Difference between revisions of "Sea lion" - New World Encyclopedia

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Within Otariidae, fur seals comprising the genera ''Callorhinus'' (one extant species) and ''Arctocephalus'' (eight extant species). The remaining five genera are classified as sea lions:  
 
Within Otariidae, fur seals comprising the genera ''Callorhinus'' (one extant species) and ''Arctocephalus'' (eight extant species). The remaining five genera are classified as sea lions:  
 
'[[Eumetopias]]'' (one extant species), ''[[Otaria]]'' (one extant species) , ''[[Neophoca]]'' (one extant species), ''[[Phocarctos]] (one extant species), and ''[[Zalophus]]'' (two extant and one recently extinct species).
 
'[[Eumetopias]]'' (one extant species), ''[[Otaria]]'' (one extant species) , ''[[Neophoca]]'' (one extant species), ''[[Phocarctos]] (one extant species), and ''[[Zalophus]]'' (two extant and one recently extinct species).
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==Description==
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Sea lions share with other otariids the ability to turn their rear limbs forward and move on all fours. 
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Sea lions generally are larger than fur seals, with male sea lions larger than the females. Male sea lions average from about 2 to 3 meters (6.5 to 11 feet) in length and from 200 to 1,000 kilograms (440 to 2,200 pounds), while females average from about 1.3 to 2.7 meters (4 to 9 feet) and 50 to 270 kilograms (110 to 600 pounds) (SDZ 2008).
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The Stellar sea lion (''Eumetopias jubatus'', also known as the northern sea lion, is the largest of the eared seals (Otariidae) and among [[pinniped]]s, it is inferior in size only to the [[walrus]] and the two elephant seals. Males on average reach a length of 2.8 to 3.3 meters and weight 600 to 1100 kilograms (1300 to 2500 pounds). Females are only slightly smaller, but have much narrower chests, necks, and general forebody structure; they reach on average 2.5 meters (8 feet) and weigh on average 300 kilograms (660 pounds).
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Male California sea lions (''Zalophus californianus'')grow to about 2.4 meters and 300 kilograms, while females are significantly smaller, at 90 kilograms (200 lb) and 2 meters (6.5 feet) long. The Galápagos sea lions (''Zalophus wollebaeki'') range from 1.5 to 2.5 meters in length and weigh between 50 to 400 kilograms.
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Male sea lions (bulls) and female sea lions (cows) congregate on land to give birth to pups. Sometime thereafter, the females go into estrous and breed, again on land. Generally this is an annual cycle. However, the the breeding cycle of the Australian sea lion is unusual within the pinniped family. It is an 18 month cycle and is not synchronized between colonies. The duration of the breeding season can range from 5 to 7 months and has been recorded for up to 9 months at Seal Bay on Kangaroo Island.
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Sea lions eat fish, mollusks (squid, clams), and crustaceans (crabs), and stellar sea lions eat other seals (SDZ 2008). Generally the food is swallowed whole, such as tossing the fish until it can be positioned to be swallowed headfirst, while using its hard back teeth to crush food with a hard shell (SDZ 2008). Their sensitive, long whiskers (vibrissa) attached to the upper lip can help a sea lion locate food in the dark (SDZ 2008).
  
 
== Interactions with humans ==
 
== Interactions with humans ==

Revision as of 18:13, 4 July 2008

Sea lion
A sea lion in Monterey, California
A sea lion in Monterey, California
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Suborder: Pinnipedia
Family: Otariidae
in part
Genera

Eumetopias
Zalophus
Otaria
Neophoca
Phocarctos

Sea lion is the common name for various eared seals currently comprising five genera and distinguished from fur seals in the same family, [[Otariidae], by lacking the underfur covered with long guard hairs and generally by larger size and less pointed snou. As otariids, seal lions also are characterized by presence of a pinna (external part of ear). Traditionally sea lions were placed in their own subfamily; however, recent studies have not justified such a taxonomic separation from the sea lions (Riedman 1990; ITIS 2006; Brunner 2003).

Seven species, including one recently extinct (the Japanese sea lion) are currently recognized, placed into the five genera of Eumetopias, Otaria, Neophoca, Phocarctos, and Zalophus.

