The world of spiders offers a diverse array of creatures, from the minuscule to the enormous. Their size often leads to questions about which spider is the largest. While fictional giant spiders exist, several real-life species achieve impressive dimensions. This exploration delves into the largest spiders on Earth, clarifying how their size is measured and what makes these arachnids remarkable.
The Reigning Champion
The Goliath Birdeater (Theraphosa blondi) holds the title of the largest spider by mass and body length. This colossal tarantula can reach a body length of 13 cm (5.1 inches) and weigh up to 175 grams (6.2 ounces), comparable to a small puppy. Its leg span can stretch up to 30 cm (12 inches), roughly the size of a dinner plate.
The Goliath Birdeater has a hairy, robust body, typically ranging from tan to light brown with golden hues. Its fangs reach 2 to 4 cm (0.79 to 1.57 inches). Primarily found in the tropical rainforests of northern South America, its “birdeater” name comes from an 18th-century engraving depicting a different tarantula consuming a hummingbird, though birds are not its primary diet. Scientists often consider both leg span and body mass when defining “biggest,” with the Goliath Birdeater excelling in mass.
Other Giants of the Spider World
While the Goliath Birdeater holds the record for mass, other spiders contend for the title of “largest” based on different metrics, particularly leg span. The Giant Huntsman Spider (Heteropoda maxima), native to Laos, has the largest leg span of any known spider, reaching an astonishing 30 cm (12 inches).
Despite its impressive leg span, the Giant Huntsman Spider is considerably lighter and less bulky than the Goliath Birdeater, with a body length of about 4.6 cm (1.8 inches) and an average weight of 167 grams (5.9 ounces). Another notable giant is the Brazilian Salmon Pink Birdeater (Lasiodora parahybana), one of the largest tarantulas by both mass and leg span. This species, endemic to northeastern Brazil, can have a leg span of up to 28 cm (11 inches), and females can weigh over 100 grams.
Life and Habits of Giant Spiders
Giant spiders typically inhabit humid, tropical environments, with many large tarantula species, including the Goliath Birdeater, preferring the rainforests of South America. They are often terrestrial, creating deep burrows in the ground or under rocks, which they line with silk for shelter. These burrows provide a secure retreat where they spend their days, emerging primarily at night to hunt.
Their diet primarily consists of large arthropods like insects, worms, and amphibians. As opportunistic predators, they will also consume small vertebrates such as rodents, lizards, snakes, and occasionally small birds or bird eggs if the opportunity arises. Giant spiders locate prey using vibrations detected through sensitive hairs on their legs and abdomen, rather than relying on their poor eyesight. Females of these large species can have remarkably long lifespans, often living for 15 to 25 years. Males, however, have a significantly shorter lifespan, typically lasting only 3 to 6 years, often dying shortly after reaching maturity and mating.
Are They a Threat?
Despite their intimidating size and appearance, large spiders like the Goliath Birdeater are generally not considered a significant threat to humans. Their venom, while present, is typically not medically significant or lethal. A bite is often compared to a bee or wasp sting, resulting in localized pain, swelling, and redness. The discomfort usually stems more from the physical puncture by their large fangs than from the venom itself.
These spiders possess various defensive mechanisms, and biting is usually a last resort. When threatened, they often hiss by rubbing bristles on their legs together, a sound audible from several feet away. They may also flick irritating, barbed hairs, known as urticating hairs, from their abdomen using their hind legs. These hairs can cause itching and irritation if they come into contact with skin or mucous membranes. Bites are rare and typically occur only if the spider feels directly provoked or cornered.