- Source: Wolf spider
Wolf spiders are members of the family Lycosidae (from Ancient Greek λύκος (lúkos) 'wolf'), named for their robust and agile hunting skills and excellent eyesight. They live mostly in solitude, hunt alone, and usually do not spin webs. Some are opportunistic hunters, pouncing upon prey as they find it or chasing it over short distances; others wait for passing prey in or near the mouth of a burrow. Wolf spiders resemble nursery web spiders (family Pisauridae), but wolf spiders carry their egg sacs by attaching them to their spinnerets, while the Pisauridae carry their egg sacs with their chelicerae and pedipalps. Two of the wolf spider's eight eyes are large and prominent; this distinguishes them from nursery web spiders, whose eyes are all of roughly equal size. This can also help distinguish them from the similar-looking grass spiders.
Description
The many genera of wolf spiders range in body size (legs not included) from less than 10 to 35 mm (0.4 to 1.38 in). They have eight eyes arranged in three rows. The bottom row consists of four small eyes, the middle row has two very large eyes (which distinguishes them from the Pisauridae), and the top row has two medium-sized eyes. Unlike most other arachnids, which are generally blind or have poor vision, wolf spiders have excellent eyesight.
The tapetum lucidum is a retroreflective tissue found in eyes. This reflective tissue is only found in four secondary eyes of the wolf spider. Flashing a beam of light over the spider produces eyeshine; this eyeshine can be seen when the lighting source is roughly coaxial with the viewer or sensor. The light from the light source (e.g., a flashlight or sunlight) has been reflected from the spider's eyes directly back toward its source, producing a "glow" that is easily noticed. Wolf spiders possess the third-best eyesight of all spider groups, bettered by jumping spiders of the family Salticidae (which can distinguish colors) and the huntsman spiders of the family Sparassidae.
Wolf spiders are unique in the way that they carry their eggs. The egg sac, a round, silken globe, is attached to the spinnerets at the end of the abdomen, allowing the spider to carry her unhatched young with her. The abdomen must be held in a raised position to keep the egg case from dragging on the ground. Despite this handicap, they are still capable of hunting. Another aspect unique to wolf spiders is their method of care of young. Immediately after the spiderlings emerge from their protective silken case, they clamber up their mother's legs and crowd onto the dorsal side of her abdomen. The mother carries the spiderlings for several weeks before they are large enough to disperse and fend for themselves.
Because they depend on camouflage for protection, they do not have the flashy appearance of some other kinds of spiders. In general, their coloration is appropriate to their favorite habitat.
Hogna is the genus with the largest of the wolf spiders. Among the Hogna species in the U.S., the nearly solid dark brown H. carolinensis (Carolina wolf spider) is the largest, with a body that can be more than 2.5 cm (1 in) long. It is sometimes confused with H. helluo, which is somewhat smaller and different in coloration. The underside of H. carolinensis is solid black, but the underside of H. helluo is variegated and has reds, oranges, and yellows with shades of black.
Some members of the Lycosidae, such as H. carolinensis, make deep, tubular burrows in which they lurk much of the time. Others, such as H. helluo, seek shelter under rocks and other shelters as nature may provide. As with spiders in general, males of almost any species can sometimes be found inside homes and buildings as they wander in search for females during the autumn.
Wolf spiders play an important role in natural population control of insects and are often considered "beneficial bugs" due to their predation of pest species within farms and gardens.
Venom
Wolf spiders inject venom if continually provoked. Symptoms of their bites include swelling and mild pain. In the past, necrotic bites have been attributed to some South American and Australian species, but further investigation has indicated that those problems that did occur were probably due to bites by members of other families or did not induce those effects.
Genera
As of June 2022, the World Spider Catalog accepts these genera:
Evolutionary history
Wolf spiders likely originated after the K–Pg extinction event sometime in the late Paleocene, with most main subfamilies likely originating during the Eocene and Early Oligocene between 41 and 32 million years ago.
Habitats
Wolf spiders are found in a wide range of coastal and inland habitats. These include shrublands, woodland, wet coastal forests, alpine meadows, suburban gardens, and homes. Spiderlings disperse aerially; consequently, wolf spiders have wide distributions. Although some species have very specific microhabitat needs (such as stream-side gravel beds or montane herb fields), most are wanderers without permanent homes. Some build burrows which can be left open or have a trap door (depending on species). Arid-zone species construct turrets or plug their holes with leaves and pebbles during the rainy season to protect themselves from flood waters. Often, they are found in man-made locations such as sheds and other outdoor equipment.
Mating behavior
Many species of wolf spiders possess very complex courtship behaviors and secondary sexual characteristics, such as tufts of bristles on their legs or special colorations, which are most often found on the males of the species. These sexual characteristics vary by species and are most often found as modifications of the first pair of legs. First-leg modifications are often divided into elongated bristles on the legs, increased swelling of leg segments, or the full elongation of the first pair of legs compared to the other three pairs. Some mating behaviors are common between wolf spider genera, and many more that are species-specific. In the most commonly studied genus of wolf spiders, Schizocosa, researchers found that all males engage in a seismic component of their courtship display, either stridulation, or drumming their forelegs on the ground, but some also dependent on visual cues in their courtship display, as well as the seismic signaling, such as waving the front two legs in the air in front of the female, concluding that some Schizocosa species rely on multimodal courtship behaviors.
The Lycosidae comprise mainly wandering spiders, and as such, population density and male-to-female sex ratio puts selective pressures on wolf spiders when finding mates. Female wolf spiders that have already mated are more likely to eat the next male that tries to mate with them than those that have not mated yet. Males that have already mated have a higher probability of successfully mating again, but females that have already mated have a lower probability of mating again.
Relationship to humans
Though wolf spiders do bite humans, their bites are not dangerous. Wolf spider bites often result in mild redness, itching, ulcers, and if the bite wound is not cleaned it could lead to infection. However, wolf spiders usually only bite when they feel threatened or mishandled.
Wolf spiders have been found to be a vital source of natural pest control for many people's personal gardens or even homes, since the wolf spider preys on perceived pests such as crickets, ants, cockroaches, and in some cases lizards and frogs. In recent years, wolf spiders have been utilized as pest control in agriculture to reduce the amount of pesticides needed on crops. A notable example is the use of wolf spiders in cranberry bogs as a means of controlling unwanted crop destruction.
In culture
South Carolina designated the Carolina wolf spider (Hogna carolinensis) as the official state spider in 2000 due to the efforts of Skyler B. Hutto, a third-grade student at Sheridan Elementary School in Orangeburg.
At the time, South Carolina was the only U.S. state that recognized a state spider. In 2015, efforts began to name an official state spider for neighboring North Carolina.
Gallery
See also
List of spiders associated with cutaneous reactions
List of Lycosidae species
Necrobotics
References
Further reading
Platnick, Norman I. (2008): The world spider catalog, version 8.5. American Museum of Natural History.
External links
Wolf Spider Website Comprehensive site with info on a range of subject, from habitat, to life-cycle, to myths and facts about bites. Includes videos of Wolf Spiders in the wild and captivity (Accessed September 7, 2015) Archived Link
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