Tarantulas Rarely Bite (And Other Facts About the Friendly Spiders)

Why Tarantulas Should Inspire Fascination, Not Fear

Tarantula
Kendall McMinimy/Photographer's Choice/Getty Images

Tarantulas are the giants of the spider world, well known due to their conspicuous size and common appearance in movies as evil forces. Because of that, many people flinch in horror at the sight of a tarantula. These big, beefy spiders strike fear in the hearts of arachnophobes everywhere, but in fact, tarantulas are some of the least aggressive and dangerous spiders around.

Here are 10 fascinating facts about tarantulas that will give you new respect for this amazing arachnid.

1. Tarantulas are quite docile and rarely bite people

Many large predators would quickly make a meal of a tarantula, so they aren't too anxious to tangle with something as large as a person. And it wouldn't do a tarantula much good defensively to bite you since its venom doesn't pack much of a punch.

A tarantula bite to a human is typically no worse than a bee sting in terms of toxicity. Symptoms from most New World species tarantulas range from local pain, swelling, and stiffness of joints. However, tarantula bites can be lethal to birds and mammals as large as dogs.

2. Tarantulas defend themselves by throwing needle-like hairs at their attackers

If a tarantula does feel threatened, it uses its hind legs to scrape barbed hairs (called urticating or stinging hairs) from its abdomen and flick them in the direction of the threat.

You'll know it if they hit you, too, because they cause a nasty, irritating rash. Some people may even suffer a serious allergic reaction as a result, especially if it comes in contact with their eyes. The tarantula pays a price, too—it winds up with a noticeable bald spot on its belly.

3. Female tarantulas can live 30 years or longer in the wild

Female tarantulas are famously long-lived. In captivity, some species have been known to live for 20 to over 30 years.

Males, on the other hand, don't make it much beyond reaching sexual maturity, with a lifespan of just 3–10 years on average. In fact, males don't even molt once they reach maturity.

4. Tarantulas come in a wide variety of colors, shapes, and sizes

Colorful tarantulas that can be kept by humans include the Mexican red knee tarantula (Brachypelma smithi), the Chilean rose (Grammastola rosea), and, most popularly right now, the pink-toed tarantula (Aricularia avicularia).

The largest tarantula known on earth is the goliath bird eater (Theraphosa blondi) which is fairly fast growing and can reach a weight of 4 ounces and a leg span of 9 inches. The smallest is the endangered Spruce-Fir Moss Spider (Microhexura montivaga); its adults reach a maximum size of .1 to .15 inch, or about the size of a BB pellet.

5. Tarantulas ambush small prey at night

Tarantulas don't use webs to capture prey, they do it the hard way—hunting on foot. These stealthy hunters sneak up on their prey in the dark of night. Smaller tarantulas eat insects, while some of the larger species will hunt frogs, mice, and even birds. Like other spiders, tarantulas paralyze their prey with venom, then use digestive enzymes to turn the meal into a soupy liquid.

Their venom is made up of a species-specific mix of salts, nucleotides, free amino acids, neurotransmitters, polyamines, peptides, proteins, and enzymes. Because these toxins are hugely varied across species, they have become a target for scientific research for potential medical uses such as biotechnology and anti-parasitic effects.

6. A fall can be fatal to a tarantula

Tarantulas are rather thin-skinned creatures, particularly around the abdomen. Even a fall from a height of under a foot can cause a deadly rupture of the tarantula's exoskeleton. The heaviest species are the most susceptible to damage from drops.

For this reason, handling a tarantula is never recommended. It's easy to get spooked, or even more likely, for the tarantula to get spooked. What would you do if a huge, hairy spider started squirming in your hand? You'd probably drop it, and quickly.

If you must handle a tarantula, either let the animal walk onto your hand or pick the spider up directly with cupped hands. Never handle a tarantula during or near the time of her molt, an annual period which can last up to a month, once a year. Record this time so you can be aware.

7. Tarantulas have retractable claws on each leg, like cats

Since falls can be so dangerous for tarantulas, it's important for them to get a good grip when climbing. Though most tarantulas tend to stay on the ground, some species are arboreal and climb trees or other objects. By extending special claws at the end of each leg, a tarantula can get a better grasp of whatever surface it is attempting to scale.

For this reason, it is best to avoid mesh tops for tarantula tanks, because the spider's claws can get caught in them.

8. Though tarantulas don't spin webs, they do use silk

Like all spiders, tarantulas produce silk, and they put this resource to use in clever ways. Females use silk to decorate the interiors of their below-ground burrows, which is thought to strengthen the earthen walls. Males weave a silken mat on which to lay their sperm.

Females encase their eggs in a silken cocoon. Tarantulas also use silk trap lines near their burrows to alert them to potential prey, or to the approach of predators. Scientists recently discovered that tarantulas can produce silk with their feet, in addition to using spinnerets as other spiders do.

9. Most tarantulas wander during the summer months

During the warmest months of the year, sexually mature males begin their quest to find a mate. Most tarantula encounters occur during this period when males disregard their own safety and wander during daylight hours.

Should he find a burrowing female, he'll tap the ground with his legs, politely announcing his presence. This suitor is a good source of much-needed protein to the female, and she may try to eat him once he's presented her with his sperm.

10. Tarantulas can regenerate lost legs

Because tarantulas molt throughout their lives, replacing their exoskeletons as they grow, they have the ability to repair any damage they've sustained. Should a tarantula lose a leg, a new one will reappear as if by magic the next time it molts. Depending on the tarantula's age and the length of time before its next molt, the regenerated leg may not be quite as long as the one it lost.

However, over successive molts, the leg will gradually get longer until it reaches normal size again. Tarantulas will sometimes eat their detached legs as a way to recycle the protein.

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