Tarantula

Habitat

Tarantulas are terrestrial or arboreal, depending on the species. They take shelter under loose tree bark or in epiphytes, in ground burrows or nests made of leaves and lined with silk.

Range
Tarantulas are common throughout Central and South America. In Costa Rica, different species become fewer and infrequent as elevation increases.

National Parks
Monteverde Cloud Forest Reserve and Santa Elena Reserve.

Physical Description
The spiders known as tarantulas are famous for being large, hairy, and poisonous. While in some places there are enormous spiders—for example, the South American bird-eating spider (Theraphosa blondi) has a leg span of 18 cm—in Costa Rica the tarantulas are not so gigantic. For having an intimidating appearance, the tarantula is quite a fragile creature and steps delicately around the forest floor habitat. It uses its front legs like antennae to feel around in front of the spider’s body, which gives the spider a stronger sense of its surroundings than the spider’s eight small eyes.

Biology and Natural History
Legends and fables have long presented the tarantula as a dangerous predator, but this spider is a timid animal that is much more apt to retreat into a hole than to attack. It is common in Costa Rica but not necessarily commonly seen. It is nocturnal, emerging at dusk or later to mate and hunt. This primitive species of spider does not spin a web, but does dig a burrow, and never strays terribly far from home. Some live for 5 to 10 years in the wild.

All tarantulas, like all spiders, have poison, but tarantulas are relatively shy creatures and are very unlikely to bite. Most tarantulas need venom to stun their prey and defend themselves, and their bodies do not replenish venom quickly. Hence they are hesitant to waste venom unless they are threatened and cannot escape. If a tarantula feels cornered and scared, it will first use its backmost legs to flick thick urticating hairs off the back of its abdomen. These hairs sting, especially if they come in contact with the eyes or mouth. Another warning sign that a tarantula is becoming aggressive is when it rears up onto its back legs, sometimes adding an angry hiss. The spider’s fangs are underneath its head and the spider needs to come down on top of what it will bite. While the venom of a tarantula is not fatal, the bite can still be deep and painful. It’s better to just admire one where it stands.

Diet
Tarantula diets vary widely depending on the species. The medium-sized species that can be found in Costa Rica, including the Orange-Kneed Tarantula and the Zebra Tarantula (Aphonopelma seemanni), eat arthropods smaller than themselves.

Height/Weight
The Orange-Kneed Tarantula and the Zebra Tarantula, for instance, have a leg span about the width of the palm of a human hand. They are very light for their size, weighing several grams.

Taxonomy
Suborder: Mygalomorphae
Family: Theraphosidae

Sources
Hogue, Charles L. Latin American Insects and Entomology. University of California Press: Berkely and Los Angeles, 1993.

Kricher, John. A Neotropical Companion: an introduction to the animals, plants, and ecosystems of the New World tropics. Princeton University Press: Princeton, NJ, 1997.

-Amy Strieter, Wildlife Writer