Crab spiders are a fascinating family of spider of the Araneae order. They are called crab spiders because they look much like crabs, with two powerful front pairs of legs angled outward and bodies that are flattened and often angular. Also, like crabs, Thomisidae can move both sideways or backwards with ease. Most crab spiders also have two large frontal eyes (in addition to their smaller ones), which gives them excellent eye sight compared to spiders in general.
Crab spiders do not build webs to trap prey, but are hunters and ambushers, sometimes waiting days to attack their pray. Some species may sit on or among flowers, bark, fruit or leaves where they grab visiting insects. Individuals of some species of crab spider are able to change color to match the flower on which they are sitting. It is, however, a very slow process that can take days, and there is not much variety in the colors that they can produce (usually yellow or white). Other species, with their flattened bodies, hunt in the crevices of tree trunks or under loose bark. Members of the genus Xysticus hunt in the leaf litter on the ground. In each case, crab spiders use their powerful front legs to grab and hold onto prey while paralyzing it with a venomous bite. However, crab spiders are not known to be harmful to humans. It is known. that spiders of an unrelated genus, Sicarius, which are sometimes referred to as “crab spiders”, are close cousins to the recluse spiders, and are highly venomous.
Crab spiders include more than 3000 species of spiders, and if this wasn’t proof of their success, consider that they have colonized all of the world except the arctic, antarctic and parts of Greenland.