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Kingdom
Animalia
Phylum
Chordata
Subphylum
Vertebrata
Class
Mammalia
Order
Carnivora
Suborder
Caniformia
Family
Otariidae
Species
Zalophus californianus
Zalophus californianus
California sea lion
2010/09/05 05:27:04.233 GMT-4
By Rebecca Price
Species:
Zalophus californianus
Geographic Range
Zalophus californianus
are found along the shore from California to Mexico including Baja and Tres Marias Islands, in the Galapagos Islands and in the southern Sea of Japan (Scheffer, 1958). The populations in each area do not interact with other populations (Scheffer, 1958) and therefore are considered subspecies. California sea lions tend to seasonally migrate long distances (Riedman, 1990). Males usually migrate north to British Columbia after the breeding season (Mate, 1978).
Habitat
Zalophus californianus
generally live along coastlines but have been found in rivers in along the northern Pacific coast. California sea lions often congregate on man-made structures such as jetties, piers, offshore buoys and oil platforms.
Zalophus californianus
tend to inhabit places which have undergone human intervention (Riedman, 1990).
Aquatic Biomes:
rivers and streams;
coastal
.
Physical Description
Mass
390 kg (high)
(858 lbs)
Length
2.40 m (high)
(7.87 ft)
Newborn pups average 75 cm in length and weigh between 5 to 6 kg. Adult males average 2.2 meters in length and 275 kg in weight but can reach length of 2.4 meters and weights of 390kg. Females are smaller, averaging 1.8 meters in length and 91 kg in weight but can reach lengths of 2 meters and weights of 110kg . Pups have a blackish brown coat, which is molted by the first month and replaced with a light brown coat. The light brown coat is shed after 4 or 5 months and replaced with the adult pelage. Adult males are mostly dark brown with lighter belly and side coloring. Adult females are dark brown but can also appear tan.
Zalophus californianus
exhibit pronounced sexual dimorphism . Adult males have an enlarged saggital crest and a lighter pelage. In addition to the head features males are more robust and larger than females. All California sea lions have black flippers which are coated with short black stubble. The typical dental formula is 3/2, 1/1, and 5/5.
(Mate, 1979,)(Jefferson et al., 1993), and (Riedman, 1990)
Reproduction
Breeding season
mating in July, births in mid-May to mid-June
Number of offspring
1 (average)
Gestation period
11 months (average)
Time to weaning
6 to 12 months; avg. 9 months
Age at sexual or reproductive maturity (female)
4.50 years (average)
Age at sexual or reproductive maturity (male)
4.50 years (average)
During breeding season males claim territories. A male consistently occupies a territory until factors change and cause him to be displaced. Typical occupation time is approximately two weeks; few
Z. californianus
males remain at their site for longer. While guarding their territory, males remain present and do not leave even in pursuit of food. As external factors change, males replace other males on the territory. Replacement occurs throughout the entire breeding season. Males are known to attack if others invade their territory. California sea lions tend to breed on islands or remote beaches.
Zalophus californianus
exhibit moderate to extreme polygyny and tend to live in colonies of a few males and many females. Female
Z. californianus
exhibit mate choice, by "respond[ing] differently to the attempts of various males"(Riedman, 1990).
The peak breeding season occurs in early July. The total gestation period is about 11 months (Riedman, 1990). Most births occur from mid-May to mid-June (Scheffer, 1958) with the majority of pups born in mid-June. The time between birth and estrus is about 28 days. California sea lions reach sexual maturity between four and five years (Riedman, 1990).
The lactation period in
Z. californianus
ranges from six months to a year. There are many possible reasons for the variation in lactation periods including availability of food resources, the mother's age and health, the sex of the pup and the birth of a new pup.
Zalophus californianus
provide more lengthy maternal care for female offspring then for male offspring, yet during lactation both males and females have equal access and receive equal resources.
Lifespan/Longevity
Extreme lifespan (wild)
17 years (high)
Extreme lifespan (captivity)
31 years (high)
The oldest recorded wild
Z. californianus
lived 17 years (Mate, 1979).
In captivity, the oldest recorded
Z. californianus
lived to be 31 years old. The age of
Z. californianus
can be determined by counting the number of rings on cross sections of its teeth (Mate, 1978).
Behavior
Zalophus californianus
are capable of diving to depths of 274 meters (Riedman, 1990) and can reach speeds of 15 to 20 miles per hour while swimming (Mate, 1978). Like certain other marine mammals,
Z. californianus
use a system of echolocation to find food, orient themselves, and navigate underwater.
Z. californianus
sometimes adopt and foster a pup that has been abandoned by its mother (Riedman, 1990).
The normal body temperature of
Zalophus californianus
is 37.5 degrees Celsius. Because
Z. californianus
cannot sweat or pant (Odell, 1981), in order to thermoregulate they must alter their exterior environment. For example, if the air temperature increases they seek cooler areas, such as water (Riedman, 1990).
Pups exhibit many different play behaviors including mock fighting (Mate, 1978).
Food Habits
Male California sea lions have been known to assemble at the mouths of fresh water rivers where there is a steady supply of fish. California sea lions tend to feed alone or in small groups unless there is an large quantity of food. Under conditions of increased food supply,
Z. californianus
hunt in larger groups.
