Piotr Naskrecki was taking a late-night stroll, as one does, through a rainforest in Guyana, when he heard the sound of an animal running. "I could clearly hear its hard feet hitting the ground and dry leaves crumbling under its weight," the Harvard scientist says. Racing toward him in the darkness was an eight-legged mammoth: a South American Goliath birdeater, the heaviest spider on earth. It weighs more than a third of a pound, and looks like something out of a horror movie. Its hairy legs span nearly a foot, and a full-grown one is about the size of as a newborn puppy. It is however, considerably less snuggly.
Naskrecki writes in his blog: "Every time I got too close to the birdeater it would do three things. First, the spider would start rubbing its hind legs against the hairy abdomen. '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. If that wasn't enough, the arachnid would rear its front legs and open its enormous fangs, capable of puncturing a mouse's skull, and try to jab me with the pointy implements. The venom of a birdeater is not deadly to humans but, in combination with massive puncture wounds the fangs were capable of inflicting, it was definitely something to be avoided. And then there was a loud hissing sound."
Soon after Naskrecki published the story of his encounter, the Internet went wild—both in response to the existence of the puppy-sized spider (of course), and the fact that Naskrecki euthanized a specimen to bring back to the Smithsonian Institute, where he works. (Collecting specimens is part of the scientific process, as Naskrecki eloquently explained on NPR.) What we were left wondering, though, was whether there was any truth to the spider's name.
It turns out that the Goliath birdeater is an inventive killer. When it consumes a rodent, it pierces its victim's skull with its fangs and injects a tissue-dissolving venom into the brain. Then, it slurps it up, like a brain slushie.
But as ominous as it sounds, the term birdeater is a bit of a misnomer. The name is derived from a fanciful 16th century illustration by the German Entomologist Maria Sibylla Merian, which shows the animal astride the corpse of a freshly-killed hummingbird, tucking into the bird's eggs.
In reality, the spider does most of its hunting on the forest floor, where it's unlikely to catch a bird. Bird eggs on the other hand, are fair game. The spider has been known to crawl into a nest, sink its fangs into the eggs, and leave behind a pile of empty, withered shells.
The spider's primary sources of sustenance are humble and flightless invertebrates, such as earthworms. Earthworms are plentiful in the forest, which is good, since the birdeater gobbles them up like candy. As Naskrecki put it in an interview with Live Science, "Earthworms are very nutritious."