The Goliath Birdeater spider (Theraphosa blondi) is widely recognized as one of the largest spiders on Earth. This massive arachnid, native to the rainforests of northern South America, captures attention due to its immense size, earning it a legendary reputation.
The True Scale of the Goliath Birdeater
The Goliath Birdeater is considered the largest spider in the world by mass, though its reach is still impressive. Its legs can span up to 12 inches (30 centimeters), a size comparable to a dinner plate. This measurement is taken from the tip of the longest leg on one side to the tip of the longest leg on the other side.
In terms of weight, it can reach up to 6.2 ounces (175 grams), which is roughly the mass of a large apple or a standard pocket billiards ball. The body length alone, excluding the legs, can measure up to 5 inches (13 cm), about the size of a human fist. While the Giant Huntsman spider (Heteropoda maxima) can have a longer leg span, the Goliath Birdeater’s substantial body weight gives it the title of heaviest spider.
The females of the species are generally larger and heavier than the males, contributing to these maximum size records. The physical bulk of the Goliath Birdeater is a significant factor in its ecological role and its reputation as a formidable predator. Its size necessitates a terrestrial lifestyle, and it is a poor climber because its weight makes it vulnerable to injury from even short falls.
Classification and Defining Physical Features
The Goliath Birdeater is a member of the Theraphosidae family, commonly known as tarantulas. It is categorized under the genus Theraphosa. Its species name, blondi, is derived from the golden hue that appears on its otherwise dark brown or reddish-brown body.
The spider’s body is covered in a dense coat of fine, bristly hair, giving it a furry appearance. These hairs include specialized stinging, or urticating, hairs on the abdomen. When threatened, the spider can flick these barbed hairs toward a potential predator, causing severe irritation to the skin, eyes, or respiratory system.
The Goliath Birdeater possesses fangs that can be over one inch (3 centimeters) long. Like all tarantulas, its chelicerae, the structures that hold the fangs, move forward and down, distinguishing them from other spider groups. While the fangs are large enough to pierce human skin, the venom they deliver is not deadly to people, with the effects often compared to a wasp sting.
Addressing the Birdeater Name and Actual Prey
The common name “Birdeater” is largely a misnomer, originating from an 18th-century engraving that showed a different tarantula preying on a hummingbird. This incident led to the genus Theraphosa being labeled as “bird eaters,” though birds are not a regular part of this spider’s diet.
The Goliath Birdeater is a nocturnal ambush predator, relying on sensitive hairs to detect vibrations rather than good eyesight. Its primary diet consists of smaller terrestrial animals and invertebrates. These typically include earthworms, insects, frogs, toads, small mammals, and reptiles such as rodents and lizards.
The spider waits in its silk-lined burrow, emerging at night to pounce on unsuspecting prey. While it is physically capable of killing and consuming a small bird, such events are rare and opportunistic, usually involving nestlings found on the ground. After a successful capture, the spider uses its venom to paralyze the prey, then secretes digestive juices to liquefy the internal tissues before sucking up the resulting liquid.