Bonnie Mitchell, age 11, of Providence, R.I., for her question:
HOW LARGE IS THE RAY FISH?
Ray is the common name for any of about 340 species of cartilaginous fishes. Cartilaginous means that they have skeletons composed mostly of cartilage rather than bone. Rays vary in size from a few centimeters to more than 20 feet in width.
The largest rays are known as devilfish, sea barts or mantas. They can attain a weight of more than 3,000 pounds.
Rays are found in almost all of the worlds seas. They are broad, flattened fish with eyes located on the upper, dark colored surface of the body. The mouth and the gills are located on the lower, light colored surface.
The pectoral fins of the ray are extremely well developed from the tail to the sides of the head. The pelvic fins are relatively small and the anal fin is absent, the tail region being reduced to a slender, whiplike organ that the ray uses as a rudder.
The huge pectoral fins serve to move the fish through the water at a slow pace. Many rays, such as the sting rays and the electric rays, have developed protective devices for defense against enemies.
Rays have small mouths containing blunt teeth, adapted for crushing the shells of the mollusks and crustaceans on which they feed.
Rays inhabit the ocean bottom, often burying themselves in the sand when not in search of food. They can change colors to camouflage themselves.
Some species of rays lay eggs. In most species, however, the young are born alive.
The ray order includes the following families: Rhinobatidae, containing the guitar fishes; Pristidae, containing the sawfishes; Rajidae, containing the skates; Dasyatidae, containing the devilfishes; Torpedinidae, containing the electric rays; and Myliobatidae, containing the the cow nosed rays.
Among many species of rays, the pectoral fins form large "wings."
Although most rays live on the sea floor and feed on such bottom dwelling creatures as clams, oysters, shellfish and certain fishes, many species dwell in coastal waters. Some live at great depths. Manta rays live in the upper waters of the open sea, however, and feed on tiny animals and plant life called plankton.
Like sharks, rays have boneless skeletons made of a tough elastic substance called cartilage. Rays also resemble sharks in having slotlike body openings called gill slits that lead from the gills. But a rays gill slits lie under the pectoral or side fins while a shark's are on the sides of the head.
The sting ray, also called stingaree, has a long, flexible tail with one or two sharp spines on the back of it near the middle. These spines have teeth along their edges. At the base of these teeth are poison glands. When bathers disturb or step on the sting ray, it swings its tail upward. In this way, it can cause a painful wound.
A type of sting ray that lives in the waters off Australia reaches a length of 14 feet.