The skeleton of theses animals are cartilaginous. The notochord, which is present in the young, is gradually replaced by cartilage. Chondrichthyes also lack ribs, so if they leave water, a larger species' own body weight would crush their internal organs a long time before they would even suffocate. The class name Chondrichthyes (“cartilaginous fish”) refers to the cartilaginous skeleton of these organisms. Actually, the skeleton of chondrichthyans is calcified or in other words, reinforced with granules of calcium carbonate deposited in the outer layers of cartilage. The calcite granules are arranged in a mosaic pattern solely in Chondrichthyes. This mosaic pattern created from small platelets or prisms is called prismatic calcified cartilage and distinguishes the chondrichthyan cartilaginous skeleton from other classes. Cartilaginous fish have paired fins reinforced with horny rays of cartilage.
Members of the class Chondrichthyes (Sharks, skates, rays, and chimaeras) were among the first vertebrates to evolve jaws and bony teeth and to this day populate the seas in great abundance.
Members of the class Chondrichthyes (Sharks, skates, rays, and chimaeras) were among the first vertebrates to evolve jaws and bony teeth and to this day populate the seas in great abundance.