Elasmobranchii () is a subclass of Chondrichthyes or cartilaginous fish. Members of this subclass are characterised by having five to seven pairs of gill clefts opening individually to the exterior, rigid dorsal fins and small placoid scales on the skin. The upper jaw is detached from the cranium and the teeth are in several series. The lower jaw articulates with the upper jaw in several different ways that are characteristic of the different clades. The pelvic fins in males are modified to create claspers for the transfer of sperm. There is no swim bladder, instead these fish maintain buoyancy with large livers rich in oil.

Elasmobranchii () is a subclass of Chondrichthyes or cartilaginous fish. Members of this subclass are characterised by having five to seven pairs of gill clefts opening individually to the exterior, rigid dorsal fins and small placoid scales on the skin. The upper jaw is detached from the cranium and the teeth are in several series. The lower jaw articulates with the upper jaw in several different ways that are characteristic of the different clades. The pelvic fins in males are modified to create claspers for the transfer of sperm. There is no swim bladder, instead these fish maintain buoyancy with large livers rich in oil.