Piotr Naskrecki was taking a nighttime walk in a rainforest in Guyana, when he heard rustling as if something were creeping underfoot. When he turned on his flashlight, he expected to see a small mammal, such as a possum or a rat.
When I turned on the light, I couldn’t quite understand what I was seeing,” said Naskrecki, an entomologist and photographer at Harvard University’s Museum of Comparative Zoology.A moment later, he realized he was looking not at a brown, furry mammal, but an enormous, puppy-sized spider.
Known as the South American Goliath birdeater (Theraphosa blondi), the colossal arachnid is the world’s largest spider, according to Guinness World Records. Its leg span can reach up to a foot (30 centimeters), or about the size of “a child’s forearm,” with a body the size of “a large fist,” Naskrecki told Live Science. And the spider can weigh more than 6 oz. (170 grams) — about as much as a young puppy, the scientist wrote on his blog.
When Naskrecki approached the imposing creature in the rainforest, it would rub its hind legs against its abdomen. At first, the scientist thought the behavior was “cute,” he said, but then he realized the spider was sending out a cloud of hairs with microscopic barbs on them. When these hairs get in the eyes or other mucous membranes, they are “extremely painful and itchy,” and can stay there for days, he said.
But its prickly hairs aren’t the birdeater’s only line of defense; it also sports a pair of 2-inch-long (5 centimeters) fangs. Although the spider’s bite is venomous, it’s not deadly to humans. But it would still be extremely painful, “like driving a nail through your hand,” Naskrecki said.