Tag Archives: tarantula

Episode 169: The Tarantula!

This week let’s learn about my nemesis (in Animal Crossing: New Horizons, at least), the tarantula!

Further reading:

Tarantulas inspire new structural color with the greatest viewing angle

My character in Animal Crossing (and the shirt I made her–yes, I know tarantulas are arachnids, not insects, but I think the shirt is funny):

Boy who is not afraid of a tarantula:

The Goliath birdeater and a hand. Not photoshopped:

The cobalt blue tarantula:

The Gooty sapphire ornamental:

The Singapore blue tarantula:

The painting by Maria Sibylla Merian that shows a tarantula eating a hummingbird (lower left):

The pinktoe tarantula that Merian painted:

The great horned baboon (not actually a baboon):

Show transcript:

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

Just over two weeks ago I got a Nintendo Switch Lite and I’ve been playing Animal Crossing New Horizons a lot. I’m having a lot of fun with it, so let’s have a slightly Animal Crossing-themed episode and learn about my nemesis in the game, the tarantula.

A tarantula is a spider in the family Theraphosidae, and there are something like twelve hundred species. They live throughout much of the world, including most of the United States, Central and South America, Africa and some nearby parts of southern Europe and the Middle East, most of Asia, and Australia.

The tarantula is a predator, and while it can spin silk it doesn’t build a web to trap insects. It goes out and actively hunts its prey. It uses its silk to make a little nest that it hides in when it’s not hunting. Some species dig a burrow to live in but will line the burrow with silk to keep it from caving in and, let’s be honest, probably to make it more comfortable. The burrow of some species is relatively elaborate, for example those of the genus Brachypelma, which is from the Pacific coast of Mexico. Brachypelma’s burrow has two chambers, one reserved for molting its exoskeleton, one used for everyday activities like eating prey. Brachypelma usually sits at the entrance of its burrow and waits for a small animal to come near, at which point it jumps out and grabs it.

Many species of tarantula live in trees, but because they tend to be large and heavy spiders, falling out of a tree can easily kill a tarantula. But also because they’re large and heavy spiders, they can’t hold onto vertical surfaces the way most spiders do, using what’s called dynamic attachment. Most spiders have thousands of microscopic hairs at the end of their legs that allow it to hold onto surfaces more easily. But no matter what you learned from Spider-Man movies and comics, this doesn’t work very effectively for heavier animals, and many tarantulas are just too heavy. The tarantula does have two or three retractable claws at the end of its legs, but it’s also able to release tiny filaments of silk from its feet if it starts to slip, which anchors it in place.

Like other spiders, the tarantula has eight legs. It also has eight eyes, but the eyes are small and it doesn’t have very good vision. Most tarantulas are also covered with little hairs that make them appear fuzzy. These aren’t true hairs but setae [pronounced see-tee] made of chitin, although they do help keep a tarantula warm. They also help a tarantula sense the world around it with a specialized sense of touch. The setae are sensitive to the tiniest air currents and air vibrations, as well as chemical signatures.

Many species of tarantula have special setae called urticating spines that can be dislodged from the body easily. If a tarantula feels threatened, it will rub a leg against its abdomen, dislodging the urticating spines. The spines are fine and light so they float upward away from the spider on the tiny air currents made by the tarantula’s legs, and right into the face of whatever animal is threatening it. The spines are covered with microscopic barbs that latch onto whatever they touch. If that’s your face or hands, they are going to make your skin itch painfully, and if it happens to be your eyeball you might end up having to go to the eye doctor for an injured cornea. Scientists who study tarantulas usually wear eye protection.

