Crustacea is a well very complex subphylum (in the Arthropda phylum, wich is one of the biggest phylum in terms of diversity) that encompass a lot of different taxons. We can distinguish crustacean using their key features: - Bilaterian - Presence of an articulated shell in two part, called a cephalothorax - A metamerized abdomen - Composed eyes - Different use of antenas - Mostly benthic and moving (the curious cirripeds taxon is composed of sessils species, copepods are planctons...) We can find common animals like: - Shrimps - Crabs - Lobsters - Hermit crabs - Sea spiders - Copepods (plancton) - Isopodes (parasites) - Barnacles (sessile organism of the [Mediolittoral](Mediolittoral.md)) The most common group is the [[Decapoda]]