Author: Jan Scholten
Zoology: crabs, lobsters, crayfish, shrimp, krill and barnacles; 67000 species; exoskeleton, they moult to grow; biramous, two-parted, limbs; nauplius form of the larvae; free-living aquatic animals, some are terrestrial (e.g. woodlice), some are parasitic (e.g. Rhizocephala, fish lice, tongue worms) and some are sessile (e.g. barnacles).