One species of tarantula famous for its urticating spines also happens to be the heaviest spider known, and almost the biggest. It’s the Goliath birdeater, which I’m pretty sure we talked about in the spiders episode in October of 2018. Its leg span can be as much as a foot across, or 30 cm, and it can weigh as much as 6.2 ounces, or 175 grams. It’s brown or golden in color and lives in South America, especially in swampy parts of the Amazon rainforest. It’s nocturnal and mostly eats worms, large insects, other spiders, amphibians like frogs and toads, and occasionally other small animals like lizards and even snakes. And yes, every so often it will catch and eat a bird, but that’s rare. Birds are a lot harder to catch than worms, especially since the Goliath birdeater lives on the ground, not in trees. It’s considered a delicacy in northeastern South America, by the way. People eat it roasted. Apparently it tastes kind of like shrimp.

Most tarantulas from the Americas, known collectively as New World tarantulas, are mostly brown in color. Some have legs striped with rusty red, black, or white, but for the most part they’re all brown. But the Old World tarantulas found in the rest of the world are often more colorful, including many species that are blue. Not that slate gray color sometimes called blue but BRIGHT BLUE. The color isn’t caused by a pigment but by crystalline nanostructures in the exoskeleton, and researchers have recently found that different species of tarantula have evolved similar blue nanostructures independently—at least eight different times. Researchers have been studying the nanostructures and recently managed to replicate it with a nano-3D printer. Eventually they hope that the nanostructure color can replace toxic synthetic dyes for many materials. In addition to not being toxic, nanostructure colors don’t fade.

No one’s sure why so many tarantulas are blue, though. Remember that tarantulas don’t have very good eyesight so they probably don’t depend on color to attract a mate, at least as far as we know.

One blue tarantula is called the cobalt blue tarantula, which lives in the rainforests of southeast Asia. It spends most of its time in deep burrows except when it’s hunting. It has a legspan of about five inches, or 13 cm, and has blue legs and a gray body. Another is the Gooty sapphire ornamental, which is bright blue with a pattern of white on its body and legs. It’s from India, has a legspan of 8 inches, or 20 cm, and is critically threatened due to habitat loss. A third is the Singapore blue, which has a legspan of 9 inches, or 23 cm, and has bright blue legs and a brown or gold body. All these species, and many others, are bred in captivity as pets even though all tarantulas have venom that can cause painful reactions in humans.

Tarantula venom varies from species to species, and as with other venomous animals, researchers have been studying its venom to find potential medical uses, especially painkillers. The venom of some tarantulas targets nerve cells the same way that capsaicin does in hot chili peppers, resulting in a burning sensation. Australian tarantulas produce venom that contains a protein that is effective at killing insects if they eat it, not just if it’s injected, which has led to studies about using the protein to produce more eco-friendly insecticides for crops.

Results of a brand new study, published just a few weeks ago as this episode goes live, finds that the venom of the Chinese bird spider can be adapted to act as a strong pain reliever. It has similar results to morphine and related painkillers without side effects or risk of addiction. It still has to go through a number of clinical trials before it can be made into a drug for doctors to prescribe, but so far the results are promising.

Female tarantulas are usually a little larger than males, although the male may have longer legs. The female usually lays eggs once a year and guards her egg sac for six to eight weeks. She may also guard the babies after they hatch until they leave the nest. Male tarantulas typically don’t live very long compared to females, which can live for several decades in captivity—sometimes up to forty years.

The tarantula molts its exoskeleton periodically as it grows, several times a year for young spiders. Fully grown tarantulas may molt once a year or so. Molting is how a spider replaces lost or injured limbs and how it replaces its urticating spines.

So, in episode 90, about spiders, we talked about a lot of mystery spiders, including giant ones. It’s possible there are larger tarantula species out there than the Goliath birdeater, since new species of tarantula get discovered almost every year. But it’s not likely to be much larger, since as we also discussed in episode 90, the size of a spider or other terrestrial invertebrate is limited by its ability to absorb oxygen.

