Wolf spiders are common, ground-dwelling predators found across the globe. While they appear hairy, the structures that give them their fuzzy look are biologically distinct from the hair found on mammals. These spiders belong to the family Lycosidae, known for their robust bodies and covering of dense, bristly appendages. Their stocky appearance and earthy camouflage contribute to their reputation as formidable hunters in the leaf litter.
The Structure of Wolf Spider “Hair”
The hair-like structures covering a wolf spider’s body and legs are not made of keratin like human hair; instead, they are specialized extensions of the exoskeleton called setae. These setae are chitinous structures, composed primarily of chitin and protein, the same material that forms the spider’s tough outer shell. They are rigid, hollow tubes that vary in size and shape, giving the spider a coarse or bristly texture. This dense covering creates the visual impression of fuzziness on the abdomen and legs. The sheer number and thickness of these structures distinguish the wolf spider, contributing to its robust appearance. While some setae are purely for touch, others function as complex sensory organs connected directly to the nervous system.
Functions of the Setae
The setae covering the wolf spider aid in the spider’s survival as an active hunter. Many of these hair-like projections function as highly sensitive mechanoreceptors, allowing the spider to detect subtle environmental changes. They are effective at sensing vibrations in the ground and air currents, which helps the spider locate prey and potential threats. Specialized setae on the legs, sometimes referred to as trichobothria, are extremely fine and can pick up the slightest movement of air, providing a sense of distance detection. Furthermore, certain types of setae on the tips of their legs are adapted for adhesion, enabling some species to climb various surfaces. The bristly coat may also assist with thermoregulation and provide protection against minor abrasions.
Key Physical Traits Beyond Hair
Eye Arrangement
The most reliable way to identify a wolf spider involves observing the arrangement of its eight eyes. These spiders have three distinct rows, a characteristic feature of the family Lycosidae. The bottom row consists of four small eyes, situated close to the mouthparts. Above this are the two most prominent eyes, which are large and forward-facing, giving the spider excellent vision. The third row, positioned toward the back of the head, contains two medium-sized eyes. This specific eye pattern, featuring the two large central eyes, is a key differentiator from other similar-looking spiders.
Body and Hunting
Wolf spiders generally have stocky, robust bodies with strong, spiny legs built for speed and chasing prey. Their body length often ranges from 10 millimeters to over 30 millimeters, depending on the species. Coloration is typically subdued, featuring shades of brown, gray, black, or tan. These colors often include darker stripes or chevron patterns that provide camouflage within their terrestrial habitats. Unlike many other spiders, they do not construct webs to capture food but instead actively stalk and pounce on their prey.