Pancrustacea
Guides
Crustacea
crustaceans
Crustacea is a major subphylum of arthropods encompassing approximately 67,000 described species, with estimates suggesting this represents only 1-10% of actual diversity. The group includes familiar aquatic forms such as crabs, lobsters, shrimp, krill, and barnacles, as well as terrestrial representatives like woodlice. Crustaceans are united by biramous (two-parted) limbs and characteristic larval development, often involving a nauplius stage. Current phylogenetic understanding places Crustacea as paraphyletic with respect to Hexapoda (insects and allies), with both groups now combined in the clade Pancrustacea. The subphylum exhibits extraordinary morphological diversity, ranging from the 100-micrometer Stygotantulus stocki to the Japanese spider crab with a 3.8-meter leg span.