The longest gestation period for any animal is that of the spiny dogfish, Squalus acanthias, at 22-24 months. It is believed that the male grasps the females' fins with his mouth and uses his two claspers to mate with her. This violent meeting leaves deep cuts and gashes behind the females head. These injuries usually heal within a week however. Internal egg laying with gestation and live birth.
Sand tigers have a unique variation of ovoviviparity called intrauterine cannibalism.
The first young in each of a sand tigers' two oviducts to reach 60mm tears open its egg and swims to the uterus where it feeds on its siblings, embryos, and the other unfertilized eggs for the rest of gestation. Usually two 3 foot long live pups are born from a mother that is only about 9 feet long. Great whites are also believed to exhibit intrauterine cannibalism. Sharks are born live and ready to fend for themselves outside the female. Viviparous species include the hammerhead, bull shark, blue shark and lemon sharks.