Members of the Family Thomisidae Sundevall, 1833 are universally known as crab spiders because of their crab-like, laterigrade leg orientation. They are cryptic dwellers of habitats ranging from foliage, flowers, tree bark and leaf litter. Thomisidae is the seventh largest family of spiders and currently includes 2171 species placed in 170 genera. The National red list of Sri Lanka (2012) list 36 nominal species of crab spiders for the island. However, most of what we know of their biodiversity is from their historic initial descriptions. The taxonomy and phylogenetic position of Sri Lankan crab spiders has been the center of focus in an ongoing island wide survey of spider diversity. We are also exploring the global biodiversity patterns of the family.