other sharks, which may have over 2,000. Like other sharks, the horn shark's teeth are regularly replaced; it takes 4 weeks for a dropped tooth to be replaced. The horn shark captures prey via suction, created by expanding its buccal cavity. Its labial cartilages are modified so that the mouth can form a tube, facilitating the suction force. Once the prey is drawn into the mouth, it is secured with the sharp front teeth and then ground into pieces by the flat lateral teeth. To extract buried or affixed prey, the horn shark grips it and adopts a vertical posture with the head and pectoral fins against the substrate and the tail arched above. The shark then acts as a lever with its pectoral fins as the fulcrum: with a downward stroke of the tail, it forces its head upwards and pulls the prey loose; this mode of feeding has not been observed in any other shark. The horn shark is also capable of protruding its upper jaw up to 15% the length of its head; this motion takes only 20 milliseconds to accomplish and allows the shark to use its upper jaw like a chisel to dislodge firmly attached prey. Life history Mating in the horn shark occurs in December or January, on a possibly annual reproductive cycle. The male chases the female to indicate interest; once she is ready both sharks settle on the bottom, where the male grips the female's pectoral fin in his teeth and inserts one of his claspers into her cloaca. After 30–40 minutes of copulation, the pair disengages and the female spins with her snout in the sand for another 30 minutes. From February to April, the females lay a maximum of 24 eggs two at a time once every 11–14 days, in water deep. The egg case has two flanges spiraling around it, and thus may take the female several hours to deposit. At first the case is soft and light brown, and over a few days it hardens and darkens in color. Not including the flanges, the case measures long and wide; sharks from the Channel Islands produce longer egg cases than those from mainland California, suggesting that they are separate populations. One of the few sharks to exhibit parental care, female horn sharks in the wild pick up their eggs in their mouths and wedge them into crevices. However, in