Unlike most bony fish, shark's eggs are fertilized inside the female's body.
Most sharks give birth to live young, but some release eggs that hatch later.
They quickly swim away, even from their mothers who might eat them. The placenta helps transfer nutrients and oxygen from the mother's bloodstream and transfers waste products from the baby to the mother for elimination. Viviparous sharks give birth to live young. The number of pups in a litter ranges from 2-20 or more. Examples of viviparous sharks include the Bull sharks, Whitetip reef shark, Lemon shark , Blue shark, Mako , Porbeagle, Salmon shark, the Silvertip shark, and Hammerheads.