Fur seal

Fur seals are any of nine species of pinnipeds belonging to the subfamily Arctocephalinae in the family Otariidae. They are much more closely related to sea lions than true seals, and share with them external ears (pinnae), relatively long and muscular foreflippers, and the ability to walk on all fours. They are marked by their dense underfur, which made them a long-time object of commercial hunting. Eight species belong to the genus Arctocephalus and are found primarily in the Southern Hemisphere, while a ninth species also sometimes called fur seal, the northern fur seal (Callorhinus ursinus), belongs to a different genus and inhabits the North Pacific.

Fur seal
Arctocephalus Pusillus Pusillus
A group of brown fur seals (Arctocephalus pusillus)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Clade: Pinnipedia
Family: Otariidae
Subfamily: Arctocephalinae
Scheffer & Rice 1963
Genera

Arctocephalus
Callorhinus

Taxonomy

Arctocephalinae
Fur seal ranges

Fur seals and sea lions make up the family Otariidae. Along with the Phocidae and Odobodenidae, ottariids are pinnipeds descending from a common ancestor most closely related to modern bears (as hinted by the subfamily Arctocephalinae, meaning "bear-headed"). The name pinniped refers to mammals with front and rear flippers. Otariids arose about 15-17 million years ago in the Miocene, and were originally land mammals that rapidly diversified and adapted to a marine environment, giving rise to the semiaquatic marine mammals that thrive today. Fur seals and sea lions are closely related and commonly known together as the "eared seals". Until recently, fur seals were all grouped under a single subfamily of Pinnipedia, called the Arctocephalinae, to contrast them with Otariinae – the sea lions – based on the most prominent common feature, namely the coat of dense underfur intermixed with guard hairs. Recent genetic evidence, however, suggests Callorhinus is more closely related to some sea lion species, and the fur seal/sea lion subfamily distinction has been eliminated from many taxonomies. Nonetheless, all fur seals have certain features in common: the fur, generally smaller sizes, farther and longer foraging trips, smaller and more abundant prey items, and greater sexual dimorphism. For these reasons, the distinction remains useful. Fur seals comprise two genera: Callorhinus, and Arctocephalus. Callorhinus is represented by just one species in the Northern Hemisphere, the northern fur seal (Callorhinus ursinus), and Arctocephalus is represented by eight species in the Southern Hemisphere. The southern fur seals comprising the genus Arctocephalus include Antarctic fur seals, Galapagos fur seals, Juan Fernandez fur seals, New Zealand fur seals, brown fur seals, South American fur seals, and subantarctic fur seals.

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

Seal Sunbathing
A fur seal at Living Coasts, sunbathing on a rock
Thousands of fur-seals on a St. Paul beach - a fur seal rookery
A fur seal rookery with thousands of seals

Typically, fur seals gather during the summer in large rookeries at specific beaches or rocky outcrops to give birth and breed. All species are polygynous, meaning dominant males reproduce with more than one female. For most species, total gestation lasts about 11.5 months, including a several-month period of delayed implantation of the embryo. Northern fur seal males aggressively select and defend the specific females in their harems.[1] Females typically reach sexual maturity around 3–4 years. The males reach sexual maturity around the same time, but do not become territorial or mate until 6–10 years. 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 pelagic existence in the open sea, pursuing their prey wherever it is abundant. They feed on moderately sized fish, squid, and krill. Several species of the southern fur seal also have sea birds, especially penguins, as part of their diets.[2][3] Fur seals, in turn, are preyed upon by sharks, killer whales, and occasionally by larger sea lions. These opportunistic mammals tend to feed and dive in shallow waters at night, when their prey are swimming near the surface. South American fur seals exhibit a different diet; adults feed almost exclusively on anchovies, while juveniles feed on demersal fish, most likely due to availability.

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.[4]

Population and survival

Seal fur braclet
Bracelet made from silver and seal fur

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 sealers, especially during the 19th century, when their fur was highly valued. Beginning in the 1790s, the ports of Stonington and New Haven, Connecticut, were leaders of the American fur seal trade, which primarily entailed clubbing fur seals to death on uninhabited South Pacific islands, skinning them, and selling the hides in China.[4] Many populations, notably the Guadalupe fur seal, northern fur seal, and Cape fur seal, suffered dramatic declines and are still recovering. Currently, most species are protected, and hunting is mostly limited to subsistence harvest. Globally, most populations can be considered healthy, mostly because they often prefer remote habitats that are relatively inaccessible to humans. Nonetheless, environmental degradation, competition with fisheries, and climate change potentially pose threats to some populations.