But there is another mystery associated with tarantulas that doesn’t have to do with their size, although it’s not a mystery that will keep you up at night. There’s a painting of tarantulas by Maria Sibylla Merian, a German artist who lived in the late 17th and early 18th centuries, that shows one tarantula eating a hummingbird. That’s actually how the Goliath birdeater and its close relations got the name birdeater. Merian painted tropical insects and other animals and plants, and unlike many of the artists of her day she was painstaking in her details and was a close observer of nature. She was also a leading entomologist back when that field was in its infancy and women weren’t supposed to do much of anything except have babies. She painted the birdeater tarantula during a trip to Dutch Surinam in South America, sometime between September 1699 and June 1701 when she returned home. It appeared in a book she published in 1705 with the help of her two grown daughters, and her paintings and notes were the first that many people in Europe had ever heard about animals and plants of the Americas. But while Merian’s paintings were meticulous in their details, no one was actually sure which tarantula she had painted.

The problem wasn’t her painting, but confusion about what species of tarantula actually live in northern South America. Carl Linnaeus described the first species of the genus Avicularia in 1758, but the tarantulas he studied, and the ones later assigned to Avicularia, were not actually all related. A few years ago, a team of spider experts in Brazil decided to figure it all out once and for all.

The team studied every specimen collected from the area, both newly collected and old ones in museums around the world. Previously, Avicularia had contained 49 species, but the team changed that to just 12—and three of those 12 were ones new to science. They separated the other species out into three new genera. One of the new species was named after Merian, Avicularia merianae.

The species Merian illustrated is the pinktoe tarantula, Avicularia avicularia, which is brown or black except for the tips of its legs, which are pinkish. Its venom is weak and its legspan is about six inches, or 15 cm. It lives in trees where it ambushes small animals, usually insects, although it will also scavenge already dead animals it finds. Researchers think this is probably the case with Merian’s painting of the tarantula eating a hummingbird, since the pinktoe is too small and weak to kill a hummingbird itself.

Some species of tarantula makes a sort of soft hissing or rattling sound if it feels threatened, called stridulating. Some other spiders and other animals make a similar noise. The tarantula rubs the hairs of its legs together to produce the noise, which sounds like this:

[tarantula stridulating sound]

The tarantula making that sound is called the great horned baboon, which is from Zimbabwe and Mozambique in southern Africa and is not a baboon but a spider. Its legspan is about six inches, or 15 cm, and it’s a very pretty black or gray with a white pattern over most of its body and legs, and a brown or tan pattern on its abdomen. But the most remarkable thing about it is the so-called horn. This is a black horn-like structure that grows from the spider’s carapace. No one is sure what the horn is for. No one except the tarantula, that is.

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 099: Island Life

Those of us in the northern hemisphere are thinking a lot about island life right about now, where it’s warm and sunny. But there are islands everywhere, not just the tropics, and the animals on islands often evolve to look strange and different from their mainland cousins. Thanks to Richard E. and Lucy for their suggestions this week!

A fossa:

A tamaraw, miniature water buffalo:

A Socotra starling, my new favorite bird:

Adorable little Galapagos penguin:

A dragonblood tree, good grief!

A blue baboon. It’s not a baboon but it is blue:

A ground dragon:

Further listening:

The unlocked Patreon bonus episode about vampire finches on the Galapagos Islands

Show transcript:

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

In a lot of episodes, we talk about animals from islands like the Galapagos and the Canaries. There’s a reason why islands give rise to strange animals. This week we’ll focus on island life—how island habitats lead to unique animals and how introduced animals can destroy an entire island ecosystem in a matter of a few years. Massive thanks to listener Richard E., who suggested the topics of introduced animals and island life!

Islands, of course, are surrounded by water and isolated from larger landmasses as a result. Some are close to the mainland so it’s easy for animals to swim or float across to the island. In cold areas, animals can sometimes walk across ice to islands. But other islands are more remote, or used to be close to the mainland but were pushed farther away by tectonic forces.

Once a piece of land is cut off from the mainland, the animals and plants on that piece of land start to evolve independently of the larger population of animals and plants on the mainland. If the island is isolated enough that potential predators can’t get to it, the animals already living on the island start to adapt to life with no or few predators. As a result, they may appear tame when humans arrive.

