Integument and Pelage

The integument (skin or pelt) of marine mammals is a very special organ! In cetaceans (dolphins, porpoises, whales) the skin is smooth and sleek and feels very similar to a hard boiled egg. In pinnipeds (seals, sea lions, and fur seals), the skin is covered in a layer of hair which can vary greatly in its thickness depending on the species.

In all marine mammals (except for sea otters) a very special tissue called blubber lies just below the skin. Blubber has many functions including acting as a storage tissue for energy (fat), it keeps the animals warm, it influences the buoyancy of the animal, and it helps reduce drag. During a necropsy, measuring the thickness of the blubber is an important tool for assessing the overall health of the animal. The normal thickness will vary by species and body site but it is usually easy to tell when an animal is very thin. In cetaceans you can look for an indentation near the base of the skull (referred to as peanut head) or for an indentation just under the dorsal fin. In pinnipeds the blubber around the abdomen usually gets very thin and in very emaciated animals you can see the ribs and vertebrae of the spine.

Detailed annotated images of the integument and pelage of a California Sea Lion are shown below.  CLICK on an image to see an enlarged view.