Fur seal
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Fur seal | |
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A group of brown fur seals (Arctocephalus pusillus) | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Carnivora |
Clade: | Pinnipedia |
Family: | Otariidae |
Subfamily: | Arctocephalinae Scheffer & Rice 1963 |
Genera | |
Fur seals are any of nine species of
Taxonomy
Fur seals and sea lions make up the family Otariidae. Along with the
Image | Name | Distribution |
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Arctocephalus É. Geoffroy Saint-Hilaire & F. Cuvier in F. Cuvier, 1826 |
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Callorhinus Gray, 1859 |
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Physical appearance
Along with the previously mentioned thick underfur, fur seals are distinguished from sea lions by their smaller body structure, greater sexual dimorphism, smaller prey, and longer foraging trips during the feeding cycle. The physical appearance of fur seals varies with individual species, but the main characteristics remain constant.
Fur seals are characterized by their external pinnae, dense underfur, vibrissae, and long, muscular limbs. They share with other otariids the ability to rotate their rear limbs forward, supporting their bodies and allowing them to ambulate on land. In water, their front limbs, typically measuring about a fourth of their body length, act as oars and can propel them forward for optimal mobility. The surfaces of these long, paddle-like fore limbs are leathery with small claws. Otariids have a dog-like head, sharp, well-developed canines, sharp eyesight, and keen hearing.
They are extremely sexually dimorphic mammals, with the males often two to five times the size of the females, with proportionally larger heads, necks, and chests. Size ranges from about 1.5 m, 64 kg in the male Galapagos fur seal (also the smallest pinniped) to 2.5 m, 180 kg in the adult male New Zealand fur seal. Most fur seal pups are born with a black-brown coat that molts at 2–3 months, revealing a brown coat that typically gets darker with age. Some males and females within the same species have significant differences in appearance, further contributing to the sexual dimorphism. Females and juveniles often have a lighter colored coat overall or only on the chest, as seen in South American fur seals. In a northern fur seal population, the females are typically silvery-gray on the dorsal side and reddish-brown on their ventral side with a light gray patch on their chest. This makes them easily distinguished from the males with their brownish-gray to reddish-brown or black coats.
Habitat
Of the fur seal family, eight species are considered southern fur seals, and only one is found in the Northern Hemisphere. The southern group includes Antarctic, Galapagos, Guadalupe, Juan Fernandez, New Zealand, brown, South American, and subantarctic fur seals. They typically spend about 70% of their lives in subpolar, temperate, and equatorial waters. Colonies of fur seals can be seen throughout the Pacific and Southern Oceans from south Australia, Africa, and New Zealand, to the coast of Peru and north to California. They are typically nonmigrating mammals, with the exception of the northern fur seal, which has been known to travel distances up to 10,000 km. Fur seals are often found near isolated islands or peninsulas, and can be seen hauling out onto the mainland during winter. Although they are not migratory, they have been observed wandering hundreds of miles from their breeding grounds in times of scarce resources. For example, the subantarctic fur seal typically resides near temperate islands in the South Atlantic and Indian Oceans north of the Antarctic Polar Front, but juvenile males have been seen wandering as far north as Brazil and South Africa.
Behavior and ecology
Typically, fur seals gather during the summer in large
The breeding season typically begins in November and lasts 2–3 months. The northern fur seals begin their breeding season as early as June due to their region, climate, and resources. In all cases, the males arrive a few weeks early to fight for their territory and groups of females with which to mate. They congregate at rocky, isolated breeding grounds and defend their territory through fighting and vocalization. Males typically do not leave their territory for the entirety of the breeding season, fasting and competing until all energy sources are depleted.
The Juan Fernandez fur seals deviate from this typical behavior, using aquatic breeding territories not seen in other fur seals. They use rocky sites for breeding, but males fight for territory on land and on the shoreline and in the water. Upon arriving to the breeding grounds, females give birth to their pups from the previous season. About a week later, the females mate again and shortly after begin their feeding cycle, which typically consists of foraging and feeding at sea for about 5 days, then returning to the breeding grounds to nurse the pups for about 2 days. Mothers and pups locate each other using call recognition during nursing period. The Juan Fernandez fur seal has a particularly long feeding cycle, with about 12 days of foraging and feeding and 5 days of nursing. Most fur seals continue this cycle for about 9 months until they wean their pup. The exception to this is the Antarctic fur seal, which has a feeding cycle that lasts only 4 months. During foraging trips, most female fur seals travel around 200 km from the breeding site, and can dive around 200 m depending on food availability.
The remainder of the year, fur seals lead a largely
When fur seals were hunted in the late 18th and early 19th centuries, they hauled out on remote islands where no predators were present. The hunters reported being able to club the unwary animals to death one after another, making the hunt profitable, though the price per seal skin was low.[5]
Population and survival
The average lifespan of fur seals varies with different species from 13 to 25 years, with females typically living longer. Most populations continue to expand as they recover from previous commercial hunting and environmental threats. Many species were heavily exploited by commercial
See also
References
- ^ Fur Seals (Arctocephalinae). afsc.noaa.gov
- S2CID 13332236.
- ^ Nigel W Bonner, S Hunter (1982). "Predatory interactions between Antarctic fur seals, macaroni penguins and giant petrels" (PDF). British Antarctic Survey Bulletin. 56: 75–79. Archived from the original (PDF) on 2012-10-31.
- ^ Pare, Sascha (4 November 2023). "Watch great white shark get mobbed by gang of seals in 'incredible and surprising' footage". livescience.com.
- ^ ISBN 0-87451-909-8.
Further reading
- Gentry, R. L (1998) Behavior and Ecology of the Northern Fur Seal. Princeton: Princeton University Press.
- ^ "MarineBio Search ~ MarineBio Conservation Society". 6 April 2017.
- ^ "MarineBio Search ~ MarineBio Conservation Society". 6 April 2017.
- ^ "MarineBio Search ~ MarineBio Conservation Society". 6 April 2017.
- ^ "Northern Fur Seal | the Marine Mammal Center".