Philodromidae

Philodromidae is a family of spiders known as running crab spiders. They resemble crab spiders of Thomisidae but are typically more slender and are fast runners. They lack the broad carapace of many Thomisidae and hold their legs laterigrade, extending to the sides.

Philodromidae is cosmopolitan, with greatest diversity in temperate regions. They occur in a variety of habitats, including tree trunks and bark, leaves and grasses, shrubs, open woodlands, and sometimes human structures. They are often found on surfaces where they can hunt without a web.

Species are small to medium in size. Adults have flattened bodies and eight eyes in two rows; eye arrangement helps distinguish them from other families. Coloration is variable, commonly mottled browns or grays that camouflage on bark or foliage. Legs I and II are often longer and held to the sides to facilitate rapid sideways movement.

Behavior and ecology: These spiders are active hunters, relying on speed and agility rather than webs. They stalk or sprint after prey such as insects and other small arthropods. Reproduction involves females spinning and guarding silken egg sacs until the young emerge.

Taxonomy and genera: The family includes several genera, with Philodromus and Tibellus among the best known; other genera include Thanatus and Ebo. The taxonomy has undergone revisions, and species identification often requires examination of genitalia.