Scientific Classification

Common Name

Ross seal

Kingdom

Animalia

Phylum

Chordata

Class

Mammalia

Order

Pinnipedia

Family

Phocidae

Genus Species

Ommatophoca rossii

Fast Facts

Description

Ross seals look different than other seals. They have a smaller, wider head, and a short snout. They also have a small mouth and the shortest hair of any seal. Instead of being spotted like many other seal species, Ross seals have a streaked pattern on the sides of the neck and down the throat. Sometimes the streaked pattern resembles a mask. Sometimes the streaked pattern resembles a mask. They have a small mouth with needle-like teeth which are well suited to catching slippery prey. Their enormous eyes may be an adaptation for hunting in dimly lit waters.

Size

Male: 1.68 to 2.09 m (5.5 ft.  to 6.8 ft.) in length
Female: 1.96 to 2.5 m (6.4 to 8.1 ft.) in length

Weight

Male: 129 to 216 kg (283 to 475 lbs.)
Female: 159 to 204 kg (350 to 449 lbs.)

Diet

The diet of Ross Seals is largely unknown, but the limited available data indicate that they eat mostly squid, with lesser amounts of fish and some invertebrates including krill.

Gestation

Approximately 11 months; includes a 2.5 to 3 month period of delayed implantation; ; pups are about 1 m (3.25 ft.) and 16 kg (35.2 lbs.) at birth.

Estral Period

Estrus cycle usually begins shortly after weaning process.

Nursing Duration

Weaning takes place at about one month of age, although little is known of the relationship between mother and pup.

Sexual Maturity

Averages around 4 years. Adults reach maximum body size at approximately nine years of age. At maturity, Ross Seals are the smallest of the four Antarctic phocids.

Life Span

20 years

Range

Ross Seals have a circumpolar distribution in Southern Ocean waters surrounding Antarctica. Vagrants have been reported from many sub-Antarctic islands including the South Sandwich Islands, the South Orknies, and Falkland, Scott, Kerguelen and Heard Islands, as well as from southern Australia.

Habitat

Ross Seals typically haul out in dense consolidated pack ice and are spread over large geographic areas.

Population

Global: The most recent circumpolar estimate of Ross Seal abundance indicates a total population of over 78,000 individuals. There is no indication of a declining trend in the population.

Status 

IUCN: Least concern
CITES: Not listed
USFWS: Not listed

Fun Facts

1. Ross seals belong to the scientific order Pinnipedia, which includes seals, sea lions, and walruses.
2. Seals differ from sea lions in a number of ways, including having no visible earflaps.
3. Antarctic seals tend to have longer, more pointed foreflippers than northern phocids.
4. Ross seals are named for James Clark Ross, the commander of the H.M.S. Erebus, a British exploration ship that entered the Ross Sea during a period of Antarctic exploration from 1839 to 1843.
5. Ross seals are known to make distinctive warbling and trilling calls in displays to attract mates and as a threat.
6. The deepest dive recorded for the species was 792 m, while the longest dives were over 30 minutes in duration.

Ecology and Conservation

Ross seals are thought to number the fewest among Antarctic seal species.

Killer Whales and Leopard Seals are presumed to be predators of the Ross Seal.

Ross Seals depend on sea ice for reproduction and at some time in the future they could be adversely affected by a reduction in sea ice due to continued climate warming.

Antarctic seals, including the Crabeater, Leopard, Weddell, Ross, Southern elephant, and Antarctic fur seals, are protected by the Convention for the Conservation of Antarctic Seals.

Bibliography

Bonner, N. Seals and Sea Lions of the World. New York. Facts on File, Inc. 2004.

Byrum, J. Pinnipeds From Pole to Pole: Seals, Sea Lions and Walruses. SeaWorld Education Department Publication. San Diego. SeaWorld, Inc. 2000.

Jefferson, T.J. Leatherwood, S. and M.A. Webber. FAO Species Identification Guide. Marine Mammals of the World. Rome. FAO, 1993.

Nowak, Ronald M. (ed.). Walker's Marine Mammals of the World. Baltimore: Johns Hopkins University Press, 2003.

Parker, S. (ed.). Grizmek's Encyclopedia of Mammals. Vol. IV. New York: McGraw-Hill Publishing Co., 1990.

Reeves, R. R., Stewart, B.S., Clapman, P.J., and J.A. Powell (Peter Folkens illustrator). National Audubon Society: Guide to Marine Mammals of the World. New York: Random House, 2002.

Reeves, R.R., Stewart, B.S. and S. Stephen. The Sierra Club Handbook of Seals and Sirenians. San Francisco: Sierra Club Books, 1992.

Ridgway, S.H. and R.J. Harrison (Eds). Handbook of Marine Mammals: Volume 2: Seals. London. Academic Press, 1981.

Hückstädt, L. 2015. Ommatophoca rossii. The IUCN Red List of Threatened Species 2015: e.T15269A45228952. http://dx.doi.org/10.2305/IUCN.UK.2015-4.RLTS.T15269A45228952.en. Downloaded on 26 September 2018.

Australian Government – Department of the Environment and Energy - Australian Antarctic Division. http://www.antarctica.gov.au/about-antarctica/wildlife/animals/seals-and-sea-lions/ross-seals
Downloaded on 26 September 2018.

Riedman, M. The Pinnipeds: Seals, Sea Lions and Walruses. Berkeley and Los Angeles. University of California Press. 1990.