Wolf Spider


Wolf Spider White Oak Canyon 150321

Common Name: Wolf Spider, Ground spider, Hunting spider – The predatory practices of the arachnid are analogous to those of a wolf; they chase and then pounce. They do not hunt in packs, however.

Scientific Name: Lycosa spp – The generic name is the Latin word for wolf. Spp is the abbreviation for species to be inclusive of any species in the genus; wolf spiders are quite variable in color and size.

Potpourri: Wolf spiders of the Family Lycosidae are hunter-killers. Unlike most of their araneidal brethren (spiders are in the order araneida), they do not ensnare prey with webs but rather seek them out in what amounts to a wolf-like hunt on eight legs; an assault characterized by ambush, speed and stamina. In this they are quite successful; the evolutionary pressures of survival endowed them with four significant attributes: runners’ legs; a wrestler’s robust strength; apatetic coloration and a well-adapted ocular capability. There are some 200 species of wolf spider in North America, including some beyond the Arctic Circle, and approximately 50 in Eurasia; wolf spiders are global, a testimony to their adaptability.

As vision is one of the most critical attributes of ranging hunters, wolf spiders are endowed with an octet of eyes arrayed in three rows that act in concert to provide near, far and peripheral vision with emphasis on the reduced light conditions that prevails in their nocturnal hunting forays. They are not unique in eye count as most spiders have eight eyes that are divided into two groups: the main or direct eyes are at the top center of the combined head and thorax fore-body or cephalothorax (called anterior median eyes or AME); the indirect eye sets are located below (posterior median eyes or PME) and on either side (posterior and anterior lateral eyes or ALE and PLE). The indirect eyes have tapeta which are layers of light sensitive crystals for low light vision; they shine in the dark when exposed to a flashlight. It is not clear why spiders evolved with multifunctional eye sets; most spiders have rudimentary vision, relying on web vibrations to direct them to their ensnared prey. It is likely that web entrapment spiders evolved subsequent to the first emergence of ancestral spiders whose vision was paramount and their ocular needs declined leading to the involution. Night-hunting wolf spiders evidently had a different set of environmental stress factors favoring four large indirect PME’s that provide a relatively clear image of their crepuscular prey.

Prey that is detected with the two AME direct eyes and localized with the four PME indirect, light sensitive eyes is step one; step two is capture. The long, spindly legs of the wolf spider provide both sprint speed and maneuverability to successfully prosecute the hunt; they can accelerate to 2 feet per second for short distances (the approximate top speed of a cockroach). On first contact, the bulk of the wolf spider is manifest as the robust fore-legs, each with three microscopic holding claws, grasp the victim and hold it steady for the coup de grâce, the injection of the paralyzing venom. As opportunistic hunters, wolf spiders will catch and eat anything that crosses their path on four, six or eight legs, favoring cricket-like insects but including small reptiles and other spiders.
The dirt brown, maculated and sometimes striped cephalothorax and abdomen of the wolf spiders emulates the dead leaves and forest detritus in which they lurk. This provides camouflage known as crypsis in the lexicon of ecology that is advantageous for successful predation; it is also important to forfend predators. One does not generally think of spiders as prey due to their prowess as predators. Wolf spiders, however, offer a relatively large meal at little expense to birds, reptiles, amphibians, mammals, and even large insects such as the (equally voracious) praying mantids. There are several types of parasitic wasps that sting and paralyze wolf spiders to lay their eggs; when the larvae hatch out, they literally eat the spider alive in one of the more egregious examples of the ingenuity of evolutionary natural selection. Wolf spiders must hide to ambush their prey and hide to avoid their predators.

Many araneids are cannibalistic and wolf spiders are no exception; they are, if anything, a bit more discerning than most spiders. In courting, the smaller male wolf spiders wave their pedipalps (the foot-like appendages on either side of the mouth) as an introductory gesture to establish conspecific identity with a larger (but none-the-less appealing) female wolf spider. If the male fails to gain the attention of the female with a “foot-wave,” then a secondary procedure is followed – tapping on dry leaves to gain attention, a sound that can be heard at some distance. It has been demonstrated by scientific field trial that the female wolf spider will eat the male more frequently if it is of smaller than normal size in 80 percent of all encounters. It is not yet established why this practice is the norm, but it is hypothesized that the larger female weighs the risk factors of a free meal relative to a guarantee of fertilization to formulate a meal or mate assessment.


Wolf Spider Eggs Furnace Mtn 5-23-04
Female Wolf Spider dragging her egg case for protection

Where is also a measured difference in response to the identity of an approaching male; one who is recognized as a cohort of the female is less likely to become lunch. For the larger males and the lucky survivors of the “Lady or the Tiger” scenario, the act of coitus consists of the deposition of the male sperm onto a web structure which is inserted into the female epigynum (arachnid genital opening) with the pedipalps. The female subsequently lays about 100 eggs into a spider-silk woven sack made for the occasion. This large and cumbersome egg-sack appendage is attached to the abdomen and carried by the female as a sort of drag-chute until the spiderlings hatch. That this is a matter of motherly care (if perhaps devoid of affection) is beyond dispute; the spiderlings are carried by the female wolf spider on her abdomen until they reach self-sustaining size when they are released (and not eaten). There is reason to believe that wolf spiders are much more capable than suggested by traditional notions of invertebrate intellect. When a male wolf spider is attacked by another male wolf spider, the pedipalp-wave employed for sexual recognition is used; normally this results in the termination of hostile behavior. Captive male wolf spiders have also been observed to mimic the pedipalp waves of successful suitors, presumably in an effort to improve their courting skills.


Female Wolf Spider with spiderlings

Wolf spiders are among the most fearsome of the araneids; their size and rebarbative appearance the epitome of the loathsome chimera conjured up lurking in the bedsheets. Only the somewhat larger and more hirsute tarantulas surpass them in execration. The two families are frequently conflated since the European wolf spider is Lycosa tarantula; it was believed that its bite caused tarantism, a nervous disease characterized by hysteria that was prevalent in the region of Taranto, Italy in the 16th Century, one of many manifestations of an incomprehensible fear of spiders. Tarantism was supposedly cured by dancing the tarantella, a fast, whirling southern Italian dance. Arachnophobia is common in many cultures; a survey in the U. K. revealed that about a quarter of all men and women felt nervous around spiders. While this does not rise to the level of phobia, which is a mental health diagnosis where there are marked and persistent fears and avoidance (according to The National Institutes of Health, 8.7 percent of the U. S. population had any kind of phobia and only 1.9 percent had severe phobia), spiders are perceived as a threat by many. Unlike snakes, some of which really are poisonous and kill, most spiders are benign; wolf spider venom is at worst an irritant, causing mild pain and itching. Native American cultural lore generally lauded spiders; in the Hopi tradition, spider woman was the goddess of the earth. The English author Tolkien’s Shelob was the monster of Mordor.