Experienced swimmers in shallow water know to shuffle their feet along sandy bottoms to find rays before stepping on them. It is easy to tell a male ray from a female. Males have two hollow tube shaped organs called claspers at the base of their pelvic fins. Claspers transfer sperm to the female to fertilize her eggs. When mating, male rays get a firm grip on females by bi ting the front of their pectoral fins long enough to mate.
Female rays carry fertilized eggs inside their bodies.
The developing young are nourished by a yolk sac and by a milky liquid given off by the mother. The young are born as free-swimming miniature versions of their parents and must fend for themselves. Ray Relations Perhaps the most impressive group of rays are the mantas. Some kinds of manta rays stretch 20 feet across and weigh more than 3000 pounds. Manta rays are active swimmers adapted for a cruising lifestyle.