And that is where the problems start. Humans don’t just arrive alone. We bring other animals with us, either on purpose, like dogs, cats, and livestock, or by accident, like rats and mice. And these animals, along with humans, can destroy an entire island habitat really easily.

I’ll use one of Richard’s examples, since it’s a good one and not one you’d think of when thinking of islands. The red squirrel is native to Europe and parts of Asia, but it also lives in the UK and Ireland. It’s usually red-brown in color, although some populations can be brown, gray, or even black. The belly is white. It has long ear tufts and a poofy tail. It lives in trees and eats seeds, nuts, berries, fungi, and occasionally eggs or baby birds.

But remember, Ireland and the UK are islands. And in the 1870s, someone thought it would be really great to import eastern gray squirrels from North America and release them in parks in the UK. In Ireland, in 1911 someone gave a bunch of gray squirrels as a wedding gift, which is not a great gift, honestly, and they got loose because of course they did. They’re squirrels.

Grey squirrels are larger than red squirrels and don’t have ear tufts. They eat the same foods red squirrels do. They also carry a disease called squirrel parapoxvirus that doesn’t bother them but which kills red squirrels. The population of red squirrels has dropped substantially as introduced gray squirrel populations climb in the UK and Ireland. The red squirrel is now protected, with conservation efforts in place that are making a difference. But that just goes to show how easy it is to lose even a well-established species on large islands when an outside species is introduced.

On islands, especially smaller islands, small animals tend to grow larger overall and big animals tend to grow smaller overall. This is called Foster’s rule. It comes about partly because there are fewer predators but limited resources. Small animals don’t need to hide as carefully from predators, large animals may not be able to get enough to eat, but medium-sized animals are able to survive short famines without starving and can take advantage of some resources smaller or larger animals couldn’t use.

One example of island gigantism is the fossa, a predator from Madagascar. If you’ve seen the Madagascar movies, you might remember the fossa as a scary predator that looks something like a big cat. Well, the fossa is a real animal, but it’s not related to cats. It’s related to the mongoose, which is a weasel-like animal, but the fossa is generally much larger than a mongoose. It grows some five feet long, or 1.5 meters, including its tail, although its legs are short compared to those of a similarly-sized cat. It spends a lot of time in trees, where it uses its long tail to help it balance. It’s reddish-brown with a paler belly and eats lemurs and other mammals, birds, insects, crabs, lizards, and even fruit.

An example of island dwarfism is the tamaraw from the island of Mindoro in the Philippines, also called a Mindoro dwarf buffalo. It looks like its close relative, the water buffalo, but is much smaller, only about three and a half feet tall at the shoulder, or 105 cm. It’s like a pocket-sized water buffalo. It has V-shaped horns and is black with some white markings on the legs. It prefers to live in mountainous forested areas with water nearby, and it eats grass, young bamboo shoots, and wild sugarcane. It’s a solitary, shy animal.

Famously, Charles Darwin worked out the theory of evolution after examining the differences in finches living on the various Galapagos Islands. He had actually already started thinking along these lines before he’d really examined the finches, but they supported his ideas and helped him work out the details. Basically, as Darwin eventually determined, a type of finch had colonized the islands at some point in the far distant past. Each island had slightly different ecology, so although the finches could fly, over the years populations living on separate islands began to adapt to better fit the resources available on those islands. For instance, the large ground finch has developed a short, heavy bill to crack nuts, while the closely related vampire ground finch has a thinner, sharper bill that it uses to eat insects, seeds, and the BLOOD OF OTHER BIRDS. I am totally not making this up. In fact, I covered the vampire finch in a patreon bonus episode earlier this year. It’s already unlocked for anyone to listen to, so if you haven’t listened to it and want to, I’ll put a link in the show notes.

Remember that squirrel disease I mentioned earlier? There’s a bird disease called avipoxvirus, or avian pox, that has affected the Galapagos finches since 1898. Researchers think it was probably spread by humans who brought infected domestic birds with them on ships. Fortunately, it hasn’t driven any finches or other birds to extinction.

