Sea lions differ from other eared seals in that the sea lion lacks the dense underfur which makes a seal coat so salable and attractive to furriers. Their flippers have no fur. They can grow to 6 to 7½ feet long and weigh 200 to 300 pounds for females, and up to 650 pounds for males.In contrast to true seals, the sea lion can sleep on its back in the water. They propel themselves at speeds of up to 15 to 25 mph by making simultaneous sweeps of their large front flippers, the hind flippers playing little part in propulsion. They can dive to 450 feet or more. The hind flippers are used for grooming. Because their hind limbs can be rotated to aid locomotion, they are able to move relatively easily on land. The male is a polygamous animal, very protective of his harem, which may contain up to 80 females. Sea lions are gregarious animals, and it is usual to see congregations of hundreds on islands along the California coast. They are very noisy and excitable.Young sea lions are precocial. They are mobile within 30 minutes of birth. The cows milk is 36% fat.