Dolphins are marine mammals that give birth to live young following a gestation period of approximately 12 months. There are 40 species of dolphins, and they are all are part of the larger order of cetaceans, which includes all whales, dolphins and porpoises.
Dolphins reproduce via sexual reproduction between a male, called a bull, and a female, called a cow. Following the birth of a calf, which occurs fluke-first, the newborn remains with the cow for up to a year or more. As highly social animals, dolphins travel in family groups called pods that include fully-grown adults, juveniles and calves.