After mating, a female produces as many as 40 fertilized embryos, separated between two separate wombs. The embryos take nearly a year to fully develop, but they begin hunting long before that. After about two months, their own yolk sacs go dry. Hungry, they start eating their brothers and sisters. After the rampant in utero cannibalization, only one shark — the biggest and strongest — is left in each womb.
At birth they’re three feet long and experienced hunters, with a good chance of survival. But the tiny brood size, nearly year-long gestation period, and relatively restricted maternal capacity — after giving birth, mothers must wait a year to reproduce again — limit the number of young sharks.
Read more about this research in artificial shark gestation at Wired Science. Link
(Image credit: Port Stephens Fisheries Institute)