Tarantulas

In their book, Insects of the Southwest, entomologists Floyd Werner and Carl Olson call tarantulas the "gentle giants of our spider world."

Appearance and Anatomy of United States' Tarantulas

• The body and legs are hairy
• Tan to reddish brown to black in color
• Body size is to three inches long and two to three inches tall
• Leg span of three to five inches
• Male tarantulas are longer and slimmer than females
• Male tarantulas have much smaller abdomens than females
• Exoskeleton (outer shell,) includes a fused head and thorax connected at a narrow waist to an oval-shaped abdomen
• Eight marginally functional eyes in two groups on the forehead
• Mouth and two backward-pointing fangs below the eyes
• Two pedipalps (leg-like appendages) for food handling near the mouth
• The abdomen contains several vital organs
• The abdomen has silk-producing spinnerets at the tip
• Four pairs of legs connect to the fused head and thorax

Worldwide Distribution of Tarantulas

"There are about 850 species [of tarantulas] worldwide," according to Barron's Tarantulas and Other Arachnids, and "Their range includes Africa and Madagascar, parts of the Middle East, southern Europe, southern Asia, the Indo-Pacific region, Australia, northern New Zealand, some of the Micronesian Islands…, all of Central and South America, parts of the Caribbean, and the United States north to central California and east to the Mississippi River." More than four dozen species populate the U. S. range, according to Hendrixson.

Habitat and Prey

Typically, in the southwestern United States, tarantulas live in solitude in desert basins, mountain foothills and forested slopes. They occupy various kinds of nests, with many species taking up residence in burrows or crevices, which may be sequestered in the ground, along cliff faces, among rocks, under tree bark, or between tree roots. Some line the burrow with silk. Some surround the entrance with a silken "welcoming mat," which vibrates like guitar strings, sending signals to the spider, cloistered in its burrow, if potential prey should touch the strands. "A tarantula will attack literally anything that it can subdue: beetles, grasshoppers, locusts, other spider, small lizards and mice," said biologist Fred Punzo, quoted by Pete Taylor in National Wildlife magazine, "Natural Inquiries." Tarantulas kill by injecting venom through their fangs into their prey.

Life Cycle

During mating season, which varies from spring through fall, depending on the species and conditions, the males leave their burrows, sometimes en masse, to seek willing females. A male, encountering the silk surrounding the entrance to a female's burrow, calls and dances amorously. He may be rejected or embraced.In either event, he may get eaten up, becoming "a readily available source of protein to fuel development of the next generation," said Pete Taylor, writing for National Wildlife magazine. Several weeks after mating, the female, said Taylor, produces an egg sac, and six or seven weeks later, "hundreds of tiny spiderlings hatch to begin the cycle anew." After a few weeks, the young disperse to take up their lives. As tarantulas mature, they molt several times, each time shedding their old exoskeleton for a new one. The males may live for several years, the females, for several decades.

A Few Tarantula Facts

The name "tarantula" apparently originated in the 14th century, in the Italian city of Taranto, where people felt compelled to dance the wildly erotic Tarantella if bitten by a spider. --BIRDSPIDERS.COM, Rick C. West, Arachnologist

One Venezuelan species has a leg span of some 11 inches; another South American species, a body diameter of some 2 ½ inches; an Arizona species, a body length of 1/3 inch. -- BIRDSPIDERS.COM, Rick C. West, Arachnologist

Most American tarantulas have barbed and mildly venomous "urticating" hairs on their abdomens, and they use their legs to "cast" the hairs into the faces of threatening animals, inflicting irritation of soft tissues and eyes. --National Health Museum Internet site, Robert J. Wolff, Ph.D.

Some species have on their feet tiny spinnerets that produce sticky silk patches, helping the spider gain a foothold for climbing on slick surfaces such as window glass. --Live Science Internet site, "Tarantulas Spin Silk From Their Feet, Too," Jeanna Bryner

Some species produce a buzzing sound, like cloth ripping, by rubbing appendages together. --mysticwicks Internet site, "Tarantula"

Tarantulas' fangs move up and down; all other spiders' fangs move horizontally. --Barron's Tarantulas and Other Arachnids

by Jay Sharp

More pictures of Tarantulas by Kenton Elliott at Calico. They were photographed on Main Street at Calico Ghost town in California.

Watch video of a Tarantula and a Tarantula Hawk.

Great American Southwest 3D puzzle Tarantula model.