Seals are mammals that split their time living on land and in the ocean. They can be found in polar, subpolar and temperate waters in both hemispheres. Though a variety of ocean mammals have been called seals, the earless seals are called the true seals.
Seals' bodies are sleek and slender but shaped like a barrel. As a result, when they swim, the movement is similar to a fish, and they dive through water exceptionally well.
Earless seals have 1 to 6 inches of blubber to keep them warm.
Earless seals have broad hind flippers to help power them through water, and smaller fore-flippers for steering. Their hind flippers are not useful for locomoting on land, so they pull themselves along on their bellies using their fore-flippers and torso musculature.
Seals have long whiskers that help them navigate through water.
So seals can quickly and efficiently move through water, their nipples are retractable, and their mammary glands and testicles are located under their skin.