Seals living in colder habitats have thicker fur coats and greater amounts of insulating blubber than seals in warmer climates. Seals regulate heartbeat and blood flow using less oxygen while diving for food. They dilate or constrict skin blood vessels to release or conserve heat depending on their environment.
Seals living in colder habitats are heavier than those living in warmer climates. They eat more to sustain their extra layers of blubber. Seals use their sensitive whiskers to feel for fish in the darkness of deep or murky waters. They have streamlined bodies built for swimming fast in the water. Some seals, such as the Harbor seal, have a higher metabolic rate than land mammals of the same size helping them generate body heat for warmth. In cold water, blood vessels in the skin constrict and blood is shunted inward, reducing heat loss to the environment. When on land, blood vessels in the skin dilate and allow heat to be released to the environment. In an action called sailing seals hold one flipper above the water as they swim on the surface. Wind flows over the flipper, cooling the flipper and the seal. Seals can also slow their heartbeats, allowing them to stay underwater from about 15 minutes to over 2 hours depending on the species. Some species of seal can dive more than a mile underwater.