For many years all that was known about these animals was learned from dead animals that had washed ashore or from those that were killed by whalers. Although whales, dolphins and porpoises still remain very elusive, modern technological advances and an increased effort to study them in the wild has increased our understanding of their distribution, behavior and life history. They are all well suited for aquatic life with strong streamlined bodies and flippers although they return to land to mate and bear their young. Eared seals and walruses use their forelimbs for swimming and can turn their hind limbs forward for walking on land. True seals use their rear flippers for swimming but cannot turn them forward for walking on land where they move about on their bellies.
All pinnipeds are flesh eaters and feeding behavior and diet vary for each species.
Harbor and gray seals prefer fish such as herring, alewives, flounder and squid and will consume about 6 to 10 percent of their body weight each day. Pinnipeds have a thick tough skin supplied with many blood vessels and covered with flat hairs which form two layers of fur that are supplied with large oil glands. Under the skin is a layer of blubber which insulates and provides buoyancy to the animal. Pinnipeds are excellent swimmers and divers and can remain submerged up to twenty minutes. The eared seals and walruses do not occur in this area of the country but harbor seals and gray seals are frequently seen along the northeastern U.S. coast, especially along the shores of Maine from Kennebunk to Machias.