Native to the rain forest regions of northern South America, these spiders have up to a 30 centimeter (12 in) long leg span when fully extended and can weigh over 120 grams. Wild goliath birdeaters are a deep burrowing species, found commonly in marshy or swampy areas. Goliath birdeaters usually live in burrows in the ground that they have either dug themselves or have been previously abandoned by rodents or other similar creatures.
Female birdeaters mature in 2.5-3 years and have an average life span of 15 to 25 years. Males die soon after maturity and have a lifespan of 3 to 6 years. Colors range from dark to light brown with faint markings on the legs. Birdeaters have hair on their bodies, abdomens, and legs. The female lays anywhere from 100 to 400 eggs, which hatch into spiderlings within two months.
Male birdeaters are one of the few tarantula species to lack tibial spurs, located on the first pair of legs of most adult male tarantula species. These spurs are used by other tarantulas to keep the fangs of the female immobilized during mating so the female doesn't eat the male.
The goliath birdeater is fairly harmless to humans, as are most species of tarantulas. Like all tarantulas, it has fangs large enough to break the skin of a human (1-2.5 cm). They do carry venom in their fangs and have been known to bite humans when threatened, but the venom is relatively harmless and its effects are comparable to those of a wasp's sting. Tarantulas generally bite humans only in self-defense, and these bites do not always result in envenomation (known as a "dry bite"). The goliath birdeater has poor eyesight and mainly relies on vibrations in the ground that they can sense from their burrows.
Birdeaters are defensive and may make a hissing noise when disturbed. This noise is called stridulation and is produced when the spider rubs the bristles on its legs together. Birdeaters can defend themselves by biting or by kicking urticating hair towards their perceived assailant. These hairs can be severely irritating to the skin and lungs, and have been reported to feel like shards of fiberglass.
Despite its name, the goliath birdeater does not normally eat birds. Rather, it eats mostly invertebrates such as crickets, mealworms and moths, as well as small vertebrates such as frogs, mice and lizards. The Goliath birdeater is one of the few tarantulas which can capture and eat a full-grown mouse. While feeding, the spider will turn and leave a web barrier to prevent interruption from other animals.