Instead, a large hump is present and behind it a series of bumps along the ridge of the back that extends to the large, notched, triangular flukes or tail flippers. Overall, the body is dark blue to slate gray on the upper parts, lighter colored underneath, and white around the mouth. Squid is the primary food of the sperm whale, and much of its biology and behavior can be attributed to the search for this food item. Instead, harems are formed, consisting of a bull leading a group of adult females and their young. Adult males without a harem travel in bachelor groups, obtaining a harem only by fighting and defeating a bull that leads one.
Males compete with one another in early spring and summer for control of a group of mature females.
A successful male will mate with all the females in his harem. Gestation lasts for about 15 months and the calf, which is 12-16 feet when born, nurses for about two years. After weaning, the female may not become pregnant again for nine months. Females reproduce only once every four years. Sperm whales are found in all of the world's oceans, except for the Arctic region.