Fur seals are nine species of marine mammals on the family of eared seals.

Physical Appearance

Fur seals  differ from the true seals in having small external earflaps and hind flippers that can be turned to face forwards. Together with strong front flippers, this gives them extra mobility on land and an adult fur seal can move extremely fast across the beach if it has to. They also use their front flippers for swimming, whereas true seals use their hind flippers.

Like other Eared seals, the males are considerably larger than the female, in some instances, up to five times as large. This makes them among the most sexually dimorphous mammals.

Fur seals differ from sea lions in that they have a dense underfur whereas sea lions have a coarse, short fur . Sea lions are also generally larger than fur seals.

Species

Fur seals are grouped into two genera:

• Arctocephalus (Southern fur seals)
  1. South American fur seal (Arctocephalus australis)
  2. New Zealand fur seal (also Antipodean fur seal, Australasian fur seal, Black fur seal, and South Australian fur seal.) (Arctocephalus forsteri)
  3. Galapagos fur seal (Arctocephalus galapagoensis)
  4. Antarctic fur seal (also Kerguelen fur seal) (Arctocephalus gazella)
  5. Juan Fernandez fur seal (Arctocephalus philippii)
  6. South African fur seal (also Cape fur seal, Australian fur seal, Brown fur seal, Giant fur seal, Tasmanian fur seal, and  Afro-Australian Fur Seal) (Arctocephalus pusillus)
  7. Guadalupe fur seal (Also Lower californian fur seal) (Arctocephalus townsendi)
  8. Subantarctic fur seal (also Amsterdam fur seal) (Arctocephalus tropicalis)
• Callorhinus (Northern fur seal)
  9. Pribilof fur seal (also Northern fur seal and Alaska fur seal) (Callorhinus ursinus)

Fur seals are closed related to sea lions, with whom they comprise the family of Eared Seals (scientific name: Otariidae). Together with the families of true seals and Walruses, Eared seals form the group of marine mammals known as Pinnipeds.

South American fur seal. Source: Wikipedia	New Zealand Fur Seal. Source: Petr Baum/BioLib/Encyclopedia of Life	Antarctic Fur Seal. Source: José Luis Orgeira/WoRMS/Encyclopedia of Life
South African fur seal. Source: Petr Baum/BioLib/Encyclopedia of Life	Guadalupe fur seal. Source:NOAA	Sub Antarctic fur seal. Source:Yan Ropert-Coudert/WoRMS/Encyclopedia of Life
Pribilof fur seal. Source: Anne Morkill/BioLib/Encyclopedia of Life

Reproduction

Fur seals are polygynous, meaning that males will establish territories (often created and protected through fighting or shows of aggression) within which they establish a harem and breed with a number of females (the range varies with species). Males will come ashore and establish their territories at the beginning of the mating season.

Females typically arrive a few weeks after the males and select their mates for the coming season. Before mating, the females will first give birth to a pup conceived during the mating season of the prior year. Mating occurs typically 6-12 days after the birth of the pup.

The fertilised egg within the female fur seal undergoes a three - four month period of delayed implantation. This ensures that that the developing pup will be born at the right time the following year when the animals return to their breeding grounds.

Females will nurse their young for anything from seven months to three years.

Distribution

Fur seals are primarily found in the southern hemisphere. Two species, the  Pribilof fur seal and Guadalupe fur seal, are found in the northern hemisphere, and a third, the Galapagos fur seal, is found on the equator. 

Conservation Status

Fur seals were heavily hunted up to the end of the nineteenth century, at which point many of the species were close (and in some cases thought be) extinct. As their name suggests, their primary value was for their skins and the thick underfur. They were also exploited for their oil and meat. Most of these species have, under legal protection, made a significant recovery. At this time, only the Galapagos fur seal is considered endangered.

Further Reading 

1. Arctocephalus, Encyclopedia of Life (accessed April 5, 2009)
2. Arctocephalus, Myers, P., R. Espinosa, C. S. Parr, T. Jones, G. S. Hammond, and T. A. Dewey, 2008, Animal Diversity Web (accessed April 5, 2009)
3. Seal Conservation Society (accessed April 5, 2009)
4. The Pinnipeds: Seals, Sea Lions, and Walruses, Marianne Riedman, University of California Press, 1991 ISBN: 0520064984 
5. Encyclopedia of Marine Mammals, Bernd Wursig, Academic Press, 2002 ISBN: 0125513402
6. Marine Mammal Research: Conservation beyond Crisis, edited by John E. Reynolds III, William F. Perrin, Randall R. Reeves, Suzanne Montgomery and Timothy J. Ragen, Johns Hopkins University Press, 2005 ISBN: 0801882559
7. Walker's Mammals of the World, Ronald M. Nowak, Johns Hopkins University Press, 1999 ISBN: 0801857899 
8. Arctocephalus, MarineBio.org (accessed April 5, 2009)