They look quite different to the traditional idea of an egg. Sharks and rays are fishes with skeletons made of cartilage, grouped together in the class Chondrichthyes. Their egg cases are sometimes ...

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 ...