Harbor seals have short, round heads with a V-shaped arrangement of the nostrils. The background color is generally brownish or gray, marked with small spots. All flippers are furred on both sides. Adult males are 59 to 79 inches long and weigh 154 to 374 pounds. Females are somewhat smaller at 47 to 49 inches long and 110 to 330 pounds in weight. They have ear openings, which they can close, but lack external ears.This species is usually solitary, the only social cohesion being between the mother and her nursing pup. Adults and juveniles form strong linear hierarchies based on size and sex, adult males being dominant. Many individuals may gather at a favorite "hauling out" site for sleeping, birthing and resting. Harbor seals are strong swimmers using black flippers in a side to side motion and can leap completely out of the water or stay submerged 20 to 43 minutes. Metabolism slows to allow this. They are non-migratory and make only limited movements in connection with foraging and breeding. Enemies include sharks, killer whales, bears, walruses and, in the case of the young, eagles. Single pups are usually 30-39 inches long and weigh 22 to 26 pounds. The pup has adult pelage and can swim at birth.