What is the largest spider by body mass?

The Goliath birdeater is the largest spider by body mass. Its scientific name is Theraphosa blondi, and it is a tarantula native to northern South America.

Large females can weigh up to about 175 grams, reach roughly 13 centimeters in body length, and have a leg span approaching 30 centimeters. The species is also often described as the largest spider by body length, while the giant huntsman spider generally has the greatest leg span. Those different measurements explain why “largest spider” can produce different answers.

Despite its dramatic name, the Goliath birdeater rarely eats birds. The name comes from an early-eighteenth-century engraving by Maria Sibylla Merian that depicted a related bird-eating tarantula. In reality, this spider mainly hunts ground-dwelling prey such as insects and other small animals.

Goliath birdeaters are nocturnal and live in burrows. They can defend themselves by rubbing irritating abdominal hairs toward a threat, and their bite is painful but not usually considered medically significant to humans. Females may live 15 to 25 years, while males generally die soon after maturity.