See also

References

  1. ^ Fur Seals (Arctocephalinae). afsc.noaa.gov
  2. ^ Daneri, G. A.; Carlini, A. R.; Harrington, A.; Balboni, L.; Hernandez, C. M. (2008). "Interannual variation in the diet of non-breeding male Antarctic fur seals, Arctocephalus gazella, at Isla 25 de Mayo/King George Island". Polar Biology. 31 (11): 1365. doi:10.1007/s00300-008-0475-3.
  3. ^ 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.
  4. ^ a b Muir, Diana, "Reflections in Bullough's Pond", University Press of New England, 2000, pp. 80ff ISBN 0-87451-909-8.

Further reading

  • Gentry, R. L (1998) Behavior and Ecology of the Northern Fur Seal. Princeton: Princeton University Press.


[1] [2] [3] [3] [4]

  1. ^ http://marinebio.org/species.asp?id=265. Missing or empty |title= (help)
  2. ^ http://marinebio.org/species.asp?id=266. Missing or empty |title= (help)
  3. ^ a b http://marinebio.org/species.asp?id=293. Missing or empty |title= (help)
  4. ^ http://www.marinemammalcenter.org/education/marine-mammal-information/pinnipeds/northern-fur-seal/-. Missing or empty |title= (help)
Antarctic fur seal

The Antarctic fur seal, sometimes called the Kerguelen fur seal (Arctocephalus gazella), is one of eight seals in the genus Arctocephalus, and one of nine fur seals in the subfamily Arctocephalinae. As its name suggests, the Antarctic fur seal is distributed in Antarctic waters. Around 95% of the world population breeds at the Island of South Georgia.

Arctocephalus

The genus Arctocephalus consists of fur seals. Arctocephalus translates to "bear head."

Arctocephalus forsteri

Arctocephalus forsteri, the Australasian fur seal, South Australian fur seal, New Zealand fur seal, Antipodean fur seal, or long-nosed fur seal, is a species of fur seal found mainly around southern Australia and New Zealand. The name New Zealand fur seal is used by English speakers in New Zealand; kekeno is used in the Māori language. As of 2014, the common name long-nosed fur seal has been proposed for the population of seals inhabiting Australia.Although the Australian and New Zealand populations show some genetic differences, their morphologies are very similar, and thus they remain classed as a single species. After the arrival of humans in New Zealand, and particularly after the arrival of Europeans in Australia and New Zealand, hunting reduced the population near to extinction.

Brown fur seal

The brown fur seal (Arctocephalus pusillus), also known as the Cape fur seal, South African fur seal, and Australian fur seal, is a species of fur seal.

Catopuma

Catopuma is a genus containing two Asian small wild cat species, the bay cat (C. badia) and the Asian golden cat (C. temminckii).

Both are typically reddish brown in colour, with darker markings on the head. They inhabit forested environments in Southeast Asia. The bay cat is restricted to the island of Borneo. Originally thought to be two subspecies of the same animal, recent genetic analysis has confirmed they are, indeed, separate species.The two species diverged from one another 4.9-5.3 million years ago, long before Borneo separated from the neighboring islands. Their closest living relative is the marbled cat, from which the common ancestor of the genus Catopuma diverged around 9.4 million years ago.

Eared seal

An eared seal or otariid or otary is any member of the marine mammal family Otariidae, one of three groupings of pinnipeds. They comprise 15 extant species in seven genera (another species became extinct in the 1950s) and are commonly known either as sea lions or fur seals, distinct from true seals (phocids) and the walrus (odobenids). Otariids are adapted to a semiaquatic lifestyle, feeding and migrating in the water, but breeding and resting on land or ice. They reside in subpolar, temperate, and equatorial waters throughout the Pacific and Southern Oceans and the southern Indian and Atlantic Oceans. They are conspicuously absent in the north Atlantic.

The words 'otariid' and 'otary' come from the Greek otarion meaning "little ear", referring to the small but visible external ear flaps (pinnae), which distinguishes them from the phocids.

Fur Seal Point

Fur Seal Point, sometimes referred to as Fur Seal Beach, is a cape midway along the eastern coast of Clarence Island, the easternmost of the South Shetland Islands of Antarctica. Just off the headland lies the small Sugarloaf Island.

Galápagos fur seal

The Galápagos fur seal (Arctocephalus galapagoensis) breeds on the Galápagos Islands in the eastern Pacific, west of mainland Ecuador.

