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Mission Trails’ misunderstood creepy crawlers

Posted: September 15th, 2017 | Columns, Featured, Mission Trails - Trail Guide | No Comments

By Audrey F. Baker | Mission Trails – Trail Guide

As October approaches, thoughts to turn to Halloween and the menagerie of nature that represents the celebration. Hoary oaks, ravens, owls, bats and more symbolize holiday fun.

Let’s face it, tarantulas have a “PR problem.” Much of the public sees them as nightmarish critters of loathsome reputation. Yes, they’re hairy and maybe scary.

The California Ebony Tarantula (Photo by Wendy Esterly)

Popular culture portrays them as deadly creatures, packing lethal venom. A bad rap! At a safe distance, they are a delightful creature to observe. As to the spider’s toxicity for humans, its bite is no worse than a bee sting.

San Diego County is home to two species — the California Black Tarantula (Aphonopelma eutylenum) and the San Diego Bronze Tarantula (Aphonopelma reversum). Also called the California Ebony, the black prefers grassy or open areas of coastal sage and chaparral, and deserts environs. The bronze is a denizen of more rocky areas. Both are about two inches in length. These are not fearless, aggressive creatures.

Let’s examine their lifestyle.

In October, while we celebrate Halloween, the California Ebony celebrates love. The docile nocturnal creature will risk daylight hours to search for a mate. (For the bronze tarantula, “spring fever” hits in summertime.)

Approaching a burrow, the male tastes the silk around the entrance to confirm the presence of a mature female. Courtship begins with an eight-legged tap dance, announcing his intentions. It’s a hurried affair. Before locating his mate, he’s already deposited his love potion onto a silk mat and has transferred it into his pedipalps (a pair of appendages near his mouth). His plan is to go prepared, quickly woe her and make a rapid departure. The female sees him in two roles, suitor and possibly a convenient source of protein. She literally would love to have him stay for dinner.

Tarantulas don’t spin webs to catch prey. They passively lay in wait near their burrows for crickets, grasshoppers, cicadas, millipedes, caterpillars and such.

Like most spiders, tarantulas use venom transferred through its fangs (chelicerae) to paralyze prey. They then secrete digestive enzymes to turn their food into a liquefied form for ingestion.

Its use of silk has many practices. Females ornament their burrow’s interior with it. The design strengthens its earthen walls and aids in climbing in and out of the residence. Females encase their eggs in silken cocoons. Should the need arise, tarantula moms can relocate the family to a new dwelling. Silk trap lines near burrows are an alert to potential prey, or conversely, an approaching of predator. Recent observation disclosed that in addition to using spinnerets as other spiders do, tarantulas can produce silk with their feet.

Our local tarantulas are most often spotted on the ground. When climbing objects is necessary, they use retractable claws on their legs to better grasp surfaces, insuring their safety. A fall can be fatal. Tarantulas are thin-skinned creatures, particularly around the abdomen. A short fall can rupture their exoskeleton.

Tarantulas can regenerate a lost leg. It reappears after it molts. A regenerated leg may be shorter than the lost one but successive molts gradually correct to the normal length.

Mild-mannered in temperament, the California Black and San Diego Bronze tarantulas’ general response to threat is to beat a hasty retreat. If a defense is required, they may rear up on their hind legs and raise their forelegs in warning. If unheeded, they employ a defense used when they fear the worse (being eaten). Employing their back legs, they pluck urticating (irritating) hairs from their abdomen and fling them at the offender. The barbed hairs can cause a nasty rash.

Tarantulas have long lives and take years to develop into reproductive maturity. Females can live 20 years or more. A male’s life expectancy is about six years. These spiders have few enemies. Its chief enemy is a specialized predator, a wasp. With a strong touch of irony, the Tarantula Hawk (Pepsis thisbe) uses her venom to perform the task. That’s another trail tale to be told, and from her perspective.

Meanwhile, have a safe and happy fall season, and when enjoying Mission Trails Park, remember to keep it wild!

—Audrey F. Baker is a trail guide at Mission Trails Regional Park. Check the MTRP events calendar published here or at mtrp.org or call 619-668-3281 for more information on the park’s free trail guide-led nature walks and opportunities to learn more about natural Southern California. Special walks can be arranged for any club, group, business or school by contacting Ranger Chris Axtmann at 619-668-2746 or at caxtmann@mtrp.org.

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