For biologist Stephanie Wood, studying harbor seals is like opening a “window into ocean life.”

What fascinates Wood about harbor seals is “They live a dual life. They live in the sea, and still return to land,” hauling out on reefs, rocks, floating glacial ice or beaches to regulate their body temperature or to rest.

A contract biologist for the National Oceanic and Atmospheric Administration, Wood said harbor seals are born in the water and adapt to it almost instantly.

“I have seen them swim within one minute of being born. They are very precocious,” she said.

Wood is talking about a unique marine mammal that comes down from the coasts of Maine into our Connecticut and New York bays and harbors from mid-November to mid-May, hunting squid, crustaceans, mollusks, rockfish, herring, flounder and other types of fish.

Harbor seals (Phoca vitulina) are part of a family of seals that have short forelimbs or flippers, no external ear flaps, nor can they rotate their hind flippers. This limits their mobility on land, forcing the seals to inch along on their bellies like a caterpillar. But they can slip through water swiftly and elegantly.

Other seals in this family include, harp, grey, hooded, spotted, ringed, monk, elephant and leopard seals.

Since harbor seals hunt most of their food in shallow waters, they usually make short dives, lasting two to three minutes. But they’re capable of plunging 600 feet deep and staying submerged for 30 minutes.

When they take deep dives, harbor seals do the opposite of what you and I would do. Instead of inhaling, they exhale to reduce the amount of air in their lungs. Then, during the dive, any remaining oxygen is stored in the blood and muscle tissues, rather than in the lungs.

Wood said harbor seals in Long Island Sound return to Maine in the spring. It is here that pregnant females give birth to their pups – one per year – between mid-May and mid-June.

At birth, harbor seal pups weigh about 24 pounds. Females eventually grow 4 to 5 feet long and weigh 110-331 pounds, while males may exceed 6 feet and weigh up to 375 pounds. These impressive animals can live 25 to 30 years.

Harbor seal nursing is brief, four to six weeks, then mother and pup part ways. The mother, meanwhile, continues to court other males.

“They are very promiscuous,” Wood said, while the pup starts a journey rife with challenges.

“Forty to 60 percent of juvenile harbor seals die in their first year,” Wood said, adding, “The biggest challenge is getting enough food.”

Rob DiGiovanni, chief scientist for the Atlantic Marine Conservation Society of Hampton Bays, N.Y. (amseas.org) said his organization, among other things, helps rescue harbor seals and other marine animals that are malnourished, have become entangled in commercial fishing nets, or receive debilitating wounds from vessel strikes.

Worse, DiGiovanni said, are seals and other marine animals that mysteriously strand themselves.

About 100 harbor seals per year strand themselves in New York waters, DiGiovanni said.

“That’s a big number, but not a huge number,” he said.

To find out answers why these animals beach themselves, DiGiovanni, Wood and other marine scientists are studying what healthy wild seal populations are doing. They take blood samples, conduct aerial surveys and tag the seals.

“We put a battery-powered device on them that can sustain pressures up to 300 feet.” DiGiovanni said.

From these devices, DiGiovanni and others obtain seal locations, diving behaviors, how much time the animals spend on the surface, and where they move.

I salute scientists like Wood, DiGiovanni and their colleagues, because without their frontline efforts, we really wouldn’t be able to understand much about life in the ocean.

Their goal is a noble one: to collect and disseminate data to environmental managers, ensuring long-term survival of animals like harbor seals.

The good news is seal populations in Long Island Sound are growing.

Now, there are approximately 75,000 harbor seals in New England waters, a stock that is “doing fairly well,” Wood said

So, if you’re driving along our shores this winter and notice a plump, dark-colored animal, resting among the rocks in a “banana-like” position, with its head and rear flippers elevated, it might be a harbor seal. Enjoy!

Bill Hobbs is a resident of Stonington and a lifelong wildlife enthusiast. For comments, he can be reached at whobbs246@gmail.com.