Another problem brought to the Galapagos Islands by humans, this one spread more recently by tourist boats, is a parasitic nest fly that kills baby birds. Researchers have started leaving cotton balls treated with a mild insecticide where the flies are known to attack endangered finches. The parent finches use the cotton balls to line their nests, which helps protect the babies once they hatch. The nest flies lay their eggs in the nests, and the larvae bite babies and mother birds and drink their blood, which can kill the babies. So far the treatment has helped reduce the number of larvae that hatch.

There’s another bird that lives on the Galapagos that is unique to the islands, and that’s the Galapagos penguin. Thanks to Lucy, who suggested it as a topic, and a shout-out to Lucy’s sister Willa too!

Lucy also wanted to hear about King and Gentoo penguins, so let’s start with them. Both species mostly nest on islands.

The King penguin is almost as big as the Emperor penguin and looks very similar, not surprising since they’re closely related. It stands over three feet tall, or 100 cm. It eats small fish, squid, and krill. Females lay one egg at a time and after the egg hatches, the baby spends its first month or so of life sitting on one parent’s feet while the other parent forages. After that both parents leave the baby in a communal nest, called a crèche, while both go foraging. A young king penguin won’t be able to fish for itself until it’s more than a year old.

The Gentoo penguin lives off the southern tip of South America, and it’s almost as tall as the king penguin, but it’s not closely related to the king and emperor penguins. The Gentoo penguin has a reddish bill and a white stripe on its head above its eyes. The female usually lays two eggs in a nest made of round stones. Gentoo penguins value good nesting stones, and a male may court a female by offering her high-quality stones. Sometimes he has stolen those good stones from other penguin nests. Watch out, ladies. The Gentoo penguin eats krill and other small crustaceans for the bulk of the diet, and also eats fish and squid.

So that gives us a sort of baseline of ordinary penguins to compare to the Galapagos penguin. All other penguins all live in the southern hemisphere, usually not all that far from Antarctica. Part of the Galapagos Islands are in the northern hemisphere, although just barely. Penguins are adapted to severe cold, so how do Galapagos penguins thrive near the equator? As it happens, the waters around the Galapagos are actually quite cold, with various oceanic currents bringing cold water north from the Antarctic and bringing cold water from the depths to the surface in the area. Unlike other penguin species, which often travel widely to find food, the Galapagos penguin stays near the islands where the water is comfortably cool and there’s enough food. On hot days, penguins go into the water to stay cool.

The Galapagos penguin is only about 19 inches tall, or 49 cm. It’s almost the smallest penguin and is definitely the rarest penguin, with only about 1,000 breeding pairs. It mates for life and females lay one or two eggs, making sure to lay eggs in the shade so they won’t get too hot in the sun. If both eggs hatch, the weaker baby usually dies as the parents concentrate on feeding the stronger one. Then again, in good years, grown babies who have moved out of the nest may continue to beg their parents for food and sometimes get fed. I know some people like that. In addition to ordinary predators like seals and hawks, the Galapagos penguin is also vulnerable to introduced predators like cats.

We’ve talked a lot about the Galapagos Islands, but every island has its own unique ecosystem. For example, the island of Socotra lies in the Arabian Sea off the coast of Yemen. It’s only 82 miles long, or 132 km, and 31 miles wide, or 50 km. There are three other, smaller islands nearby. It’s been so isolated for so long that even its trees are bizarre-looking, like the dragon’s blood tree that has dense branches with leaves sticking up at the very top so that it looks like grass growing on top of a weird tree-shaped cliff. The tree also has red sap that has been traditionally used as a dye or varnish.

