It was widely believed the whale shark reproduction process and whale shark birth was like other fish (oviparous - egg cases expelled from the female's body and hatched on the sea floor). This would involve a female whale shark laying her eggs and the male whale shark fertilised them. We now know that a female whale shark keeps her eggs inside her body until the babies are ready to be born (viviparous - egg cases hatching in the mother's uteri, with the female giving birth to live young).
A whale shark may have hundreds of thousands of eggs inside her but not every egg will become an embryo. Some of these eggs are actually food for the other eggs that do develop into embryos. An embryo eats the other eggs for energy and therefore to grow.
In 1995 a team of scientists found an 11 metre female whale shark in Taiwan that had been killed by a fisherman. There were about 300 embryos inside the pregnant whale shark ranging in length from 42 to 63cm. Amazingly, 15 of the embryos were still alive and were ready to be born - an extremely rare form of whale shark birth. The egg capsules of this whale shark were amber in colour, with a smooth texture and had a respiratory opening on each side. There were an equal number of male and female babies.
The whale sharks that are born are called pups. For whale shark reproduction and baby whale shark birth, the pups are over 60cm (2 feet) long.
Sexual maturity in whale sharks does not occur until they reach about 9metres long. This means a whale shark reproduction maturity age of about 30 years old. Whale sharks live for about 60-100 years.
This is one of five pages relating to Whale Sharks.