Zalophus californianus
have been known to feed cooperatively with cetaceans, seabirds and harbor porpoises. Often one species locates a school of fish and signals the presence of food to the other species. While rare, it has been recorded that California sea lions drink seawater while not breeding (Riedman, 1990).
Foods eaten include: cephalopods, anchovies, herring, Pacific whiting, rockfish, hake, salmon, squid and octopuses (Riedman, 1990).
Animal Foods:
fish; mollusks.
Economic Importance for Humans: Negative
California sea lions are thought by some to seriously reduce stocks of commercially-valuable fish such as salmon. They also may interfere with nets used by fishermen.
Ways that these animals might be a problem for humans:
crop pest.
Economic Importance for Humans: Positive
Zalophus californianus
used to be hunted for their hides and for animal food. California sea lions are also used by the U.S. Navy for retrieval programs, including search and rescue and retrieval of military hardware. They are also used to patrol areas in search of threats. California sea lions are widely used in educational programs throughout the world because of their agility and trainability. They are charming ambassadors for their sea lion cousins.
(
Mate, 1978
;
Mate, 1979
)
Ways that people benefit from these animals:
ecotourism
; research and education.
Conservation Status
IUCN Red List:
[link]
:
Lower Risk - Least Concern.
US Federal List:
[link]
:
No special status.
CITES:
[link]
:
No special status.
Zalophus californianus
are well protected in most areas. Occasionally, they are trapped with a permit for display in zoos, aquariums, and circuses (Mate, 1979). In Mexico, a few California sea lions are trapped each year, while in the United States they are fully protected under the Marine Mammal Protection Act.
Occasionally California sea lions pose a problem for fishermen by stealing fish from commercial fishermen netting. A significant number of California sea lions have been killed as a result of getting tangled in discarded fishing gear. (Riedman, 1990). From 1983 to 1984,
Z. californianus
experienced a decline of 60 percent in pup production from previous years. Also during this time food resources declined, which led to inhibited growth and increased mortality. During this time mothers left their pups earlier in search of food, which truncated the lactation period, thus reducing the amount of nutrients a pup received and making it more susceptible to death.
According to IUCN, the following subspecies are recognized:
Zalophus californianus ssp. japonicus
(extinct)
Zalophus californianus ssp. wollebaeki
(vulnerable)
Zalophus californianus ssp. californianus
(no special status).
Other Comments
Because
Z. californianus
are highly trainable (Riedman, 1990), they are often used as performing animals in zoos, circuses and aquariums (Jefferson et al., 1993).
In 1970, a disease called leptospirosis spread throughout the California sea lion population via urine. This disease was the first documented widespread disease in marine mammals. The origin of the leptospirosis was believed to be Mexico due to the warmer water there, which was conducive to bacteria growth. (Mate, 1978)
For More Information
Find
Zalophus californianus
information at
Contributors
Rebecca Price (author), University of Michigan.
Kate Teeter (editor), University of Michigan.
References
Jefferson, T., S. Leatherwood, M. Webber. 1993.
Marine Mammals of the World
. Rome, Italy: United Nations Environment Programme and Food and Agriculture Organization of the United Nations.
Mate, B. 1978. California Sea Lion. Pp. 172-177 in D. Haley, ed.
Marine Mammals of Eastern North Pacific and Artic Waters
. Seattle, Washington: Pacific Search Press.
Mate, B. 1979. California Sea Lion. Pp. 5-8 in FAO Advisory Committee on Marine Resource Research Working Party on Marine Mammals, ed.
Mammals in the Sea vol. 2 Pinniped Species Summaries and Report on Sirenians
. Rome, Italy: Food and Agriculture Organization of the United Nations.
Odell, D. 1981. California Sea Lion - *Zalophus californianus*. Pp. 67-97 in S. Ridgway, R. Harrison, eds.
Handbook of Marine Mammals: vol. 1: The Walrus, Sea Lions, Fur Seals and Sea Otter
. London: Academic Press.
Riedman, M. 1990.
The Pennipeds: Seals, Sea Lions, and Walruses
. Berkeley, California: University of California Press.
Scheffer, V. 1958.
Seals, Sea Lions and Walruses: A Review of the Pinnipedia
. Stanford California: Stanford University Press.
2010/09/05 05:27:05.623 GMT-4
To cite this page:
Price, R. 2002. "Zalophus californianus" (On-line), Animal Diversity Web. Accessed September 06, 2010 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Zalophus_californianus.html.
Disclaimer:
The Animal Diversity Web is an educational resource
written largely by and for college students
. ADW doesn't cover all species in the world, nor does it include all the latest scientific information about organisms we describe. Though we edit our accounts for accuracy, we cannot guarantee all information in those accounts. While ADW staff and contributors provide references to books and websites that we believe are reputable, we cannot necessarily endorse the contents of references beyond our control.
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Sponsored in part by the Interagency Education Research Initiative,
the Homeland Foundation and the
University of Michigan
Museum of Zoology
.
This material is based upon work supported by the
National Science Foundation
under Grants DUE-0633095 and DRL-0628151.
The ADW Team gratefully acknowledges their support.
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