Tarantulas

There is some confusion about the name tarantula. It is not really a scientific name. It was originally given to this species because it is common around the southern Italian town of Taranto. It is a big spider by European standards, with a body that can be 30 millimeters (1 inch) long, and it is greatly feared. It was believed during the Middle ages that the only cure for anyone bitten by such a spider was to dance violently and continuously until the patient fell down from sheer exhaustion. So a very vigorous dance popular in the region then acquired the name of tarantella. Indeed groups of musicians traditionally traveled throughout the countryside ready at all time to assist in cure.

The tarantula is one of the biggest of European spiders, so when big hairy bird-eating spiders were discovered in the New World, even they grew to a much greater size than the original tarantula, they too were given that name. Now 'tarantula' is widely used on both sides of the Atlantic as a name for the mygalomorph bird-eating spiders of the New World.

Tarantulas belong to the group called Mygalomorphae which includes the most "primitive" of the spiders, such as the trapdoor spiders (Ctenizidae), funnelweb tarantulas (Dipluridae) and tarantulas or bird spiders (Theraphosidae). Their fangs are long and point strait down, as opposed to those of the Araneomorphans, which cross each other.

Tarantulas spend their days in silk-lined retreats and hunt by emerging at dusk and sitting and waiting for something to pass by. A spider lies in wait in its burrow and attacks any prey that comes too close to the entrance; then it rushes out and grabs the prey. It lifts up its front legs and sinks its fangs into its prey. It injects the prey with a lethal venom. Having killed its prey, the spider injects digestive juices into the prey's body, which turns its inside into liquid. The spider then sucks up the flesh through its mouth. All spiders are strict carnivores.4

American tarantulas can take up to 10 years to mature (depending ont he species and food availability). Females can live for 20 years beyond that. The tropical species have higher metabolic rate and mature faster, with most species taking two to three years to mature.

Pinktoe tarantula, Avicularia avicularia

The Latin genus name Avicularia refers to bird eating (Avi-=bird, -cularia = eating), was not brought to the attention of naturalists until 1705 when Maria Sibylla Marian, a Swiss naturalist visiting Suriname, included a painting of a large, hairy spider eating a hummingbird in her book on the insects of Suriname. This tarantula was the pinktoe tarantula. However, this dramatic birdeating behavior is certainly rare in the wild. For better or worse, the name tarantula is now accepted as applying to the big, hairy theraposids we find so fascinating.2


Mexican redknee tarantula

Mexican redknee tarantulas live in the deserts of northwestern and central Mexico. They are an endangered species because too many people took them as pets. A Mexican redknee tarantula feeds on insects, small lizards and rodents.

Predators of Tarantulas

Tarantulas may seem to be big and nasty enough that nothing in the deserts or jungles where they live would want to mess with them. However, their large size makes a nice meal for many kinds of predator. These include wasps and the coatimundi, a tropical relative of the raccoon.

The Trinidad chevron tarantula comes from the Caribbean island of Trinidad just off the northeast coast of Venezuela. Here it can be found in silken retreats along road bank, on houses, and in trees. It is olive green with dark stripes on the top of the abdomen. They also have red stripes on the foot segments. Males are the same general color scheme as females but much smaller. They have distinct feathering on the legs that allow them to parachute if they fall.2

[Photo of Chilean rose tarantula, Grammostola rosea]

Chilean rose tarantula
Grammostola roseai
Author: Martin Domek, BioLib  

Goliath Bird-eating Spider

The heaviest spiders are female bird-eating spiders (family Theraphosidae). A female scarlet bird-eater (Lasiodora klugii) was quoted as one-time record holder, although females of the Goliath bird-eating spider (Theraphosa blondi) are usually thought of as the heaviest. There is a record of a captive T. blondi that weighed in at 155 g (5. oz). Despite the name, they do not normally eat birds.5 With a record-breaking leg span of 28 cm - about the size of a dinner plate - the Goliath bird-eating tarantula is probably the largest.

References

  1. Life in the Undergrowth. David Attenborough
  2. Tarantulas and other arachnids. Samuel D. Marshall
  3. Bites and Stings: The World of Venomous Animals. John Nichol
  4. Dangerous insects and spiders By Chris McNab
  5. Animal Records By Mark Carwardine




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