Theraphosidae - tarantulas



There are 903 species in the Theraphosidae family which includes the hairy spiders commonly known as the tarantulas, see the bird eating tarantula above. There are about 40 species in the U. S. mainly in the south west. They have eight small eyes. Most are ground dwellers and live in burrows. They hunt by touch, usually around dusk. In this family the spider body length ranges from 2.5 - 10 cm, and leg span can be as large as 30 cm. Some females in this family can live for over 20 years.

Baboon spiders, Pterinochilus sp.

Baboon spider, Pterinochilus sp.

Baboon spiders, see above, are found in Africa, and are called Baboon spiders because the last two leg segments are said to resemble the fingers of a baboon. They attack their prey by ambush.

Trinidad chevron tarantula, Psalmopoeus cambridgei

Trinidad chevron tarantula, Psalmopoeus cambridgei

As its common name suggests the Trinidad chevron tarantula, Psalmopoeus cambridgei, is native to Trinidad, but is now found worldwide as it has become popular as a pet. The female has black chevron markings on her abdomen, and the background colour varies from green through to brown. It can have a leg span of 17 cm, with males being smaller. Males have a life span of just 2 - 3 years, whilst females can live up to 12 years.

In the wild it lives in trees in a silken tube, in bark crevices or amongst the epiphytic plants that grow on trees. This is a fast moving and aggressive spider. When threatened it will raise itself up and extend its front legs; if provoked further it will lunge and bite. It will eat almost any live food, with fully grown individuals being capable of catching small lizards, bats, frogs and mice. Its eyesight is not good, and the prey is not trapped in a web, but is hunted and detected by smell and vibration. Once caught the prey is injected with venom which is fast acting to stun the prey, then kill it, and start the liquefaction process. The spider drags its prey back to its retreat or tunnel to be eaten at leisure.

Mating happens at night when the male goes in search of a mature female, whom he detects by the pheromones she emits. He courts her by shaking his body and leads her out of her tunnel/retreat. After mating the female produces two egg sacs each with 100 - 150 eggs. She guards the eggs sacs, and after about six weeks the spiderlings hatch, and disperse about two weeks later after their first moult.

Its venom of this spider is used to treat stroke patients.

Theraphosa blondi Goliath bird-eating spider

Theraphosa blondi

The Goliath bird-eating spider, Theraphosa blondi, above, is the largest spider in the world by mass. Its leg span can reach 28 cm, body length of 12 cm, fangs of 2 cm, and weigh 175 g. It is native to the northern rain forests of South America, where it is found in marsh and swamp. By day it lives in a deep, silk-lined burrow, emerging at night. Locally it is considered a delicacy when the stinging hairs have been removed and it is roasted.

Females take 3 - 6 years to mature, and may live as long as 25 years. Males die soon after they reach sexual maturity which happens when they are 3 - 6 years old. Unlike many other spiders the male is not usually eaten during or after mating. Before mating the male approaches the entrance of the female's burrow to entice her out to mate with him. The female lays 100 - 200 eggs, which she places in a large egg sac, these hatch about 2 months later. Irritating hairs may be incorporated into the construction of the egg sac providing protection from parasitic flies. The egg sac and female move down into the burrow, and the female seals off the entrance. She will not feed for the next two months while she guards her eggs. The spiderlings remain with their mother until after their first moult.

This is considered to be the most dangerous of the tarantula species as its defensive behaviour includes rubbing its legs to release clouds of stinging hairs. Its venom is less harmful to humans, and has been compared to a wasp sting. It also has a threat display of standing up on its rear legs and displaying it large fangs. Its prey is mainly earthworms and toads, but anything straying within reach will be grabbed by a hungry individual. Its eyesight is poor, and it senses its prey by vibrations carried through the ground. Usually it does not stray too far from its burrow.