Crustaceans (crustacea ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. the crustacean group can be treated as a subphylum under the clade mandibulata. it is now well accepted that the hexapods emerged deep in the crustacean group, with the completed group referred to as pancrustaceans. some crustaceans (remipedia, cephalocarida, branchiopoda) are more closely related to insects and the other hexapods than they are to certain other crustaceans.the 67,000 described species range in size from stygotantulus stocki at 0.1 mm (0.004 in), to the japa...

Source: Wikipedia