California sea lions give birth on the rocky islets of Los Islotes in the summertime. Soon afterwards they will mate again and the reproductive process will start afresh. A dominant bull may mate with many females in a day during the season, defending a territory against other males. While he is busy, younger males may sneak in to try and disperse their own genes. An interesting aspect of sea lion reproduction is thought to involve delayed implantation, where a fertilized egg divides only to the blastula stage and then arrests. If conditions are favorable later in the season, implantation on the uterine wall will occur and development will continue until birth. This allows reproduction to occur on an annual cycle, rather than on a cycle based on a fixed gestation period.
Sea lion pups may nurse for up to a year before they are completely independent. The mothers and pups will recognize each other by their voices. Other mothers will not usually nurse an orphaned pup. Young sea lions will play and joust, becoming stronger and learning about social aspects of their culture. Sensitive whiskers give them information about their environment and help them to find food. Large eyes with light receptive cells enable them to see in low light conditions under water. Their eyes are shaped to see above and below the water. Using their powerful fore-flippers they are quick and agile swimmers, putting us to shame and making us feel like aliens in the water, yet still show the curiosity and playfulness that is important for the development of a young mammal. Our interactions with these animals can have great emotional impact and create life-long memories.
