On reaching sexual maturity, the males develop a large bony crest on the top of their heads. It is this very features that earns the animal the generic name Zalophus. 'Za' stands for emphatic, while 'lophus' relates to the forehead. Literally translated, Zalophus californianus means 'Californian big-head'.
Other than the waters around California, this sea lion is also sighted near coasts and bays of Oregon, British Columbia, Washington, Mexico and the islands of Channel and San Nicolas.
Depending on the amount of food available, they may choose to eat alone or in a group. This mammal exhibits unique social behavior, as it co-exists and feeds alongside dolphins, seabirds, and even sharks, who simultaneously feed on large schools of migratory fish.
They mainly breed between May and June. The males are known to fast during the courting period, using their blubber as an energy reserve. Size plays an important role in a fight over a female.
Male fights involve ritualized roaring, bluff plunges, and head-shaking. After a gestation period of a year, females give birth to pups either on land or in water. The new-born pups instantly vocalize with the mother. They nurse for up to six months on milk that does not contain lactose. Within two months, the pups swim and hunt alongside their mothers.