Victoria, Australia. It’s also a subsoil worm and is about 8 inches long, or 20 cm…when it’s first hatched. It can grow almost ten feet long, or 3 meters. It’s mostly bluish-gray but you can tell which end is its head because it’s darker in color, almost purple. It lives beneath grasslands, usually near streams, and is so big that if you happen to be in the right place at the right time on a quiet day and listen closely, you might actually hear one of the giant worms moving around underground. When it moves quickly, its body makes a gurgling sound as it passes through the moist soil in its burrow.

The Giant Gippsland earthworm is increasingly endangered due to habitat loss. It also reproduces slowly and takes as much as five years to reach maturity. Conservationists are working to protect it and its remaining habitat in Gippsland. The city of Korumburra used to have a giant worm festival, but it doesn’t look like that’s been held for a while, which is too bad because there aren’t enough giant worm festivals in the world.

To finish us off, let’s learn what the longest worm ever reliably measured is. It was found on a road in South Africa in 1967 and identified as Microchaetus rappi, or the African giant earthworm. It’s mostly dark greenish-brown in color and it looks like an earthworm, because it is an earthworm. On average, this species typically grows around 6 feet long, or 1.8 meters, which is pretty darn big, but this particular individual was 21 feet long, or 6.7 meters. It’s listed in the Guinness Book of World Records as the longest worm ever measured. Beat that, other worms. I don’t think you can.

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. If you like the podcast and want to help us out, leave us a rating and review on Apple Podcasts or Podchaser, or just tell a friend. 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 253: The Sand Striker

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This week let’s learn about a weird marine worm and its extinct ancestor!

Further reading:

Eunice aphroditois is a rainbow, terrifying

The 20-million-year-old lair of an ambush-predatory worm preserved in northeast Taiwan

Here’s the money shot of the sand striker with its jaws open, waiting for an animal to get too close. The stripy things are antennae:

The fossilized burrow with notes:

Show transcript:

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

This week we’re going back in time 20 million years to learn about an animal that lived on the sea floor, although we’ll start with its modern relation. It’s called the sand striker and new discoveries about it were released in January 2021.

Ichnology is the study of a certain type of trace fossil. We talked about trace fossils in episode 103, but basically a trace fossil is something associated with an organism that isn’t actually a fossilized organism itself, like fossilized footprints and other tracks. Ichnology is specifically the study of trace fossils caused by animals that disturbed the ground in some way, or if you want to get more technical about it, sedimentary disruption. That includes tracks that were preserved but it also includes a lot of burrows. It’s a burrow we’re talking about today.

Because we often don’t know what animal made a burrow, different types of burrows are given their own scientific names. This helps scientists keep them organized and refer to a specific burrow in a way that other scientists can immediately understand. The sand striker’s fossilized burrow is named Pennichnus formosae, but in this case we knew about the animal itself before the burrow.

The sand striker is a type of polychaete worm, and polychaete worms are incredibly successful animals. They’re found in the fossil record since at least the Cambrian Period half a billion years ago and are still common today. They’re also called bristle worms because most species have little bristles made of chitin. Almost all known species live in the oceans but some species are extremophiles. This includes species that live near hydrothermal vents where the water is heated to extreme temperatures by volcanic activity and at least one species found in the deepest part of the ocean that’s ever been explored, Challenger Deep.

A polychaete worm doesn’t look like an earthworm. It has segments with a hard exoskeleton and bristles, and a distinct head with antennae. Some species don’t have eyes at all but some have sophisticated vision and up to eight eyes. Some can swim, some just float around, some crawl along the seafloor, and some burrow in sand and mud. Some eat small animals while others eat algae or plant material, and some have plume-like appendages they use to filter tiny pieces of food from the water. Basically, there are so many species known—over 10,000, with more being discovered almost every year, alive and extinct—that it’s hard to make generalizations about polychaete worms.

