Physical Characteristics - California Sea Lion

SIZE

1. Male California sea lions reach about 2 to 2.5 m (6.5–8 ft.) and 200 to 400 kg (440–880 lb.). At maturity male California sea lions are much larger than females. 2. Female California sea lions reach about 1.5 to 2 m (5–6.5 ft.) and 50 to 110 kg (110–240 lb.). Mature male California sea lions are much larger than females.

BODY SHAPE

1. A California sea lion has a fusiform body shape that is sleek and streamlined. The bodies of California sea lions are tapered at both ends giving them a sleek, fusiform shape.

COLORATION

1. California sea lion coat colors vary. Generally, adult males are chocolate brown, females and young males are tan, and pups are dark chocolate brown. As adult males age, the hair around their heads lightens to a light tan. California sea lion pups are noticeably darker in color than the adults. 2. Most California sea lions appear dark brown to black when wet. When dry, the light to golden brown of the California sea lion's fur is more apparent. When they are wet, they become dark brown to black.

FOREFLIPPERS

1. A California sea lion's foreflippers are large and winglike. Sea lions have large, wing-like foreflippers. 2. The foreflippers have all the major skeletal elements of the forelimbs of land mammals, but they are modified for swimming. The "arm" bones are shortened, and the flippers are lengthened by cartilaginous extensions at the tips of the finger bones. This illustration shows the major skeletal elements of the foreflippers and the elongated, larger first digit. 3. The first digit is larger than the others. It's strengthened by fibrous tissue along the leading edge. The first digit on the sea lion's foreflipper is longer than the others and contains fibrous tissue along the leading edge. 4. There are no claws or hair on the foreflippers. California sea lions have no hair or claws on their front flippers. 5. California sea lions use their foreflippers in an up-and-down, wing-like motion to propel themselves through the water.

HIND FLIPPERS

1. Like land mammals, sea lions have five digits in the hind limbs. They are lengthened by cartilaginous extensions. Sea lions have five digits on their hind flippers that are all roughly the same length. 2. Nails are visible on the middle three digits. The middle three digits on California sea lions' hind flippers have noticeable nails that are used to groom their fur. 3. On land, a sea lion can rotate its hind flippers underneath the pelvic girdle, enabling it to support its weight and walk on all fours. 4. In the water, a sea lion extends its hind flippers and uses them to help steer. Sea lions have large, wing-like foreflippers, and smaller hind flippers that can be rotated underneath the body giving sea lions the ability to walk and stand on all fours limbs.

HEAD

1. The California sea lion has visible ear pinnae (ear flaps) on either side of its head. Sea lions have visible external ear flaps on either side of their heads. 2. California sea lions have large eyes. 3. There are about 20 to 30 vibrissae (whiskers) on each side of the muzzle, a total of about 40-60. These tactile organs are well supplied with muscles and nerves. 4. California sea lions have 34 to 38 teeth: four large canine teeth, smaller incisors, and cone-shaped cheek teeth. The teeth are designed for grasping and tearing (not chewing) food. Deciduous teeth (milk teeth) are shed before birth. This adult male California sea lion has the typical large, round eyes, numerous vibrissae and large canine teeth of this species. 5. When relaxed, the nostrils are closed. A sea lion voluntarily opens its nostrils by contracting its mystacial (cheek pad) muscles. When relaxed, their nostrils are closed. To open their nostrils, sea lions contract their mystacial musceles. 6. Adult male California sea lions have a raised forehead. This area of the skull is called the cranial, or sagittal crest. At about ten years, the male's sagittal crest reaches full size, up to 4 cm (1.5 in.). Females have a lower, smoother forehead. Male California sea lions have a raised forehead called the cranial or sagittal crest.

TAIL

1. A California sea lion has a small, flattened tail between the hind flippers. Sea lions have a small, flattened tail between their hind flippers.

HAIR

1. A sea lion's coat consists of guard hairs with shorter fine underhairs. Each guard hair is associated with several underhairs. A thin film of oil secreted by glands under the skin waterproofs the coat. Like all mammals, sea lions have hair. California sea lions have short stiff hair covering their bodies. 2. California sea lions molt (shed their hair) once each year, gradually shedding and replacing most of the guard hairs and underhairs. This molt usually occurs after the breeding season. • Immature and nonbreeding females molt in August and September. • Lactating females and subadult males molt in September and October. • Adult males molt from November to February. 3. On land, California sea lions groom their coats. One common grooming behavior is a doglike scratching using the nails of one of the hind flippers. They also rub against rocks or other sea lions or rub their hair with their foreflippers.