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Tarantula Facts

world's largest spider
This is not the world
Credit: Ioannis Pantzi, Shutterstock

As the world’s largest spiders, tarantulas are both feared and beloved. There are more than 800 speciesof 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, and though painful, their bites are not harmful. In fact, tarantulas have become a popular pet for arachnophiles around the world.

Appearance and physiology

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. Their coloring and size vary wildly depending on location and species. While many are dull brown or black, some tarantulas are brilliantly colored or striped.

Many species from the Americas have special urticating hairs, or bristles, on their abdomens. When disturbed, tarantulas flick the hairs at the attacker. The hairs become lodged in the attacker’s eyes or mucus membranes, causing great discomfort and itching.

Tarantulas periodically molt, shedding their exoskeletons to grow. While molting, they can also replace internal organs — including female genitalia or stomach lining. They can even regrow lost legs or pedipalps (short sensory appendages).

Female tarantulas can live up to 30 years, while males live around seven.

Feeding

Tarantulas primarily eat insects, though some species enjoy larger game like frogs, mice and small lizards.

Most 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. This acts a trip wire, alerting the spider to prey that is nearing its home.

When prey comes close, tarantulas ambush it, seizing it with their legs, paralyzing it with venom, and then killing it with their fangs. They can also crush prey with their strong jaws. After the prey is dead, tarantulas inject digestive enzymes into the prey to liquify the body and suck it up through its straw-like mouth.

Mating

Before he can mate, the male spins a hammock-shaped web and sprays it with sperm. Afterward, he rubs himself on the web, loading his sex organ (embolus) with it. He then mates with the female, holding her fangs back with his legs. When he’s finished, he needs to hurry away quickly, lest the female eat him.

tarantula
Meet the tarantula as big as your face, Poecilotheria rajaei.
Credit: Ranil Nanayakkara / British Tarantula Society

Species

Some notable species of tarantula are:

Chilean Rose Hair: Often called “Rosie” by arachnid-enthusiasts, these Chilean spiders are a rich brown color with pink-tinged hairs. They grow to be about six inches long.

Cobalt Blue: Under certain lights, these Southeast Asian tarantulas are a bright, brilliant blue. Otherwise, they look black. They are among the most aggressive types of tarantula, and also one of the most rare.

Pink Toe: These smallish Caribbean tarantulas start life with a beautiful green or turquoise iridescence. Their color darkens as they mature, but their feet remain pale--hence their common name.

Goliath Bird-Eating: A real giant, this behemoth has a leg span of nearly 12 inches (30 cm). True to its name, this tarantula can eat birds, though the behavior is rare. It is native to Northern areas of South America and lives in swamps.

Tiger spider: This newly discovered species has a leg span of 8 inches (20 cm) and enough venom to kill mice, lizards, small birds and snakes. Poecilotheria rajaei was discovered on the island nation of Sri Lanka.

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