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California Sea Lion

Photo Credit: Glen Tepke
http://www.pbase.com/gtepke/

SCIENTIFIC NAME: Zalophus californianus
 
OTHER NAMES:   Sea lion or seal
 
DESCRIPTION: The California sea lion has a streamlined body that contains a layer of blubber under the skin to provide warmth and buoyancy. Their large eyes help them adjust to low levels of light in underwater environments, while their whiskers augment their sense of touch. Their nostrils automatically close once they hit the water. California sea lions are known for their intelligence, playfulness, and noisy barking. Their color ranges from chocolate brown in males to a lighter, golden brown in females. Males may reach 1,000 lbs (more often 850 lbs.) and seven feet in length. Females grow to 220 lbs. and up to six feet in length. They have a “dog-like” face, and at around five years of age, males develop a bony bump on top of their skull called a sagittal crest. The top of the male’s head often gets lighter with age. These members of the walking seal family have external ear flaps and large flippers that they use to “walk” on land. The trained “seals” in zoos and aquariums are usually California sea lions.
 
HABITAT: California sea lions are found from Vancouver Island, British Columbia to the southern tip of Baja in Mexico. They breed mainly on offshore islands, ranging from southern California’s Channel Islands south to Mexico, although a few pups have been born on Ano Nuevo and the Farallon Islands in central California. There is a distinct population of California sea lions at the Galapagos Islands. A third population in the Sea of Japan became extinct, probably during World War II.
 
FEEDING HABITS: California sea lions are opportunistic eaters, feeding on shell fish, squid, octopus, herring, rockfish, mackerel, and small sharks. In turn, sea lions are preyed upon by Orcas (killer whales) and great white sharks.
 
LIFE HISTORY AND ECOLOGY:   California sea lions are very social animals, and groups often rest closely packed together at favored haul-out sites on land, or float together on the ocean’s surface in “rafts”. Their long fore flippers enable them to make powerful strokes while swimming and reach speeds up to 25 mph. They are very vocal and bark like dogs; the pups have a bleat like call. Most pups are born in June or July and weigh 13 to 20 lbs. They nurse for five to six months and sometimes over a year. California sea lions are the only mammals whose milk does not contain lactose. Mothers recognize pups on crowded rookeries through smell, sight, and vocalizations. Breeding takes place a few weeks after pups are born and females have a 12-month gestation period.  
 
Males patrol territories and bark almost continuously during the breeding season. The current population is approximately 200,000 and is growing steadily. Natural mortality of sea lions is known to occur from diseases such as pneumonia and bacterial infections. Toxic aquatic algal blooms are also harmful to sea lions. Other problems for California sea lions involve humans. Sea lions have been found illegally shot and also caught in fishing nets and other marine debris.  California sea lions are intelligent and adaptable, and are often trained by researchers studying interspecies cooperation in marine environments. They are also used in military applications as sentries, and for equipment recovery, by the U.S. Navy Marine Mammal Program.
 
REFERENCES:
 
The Marine Mammal Center www.marinemammalcenter.org/learning/education/pinnipeds/casealion.asp
 
The California Sea Lion http://en.wikipedia.org/wiki/California_Sea_Lion
 
The California Sea Lions of British Columbia, Canada www.bcadventure.com/adventure/wildreness/animals/sealion.htm
 
AUTHOR: David Nelson, Supervising Wildlife Biologist, Alabama Division of Wildlife and Freshwater Fisheries, October 2006. 

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