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Goliath Birdeater Tarantulas Seldom Eat Birds

Dorothy is a Master Gardener, former newspaper reporter, and the author of several books. Michael is a landscape/nature photographer in NM.

A Goliath birdeater tarantula (Theraphosa blondi) is the largest tarantula in the world in mass and size (about the size of a large dinner plate).

A Goliath birdeater tarantula (Theraphosa blondi) is the largest tarantula in the world in mass and size (about the size of a large dinner plate).

The Goliath Birdeater Doesn't Eat Birds Often

Explorers who witnessed a tarantula (Theraphosa blondi) eating a hummingbird many years ago named that spider the Goliath birdeater.

But actually, living deep in the rainforests of northern South America, the Goliath birdeater tarantulas, although they have the ability to live up to their name, don't eat birds very often. Quite possibly, it's because they don't see very well. Instead, they use the hairs on their legs and abdomen to sense vibrations on the ground or up in the air.

They will, however, eat almost anything that is smaller than they are, including invertebrates and lizards, mice, and frogs. When they are kept as pets, these spiders are often fed cockroaches.

A very large spider

A very large spider

Solitary Creatures' Mating Rituals

Goliath birdeater tarantulas only get together for mating purposes. They are very solitary creatures and prefer to simply be left alone.

Male Spiders

The male spiders are attracted to the female because of the chemicals she emits, and there are often fights among several aggressive males trying to be the lucky "chosen" one that will be allowed to mate with the female. The female, however, is very selective and she allows the male to live after mating, something many other spider species don't do.

Once a spider's maturation molt is complete, the male spiders develop a finger-like protuberance on the underside of the front legs. That protuberance is used to hook and lock a female spider's fangs (and also to steady themselves during the mating process). The male spider dies within only a few months after mating. The entire lifespan of a male Goliath birdeater tarantula is only three to six years. By comparison, the female's lifespan can be up to 25 years.

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Female Spiders

The females eat a lot prior to mating because once they have their egg sac in place, they won't eat at all, focusing on only one thing, which is protecting her young to ensure their survival. The female can deposit up to 200 eggs and the spiderlings will arrive about eight weeks after the mating has occurred.

It is necessary for a female spider to have recently molted in order to reproduce or any sperm acquired will be lost when she does molt. After mating, the female will create a web in which she will lay up to a few hundred eggs that are fertilized as they are passing out of her body. She will then wrap the eggs into a ball and begin carrying the egg sac, which is about the size of a tennis ball, with her.

Baby Spiders

The 50-70 or so spiderlings that are in the egg sac must go through several molts in order to grow. They must shed their old exoskeleton, then emerge in a larger one. The spiderlings can molt five or six times during their first year, then take about two to three years to reach maturity.

Defense Mechanisms

Rubbing bristles on its legs together, this tarantula creates a hissing noise stridulation that is loud enough to be heard several feet away, which is one of their defense mechanisms. The hissing noise sounds a bit like velcro being pulled apart. They are also able to flick their hairs toward an attacker and might rear up on their hind legs, displaying some pretty ferocious two-inch fangs, which might be enough to scare a potential predator away. Those fangs are strong enough to pierce a small animal's skull.

The tiny, barbed hairs that are produced when it rubs its legs against its abdomen can get in the eyes and mucous membranes of its prey, causing extreme pain and itching that can last for days.

As for humans, these spiders pose a limited threat because though their bite is venomous, it is not deadly. However, if you do manage to get bitten by one it might feel as if you had just been stung by a nasty wasp, so it's best not to get put into a situation where that might happen. Those fangs are strong enough to puncture the skin of a human being and that thought alone should be enough to make you take proper precautions.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2018 Mike and Dorothy McKenney

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