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Harbor seal

life science Maturity 7-9 Next article →

The harbor seal, scientifically known as Phoca vitulina, is a highly successful marine mammal.

Common Seal Phoca vitulina
Common Seal Phoca vitulina

These animals are classified as true seals, which distinguishes them from other pinnipeds like walruses or eared seals. They are widely distributed across the temperate and Arctic marine coastlines of the Northern Hemisphere. You can find them in the coastal waters of the North Atlantic and North Pacific oceans. They also inhabit the Baltic and North seas. Because they live in many different environments, they are considered the most widely distributed species of pinniped.

Physically, the harbor seal is built for life in cold, aquatic environments.

Harbor seal mammal phoca vitulina
Harbor seal mammal phoca vitulina

Their bodies are somewhat short, and they have rounded heads. One very distinctive feature is their V-shaped nostrils. Unlike eared seals, true seals like the harbor seal do not have an external ear flap, or pinna. Instead, an ear canal may simply be visible behind the eye. Their skin features a unique pattern of spots, which can be dark on a light background or light on a dark one. This means every individual seal has a pattern that is entirely its own. Their coloring varies from brownish black to tan or grey, with generally lighter underparts.

To survive in chilly waters, harbor seals rely on a thick layer of fat called blubber.

Phoca vitulina skeleton
Phoca vitulina skeleton

This blubber sits under the skin and helps maintain a steady body temperature. An adult seal can reach a length of 1.85 meters, or about 6.1 feet. They can weigh anywhere from 55 kg to 168 kg, which is roughly 120 to 370 pounds. Females are generally smaller than males. In terms of lifespan, females tend to live longer than males. Females typically live between 30 and 35 years, while males live between 20 and 25 years.

Harbor seals follow specific patterns for resting and raising their young.

Harbor Seal with young pup
Harbor Seal with young pup

They use familiar resting spots called haulout sites. These are often rocky areas, but they might also use ice, sand, or mud. These sites provide protection from predators and bad weather while remaining near foraging areas. Reproduction involves a nine-month gestation period, after which the female bears a single pup. The mother cares for the pup alone. These pups are remarkably capable, as they can swim and dive within just a few hours of birth. They grow rapidly by consuming fat-rich milk and are typically weaned after four to six weeks.

Scientists recognize several different subspecies of Phoca vitulina.

White harbor seal on moss by Dave Withrow, NOAA
White harbor seal on moss by Dave Withrow, NOAA

The Eastern Atlantic common seal lives in Europe and northwestern Asia. The Western Atlantic common seal is found in eastern North America, though genetic evidence makes its status as a separate subspecies questionable. The Pacific harbor seal, or P. v. richardii, inhabits western North America. In Eastern Asia, the Insular seal was once considered a subspecies, but it is not currently recognized as one. Finally, the Ungava seal, or P. v. mellonae, lives in the fresh waters of eastern Canada and is currently considered endangered.

Historically, the harbor seal faced massive challenges from human activity.

Along the Atlantic coast, seals were once wiped out by hunting and heavy pollution. In places like New York and Boston, toxic chemicals such as PCBs and dioxin made the water nearly uninhabitable. However, the species has shown incredible resilience. As water quality improved, such as in New York Harbor, the seals began to return. They have reclaimed ancestral territories and even use certain areas as "resorts" during the winter. Today, many nations have passed laws to protect them, such as the Marine Mammal Protection Act in the United States.

In their daily lives, harbor seals play a vital role in the marine ecosystem.

Pinniped underwater
Pinniped underwater

They are top-level feeders in habitats like kelp forests, which helps increase species diversity. Their diet is quite varied, including herring, flounder, hake, anchovy, cod, and sculpin. They also eat shrimp, crabs, mollusks, octopus, and squid. They are highly mobile and can travel up to 50 km to find food. Some even swim over 100 km upstream into fresh water to hunt for migratory fish like salmon. While they are successful hunters, they must also watch for predators like killer whales and white sharks.

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🖼️ Images & Media (15)
File:Phoca vitulina 05 MWNH 1464.JPG
Phoca vitulina 05 MWNH 1464.JPG
File:Phoca vitulina skeleton.jpg
Phoca vitulina skeleton.jpg
File:Common Seal Phoca vitulina.jpg
Common Seal Phoca vitulina.jpg
File:Harbor seal mammal phoca vitulina.jpg
Harbor seal mammal phoca vitulina.jpg
File:Harbor Seal with young pup.jpg
Harbor Seal with young pup.jpg
File:Antur 1.jpg
Antur 1.jpg
File:White harbor seal on moss by Dave Withrow, NOAA.png
White harbor seal on moss by Dave...
File:A Harbor Seal nursery on ice in front of The Grand Pacific Glacier in Glacier Bay National Park, Alaska.jpg
A Harbor Seal nursery on ice in front of...
File:Harbor seal (Phoca vitulina) at Magdalen fjord, Svalbard (1).jpg
Harbor seal (Phoca vitulina) at Magdalen...
File:Phoca vitulina (harbor seal).jpg
Phoca vitulina (harbor seal).jpg
File:Harbor seal in Holyoke, MA. Connecticut River. 01.jpg
Harbor seal in Holyoke, MA. Connecticut...
File:Pinniped underwater.jpg
Pinniped underwater.jpg

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