Humans have lived on the Socotra for 2,000 years, so many endemic species have gone extinct due to habitat loss, hunting, and competition or predation by introduced animals like cats and cattle. But there are still a lot of unusual animals that are found nowhere else in the world. The island has only one native mammal species, a bat, and no amphibians, but it has lots of reptiles and some birds found nowhere else in the world. For instance, the Socotra starling. It’s a large, beautiful songbird with a black body and soft gray head and neck, a heavy black bill, and a black eye with a thin white eye ring. It eats insects and fruit. Socotra is also surrounded by coral reefs with lots of unique fish and crabs.

One interesting animal that lives on Socotra Island is called the blue baboon. But it’s not a baboon or any other kind of primate. It’s not even a mammal. It’s a tarantula, and it’s beautiful! It’s a lovely indigo blue in color with white hairs on the abdomen and the top joints of the legs. Its legspan is about five inches across, or 12 cm, and males are smaller than females. Unlike most other tarantula species, it tolerates others instead of being solitary, so people often keep them as pets. Fortunately, it’s become so popular in captivity that there are lots of captive-bred blue baboons readily available, so the market for illegally collected wild specimens has diminished.

I’ve talked a lot about how animals in island habitats can be driven to extinction very easily, but there are success stories too. For instance, the island of Redonda. It’s a tiny island in the Caribbean, only about a mile long, or 1.6 km, with no source of fresh water and land that’s basically just rock. For centuries no one bothered Redonda because no one wanted to live there, but in the late 19th century it was mined for bird guano, or bird poop, which was used as fertilizer. This went on until 1914, and then in 1929 a hurricane destroyed what was left of the mining equipment. The few people who lived there left, but there were still rats and feral goats that ate everything they could find.

Redonda might have become a wasteland with nothing but rats, goats, and a few birds, but an ambitious conservation effort is paying off. First, the rats and goats were trapped and removed from the island. The rats were mostly killed, but the goats were taken to nearby Antigua where they’ve found homes. Then—and this is important—people left the island alone. Without introduced species and without human interference, the population of endemic animals have begun to rebound. Native plants and trees have started growing back. Rare seabirds nest there again. Instead of a big rock, the island now appears green again.

And the population of lizards on the island is rebounding like crazy. In just a year, the number of ground dragons has almost doubled. Ground dragons are lizards only found on the island. They’re shiny black with long tails and eat pretty much anything they can catch, including young ground dragons.

Sometimes all it takes for nature to be set right is to just leave it alone to do what it does best. Sometimes humans have to help by restoring keystone species to a habitat. This has happened with giant Aldabra tortoises, which were once common on the island of Mauritius, the same island where the dodo once lived. A species of ebony tree had nearly been driven extinct by logging, but even after logging was stopped in the 1980s, the trees hadn’t rebounded. Researchers determined that giant tortoises had once eaten the ebony tree fruit and pooped out the seeds, much like the dodo and the rare dodo tree palm. When giant tortoises were reintroduced to Mauritius, new ebony trees started to sprout.

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

Thanks for listening!

Episode 090: Spiders! NO COME BACK, IT’S SAFE TO LISTEN

As we get closer and closer to Halloween, the monsters get scarier and scarier! Okay, spiders are not technically monsters, but some people think they are. Don’t worry, I keep descriptions to a minimum so arachnophobes should be okay! This week we learn about some spider friends and some spider mysteries.

I stole the above cartoon from here. I am sorry, Science World.

A cape made from golden silk orbweaver silk:

Further reading and listening:

Blue spiders

Varmints! Podcast scorpions episode

Show transcript:

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

It’s almost Halloween! I’m on the third bag of gummi spiders, although they’ve changed the flavor from last year so I only eat the orange and yellow ones. The purple and green ones are in the bucket to give out to unsuspecting children.

Speaking of spiders…yes, I’m going there. I realize a lot of people are scared of spiders, but they’re beautiful, fascinating animals that are associated with Halloween. Don’t worry, I will try hard not to say anything that will set off anyone’s arachnophobia. Besides, there are some mysterious spiders out there that I think you’ll find really interesting.

