Tuesday, September 25, 2018

Famous Faces of the Desert – Tarantulas

In the interest of full disclosure, I’d like to make it clear that I am not a fan of spiders. All those skittering legs, yucky webbing and fierce fangs just make my skin crawl. This attitude is the direct result of a horrifying incident with a giant spider and its web when I was a child in Panama. I can’t bear thinking about it to this day.
Large grey tarantula
Photo by Valerie, Customer Service

Having said all that, I do rather like tarantulas. After numerous encounters with these spiders, both in the wild and as someone’s pet, I see that they are gentle and delicate creatures. They are probably the most misunderstood of all the iconic desert creatures we have here in Arizona.

Unlike other desert creatures I have talked about in this series, I have not encountered tarantulas in or around our office. However, most of our crew has had them around their homes; so I asked for pictures from them. Mike, our Shipping Manager, contributed an image of a large black one found in his garage and Valerie, Customer Service, donated one of a lovely grayish specimen. These two pictures, taken just a few miles from each other, show the variety of tarantula species in our area.

Large black tarantula on a garage floor
Photo by Mike, Shipping Mgr
Despite their rather fearsome appearance and their unwarranted reputation as being dangerous, the truth is tarantulas are more shy and reclusive than anything else. They live solitary lives in holes, burrows or crevices and rarely venture far from them. Around here, if you find a hole about the size of a quarter, it may be a tarantula hole. If you see silk in or around the hole, it is actively occupied. The silk helps prevent cave-ins and makes the perfect nesting material. They often extend the silk lining outside the entrance. This outside webbing has two purposes: waterproofing and an early warning system. Tarantulas do not like water and their silk helps keep their burrows dry. If a burrow floods, the tarantula will flee. This is one reason that they are more
likely to be seen during monsoon season here. Outside webbing also serves to let the spider know that prey is nearby. They can sense vibrations and the slightest touch to the webbing will send the tarantula out to snag its dinner. When it is time to hibernate for the winter, the spider will mix the silk with a little dirt dirt and create a plug for the opening.

A tarantula lying on its silk in its nest
A tarantula resting on its silk
Females will always be in or very near their burrows, but males will head out looking for love during mating season (generally September-October). In some places, tarantula males head out in large numbers, making for an unsettling display of devotion to reproduction. Once a male finds a female’s burrow, he will “knock” on the silk around the door. The female will rush out and, in that split-second, make her decision to mate with him, eat him or both. After the long trek to get to her, it is the worst kind of blind date. With what he goes through for love, it should come as no surprise that females live twice as long as males.

Although their bite can be painful, a tarantula’s venom is not dangerous to humans. Because they feed on small prey like other insects, arthropods and the occasional small lizard or mouse, they have no need for venom strong enough to disable or kill a large being. Unless the person has a severe allergic reaction, a tarantula bite is no more serious than a bee sting.

The hairs on a tarantula can cause a person more trouble than their venom. They have hundreds of hairs on their upper abdomen called urticating hairs that are used as a defense mechanism. They will flick these barbed hairs at would-be tormentors. Once lodged in their target, these hairs are extremely irritating and difficult to remove. They can cause real damage if embedded in the eye or inhaled. Just give them their space and they will give you no trouble.

Tarantulas have very thin skin, especially in the abdominal area. This makes them very vulnerable to damage from falls. A height of less than a foot can kill a tarantula. This makes for another good reason not to handle them.

While they cannot handle falls, losing a leg is something most tarantulas can overcome. They will simply regenerate a new leg the next time they molt. Never one to turn down a meal, the tarantula may even eat its detached leg. Since males rarely molt once they reach sexual maturity, it will be the females or immature males re-growing legs. We used to have a very large (about 4½”) 7-legged fellow who hung out in the tree by our front door.

Tarantulas appear in many legends around the world  and in many myths of native peoples. Underscoring its importance as an essential part of our Southwestern world, the Navajo, Zuni, Apache and Pima all have traditional lore surrounding the tarantula.

When it comes to predator and prey, tarantulas are equal parts of each. They are valuable predators for pest insects such as cockroaches, but they are also preyed upon in all stages of their lives. Ants invade their burrows and feast on their eggs and large predators gobble them up when they are old enough to leave their burrows. The most terrifying and gruesome nemesis of a tarantula is the Tarantula Hawk (Pepsis spp).These insects prey on and parasitize the spider as part of their
Close-up of an individual tarantula hawk
Tarantula hawk
reproductive cycle. I will save the specifics of their predation for one of my October blogs on insect mummies and zombies. Suffice to say, it’s pretty gross.

Usually, at this point in the blog, I would direct you to ways to control the creature I’ve been discussing. With tarantulas, however, I have no control recommendations. These benign creatures mean you no harm and can easily be guided away from you, your yard and your pets.

Submitted by Pam

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