The Goliath Birdeater: A massive predator that uses microscopic missiles for defense

Society · Published 8 October 2026 Swipe more like this →

In short: Spanning nearly a foot across, the Goliath birdeater is the world's largest arachnid by mass. While its name suggests a diet of birds, this Amazonian giant relies on a much more common menu and a specialized, irritating defense mechanism that functions like airborne fiberglass.

Found in the northern South American Amazonian rainforests, from Venezuela to northern Brazil, the Goliath birdeater (*Theraphosa blondi*) is a formidable ambush predator. It is widely considered the largest known arachnid by mass, weighing up to 170 grams (6 ounces)—roughly the weight of a regulation pocket billiards ball. While its common name implies a specialized diet, the spider's primary food source is actually large insects. However, it is an opportunistic hunter, capable of consuming earthworms, frogs, toads, lizards, snakes, and small mammals like rodents or bats.

The spider's most distinctive feature is its defense mechanism. When threatened, it uses its hind legs to flick urticating hairs from its abdomen. These hairs are equipped with microscopic, harpoon-shaped barbs that can stick into the eyes, skin, or nasal passages of a predator. This mechanism is so effective that it was historically used to create 'itching powder' by mixing the hairs with talcum powder. Because these hairs can become airborne and irritate everything they touch, experts recommend keeping these spiders in heavily planted vivariums to manage the debris.

Physically, the Goliath birdeater is a striking creature with a leg span reaching up to 28 cm (11 inches). Its fangs can exceed 3 cm (1 inch) in length. While its venom is powerful and can cause extreme pain—comparable to a wasp sting—it is not considered lethal to humans. Despite their size, these nocturnal hunters have poor vision and instead rely on sensitive hairs on their legs and abdomen to detect vibrations from nearby movement.

General information, not professional advice. Spotted an error? Flag the card or see corrections and complaints.

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