Guadalupe fur seal

The Guadalupe fur seal (Arctocephalus townsendi) is one of six members of the fur seal genus Arctocephalus. Sealers reduced the population to just a few dozen by the late 19th century, but the species had recovered to 10,000 in number by the late 1990s. Many individuals can be found on Mexico's Guadalupe Island.

Indian brown mongoose

The Indian brown mongoose (Herpestes fuscus) looks similar to the short-tailed mongoose from Southeast Asia and is sometimes believed to be only a subspecies of this latter. The Indian brown mongoose is found in southwest India and Sri Lanka.

Juan Fernández fur seal

The Juan Fernández fur seal is the second smallest of the fur seals, second only to the Galápagos fur seal. They are found only on the Pacific Coast of South America, more specifically on the Juan Fernández Islands and the Desventuradas Islands. There is still much that is unknown about this species. Scientists still do not know the average life span of this species, or the diet and behavior of males apart from the breeding season.

Lutrogale

Lutrogale is a genus of otters, with only one extant species—the smooth-coated otter.

North Pacific Fur Seal Convention of 1911

The North Pacific Fur Seal Convention of 1911, formally known as the Convention between the United States and Other Powers Providing for the Preservation and Protection of Fur Seals, was an international treaty signed on July 7, 1911, designed to manage the commercial harvest of fur-bearing mammals (such as Northern fur seals and sea otters) in the Pribilof Islands of the Bering Sea. The treaty, signed by the United States, the United Kingdom of Great Britain and Ireland, the Empire of Japan, and the Russian Empire, outlawed open-water seal hunting and acknowledged the United States' jurisdiction in managing the on-shore hunting of seals for commercial purposes. It was the first international treaty to address wildlife preservation issues.

Northern fur seal

The northern fur seal (Callorhinus ursinus) is an eared seal found along the north Pacific Ocean, the Bering Sea, and the Sea of Okhotsk. It is the largest member of the fur seal subfamily (Arctocephalinae) and the only living species in the genus Callorhinus. A single fossil species, Callorhinus gilmorei, is known from the Pliocene of Japan and western North America.

Paradoxurus

Paradoxurus is a genus within the viverrid family that was denominated and first described by Frédéric Cuvier in 1822. As of 2005, this genus was defined as comprising three species native to Southeast Asia:

the Asian palm civet (P. hermaphroditus)

the golden palm civet (P. zeylonensis)

the brown palm civet (P. jerdoni)In 2009, it was proposed to also include the golden wet-zone palm civet (P. aureus), the Sri Lankan brown palm civet (P. montanus) and the golden dry-zone palm civet (P. stenocephalus), which are endemic to Sri Lanka.

Pusa

Pusa is a genus of the earless seals, within the family Phocidae. The three species of this genus were split from the genus Phoca, and some sources still give Phoca as an acceptable synonym for Pusa.

The three species in this genus are found in Arctic and subarctic regions, as well as around the Caspian Sea. This includes these countries and regions: Russia, Scandinavia, Britain, Greenland, Canada, the United States, Iran, Azerbaijan, Kazakhstan, and Japan. Due to changing local environmental conditions, the ringed seals found in the Canadian region has varied patterns of growth. The northern Canadian ringed seals grow slowly to a larger size, while the southern seals grow quickly to a smaller size.

Only the Caspian seal is endangered.

South American fur seal

The South American fur seal (Arctocephalus australis) breeds on the coasts of Peru, Chile, the Falkland Islands, Argentina, Uruguay and Brazil. The total population is around 250,000. However, population counts are sparse and outdated.

The population of South American fur seals in 1999 was estimated at 390,000, a drop from a 1987 estimate of 500,000. Although overall species numbers are healthy, the downward trend is causing some concern. Uruguay has the largest numbers of seals along its coast, numbering over 200,000.

Speothos

Speothos is a genus of canid found in Central and South America. The genus includes the living bush dog, Speothos venaticus, and an extinct Pleistocene species, Speothos pacivorus. Unusually, the fossil species was identified and named before the extant species was discovered, with the result that the type species of Speothos is S. pacivorus.

Subantarctic fur seal

The subantarctic fur seal (Arctocephalus tropicalis) is found in the southern parts of the Indian, Pacific, and Atlantic Oceans. It was first described by Gray in 1872 from a specimen recovered in northern Australia—hence the inappropriate specific name tropicalis.

Extant Carnivora species

This page is based on a Wikipedia article written by authors (here).
Text is available under the CC BY-SA 3.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.