Our Window on Nature

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Hairy, Scary Spiders

Filed under: Bugs — Lowell Christie -- October 21, 2007 @ 11:00 am

TarantulaKaye still remembers the first time she saw a live tarantula. She was glancing out the front window of our California home when an enormous, hairy spider crawled past the front of the house. It was huge. Conditioned by adventure movies to believe that tarantulas are both deadly and intent upon attacking innocent people, Kaye allowed the critter to continue right on down the road.

Her next tarantula sighting wasn’t until after we’d begun traveling, and by that time we knew enough about spiders to realize that although a chase scene featuring a tarantula may make good theater, it doesn’t represent the facts. These spiders aren’t pretty, but neither are they hostile; they’re simply fascinating.

Even decades after the event, we can make certain assumptions about Kaye’s early tarantula sighting. She probably saw the spider in late summer or early fall; it probably was an adult male on the prowl in search of a mate; and in all likelihood it wasn’t as huge as it appeared. So, since tarantula season is here and since at least some of you who are reading this column will be traveling into the spiders’ territory during the months ahead, we’ve compiled a few facts about these hairy spiders.

Tarantulas are the largest spiders in the world. They are tropical creatures; therefore, in this country they are found primarily in the Southwest – Texas, New Mexico, Arizona, and southern California. The word tarantula is derived from the name of the Italian city of Taranto, even though the tarantulas of that region actually are wolf spiders. The idea that dancing the “tarantella” cured the bite of this spider was partly folk myth and partly an excuse to perform an illegal street dance. Apparently, the Italian wolf spider isn’t any more venomous than our tarantula.

One of the tarantula’s more noticeable features, other than its size, are the hairs that cover its legs and body. These serve the spider as self-defense mechanisms. When alarmed, the spider raises its back legs and kicks off hairs into the face of its predator. The stinging sensation generated by the chemical in the hairs causes the dog, coyote, javelina, lizard, or snake enough discomfort to permit the spider’s escape. One animal, the coati, has managed to overcome this defense mechanism; when it catches a tarantula the coati rolls the spider around in the dirt to rub off the hairs before eating it. Your pet dog probably doesn’t know this trick, so be sure that it doesn’t harass a tarantula. The dog will lose.

From time to time you hear someone claim to have seen a tarantula jump several feet into the air. That’s highly unlikely for several reasons. For one thing, tarantulas have very poor eyesight. Even with eight tiny eyes clustered on top of its head, a tarantula sees little but patterns of light and dark. It has no ears, so it does its hunting on the ground, sitting motionless until some creature strays across its path. Even then it waits until the prey actually brushes against one of its legs before it grabs, and not always with any accuracy.

If you are visualizing the tarantula biting off chunks and chewing its food, don’t. The spider injects a liquefying fluid into a portion of the prey, waits for it to soften, and eats; then it moves on to the next area. By the time the spider is finished, the only thing that remains of the prey is a ball of exoskeleton.

For the most part, tarantulas lead very boring lives. You might find the silk-lined opening of the tunnel that a tarantula calls home, but it’s highly unlikely that you’ll see its owner abroad except during late summer and fall. Young spiders make their burrows soon after leaving those of their mothers, and they stay within a few feet of the burrow for the next 10 years. They eat and molt, eat and molt for approximately a decade before becoming sexually mature, and then the males go on the prowl. Even solitary creatures such as tarantulas must unite to provide for future generations. It happens like this.

In late summer, mature male tarantulas leave the protection of their burrows to seek mates. At that time you’ll begin to see the giant spiders walking across the roads. Suddenly spiders you never knew existed seem plentiful. When a male reaches a female’s burrow, he taps on her web to invite her outside. If she is feeling receptive, she emerges. He then touches her with his foreleg. Then, if she responds gently rather than by trying to eat him, they mate. Afterward he backs off very respectfully. Should he hang around too long, the female will consider him dinner, rather than the father of her offspring. However, most males survive to mate with other female tarantulas.

Now comes the strange part. During this period, the male busily seeks out mates, because he is truly in the autumn of his life. He molted for the last time that summer, and now he enters a rapid aging stage. He won’t survive the winter.

The female, on the other hand, stores the semen in her body until the following spring. Then she spins a thick layer of silk at the mouth of her burrow to serve as a cradle, lays 200 to 300 eggs on it, and rolls the eggs into a neat bundle that she tends for the next three weeks. On warm days the mother rolls her egg sac out into the sun, turns it over occasionallv to allow the sun to warm it evenly, and then hauls it back into her burrow before nightfall. She continues to act the part of a good mother after the eggs hatch, protecting them for another six to seven weeks. Then the spiderlings disperse and make their own burrows. Mom needs to store up energy for autumn and another breeding season, for although she has a new young mate every year, a female tarantula may live for 25 years.

In all the time we’ve spent in the Southwest, we’ve never spotted a female tarantula in the wild. We see males often at this time of year – when we are driving desert back roads and occasionally as we stroll around the campground. We relish their presence, for while we travel freely throughout our lives, tarantulas have only one opportunity to be vagabonds.

FMC1087


For more information: Check out the articles at the American Tarantula Society Headquarters or if you want a quiet pet, try this book.

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