Tarantulas are spiders belonging to the family Theraphosidae. Most species are large and hairy but there are smaller species as well. There are approximately 900 known tarantula species and tarantulas are found all over the world, from tropical environments to desert regions. Some species are arboreal while others live and hunt on the ground. The name tarantula originally referred to the European wolf spider only and can be traced to the Italian city of Taranto. The name was then used for all Theraphosids spiders when Europeans started to explore areas that had a lot of large spiders, such as the Americas.

Tarantulas are ambush predators that mainly eat other insects, but larger species will also eat small reptiles, amphibians, mice and birds which have led to them being referred to as bird spiders. Tarantulas are venomous and use their venom to kill their prey. Most species are however harmless to human. The most dangerous species produce venom that will cause extreme discomfort, sometimes lasting for days, but a bite will not kill a human unless an allergic reaction occurs. No deaths have been attributed to tarantula spiders. Although they do not spin webs to hunt, all species of tarantulas can produce silk any many species sleep in a silk tent, while others use silk to reinforce the walls in their burrows. They can also use the silk to help them climb.

Tarantulas have a similar anatomy to other spiders and you can read more about spider anatomy by visiting our spider section.

Some tarantula species show sexual dimorphism; the males are usually smaller and have a duller colouration compared to the females. The males in some species have tibial hooks which are used to restrain the female during mating. The sex of juvenile tarantulas can be determined by the fact that male tarantulas have a cast exuvium for exiandrous fusillae or spermathecae while females don’t. It also possible to perform ventral sexing but this is less reliable, especially since it is hard to carry out correct.

Male tarantulas have a shorter life span than females and many die soon after maturing, something which occurs at 2-10 years of age depending on species. Female tarantulas can live to be 30-40 years when kept in good conditions in captivity. The oldest known tarantula lived to become 49 years old. This age is likely very rare in the wild due to predation. There are numerous animals that eat tarantulas, including a parasitic wasp, the tarantula hawk, which lays its eggs in tarantulas and let the spiders become a food source for the larvae.

In the pet trade, females are more sought after and therefore quite often more expensive. This is chiefly due to the fact that they are more long lived. Most wild caught tarantulas are adult males that might not have much longer to live. This skewed male-female ratio is caused by the fact that males wander around more while females stay in and near their burrow. Males are therefore more likely to end up in the hands of tarantula catchers.

Tarantulas reproduce through internal fertilization. The male inserts his pedipalps into the female spider’s opithosoma, an opening on the lower abdomen. The male get his semen onto his pedipals by releasing the semen into a web he has spun on the ground and then inserting the pedipalps in the small pool of semen. The pedipalps absorb the semen and store it until a suitable female can be found. The male will have to leave the scene quickly after mating or the female might eat her smaller male. Actually being eaten is however rare if there is enough room for the male to retreat. After mating, the female tarantula lays 50-2000 eggs (depending on size and species). The eggs are deposited in a silk sac and guarded by the female until the offspring hatches after 6-7 weeks. The young spiders still have some left of their yolk sac and will live on that for the first days before leaving the safety of their mother’s burrow. Young spiders like these are often referred to as spiderlings.