Geeks with arachnophobia have much reason to be scared based on a recent discovery by an entomologist that was out walking in the Guyana Forest in South America recently when he made the frightening discovery. Check out the details according the friendly folks over at

“The South American Goliath birdeater is the largest spider in the world. For all the arachnophobes out there this is probably a good excuse to pave over large swaths of the Amazonian rainforest, but for the rest of us this species is one of biodiversity’s crown jewels. Although far from being the largest member of the subphylum Chelicerata – this honor belongs to horseshoe crabs – Goliath birdeaters are ridiculously huge for a land arthropod. Their leg span approaches 30 cm (nearly a foot) and they weigh up to 170 g – about as much as a young puppy.”

Puppy-Sized Spiders Found in South America, Get the Shotguns!

Puppy-Sized Spiders Found in South America, Get the Shotguns!

The spiders grow to be so large because of their metabolic rate, which is lower than their relatives, according to one study:

“This allows it to function with lower levels of oxygen reaching its tissues and organs than those required by smaller, more active spiders”. “In other words, the bigger the body the more difficult it is to provide oxygen to all its parts if the metabolic rate is to remain constant.”

Hopefully there will be no accidents involving nuclear reactors and an outbreak of South American Goliath birdeaters at the same time!