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Arkansas Tarantula Survey
The Life of Arkansas Tarantulas
Life Underground
Tarantulas in Arkansas spend the majority of their lives in underground burrows. Tarantulas are capable of digging their own burrows, though sometimes they will take up residence in unused small mammal burrows. To dig, tarantulas use parts of their body called pedipalps. Pedipalps are a pair of short appendages that resemble legs. They are located at the front of the spider on either side of the fangs. The pedipalps are used to loosen and scrape away soil for burrow excavation. As soil is removed it is bound together with silk, carried from the burrow, and patted down. Construction of burrows likely begins soon after tarantula spiderlings hatch from eggs and disperse. Female tarantulas may spend their entire lives within the same burrow. Burrows of adult tarantulas can be 10-24 inches deep. During the winter months, tarantulas plug the entrances of their burrows with soil held together with silk. Arkansas tarantulas typically plug their burrows sometime between late September and early November. Once their burrows are plugged, tarantulas enter a dormant state and remain underground until the following spring.
Ground Beetle: potnetial tarantula food
(© 1998-2003 Troy Bartlett)
During late-February into May, as temperatures begin to warm, tarantulas remove the soil plugs from their burrows. After opening their burrows, they spend time at the entrance warming their bodies. Once warm, they begin to spin silk around the entrance of their burrow. The silken collar that is constructed around the entrance is not used to capture prey, but may be used to some extent in prey detection.
Tarantulas are not active, roaming hunters. Instead, they prefer to sit in or near the entrance of their burrow and wait for something like a beetle or grasshopper to pass by. Once detected, the tarantula rushes forward seizing the prey, inserting its fangs, and injecting venom to immobilize its capture. Tarantulas are known to include a variety of arthopods in their diets including beetles, crickets, grasshoppers, cicadas, and other spiders.
Bird, Bees, and Tarantulas
As spring turns to summer, adult females that mated the previous year begin to construct egg sacs. Egg sac construction takes place sometime during June to July. Anywhere from 200 to 800 eggs are deposited in these silken sacs. Once finished, the egg sac is carefully guarded by the female.
Tarantula eggs hatch some 45 to 60 days after being laid. Young spiderlings that emerge from these eggs are initially white, but after a few days begin to turn light brown. For the first few days after hatching the young spiderlings stay in close proximity to their mother. Sometime after this, the spiderlings disperse and begin to construct their own burrows. As they disperse, tarantula spiderlings are apt to be preyed upon by a number of organisms such as ants, centipedes, wasps, and beetles. Cannibalism is also common in tarantulas and the young spiderlings could fall prey to members of their own species.
Wandering male tarantula (John Pelton)
Shortly after her spiderlings leave in August, the adult female prepares to mate again. Both male and female tarantulas reach sexual maturity at about 8-10 years of age. Whereas female tarantulas spend nearly all of their lives in or near their burrows, once males reach sexual maturity they leave their burrows and begin to search for mates. Adult males typically abandon their burrows from August into November. These wandering males travel at night and rest during the day in the shelter of vegetation or rock outcrops. They may travel long distances, nearly up to a mile, in search of a mate.
In their search for mates, males must rely more upon touch than sight to locate the burrows of receptive females. Tarantulas have extremely limited vision and cannot see much beyond two inches. In the absence of visual observation, males most likely locate females through the presence of silk near their burrow entrances. Once located, the male taps the silk collar at the burrow entrance with his forelimbs. This tapping draws the female out of her burrow. As the female exits, rearing up and exposing her fangs, the male withdraws for his safety. The male then approaches the female and hooks her fangs on special spurs located on his front legs. The male then lifts the female slightly and inserts sperm. Once mating is completed the male beats a hasty retreat. The female returns to her burrow and will soon seal it for the coming winter. The male will wander off and eventually succumb to starvation and cold weather.
Enemies and Defenses of Tarantulas
Tarantula Hawk
(Bob Jensen)
Although fearsome predators to some, to others tarantulas represent a meal. Mammals such as raccoons and skunks and birds such as roadrunners have been known to prey on tarantulas. One of the more dramatic predators of tarantulas are a group of wasps called "tarantula hawks". Tarantula hawks are among the largest wasps in the U.S. and put this size to good use to capture and subdue tarantulas to raise their larvae on. It is the female tarantula hawk that is the most dangerous to tarantulas. The female tarantula hawk generally locates tarantulas by wandering on the ground in search of burrows. Once a burrow is located, the tarantula hawk will enter and expel the tarantula living within. With the tarantula out of the burrow, the tarantula hawk attempts to deliver a paralyzing sting to the tarantula. If she is successful in delivering a sting, the tarantula will become paralyzed but will not die. The tarantula hawk will then drag the tarantula to a burrow it has constructed, lay a single egg on top of the immobilized spider, and seal the burrow. Soon the egg will hatch and the developing tarantula hawk larvae will begin to feed on the paralyzed, living tarantula.
Tarantula (© 1998-2003 Troy Bartlett)
Our native tarantulas are not defenseless, however. Although their main form of defense is simply hiding in their burrows, tarantulas do have two potent means of deterring would-be predators. Mounted on the front of their cephalothorax (head region) are a pair of large fangs that are linked to venom glands. If molested, tarantulas can deliver a relatively painful bite. For humans, the bite has been described as being about as painful as a bee sting. Although the tarantulas that occur in Arkansas do not generally deliver life-threatening bites, just as with bee stings, some individuals may be allergic to tarantula venom and develop serious complications. In general, it is a good idea not to handle tarantulas you come across. A second line of defense lies in the hairs that cover the abdomen of the tarantula. These hairs are known as urticating or "stinging" hairs and possess large numbers of backward pointing, microscopic barbs. When bothered, tarantulas will sometimes rapidly rub their abdomens with their back legs, creating a small cloud of hairs. These hairs can lodge themselves in skin, causing an itching and stinging sensation. If these barbs get in the eyes they can cause severe pain/damage to the eye that might require medical attention. For these reasons, it is wise to put a respectable distance between yourself and a tarantula.
