In addition to a highly flattened body, rays have large pectoral fins which are adjacent to the head. Mouth, nostrils, and five pairs of gills are located on the flat, usually pale underside. On the top portion of the ray are the eyes and also the valve orifices through which water enters so it can breathe. The tail is usually drawn out whip-like. The colour of the top part of the ray adapts to its respective habitat and turns from sand colour to black. Rays are cartilaginous fish with over 500 different species and live in all oceans around the world. Some species also live in the deep sea. Most rays feed on clams, crabs and echinoderms.