The range of sea lions extends from the subarctic to tropical waters of the global ocean in both the northern and southern hemispheres with the notable exception of the Atlantic Ocean. They are generally found in shallow waters of coastal areas of both with abundant food resources (SW 2008).

Overview

File:Sea Lion Headshot.JPG
A resting Sea Lion in Galapagos National Park, Ecuador.
Hundreds of California Sea Lions sunbathing on Pier 39 in San Francisco.
GiGi, a sea lion trained by the U.S. Navy for underwater recovery, nuzzles merchant mariner Capt. Arne Willehag of the USNS Sioux during a 1983 training session.
Sea Lions at Moss Landing

Sea lions are a type of "eared seal"; that is, marine mammals comprising the pinniped family Otariidae and characterized by presence of a pinna (external part of ear), the ability to invert their hind-flippers under the body, aiding land movement, proportionally long and relatively muscular fore-flippers, and a swimming motion using their long front flippers to propel them through the water. There are 16 extant species of otariids placed into 16 species and variously known as either fur seals or sea lions.

Until recently, sea lions were all grouped under a single subfamily of Pinnipedia called Otariinae, while fur seals were grouped within the subfamily Arctocephalinae. This was based on the most prominent common feature of fur seals, namely the coat of dense underfur intermixed with guard hairs, which is lacking in those known as sea lions. This underfur with long guard hairs give them a "somewhat grizzled appearance" (Riedman 1990). Recent genetic evidence, however, suggests that Callorhinus, the genus of the Northern fur seal, is more closely related to some sea lion species than to the fur seal genus Arctocephalus. (Wynen et al. 2001), and the fur seal/sealion subfamily distinction has been eliminated from most taxonomies (Brunner 2003; ITIS 2006). Nonetheless, all sea lions have certain features in common: the coarse, short fur, greater bulk, larger prey, less pointed snouts, shorter fore-flippers, shorter and closer foraging trips, and so forth. Their pelage also tends to be lighter and the vibrissae (whiskers) less prominent. For such reasons, the distinction between sea lions and fur seals remains useful, although it is not a formal taxonomic rank.

Within Otariidae, fur seals comprising the genera Callorhinus (one extant species) and Arctocephalus (eight extant species). The remaining five genera are classified as sea lions: 'Eumetopias (one extant species), Otaria (one extant species) , Neophoca (one extant species), Phocarctos (one extant species), and Zalophus (two extant and one recently extinct species).

Description

Sea lions share with other otariids the ability to turn their rear limbs forward and move on all fours.

Sea lions generally are larger than fur seals, with male sea lions larger than the females. Male sea lions average from about 2 to 3 meters (6.5 to 11 feet) in length and from 200 to 1,000 kilograms (440 to 2,200 pounds), while females average from about 1.3 to 2.7 meters (4 to 9 feet) and 50 to 270 kilograms (110 to 600 pounds) (SDZ 2008).

The Stellar sea lion (Eumetopias jubatus, also known as the northern sea lion, is the largest of the eared seals (Otariidae) and among pinnipeds, it is inferior in size only to the walrus and the two elephant seals. Males on average reach a length of 2.8 to 3.3 meters and weight 600 to 1100 kilograms (1300 to 2500 pounds). Females are only slightly smaller, but have much narrower chests, necks, and general forebody structure; they reach on average 2.5 meters (8 feet) and weigh on average 300 kilograms (660 pounds).

Male California sea lions (Zalophus californianus)grow to about 2.4 meters and 300 kilograms, while females are significantly smaller, at 90 kilograms (200 lb) and 2 meters (6.5 feet) long. The Galápagos sea lions (Zalophus wollebaeki) range from 1.5 to 2.5 meters in length and weigh between 50 to 400 kilograms.

Male sea lions (bulls) and female sea lions (cows) congregate on land to give birth to pups. Sometime thereafter, the females go into estrous and breed, again on land. Generally this is an annual cycle. However, the the breeding cycle of the Australian sea lion is unusual within the pinniped family. It is an 18 month cycle and is not synchronized between colonies. The duration of the breeding season can range from 5 to 7 months and has been recorded for up to 9 months at Seal Bay on Kangaroo Island.

