Living fishes are comprised of two primary taxonomic groups. Rays, along with sharks and chimaeras (elephant fish, ghost sharks, rabbitfishes and spookfishes), collectively known as the ‘cartilaginous fishes’, form one of these two major groups of modern fishes, the class Chodrichthyes having skeletons built of cartilage with superficial calcification rather than bone).
Rays are found in all oceans of the world. They are the largest subgroup of the chondrichthyan fishes and presently comprise 26 families and 633 valid named species.
These can divided into several groups: skates, electric rays, sawfish and stingrays. Rays vary in size. The little or hedgehog, skate is less than 20 inches (5 centimeters) long. The Atlantic manta, or giant devil ray, has wingspan of up to 23 feet (7 meters).
Although rays lack the bony scales of the placoderms and osteotracans, their skin is cored with small toothlike scales that give it the feel of sandpaper.
Rays: superorder of cartilaginous fish
