Ivan's Place
In honor of the greatest moralist who never lived
Copyright © 2004 by Bill Becker

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Tarantula!!

The first three photos below are of two different tarantulas who set up housekeeping in abandoned gopher holes in my yard. They are females, and are substantially heftier, and to my mind, substantially prettier than the males. The males are black, and have smallish abdomens in comparison to the females. The tarantuals generally seen walking around on the surface are the males. When I was a kid growing up in the San Fernando Valley in the 50s, my friends and I would coax the males onto our hands and walk around with them as the spiders walked on our palms, which we rotated escalator-fashion. Passing motorists almost always did a double-take.

In my neighborhood, the female tarantula generally chooses an abandoned gopher hole for her den. She lines the entrance with silk, and probably also cleans the tunnel of debris so as to make for more space. (Whether these arachnid homemakers also build little closets, I don't know.) The spiders often position themselves near the entrance, and they scurry quickly back into the tunnel at my approach, or even when my shadow falls across the den opening. I assume that they are waiting for insects to walk by, or for a male to approach. I think that the spiders can sense ground vibrations as insects walk by, and also that the males actually tap the ground with their forelegs, or perhaps tug a bit on the web lining in a code that tells the female that a suitor, rather than dinner, is waiting outside.

I believe, too, that many dens are destroyed when a gopher breaks through the abandoned tunnel from underground, and simply pushes dirt over and through the nest; probably killing any baby spiders that may be there. It may also be that the females also bring dirt up to block the entrance after they have their babies, so as to keep them from going out before they are ready. In one case, a very small opening remained in a filled-in entrance, and I mistakenly thought that a gopher had ruined the den. After I had very gently and carefully spooned about 1/3 of the dirt away from the entrance, the female tarantula rushed up to protect it. I tried to restore the blockage, but was not able to tell subsequently whether I had irreparably damaged the den, or caused harm to any young spiders that the female might have been protecting.

For more information on U.S. tarantulas, go to Desert USA. I don't know if the tarantula species discussed there are the same as in my photos below. For a simple diagram of tarantula anatomy, go to The Tarantula's Burrow.

Standard copyright rules apply to the pictures below, of course.

Here I lured the female out of the den by brushing the entrance with the dried oat straw seen bottom left. This picture shows clearly the chelicerae, the large forward-directed appendages which carry the tarantula's fangs on the underside. When I poke a stiff oat straw down into the den a bit, I can feel thumps as the spider hits at it with her fangs. I suspect that the chelicerae project a fair amount of force, and are somewhat flexible in directing the fangs at the spider's victim or attacker.

Here the female has completely exited the den. Her eight eyes don't show well here, but the small cluster of dark dots at the top front of her shield-like carapace are her largest 4(?) eyes. I have no idea how good tarantula vision is.

This is a different female. I had rattled her enough that she decided the den was actually under attack, and went into full defensive posture. This consists of filling the entire entrance with her body, fangs forward and ready to strike. I suspect that she is working blind here, and relies on a keen sense of touch to tell her when and where to strike. My guess is that if possible, she holds the victim or attacker with her front legs, and strikes multiple times with her fangs. I didn't even consider testng her ability to defend herself with my finger, nor did I further provoke her into striking at a straw. After a while she decided that the danger had passed and went back into the depths of the tunnel. Note the softish-appearing "toes" at the tips of her legs.

Summer 2007. Below is one of two tarantula dens in my front yard. I left them alone, and as I expected, after a while each female wove a barrier of silk across the entrance. My best guess is that these were spun after the female had been impregnated by a male.

Not long after this web barrier is spun, a plug of dirt like the one shown here replaces it, probably at night. The plug appears to be a mixture of spider silk and dirt, because a light push of a finger shows that it is not firm, like a gopher's column of dirt would be, but thin, and rather "bouncy." It would take no effort at all to push completely through the plug to the open tunnel below it.

I surmise that the females and their babies are somewhere in the maze of gopher tunnels that undermine my yard. I'll keep an eye on these two dens to see if the female ever opens them up again; assuming that would be when the young spiders are grown enough to survive outside the den.

July 17, 2007: I was right. A month later, the site above became rather messed up, with debris covering the formerly well-formed plug and giving it the appearance of no longer even being there. But, I poked around a bit, and located the spongy section. It felt firmer than before, so I decided to open it up. After some more poking and pushing, I broke through and began to pull dirt out of the hole. When my middle and index finger were fully extended into the hole I felt a sharp sting on my middle finger and yanked my hand back. Looking into the hole, I could see the female's legs just below the entrance. She was clearly ready to spring again.

I am now certain that she is guarding baby tarantulas, and again I feel bad for letting my curiosity get the better of me, and possibly damaging her sanctuary. I quickly stuffed a solid plug of debris back into the entrance, and I'm pretty sure that it is as solid a barrier as she had created. I'll check to see if she does any repair or corrective work. I now think that the female tarantulas might spend the entire summer underground to avoid the heat.

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The photo below shows the two fang marks, one a clean, but shallow slice just above the cuticle on the bottom, the other above it still with a bit of dirt from the digging. They are spaced just about as the photo of the female's fangs above would indicate; my guess is that the chelicerae are widely spread when in strike position. The bites are not at all painful, and were soon barely noticeable.

As it happens, on June 1st, I found a baby rattlesnake at the bottom of my deck stairs. I lost focus on holding it while I was trying to measure it, and it wiggled free enough to hook me on my left index finger with one fang. It is not an experience I want to repeat. I'll post a couple of photos of the culprit soon on another page.

This is a male tarantula. The picture was taken years ago somewhere in the West San Fernando Valley.

I believe this is what is called a Mexican Red-legged Tarantula. Isn't she beautiful? (I think it's a "she".) She was given to me as a gift. When I went to Central America in 1983, I entrusted her to friends, who decided they wanted to keep her after I returned. She lived to a ripe old age.

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Page updated July 17, 2007