Thin-legged Wolf Spider
Pardosa sp.
Length about 8mm, excluding legs. This spider was hunting for soft bodied dipterans adjacent to a seasonal stream in the Superstition Wilderness, Arizona. August 2012.
Lycosidae -- Wolf Spider Family
Spider silk is the multi-purpose evolutionary trick or the arachnid clan. Many spiders of course use silk to construct snares in which to capture prey. But many species, including this one do not use silk in such a way. Here silk is used to construct a tough, portable sac in which to carry the eggs. With specialized clasping spinnerettes wolf spider moms bring the sac behind them as they continue to hunt for food.
Pardosa wolf spiders (there are a number of species in the Sonoran Desert) can often be found on damp sand adjacent to riparian streams where prey of all sorts is abundant. Once the spider arrives at a likely spot it may remain motionless awaiting the movement of an insect nearby. With good eyesight and even better vibration detectors the spider will sprint and pounce on a soft-bodied insects that happens too close. The eyes all the while must be fully aware of danger to the spider itself in the form of a bird or lizard. Four larger eyes are for identifying prey or mates, whereas the four smaller eyes are best suited to detect movement above that could be danger. Danger will send the spider scurrying at top speed on the long slender legs.