They are called sea lions because they resemble the terrestrial lion of Africa and Asia. Large adult male Steller's sea lions have disproportionately large necks and shoulders. This, coupled with longer, coarser hair on the neck and shoulders, gives them the appearance of having manes, as do lions.
Color gradually lightens as the animal ages and periodically molts.
Most adult females are a yellowish, cream color on the back, although some remain darker. Males and females have a marked size difference. Females grow rapidly during the first four years but slow by the fifth year, with little growth after age 6. Males continue to grow until the eleventh year. Although there are variations, most females reach maximum size by the seventh year, and males reach adult size by the twelfth year.