Sperm Whale | Whale Watching Handbook

Biology and Ecology

Feeding

Sperm whales generally feed at depth in search of their preferred prey which consists of a variety of squid species, including the giant squid, Architeuthis.  Female sperm whales almost exclusively eat squid while males have been documented to prey on bottom dwelling fish, including sharks, rays, cod and hake1.   Sperm whales typically dive to an average depth of 800 meters for 50 minutes in search of food.  Their bodies are uniquely adapted for this deep diving, with features such as high concentrations of the oxygen-carrying protein, myoglobin, in their muscles3,  and a collapsible rib cage that allows their lungs to be compressed during deep dives.

Social structure, reproduction and growth

Sperm whales form highly stable social groups based around related females and their offspring.  These groups tend to live in open ocean areas, and are occasionally visited by males who range widely across the oceans.  Calves are born after a 14-16 month gestation period, and stay with their mothers for many years.  A calf will start to eat solid foods by the age of 1 year, but may continue suckling for several more years until the next calf is born.  Young males will leave their female family unit when 4-21 years old, and will often join a ‘bachelor herd’ with other males of approximately the same age and size. These bachelor herds are observed in colder waters toward the poles. Females, however, stay with their family unit of 4-21 individuals and help to care for young in the group until they are mature enough to have their own calves.   Like killer whales, they are one of the only mammal species other than humans, in which females continue to live and play a role in family/social groups after they have stopped producing calves.  Fully mature males return to the warmer waters where the females are found in order to mate, sometimes spending only a few minutes or hours with a group before moving on again1,4.

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