The question of the world’s biggest spider is complicated because “biggest” can refer to either sheer body weight or maximum leg span. To accurately answer the question, a distinction must be made between the heavyweights, which possess immense bulk, and the long-legged champions, which spread out over the greatest distance. Both categories feature spiders whose dimensions are startling, but they belong to different families and employ distinct physical strategies.
The Goliath Birdeater: Champion by Mass
The undisputed heavyweight champion of the spider world is the Goliath Birdeater, Theraphosa blondi, which belongs to the tarantula family. This spider is recognized as the largest by mass and body size, with specimens weighing up to 175 grams. Its body length alone can reach 13 centimeters, and its leg span can measure nearly 30 centimeters.
This impressive bulk is supported by a robust, reddish-brown to golden-hued body covered in dense hairs. The Birdeater is a terrestrial, burrowing species found in the upland rainforests of northern South America, including Suriname, Guyana, and northern Brazil. It is a nocturnal hunter that relies heavily on detecting vibrations on the ground, as its eyesight is poor.
Despite its intimidating common name, which originated from an 18th-century engraving, the T. blondi rarely preys on birds. Its diet primarily consists of large invertebrates, such as worms and other arthropods. However, its opportunistic nature allows it to consume small terrestrial vertebrates like frogs, toads, rodents, and snakes. The spider liquefies the insides of its captured prey before consuming the meal.
The Giant Huntsman: Champion by Leg Span
While the Goliath Birdeater is the heaviest, the title for the longest leg span belongs to the Giant Huntsman Spider, Heteropoda maxima. This species can boast a maximum leg span of up to 30 centimeters. Unlike the Birdeater, the Giant Huntsman possesses a relatively smaller body, measuring only about 4.6 centimeters in length, making its long, spindly legs its defining characteristic.
The Giant Huntsman belongs to the Sparassidae family and is characterized by its flattened body structure, an adaptation that allows it to squeeze into narrow crevices. Its legs are twisted forward in a crab-like fashion, contributing to its other common name, the giant crab spider.
This spider is an active hunter, using its speed to chase down prey rather than relying on a web. This arachnid is native to the caves of Laos in Southeast Asia, where its pale, yellowish-brown coloration provides camouflage. Its hunting technique involves injecting prey with venom and strong mouthparts, allowing it to consume insects, other spiders, and small reptiles.
Assessing the Actual Danger of Giant Spiders
The sheer size of both the Goliath Birdeater and the Giant Huntsman fuels public fear, but their actual threat level to humans is low. The venom of both species is not considered medically significant. A bite is painful due to the size of the fangs, which can be over 3 centimeters long on the Birdeater, but the effects are limited to localized pain and swelling.
The Birdeater possesses a unique defense mechanism in the form of urticating hairs, which are barbed bristles on its abdomen. When threatened, the spider can rub its legs together to flick these hairs toward an aggressor. Exposure to these hairs is the more common source of discomfort, causing severe itching, rashes, and potential respiratory issues if inhaled.
The Giant Huntsman, while capable of delivering a bite, is known for its speed and tendency to flee rather than confront. For the average person, the primary consequence of an encounter with either of these giants is the shock of their imposing size, not a severe medical emergency.