Whales are mammals, just like humans, and so they have live births after a period of gestation. Baby whales (called calfs) remain in their mother’s womb for between nine and 18 months, depending on the species, and are then born underwater. They emerge from their mother tail-first to prevent drowning, and can swim straight away, enabling them to get to the surface to breathe. Although they are already well developed – some may be a third of the length of their parents at birth -calves remain with their mother for between six months to two years.

During this time they suckle on her nipples, which produce milk that is full of the nutrients the calf needs to grow. Once the mother stops producing milk, the young whale will switch to eating solid food and become independent. When it reaches sexual maturity, which is usually between the ages of five and 20, it will produce young of its own.

Female whales, known as cows, give birth to a single offspring every one to six years. Many species migrate to warmer oceans to breed, and will mate with more than one male to increase their chances of producing healthy offspring.