Which rainforest spider is widely considered the world’s largest spider by mass?

The Goliath birdeater is widely considered the world’s largest spider by mass.

This South American tarantula lives in humid lowland rainforest, especially in the Guiana Shield and northern Brazil. Despite its name, it rarely eats birds; its usual prey includes insects, frogs, lizards, and small rodents. The name comes from an old illustration showing one feeding on a hummingbird.

Adults can have a body length of about 13 centimetres, while their leg span may reach roughly 30 centimetres. Its impressive size is not the same as being the spider with the greatest leg span, a distinction often associated with large huntsman spiders.

Like other tarantulas, it can defend itself by rubbing irritating abdominal hairs toward a threat. Its bite is medically significant but generally not considered fatal to humans.