Episode 416: The heaviest tarantula and the bitey-est ant

Thanks to Siya, Sutton, Owen, and Aksel for suggesting this week’s topic, the Goliath birdeater tarantula and the fire ant! Further listening: The TEETH Podcast Further reading: Tropical fire ants traveled the world on 16th century ships The Goliath birdeater tarantula, bigger than some kittens: Fire ants: Show transcript: Welcome to Strange Animals Podcast. I’m your host, Kate Shaw. This week we’re going to talk about two invertebrates, a spider and an insect. Thanks to Siya, Sutton, Owen, and Aksel for suggesting them! We’ll start with the spider, which Siya and Sutton both suggested. It’s the goliath tarantula, also called the goliath birdeater. You know it has to be a big spider if it’s called a birdeater. We’ve talked about it before, but not in a long time. The goliath birdeater is the heaviest spider in the world. If you think of the usual spider, even a big one, it’s still pretty lightweight. Let’s use a wolf spider as an example, which is found just about everywhere in the world. It’s a hunting spider that doesn’t spin a web, and while different species vary in size, the biggest is the Carolina wolf spider found in many parts of North America. A big female can have a legspan of four inches across, or 10 cm, with a body up to an inch and a half long, or 35 mm—but it weighs less than an ounce. That’s barely 28 grams, or just a little heavier than five sheets of printer paper. In comparison, the goliath birdeater tarantula can weigh over 6 ounces, or 175 grams. That’s heavier than a baseball, or two packs of cards. Its legspan can be as much as 12 inches across, or 30 cm with a body length of about 5 inches, or 13 cm. 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 or 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. Because it’s so large, the goliath looks like it would be incredibly dangerous to humans. It does have fangs and can inflict a venomous bite, but it’s not very strong venom. The danger comes from a very different source, because the goliath birdeater is famous for its urticating spines. Many species of tarantula have special setae, hairlike structures 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. The goliath birdeater tarantula is considered a delicacy in northeastern South America. People eat it roasted. Apparently it tastes kind of like shrimp. Next, Owen and Aksel wanted to learn about fire ants. I couldn’t believe that we’ve never talked about fire ants before! Fire ant is the name for any of the more than 200 species in the genus Solenopsis, but it’s typically used to refer to the species Solenopsis invicta. It’s native to tropical South America but has been introduced to parts of North America, Australia, China, Taiwan, India, Africa, and many other places where the climate is tropical or sub-tropical. The fire ant initially became so invasive due to Spanish galleons in the 16th century, which carried trade goods around the world. A ship that’s meant to carry a lot of cargo is built so that it needs to be weighted down to a certain degree to sail safely. A lot of times if a Spanish ship didn’t have enough goods in its hold to make it weigh enough, the captain would bring a few tons of soil onboard to make up the difference. Then, when the ship got to its next port where it was supposed to pick up new cargo, it would just dump the dirt wherever it was. It didn’t matter to the fire ant if the dirt was dumped into the water, because fire ants are prepared for their nests getting flooding. They cling together and form huge rafts that the wind pushes to shore. But more often, the dirt would get dumped on land for other ships to re-use. A team of scientists figured out where the invasive fire ant populations came from by comparing the genetic signatures of 192 different populations. They hypothesized that the ants with the highest genetic diversity were the original population, and that as the ants were moved around the world by ship, genetic diversity would get lower and lower, since all the ants were descendants of the original colony or colonies transported accidentally in the dirt. They mapped out the genetics, then compared the results to Spanish trade routes in the mid-1600s, and it all matched up. The fire ant made it to the United States in the late 1930s or early 1940s, the West Indies around 1980, and Australia around 2001. These days a lot of fire ants end up transported to new areas in golf course sod imported from Florida. A fire ant colony consists of a queen, thousands of worker ants, and larger soldier ants that protect the workers and especially the queen. Some colonies have more than one queen. The ants eat anything, including seeds and insects, and even small animals, but also including dead animals they find. The colony can have as many as a quarter million ants. The nest is underground and entrances can be far from the nest itself, and nests can be so large that they can cause structures built over them to collapse. Invasive animals of any kind aren’t good for the native animals, and the same is true for the fire ant. The fire ant specializes in colonizing areas where humans have disturbed the ground, whereas native ants often have trouble surviving in disturbed areas. The fire ants crowd out native ants and can destroy some native plants. But the main reason why people don’t like fire ants is that they bite and they’re venomous. The bites cause a burning sensation and painful swelling, but some people are allergic to the venom and can actually die from ant bites. Luckily, that’s rare, but the bites are still painful. Some countries have spent millions of dollars trying to eradicate the fire ant, including Australia and New Zealand. New Zealand seems to have succeeded, but Australia is still struggling to get the invasion under control. Fortunately, a lot of animals eat fire ants, which helps. One of the animals that especially loves to eat fire ants is the wolf spider, so now we’ve come full circle in this episode. 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 [email protected]. 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! If you are wishing that I’d gone into more detail about fire ant attacks, you might like the TEETH podcast. It’s the only podcast where you’ll hear wild animal attack stories directly from the survivors, hosted by a wilderness guide and attack survivor himself. I’ll put a link in the show notes so you can go listen. It’s appropriate for all ages. I don’t think they’ve actually covered a fire ant attack, but they’ve got lots of other fascinating accounts.