Sea lions eat fish, mollusks (squid, clams), and crustaceans (crabs), and stellar sea lions eat other seals (SDZ 2008). Generally the food is swallowed whole, such as tossing the fish until it can be positioned to be swallowed headfirst, while using its hard back teeth to crush food with a hard shell (SDZ 2008). Their sensitive, long whiskers (vibrissa) attached to the upper lip can help a sea lion locate food in the dark (SDZ 2008).

Interactions with humans

Some species of sea lions are readily trainable and are often a popular attraction at zoos and aquariums. The archetypal circus seal performing behaviors such as throwing and catching balls on its nose and clapping is almost always, in fact, a sea lion.

The government of Japan has set a quota of 116 kills per year in Hokkaido,[citation needed] as sea lions are seen as a threat to commercial fisheries. International environmentalists and local fishery advocates continue to debate the issue.

The Norwegian government has set a quota of 200 kills per year.[citation needed]

Sea lions have been trained by the U.S. Navy's Marine Mammal Program, based in San Diego, to detain scuba divers.[1]

Sea lion attacks on humans are rare, but have occurred in at least a single notable case, in which a 13 year-old Australian girl was attacked while in the water. Sources said that the likeliest explanation was that the animal was attempting to play with the girl.[2][3][4]

The Moche people of ancient Peru worshipped the sea and its animals. They often depicted sea lions in their art.[5]

Species

  • SUBORDER PINNIPEDIA
  • Family Otariidae
    • Genus Arctocephalus (southern fur seal species)
    • Genus Callorhinus (northern fur seal)
    • Genus Eumetopias
      • Steller Sea Lion, E. jubatus
    • Genus Neophoca
      • Australian Sea Lion, N. cinerea
    • Genus Otaria
      • South American Sea Lion, O. flavescens
    • Genus Phocarctos
      • New Zealand Sea Lion or Hooker's Sea Lion, P. hookeri
    • Genus Zalophus
      • California Sea Lion, Z. californianus
      • Japanese Sea Lion, Z. japonicus - extinct (1950s)
      • Galapagos Sea Lion, Z. wollebaeki
  • Family Phocidae: true seals
  • Family Odobenidae: Walrus

Hybrids

A hybrid sea lion from a cross between the California sea lion (Zalophus californianus) and the South American sea lion (Otaria byronia) has occurred.[citation needed]

References
ISBN links support NWE through referral fees

  1. Watkins, Thomas (2007-02-12). Navy may deploy anti-terrorism dolphins. Associated Press. Retrieved 2007-02-12.
  2. BBC News: Sea lion attacks Australian girl
  3. news.com.au: Monster sea lion likely to be 'playing' with teen
  4. Sea lion mauls girl
  5. Berrin, Katherine & Larco Museum. The Spirit of Ancient Peru:Treasures from the Museo Arqueológico Rafael Larco Herrera. New York: Thames and Hudson, 1997.
  • King, J. E. 1983. Seals of the World, 2nd edition. Cornell University Press, New York. ISBN 9780702216947.
  • Riedman, M. 1990. The Pinnipeds: Seals, Sea Lions, and Walruses. Berkeley: University of California Press. ISBN 0520064976.
  • Savage, R. J. G., and M. R. Long. 1986. Mammal Evolution: An Illustrated Guide. New York: Facts on File. ISBN 081601194X.
  • Wozencraft, W. C. 2005. Order Carnivora. In D. E. Wilson and D. M. Reeder, eds., Mammal Species of the World, 3rd edition. Baltimore: Johns Hopkins University Press. ISBN 0801882214.


San Diego Zoo (SDZ). 2008. Mammals:Sea Lions. Zoological Society of San Diego, Animal Bytes. Retrieved July 4, 2008.


Sea World (SW). 2008. . [1] Sea Lions and Fur Seals.


See also

External links

Credits

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  1. ANIMAL BYTES - Sea Lions & Fur Seals. Retrieved 2007-07-21.