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How do sharks and rays transfer sperm during internal fertilization?

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A porcupine fish in the Andaman Sea — fish *Diodon hystrix* is a species of porcupine fish. These fishes are short and broad-bodied, with large eyes and spines covering their skin. Like puffer fishes, they inflate their bodies when threatened.

Sharks and rays, which belong to the class Chondrichthyes, utilize internal fertilization to reproduce. To transfer sperm, male sharks and rays are equipped with two specialized copulatory organs called claspers, which are modified extensions of their pelvic fins.123

During mating, the male typically grasps the female’s pectoral fin with his teeth to hold her in position. He then inserts one of his claspers into the female’s cloaca and into her oviduct. Each clasper features a groove that serves as a guide for the sperm, which is conveyed into the female’s reproductive tract. The claspers are supported by modified fin cartilages and are erected by muscles at their base to facilitate this transfer. While males generally use only one clasper at a time, some species of rays have been observed using both. Once the sperm reaches the anterior end of the oviduct, it fertilizes the eggs.143