It is postulated that they can possibly discriminate colors in the blue-green spectrum. All pinnipeds have a membrane at the back of their eyes called a tapetum lucidum to aid in night vision. Cats also have a tapetum lucidum and this is why the eyes of both cats and sea lions glow at night. On land, their eyes are protected by a nicitating membrane which wipes away sand and debris. Females use smell for pup recognition and males use it for breeding purposes to recognize females in estrous.
Sea lions are tactile mammals.
Their whiskers contain nerve fibers which make them sensitive. They may use their whiskers to aid in navigation or to detect vibrations from prey in the water. On land, sea lions will sleep in a variety of positions, often on top of their friends. California sea lions have been seen interacting with other species of pinnipeds, such as northern elephant seals, harbor seals, northern fur seals, and Stellar sea lions. In the water they sink to the bottom of shallow areas and occasionally rise to the surface for air.