While crab spiders don’t actively hunt; they can’t be bothered spinning a web and waiting around to entangle their prey. Instead, they rely on their camouflage abilities more than most spiders do, attacking their unsuspecting prey at close range with their crab-like front legs. Along with their larger front legs, Thomisidae hold all of their legs out to their sides like crabs and when provoked, move sideways as well, hence their name.
Ranging from the male spider at 0.3” long to the 0.16” long female spider, female crab spiders can be white, yellow or pale green and are much larger than their darker patterned, longer legged male counterparts. Females wrap their eggs in silk on a folded leaf and stand guard over their young spiders until they hatch. Crab spiders also have excellent eyesight with eight eyes and the eyes on the edges of their bodies are often raised up, so they can see in every direction. Abundant in Australia, North America, South America, Europe, Hawaii and Asia, crab spiders include about 175 genera and over 2,100 species and live almost everywhere except in extremely dry desert environments or in severely cold climates.
Most crab spiders are not active hunters but instead, make more creative use of their camouflage techniques than other spiders do. Color adapting to their hunting terrains, which include flowering plants and sometimes leaves, crab spiders wait until a pollinator arrives and spring on it, catching their prey off-guard. Armed with venom that is toxic to bees, many crab spiders can overcome prey much larger than themselves, poisoning their victims with their venomous bites and then sucking them dry. Because crab spiders prey on pollinators, they can actually reduce pollination by bees, flies and butterflies that learn to steer clear of them. Crab spiders perform some pollination as well. Because crab spiders are easily spotted on leaves, they also make easy prey for predators that include wasps, lizards, ants and birds. However, crab spiders help control pests by eating mosquitoes.
Giant crab spiders, Arizona natives, are actually a different family of spiders, Sparassidae, or huntsman spiders, named for their speed and mode of hunting are also called giant crab spiders because of their size and appearance.