 A social unit is a group of sperm whales who live and travel together over a period of years . Individuals rarely , if ever , join or leave a social unit . There is a huge variance in the size of social units . They are most commonly between six and nine individuals in size but can have more than twenty . Unlike orcas , sperm whales within a social unit show no significant tendency to associate with their genetic relatives . Females and calves spend about three quarters of their time foraging and a quarter of their time socializing . Socializing usually takes place in the afternoon . 
