The spiders commonly known as tarantulas are found in tropical and subtropical forests and deserts in Central and South America, Africa, and the southern United States. In fact, there are more than 650 species of the large and hairy arachnids most of us call tarantulas; however, the vast majority of these spiders are small, often with legs measuring less than two centimeters in length.
The name “tarantula” comes from Italy, not the world’s tropical zones. Specifically, the name is derived from that of the southern Italian town of Tarantella, where local residents first identified the wolf spider which would become known to science as Lycosa tarantula. Subsequently, as Europeans explored and colonized other parts of the world, any large or hairy spider they came across also became known as a tarantula.
Tarantulas inspire fear among humans because of the hairy bodies and large size of the most emblematic species. But, while it is true that their bite can be painful, their venom is actually weaker than that transmitted by a normal bee sting.
Tarantulas are nocturnal predators. During the day they will remain holed up in their burrows, only emerging at night to hunt the insects which are their preferred prey. In addition to insects, larger species of tarantula will also hunt small frogs, toads and mice. Tarantulas hunt by ambushing their prey. While they do not build webs, they do use their silk to make doors for their burrows. Across different species, tarantulas may be ground-living or tree-dwelling.
The spiders most people imagine when they think of tarantulas are in fact those arachnids which belong to the family Theraphosidae, better known as “bird-eating spiders”. While there are more than 650 species of Theraphosids, the entire family is defined in the popular imagination by its giant members, such as South America’s Goliath bird-eater (Theraphosa blondi), which is the world’s largest spider; however, despite its fearsome name and disconcerting size (with a body length of up to 12 centimeters, or almost 5 inches), this enormous arachnid mostly feeds on insects, worms, amphibians and other spiders, rather than birds. In Tambopata National Reserve, the most abundant tarantulas are those of the Pamphobeteus genus, commonly known as chicken spiders.
In common with other spiders, as part of their growing process tarantulas shed their external skeletons. During this molting process they also replace internal organs, including their stomach lining, and are even able to re-grow lost legs. Young tarantulas will engage in this process many times a year, while older spiders may only molt once a year, or when they need to replace a lost limb. Larger species of tarantula, like the Goliath bird-eater, can live for more than 25 years.
Tarantulas have few natural predators. Their main enemy is the wasp known as the tarantula hawk. These parasitic wasps belong to the Pepsis genus, and across the world there exist more than 250 species of this formidable insect. Tarantula hawks use their sting to paralyze their arachnid prey, after which they drag it to their nest and use it as living food. Keeping the spider alive, the tarantula hawk lays a single egg in its body, and then leaves its larva to slowly feed upon the unfortunate arachnid.