First off, you don’t have to worry about gigantic spiders like in the movies. Spiders have an exoskeleton like other arthropods, and if a spider got too big, some researchers think its exoskeleton would weigh so much the spider wouldn’t be able to move. Not only that, spiders have a respiratory system that isn’t nearly as efficient as that of most vertebrates, so giant spiders couldn’t exist because they wouldn’t be able to get enough oxygen to function.

Specifically, some spiders have a tracheal system of breathing, like most insects and other arthropods also have. These are breathing tubes that allow air to pass through the exoskeleton and into the body, but it’s a passive process and spiders don’t actually breathe in and out. Other spiders have what are called book lungs. The book lung is made up of a stack of soft plates sort of like the pages of a book. Oxygen passes through the plates and is absorbed into the blood, which by the way is pale blue. This is also a passive process.

In other words, that picture that’s forever popping up on facebook of the enormous spider on the side of someone’s house, it’s photoshopped. In fact, pretty much any photo you see of a gigantic spider or insect or other arthropod is either photoshopped or made to look bigger by forced perspective. Also, spiders with wings are photoshopped, because no spider has ever had wings, even fossil spiders all the way back to the dawn of spider history, over 300 million years ago. So that’s one less thing to worry about.

Spiders live all over the world, everywhere except in the ocean and in Antarctica. The smallest spider known is .37 mm, so basically microscopic. It lives in Colombia and basically lives out its whole life not knowing most things about the world, like what whales are and how to operate a smart phone. On the other hand, the largest spider in the world is a tarantula called the goliath birdeater, and it probably also doesn’t know what whales are and how to use a smartphone. The goliath birdeater is the heaviest spider at a bit over 6 ounces, or 175 g, and has a legspan of 11inches, or 28 cm. Despite its name, it mostly eats insects but it will occasionally eat frogs, small rodents, small snakes, and worms. It lives in swampy areas in the rainforests of northeastern South America.

The spider with the biggest legspan—yes, I know, some of you are freaking out but I can’t do an episode about spiders and not talk about the biggest spiders. The spider with the biggest legspan is the giant huntsman, which lives around cave entrances in Laos, a country in southeast Asia. And it’s not much bigger than the goliath birdeater, with a legspan of one foot, or 30 cm.

All spiders produce silk but not all of them make webs. I won’t go into the process of how a spider generates silk, because it’s complicated and I just read about it and have already forgotten all the details, but spiders use silk to wrap up their eggs safely, line the walls of burrows to make a comfortable home, wrap up prey so it can’t escape, and of course make webs and get around without falling off tall things.

Most spider silk appears white, but the golden silk orb-weaver produces golden silk. The spider itself is gorgeous, with striped legs and a body that can be yellow, red, greenish, or brown, often with white spots and delicate patterns. It lives all over the world in warm climates, especially Australia. It builds webs that can be several feet across, or over a meter, and it occasionally catches and eats small birds as well as insects. One was even spotted eating a small snake that had been caught in its web. Its silk has occasionally been used to make cloth, but spider silk is difficult to collect in the quantities needed for textiles.

Most spiders eat insects, although one spider eats plants. Just one. It lives in Central America. Some baby spiders eat nectar until they get big enough to catch prey. Some spiders will scavenge on dead insects, some will eat fruit as well as insects, many eat pollen that gets caught on their webs, and some eat each other. Some spiders are adapted to swim in freshwater, and while they mostly eat aquatic insects, they will catch and eat small fish. Some spiders also catch and eat small birds and bats.

Basically, there are too many spiders to cover everything about them in one episode. Besides, what we all really want to know about are the mystery spiders. Because it’s almost Halloween!

Our first mystery spider is from Africa, specifically the jungles of central Africa. In 1938, an English couple, Reginald and Margurite Lloyd, were driving through the jungle when what looked like a monkey or cat stepped onto the dirt road. They stopped the car so it could cross the road, at which point they saw it was a spider. It looked like a tarantula but was huge, with a legspan of up to three feet, or almost a meter. Before Reginald Lloyd could grab his camera, the spider disappeared into the undergrowth.