Most species of polychaete worm are small. The living species of sand striker generally grows around 4 inches long, or 10 centimeters, and longer. We’ll come back to its size in a minute. Its exoskeleton, or cuticle, is a beautifully iridescent purple. It doesn’t have eyes, instead sensing prey with five antennae. These aren’t like insect antennae but look more like tiny tentacles, packed with chemical receptors that help it find prey.

The sand striker lives in warm coastal waters and spends most of its time hidden in a burrow in the sand. It’s especially common around coral reefs. While it will eat plant material like seaweed, it’s mostly an ambush hunter.

At night the sand striker remains in its burrow but pokes its head out with its scissor-like mandibles open. When the chemical receptors in its antennae detect a fish or other animal approaching, it snaps its mandibles on it and pulls it back into its burrow. Its mandibles are so strong and sharp that sometimes it will cut its prey in half and then, of course, it pulls both halves into its burrow to eat. If the prey turns out to be large, the sand striker injects it with venom that not only stuns and kills it, it starts the digestive process so the sand striker can eat it more easily. It does all this so quickly that it can even catch fish and octopuses. The mandibles are at the end of a feeding apparatus called a pharynx, which it can retract into its body.

If a person tries to handle a sand striker, they can indeed get bitten. The sand striker’s mandibles are sharp enough to inflict a bad bite, and if it injects venom it can make the bite even more painful. Not only that, the sand striker’s body is covered with tiny bristles that can also inflict stings, with a venom strong enough that it can cause nerve damage in a human that results in permanent numbness where the person touched it. Don’t pet a sand striker.

Remember how I said the sand striker grows 4 inches or longer? That’s actually the low end of its size. The average sand striker is about 2 feet long, or 61 centimeters, but it can sometimes grow 3 feet long, or 92 centimeters, or even more. Sometimes a lot more.

In January 2009, someone noticed something in a float along the side of a mooring raft in Seto Fishing Harbor in Japan. The mooring raft had been in place for 13 years at that point and no one knew that a sand striker had moved into one of the floats. It had a nice safe home to use as a burrow. Sand strikers grow quickly and this one was living in a more or less ideal situation, so it just grew and grew until when it was found, it was just shy of 10 feet long, or 3 meters. Even so, it was still only about an inch thick, or 25 millimeters.

There are unverified reports of even longer sand strikers, some up to 50 feet long, or 15 meters. Look, seriously, do not pet it. Since sand strikers spend most of the time in burrows, it’s rare to get a good look at a full-length individual in the wild and we don’t know how long they can really get.

In case you’d forgotten, though, we started the episode talking about a fossilized burrow. In a fossil bed in northeast Taiwan, a team of paleontologists uncovered hundreds of strange burrows dating to about 20 million years ago. The burrows were L-shaped and as much as 6.5 feet long, or 2 meters, and about an inch across, or 2.5 centimeters. Even more confusingly, the fossilized sediment showed feather-like shapes in the upper section of the burrows.

The team of scientists studying the burrows had no idea what the feather-like structures were. The burrows were mysterious from start to finish anyway, since they were so much larger than most burrows in the seafloor.

They decided to do something unusual to solve some of the mysteries. They reached out not only to marine biologists but to marine photographers and aquarium keepers to get their insights. And, as you’ve probably guessed by now, the fossilized burrows most closely match those of the sand striker.

They even found out what the feather-shaped structures were. When a sand striker grabs a fish or other prey and drags it into its burrow, a lot of time it’s still alive, at least at first. Its struggles to get away can cause the sides of the burrow to shift. The sediment can’t collapse all the way because the worm lines it with mucus, so the partial collapsing and shifting results in feathery shapes.

These fossilized burrows are the first trace fossils known to be made by a marine ambush predator, which is pretty awesome. It’s even more awesome that some modern sand strikers are using the same type of burrows over 20 million years later.

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. If you like the podcast and want to help us out, leave us a rating and review on Apple Podcasts or Podchaser, or just tell a friend. 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!