Cambaridae is the largest of the three families of freshwater crayfish, with over 400 species. Most of the species in the family are native to North America east of the Great Divide, such as the invasive species Procambarus clarkii and Orconectes rusticus, with fewer species, all in the genus Cambaroides, living in eastern Asia. A 2006 molecular study suggested that the family Cambaridae may be paraphyletic, with the family Astacidae nested within it, and the status of the genus Cambaroides remains unclear.