Supposedly, the same giant spider was reported in the 1890s by a British missionary named Arthur John Simes. Some of his men got tangled in a huge web and a pair of spiders came out and attacked them. The larger of the spiders, presumably the female, was four feet across, or 1.2 meters. Simes was bitten but shot one of the spiders and was able to escape. He ultimately died of the bite.

This seems less than believable, to put it gently. The largest spider that catches prey with a web is our friend the golden silk orbweaver, but its legspan is only five inches across, or 12 cm. The biggest spiders in the world are tarantulas and other spiders that hunt actively, none of which build webs.

A more believable giant-spider mystery is called the up-island spider, which is supposed to be an extra-large variety of wolf spider from parts of Maine in the United States. Its legspan is supposed to be as much as 8 inches across, or 20 cm. Wolf spiders are common throughout the world, and while they look scary, they bite people very rarely and their venom is weak, no worse than a bee sting. The wolf spider with the biggest legspan is Hogna ingens, with a legspan less than 5 inches, or 12 cm. Hogna ingens lives on one island in the Maderia archipelago, and is a beautiful soft grey with white stripes on the legs. It’s critically endangered, but Bristol Zoo in England has a successful captive breeding program underway so it won’t go extinct. The species of wolf spider most commonly found in Maine is probably Tigrosa helluo, but it’s not very big, only a couple of inches across at most, or maybe five cm. It’s likely that the up-island spider is actually the Carolina wolf spider, which can have a legspan of four inches, or 10 cm, but I can tell you from personal experience that they look a whole lot bigger if you see one in your garage or basement when you flip on the light. The Carolina wolf spider does live in Maine, but it’s not very common in the area.

Zoologist Karl Shuker has a blog post from 2010, with some later updates, about spiders that are normal sized except for being blue, in species that aren’t normally blue. It’s an interesting post and I’ll link to it in the show notes if you want to read it and look at the pictures he posts. He discusses a number of blue spiders readers have reported to him, and while one seems to have been spraypainted blue, the rest appear naturally colored blue.

As it happens, there are lots of reports of blue spiders out there—and other blue invertebrates like woodlice. According Shuker’s post, some of these have been studied and found to be suffering from a virus called invertebrate iridovirus, or IIV. This infects invertebrates and sometimes is so highly concentrated in the animal’s tissues that it forms crystalline aggregations that emit blue iridescence and make the animal look blue. I should stress that you can’t catch IIV if you are a mammal, bird, reptile, fish, or anything else with a backbone, which I am assuming is most of my listeners.

The ancestors of spiders evolved around 380 million years ago, although those animals probably couldn’t generate silk. They did have eight legs, though. True spiders date to around 300 million years ago. Those spiders had silk spinnerets in the middle of the abdomen instead of at the end, and modern spiders appeared around 250 million years ago. We have fossil spiders and we also have spiders preserved in amber, the resin of certain trees that later fossilizes but remains at least partly transparent. We even have a spider web preserved in amber and dated to 110 million years ago, along with several insects that had been trapped in the web.

Spiders are closely related to whip scorpions, also called whip spiders because they look superficially similar to spiders in some ways except that they are HORRIFYING and I cannot look at pictures of them right now, I just can’t. While whip scorpions have eight legs, they only walk on six of them. The front pair are more like feelers and are elongated. Other whip scorpions have long, thin tails and are sometimes called vinegaroons, because if they’re disturbed they squirt a liquid that smells like vinegar. Some whip scorpions look a lot like scorpions. I don’t want to talk about scorpions. In fact, I’m just going to stop talking entirely, because while spiders don’t bother me, scorpions do and I cannot look at these pictures anymore, okay? If you want to learn about scorpions, Varmints! Podcast just released a scorpions episode. I’ll put a link in the show notes. Eventually I’ll manage to listen to it myself.

Happy Halloween?

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