Puppy-Size Tarantula Found: Explaining World’s Biggest Spider

The world’s largest spider has crept back into the spotlight, thanks to a scientist who describes a harrowing encounter with a tarantula.

Harvard entomologist Piotr Naskrecki recently recounted on his blog coming across a puppy-sized, foot-long (0.3-meter) South American Goliath birdeater (Theraphosa blondi) a few years ago in Guyana (map).

“I could clearly hear its hard feet hitting the ground and dry leaves crumbling under its weight,” Naskrecki wrote about his nighttime run-in.

“I pressed the switch and pointed the light at the source of the sound, expecting to see a small mammal, a possum, a rat maybe. And at first this is what I thought I saw—a big, hairy animal, the size of a rodent.” (Watch a video of the world’s biggest spider eating a mouse.)

Instead it was a specimen of T. blondi, a tarantula whose weight can reach six ounces (170 grams). Last Halloween, Carrie Arnold wrote an explainer about this monster of the spider world, which we’ve drawn from for this article.

Commonly known as the Goliath birdeater due to an 18th-century engraving showing another member of the tarantula family eating a hummingbird—which gave the entire Theraphosa genus the nickname of “bird eaters”—the gargantuan spider is not quite as menacing as it might seem, Arnold reported.

Gentle Giant

Despite its nickname, T. blondi only rarely devours birds. According to spider expert Gustavo Hormiga at George Washington University, T. blondi mostly eats arthropods.

“They are general predators, and if they run into other vertebrates, like a small mouse or lizard, they can eat those too,” Hormiga said in 2013.

But don’t expect this Goliath to use a giant web to snare its prey. T. blondi hunts for its meals the old-fashioned way—using its large fangs to bite and kill. (Watch video: “How to Survive a Giant Tarantula Encounter.“)

Like most spiders, T. blondi produces venom, although Hormiga notes that it’s not particularly toxic to humans.

The bites, which have been described as feeling like wasp stings, almost never require medical attention.

Beware the Hair

Although T. blondi doesn’t weave a web, it does produce and use silk. The spider lives in burrows beneath the forest floor, which it lines with silk to give the structure more stability. Should a mammal try to dig up the burrow for a tasty spider snack, T. blondi has a weapon more useful than venom: urticating hairs on its abdomen.

(The technical term is “bristles,” as only mammals have hair, but even scientists use the more popular term in conversation.)

“These are shaped like little harpoons if you look at them under the microscope,” Hormiga said, which gives the hairs the ability to embed in the skin.

“These spiders very quickly rub their fourth pair of legs on their abdomen to release the hairs, which then become airborne. These are very itchy.” (Related: “Tarantulas Shoot Silk From Feet, Spider-Man Style”)

The urticating hairs don’t need to be airborne to do their damage, however—researchers and owners of pet spiders need to handle the Goliath birdeaters with gloves. To large animals like humans, the hairs are merely irritating and itchy, but they can be fatal to smaller mammals like mice.

Naskrecki had a firsthand experience with these hairs—and the damage they inflict.

“The spider would start rubbing its hind legs against the hairy abdomen,” he wrote on his blog. “‘Oh, how cute!’ I thought when I first saw this adorable behavior, until a cloud of urticating hair hit my eyeballs, and made me itch and cry for several days.”

T. blondi females lay between 50 and 150 eggs in a giant sac that can measure over an inch (30 millimeters) in diameter. They cover the sac in urticating hairs to keep predators away.

It takes about two to three years for these hatchlings to mature; they spend significant time living with their mother in her burrow until they’re old enough to fend for themselves. Although females can live up to 20 years, males have a life span of only three to six years, often dying soon after reaching maturity and mating.

Tastes Like Prawns

Many of the locals in northeastern South America regard T. blondi as a tasty snack. They first singe off the urticating hairs, then wrap the spider in banana leaves to roast it. Tarantula expert Rick West, who once sat down for a meal of these spiders with the local Piaroa people of Amazonas in Venezuela, says T. blondi can be surprisingly tasty and moist. (Also see “UN Urges Eating Insects; 8 Popular Bugs to Try.”)

“The white muscle ‘meat’ tastes like smoky prawns, while the gooey abdominal contents is hard-boiled in a rolled leaf and tastes gritty and bitter,” West says. “The three-quarter-inch [two-centimeter] fangs are used after the meal as toothpicks to remove T. blondi exocuticle from between one’s teeth.”

It’s not often that your dinner comes with built-in toothpicks. Despite the Goliath birdeater’s  shrimplike taste, however, you probably won’t see it on a restaurant menu anytime soon.

As for Naskrecki, he wrote he was “ecstatic about finally seeing one of these wonderful, almost mythical creatures in person.”



Meet the Author
Christine Dell'Amore, environment writer/editor for National Geographic News, has reported from six continents, including Antarctica. She has also written for Smithsonian magazine and the Washington Post. Christine holds a masters degree in journalism with a specialty in environmental reporting from the University of Colorado at Boulder. Her book, South Pole, was published in 2012.