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Cartilaginous fishes are jawed fish with paired fins, paired nares, scales, a two-chambered heart, and skeletons made of cartilage rather than bone.
They also have five to seven gill slits on each side of the body.
 Sharks and rays reproduce by passing sperm from the male to the female.
The male using modified fins called claspers.
Some species produce large egg cases (usually those that live on the bottom) whilst others produce live young (usually those that swim in the water column).
They are divided into two classes :
Elasmobranches (sharks, rays and skates)
Holocephili (chimaeras, sometimes called ghost sharks, which are sometimes separated into their own class).
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