The harbor seal, also known as the common seal is a species of a seal.
Most harbor seals occur in habitats that are sea ice free throughout the year, or at least where their coastal haulout and rookery sites are clear of sea ice during the breeding season.
They populate the shallow waters of coastal areas, bays, rocky islets, estuaries, and even freshwater lakes.
Male harbor seals live an average of 20-25 years of age compared to the female life span of 25-30 years.
The adult male may attain a length and weight of about 1.8 meters (6 feet) and 130 kg (290 pounds); the female is somewhat smaller.
The harbor seal is whitish or grayish at birth and as an adult is generally gray with black spots.
The body and flippers are short, heads are rounded. Nostrils appear distinctively V-shaped. As with other true seals, there is no ear flap. An ear canal may be visible behind the eye.
However, harbor seals have a well-developed sense of hearing, especially in the water. Their vision under water is better than a human’s, but inferior on land.
Their fur protects their skin from damage and blubber under the seal’s skin helps to maintain body temperature.
Harbor seals are solitary, but are gregarious when hauled out and during the breeding season, though they do not form groups as large as some other seals.
They tend to be coastal, not venturing more than 20 km (12.4 mi) offshore.
Harbor seals can swim up to 19 km/h (12 mph), but they generally cruise at slower speeds.
Adult harbor seals can stay submerged for up to 30 minutes, but dives usually last only about 3 minutes.
They forage at an average depth of 90 meters (295 feet) , but can go as deep as 427 meters (1,400 feet).
Adult harbor seals eat squid, crustaceans, molluscs, and a variety of fish; including, rockfish, herring, flounder, salmon, hake, and sand lance. A harbor seal’s diet varies seasonally and regionally and often is subject to local prey availability.
Harbor seals don’t chew their food. They swallow their food whole or tear it into chunks. With their back molars, they crush shells and crustaceans.
When not actively feeding, they haul to rest.
Harbor seals sleep on land or in the water. In the water they sleep at the surface and often assume a posture known as bottling – their entire bodies remain submerged with just their heads exposed. This enables them to breathe when necessary.
Mating season varies among the subspecies but generally occurs in late spring through fall. Harbor seals usually return to the same breeding grounds every year. During the mating season, male harbor seals exhibit underwater vocal displays during short dives, which are probably associated with mating.
Females bear a single pup after a nine-month gestation, which they care for alone. Pups can weigh up to 16 kg (35 lb) and are able to swim and dive within hours of birth. They develop quickly on their mothers’ fat-rich milk, and are weaned after four to six weeks.
The global population of harbor seals is 350,000–500,000, but subspecies in certain habitats are threatened.