Via Discovery: 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.