cartilaginous fish, Chondrichthyes; and jawless fish, Agnatha. The discipline can include the biology, taxonomy and conservation of fish, as well as husbandry and commercial fisheries.

There are two classes of fish – bony fish (Osteichthyes) and cartilaginous fish (Chondrichthyes). Sharks – all 500 species – belong to the latter class, as they have jaws and skeletons that ...