Crustacean

Crustaceans (Crustacea) form a very large group of arthropods which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 67,000 described species range in size from Stygotantulus stocki at 0.1 mm (0.004 in), to the Japanese spider crab with a leg span of up to 12.5 ft (3.8 m) and a mass of 44 lb (20 kg). Like other arthropods, crustaceans have an exoskeleton, which they moult to grow. They are distinguished from other groups of arthropods, such as insects, myriapods and chelicerates, by the possession of biramous (two-parted) limbs, and by the nauplius form of the larvae. Most crustaceans are free-living aquatic animals, but some are terrestrial (e.g. woodlice), some are parasitic (e.g. Rhizocephala, fish lice, tongue worms) and some are sessile (e.g. barnacles). The group has an extensive fossil record, reaching back to the Cambrian, and includes living fossils such as Triops cancriformis, which has existed apparently unchanged since the Triassic period. For more information visit the Wikipedia Entry Get back to Arthropoda
Amphipods	Barnacles	Branchiopoda
Caridean shrimps	Crabs	†Eryon
Hermit & King crabs	Horseshoe shrimp	Isopoda
Lobster and Crayfish	Mantis shrimp	Ostracods
Shrimp and prawns	†Sidneyia	Spiny lobsters