Description: Bat rays feed chiefly upon mollusks and crustaceans. In bays and sloughs they feed heavily upon clams, oysters, shrimp and crabs. On the open coast they eat abalones and various other snails. When feeding, they swim along the bottom until they encounter currents of water expelled from the siphons of clams. They dig clams by suction created by flapping their wings. The shell of the ingested clam is crushed by their millstone like jaw teeth. Mating takes place during the summer months and the young are born alive, apparently the following summer, when they are 12 to 14 inches in width and weigh about 2 pounds. The young are always born tail-first with their wings rolled up over the body. They come equipped with a stinger and can cause severe painful wounds. Females apparently weigh at least 50 pounds and males 10 pounds before they are mature. Females of 50 to 60 pounds usually have two to four young; whereas, females of 130 to 140 pounds may have 10 or 12 young.