Shark
Some sharks are viviparous, meaning that the females give live birth: the eggs hatch inside the female's body, and the babies are fed by a placenta. The placenta helps transfer nutrients and oxygen from the mother's bloodstream and transfers waste products from the baby to the mother for elimination. Examples of viviparous sharks include the bull sharks, the whitetip reef sharks, the lemon sharks, the blue sharks, the silvertip sharks, and the hammerhead sharks. Although long thought to be oviparous, whale sharks are viviparous, and pregnant females have been found containing hundreds of pups.