The Biggest Spider on the Planet

The Goliath birdeater spider is a stealth hunter in South American forests.
Common Name:
Goliath Birdeater
Scientific Name:
Theraphosa blondi
Diet:
Carnivore
Average Life Span:
Females, 20 years; males, 3 to 6 years
Size:
Leg span up to 12 inches
Weight:
Up to 6 ounces
Current Population Trend:
Unknown

The Goliath birdeater is the king of spiders. Weighing up to six ounces and with a leg span of nearly a foot, this tarantula is the largest arachnid on the planet.

Goliaths don’t usually eat birds, but they are big enough to be able to—and occasionally they do. “Birdeater” came from an 18th-century engraving that showed another kind of tarantula eating a hummingbird, which gave the entire Theraphosa genus the name birdeater.

Goliath birdeater diet

Insects make up most of the Goliath diet, but frogs and rodents are on the menu too. Goliaths prowl the Amazon in northern South America. When a Goliath pounces on a mouse, for example, its inch-long fangs act like hypodermic needles, pumping neurotoxins into the hapless prey. The spider then drags the dying animal back to its burrow and begins the digestion process. Spiders can’t ingest solid material, so they first liquefy the prey’s insides, then suck it dry.

Unusual defense

Unlike jumping spiders, Goliath birdeaters have bad eyesight. They rely instead on modified leg hairs, sensitive to vibration, to warn them of danger. If a predator like a coati gets too close, the Goliath has an unusual weapon: harpoon-shaped hairs (called urticating hairs) tipped with stinging barbs. The spider rubs its legs together, launching a shower of miniature missiles into the air. The hairs connect with the would-be assailant’s eyes and skin, sending it scurrying.

Female Goliaths use those same urticating hairs to cover their large egg sacs, which hold between 50 and 150 eggs. Hatchlings stay close to their mother until they fully mature at two to three years.

Goliath habitat

Though they don’t spin webs to trap food, Goliaths do use their weaving skills in another way: to line their burrows under the forest floor.

It's deadly to small creatures, but the Goliath’s venom is not lethal to humans. A bite would sting about as much as a wasp’s. The giant spider is a delicacy in some parts of South America—though its urticating hairs are carefully singed away before the spider is roasted in banana leaves.

As its scientific name suggests, the Antilles pinktoe (<i>Avicularia versicolor</i>) changes color as it matures. The spider’s abdomen turns from blue to pink or red and the carapace becomes metallic green. This juvenile Antilles pinktoe was photographed at the Henry Doorly Zoo in Omaha, Nebraska.
As its scientific name suggests, the Antilles pinktoe (Avicularia versicolor) changes color as it matures. The spider’s abdomen turns from blue to pink or red and the carapace becomes metallic green. This juvenile Antilles pinktoe was photographed at the Henry Doorly Zoo in Omaha, Nebraska.
Photograph by Joel Sartore, National Geographic Photo Ark

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