The subclass
Holocephali ("complete heads") is a
taxon of
cartilaginous fish in the
class Chondrichthyes. Members of the subclass move by using sweeping movements of their large pectoral fins. They have long slender tails and live close to the seabed feeding on
benthic invertebrates. They lack a stomach, food moving directly into the intestine. The earliest
fossils are of teeth and come from the
Devonian period. Little is known about these primitive forms, and the only surviving group in the subclass is the
order Chimaeriformes. This group includes the rat fishes in the
genus Chimaera, and the elephant fishes in the genus
Callorhynchus.
