Rays have cartilaginous skeletons, flattened bodies, and greatly expanded pectoral fins fused to the head, giving them a disc-like shape. Below the pectoral fins are five gill slits. Many have a whip-like tail armed with one or two sharp spines, which are used for defense.
Rays are not aggressive and retaliate only if provoked. Sand sharks appear more ray-like than shark-like. They have a flat body with expanded pectoral fins and a well-developed tail. Most rays and sand sharks live close to sandy bottoms and have a very distinctive way of swimming which resembles a large bird flying.