Tarantulas

Large hairy spiders might not be what you want to see in your garden, but tarantulas are actually gentle, beneficial creatures.

Female Mexican red-kneed birdeater tarantula (George Chernilevsky, Public Domain)

Tarantulas are the largest spiders on Earth and they have been around for 150 million years. There are approximately 1,000 species of tarantula around the world. ​

Global tarantula distribution (Sarefo) CC BY-SA 3.0

Before you run away in a panic, you might be surprised to learn some of the more unique characteristics of tarantulas. For example, did you know that tarantulas use special hairs on their legs and feet that are used to taste things? Or that their sense of smell is in their feet? Read on!

A tarantula next to a U.S. size 11 shoe, taken near Austin, Texas (Davejenk1ns) CC BY-SA 3.0

Tarantula description

We have all seen images of these large, hairy spiders, but there is far more to tarantulas than their appearance. Like other Arachnids, tarantulas have eight eyes and eight legs. Each of these legs has 7 segments and 2 or 3 retractable claws used for climbing and hunting. Tarantulas have 2 large eyes and 3 smaller eyes on either side. Tarantulas have hollow fangs used to inject their prey with venom. These fangs are unique in that they are articulated, which means they can be pointed forwards to attack or folded backwards for storage. [Imagine doing that with your teeth!]

Claws at the end of a tarantula leg (HTO, Public Domain)

Depending on the species, tarantulas range in body size from 1” to 4” long with leg spans of 3” to 12” wide. The Goliath birdeater, from Brazil and Venezuela, is the largest tarantula. While most North American tarantulas are brown, other species can be black with white stripes, iridescent purple, cobalt blue, yellow-legged, and one species, the Venezuelan greenbottle blue, has an orange back and metallic blue legs!

Venezuelan greenbottle blue tarantula (Biomechanoid56, Public Domain)

Speaking of legs, a tarantula can regrow a lost leg. A tarantula may pull off an injured leg and eat it, making room (and providing nutrients) to grow a new one. Did you know that all tarantulas can produce silk? Or that some Old World species can hiss? I didn’t either.

Tarantula lifecycle

Female tarantulas take 3 to 5 years to mature, depending on the species, and they can live for 15 to 30 years. Male tarantulas are smaller than females and they only live for 3 to 6 years. Like most other spiders, most female tarantulas often eat the males after mating. [Sorry, guys.] This provides her with the nutrients she needs to raise her young. Even if they are not eaten, male tarantulas normally die soon after mating.

Eggs are laid once a year in clusters of 50 to 2,000, depending on the species. Females are rather protective of their egg sacs, turning them frequently, the same way a broody hen will roll her eggs around in the nest. In both cases, this action prevents the offspring from becoming deformed.

Tarantulas are nocturnal predators. They used touch to find and ambush their prey. They mostly eat large insects, centipedes, millipedes, and other spiders. The larger species also capture and eat small bats, birds, lizards, mice, snakes, and tree frogs.

Tarantulas that hunt on the ground tend to live in silk-lined burrows in the ground. Tarantulas that hunt in trees tend to build silken nests for themselves, up in a favored tree.

​As a tarantula grows, it must shed its protective exoskeleton. These molts are dangerous times for a tarantula because they cannot move while they are molting. Baby tarantulas, or spiderlings, molt every couple of weeks. Mature tarantulas molt once a year.

Tarantulas as prey

Tarantulas may look fierce and intimidating, but they look like lunch to a variety of other predators, including scorpions, giant centipedes, opossum, honey badgers, mongooses, kinkajou, and coati, depending on your continent. Even other tarantulas will feed on tarantulas. One of the biggest threats to tarantulas is a type of wasp, called a tarantula hawk. Tarantula hawks must sting the underside of a tarantula to subdue and paralyze it. The wasp then drags the tarantula to its den where it lays an egg on the tarantula’s belly before sealing it inside the tunnel. When the egg hatches, it will consume the tarantula.

Tarantulas as pets

Many people keep tarantulas as pets, swearing that they are affectionate, gentle beings. That may be so, but you do need to know that New World species of tarantula have special stinging, barbed hairs, called urticating hairs, that can become embedded in your skin, eyes and lungs. These hairs are very similar to the stinging hairs found in nettles and are used to mark territory and protect nesting areas.

Sadly, as a result of pet trade, some tarantula species are threatened with extinction. This is especially true for the Mexican red-knee tarantula. If you must have a tarantula as a pet, make sure you get it from a reputable dealer. Better yet, if you happen to see a tarantula in your garden, simply leave it alone and let it take care of some of those pesky millipedes!

​Are tarantulas dangerous?

Tarantulas would much rather run away and hide than attack a person. Contrary to popular belief, North American tarantula bites are not particularly dangerous, though they are said to feel like bee stings. Tarantula bites can be very dangerous to people who are allergic. Tarantula species found in other parts of the world, particularly the Indian ornamental tarantula, can be quite deadly to humans.

Brazilian tarantula in defensively threatening posture (Sascha Grabow)

Did you know that some people also eat tarantulas? Apparently, in Cambodia and Venezuela, tarantulas are roasted over an open fire to burn off the hairs before being eaten. They can also be deep fried. And the fangs are used as toothpicks.

Now we know.