 Adult males who are not breeding live solitary lives , whereas females and juvenile males live together in groups . The main driving force for the sexual segregation of adult sperm whales is scramble competition for mesopelagic squid . Females and their young remain in groups , while mature males leave their " natal unit " somewhere between 4 and 21 years of age . Mature males sometimes form loose bachelor groups with other males of similar age and size . As males grow older , they typically live solitary lives . Mature males have beached themselves together , suggesting a degree of cooperation which is not yet fully understood . The whales rarely , if ever , leave their group . 
