The sandy bottom of the sheltered cove seems to melt into the shallow water above. All you hear is your own breathing and release of bubbles from your scuba gear. Everything is calm as you swim to the bottom to take a close look at an empty shell. Shedding sand as it rises, the moving bottom becomes a stingray, with a wide body and long tail. It coasts to another spot and quickly shrugs back under a blanket of sand.
Rays are surprising animals no matter where they are encountered.
Their flat bodies have wide pectoral fins, two smaller pelvic fins, and a long thin tail that may have zero, one or two small dorsal fins on top. Rays, with skates and sharks, belong to the class Chondrichthyes, or cartilaginous fish. Their entire skeleton is made of cartilage, a strong flexible connective tissue. People have cartilage in their outer ears and soft tips of noses, but our bones are made of calcium phosphate and living tiss ue. The cartilage in rays and sharks is more flexible and lightweight than bone.