2004 - Draper, Salt Lake County, Utah - ©Nicky Davis
Spiders of this family have a distinct crab-like appearance.
Legs I and II are much longer and stouter than legs III and IV. Legs I
and II are held out to the sides and project forward while legs III and
lay backward against the body. Body hairs are simple and erect. Lateral
eyes are elevated on tuburcles. Xysticus species come in various shades
of brown and gray, and frequently bear white or yellow markings.
Body is compact, broad, and wider than it is high. There are two claws
on each tarsus. Males ( around .10 inch) are smaller than females
(around .40 inch) Colors and markings are quite variable within
species. Before mating the female is offered a present and secured by
some silk threads. These threads are so tiny that it does not fasten
her for real but she pretends it does. Crab spiders do not spin webs.
They are wandering predators that secure prey by stealth and ambush.
They are crab like in motion, moving sideways, backwards, or
forward. Females guard egg sacks, but normally die before
spiderlings hatch. Some species are capable of changing color to match
their surroundings (over a period of days. They tend to be forest
dwelling, living on and under loose bark, under leaves and stones on
the forest floor, and on low lying vegetation.