Tarantula Facts

As the world’s largest spiders, tarantulas are both feared and beloved. There are more than 850 species of these often hairy, nocturnal arachnids. Tarantulas live primarily in the tropical, subtropical, and desert areas of the world, with the majority found in South America.

In the United States, tarantulas are found in southwestern states. Despite their fearsome appearance, tarantulas are not threatening to humans. Their venom is milder than a honeybee, according to National Geographic, and though painful, their bites are not harmful. In fact, tarantulas have become a popular pet for arachnophiles around the world.

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Tarantulas’ size and coloring can vary wildly depending on location and species. From front right leg to rear left leg, tarantulas range from 4.5 to 11 inches (11.4 to 28 centimeters) in length. They weigh from 1 to 3 ounces (28.3 to 85 grams) and have strong jaws and fangs. “The position of the fangs is distinctive as they are parallel to each other and face downwards like a vampire’s,” said Jo-Anne Nina Sewlal, an arachnologist at the University of the West Indies in Trinidad. While many tarantulas are dull brown or black, some species are brilliantly colored or striped.

“Probably [tarantulas’] most distinctive physical characteristic is that they possess very hairy legs and bodies,” said Sewlal. She explained that some species use these bristly hairs, called urticating hairs, as a defense mechanism. If the attacker makes physical contact with the spiders, the hairs can be “rubbed off on . . . [or,] flicked toward potential attackers. These hairs are quite irritating if they land on the eyes or mucus membranes.”

According to Texas Parks and Wildlife Magazine, most terrestrial species of tarantulas are burrowers. Unlike many spider species, tarantulas do not use webs to catch their prey. They do, however, spin silk. If a tarantula lives in a place with dry soil, it will burrow into the ground and line the walls of the hole with silk to help keep sand and dirt out. If a tarantula does not burrow, it might spin a burrow out of silk, or live under a log or rock. Sometimes, tarantulas spin a line of silk near the entrance to a burrow, which, reports National Geographic, acts as a trip wire, alerting the spider to prey that is nearing its home.

Sewlal described tarantulas’ distinctive mating ritual. Before he can mate, the male spins a “small special web” and sprays it with sperm. Afterward, he rubs himself on the web, loading his pedipalps with it. He then searches for a female’s burrow, using the pheromones she gives off as a guide. According to the National Parks Service, when a male tarantula finds a female burrow, he “taps his foot to alert the female to his presence.”

Goliath Bird-Eating (Theraphosa blondi): A real giant, this behemoth has a leg span of nearly 12 inches (30 cm), according to Blue Planet Biomes. It is native to Northern areas of South America and lives in swamps. True to its name, this tarantula can eat birds, though the behavior is rare. Sewlal said, “In addition to insects, the primary prey of this species is actually earthworms. However, due to its size it is capable and it does kill and consume small vertebrates such as, frogs, snakes, lizards and even bats and rodents . . . and occasionally young birds. But birds do not comprise their main diet.”

Jessie Szalay is a contributing writer to FSR Magazine. Prior to writing for Live Science, she was an editor at Living Social. She holds an MFA in nonfiction writing from George Mason University and a bachelor's degree in sociology from Kenyon College.