Scientific Classification

Common Name

Weddell seal

Kingdom

Animalia

Phylum

Chordata

Class

Mammalia

Order

Pinnipedia

Family

Phocidae

Genus Species

Leptonychotes weddellii

Fast Facts

Description

The Weddell seal is a large seal with a bulky body, a relatively small head, and a short, wide snout. The adults are dark gray to brown with dark and light patches on the ventral side and silvery white dorsally. The front flippers are small relative to body size. Pups are born with light gray or occasionally golden fur.

Size

Male: 2.9 m (9.5 ft.)

Female: 3.3 m (10.7 ft.)

Weight

Adults in their prime weigh 400 to 450 kg (880 to 990 lbs.), with females being somewhat heavier than males, sometimes reaching over 500 kg (1,100 lbs.) Adult female weight fluctuates dramatically during the year with significant weight loss occurring after birth and during lactation.

Diet

Their diet primarily consists of icefish, particularly the Antarctic Silverfish which largely dominates their diet in certain areas but also includes Antarctic Toothfish, Myctophids and cephalopods.

Gestation

11 months, including two months of delayed implantation. Newborns are about 1.5 m (4.9 ft.) long and average 29 kg (64 lbs.). 

Estral Period

Females enter estrus approximately one week before weaning their pup, and copulation occurs underwater, where males maintain territories by controlling access to breathing holes and cracks.

Nursing Duration

45 to 50 days; the mother and pup stay together for 5 or 6 weeks

Sexual Maturity

Male: 7 to 8 years

Female: 3 to 6 years

Life Span

Longevity is approximately 25 years

Range

Weddell seals live around Antarctica in the Southern Ocean. They are the world’s southern-most breeding mammal. A small population lives all year on South Georgia. Weddell seals are present at many islands along the Antarctic Peninsula that are seasonally ice-free. Vagrants have been recorded in many areas north of the Antarctic in South America, New Zealand and southern Australia.

Habitat

Weddell seals occur in large numbers on fast ice, right up to the shoreline of the Antarctic continent. They also occur offshore in the pack ice zone north to the seasonally shifting limits of the Antarctic Convergence.

Population

Global: The global population of Weddell Seals has been variously estimated at 200,000 to 1,000,000 individuals, although there is large uncertainty in these figures.

Status 

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

Fun Facts

1. Weddell 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. Weddell seals are named for Captain James Weddell, an explorer in the 1820s whose book described and illustrated Weddell seals.
5. Weddell seals have the southernmost distribution of any pinniped.
6. Weddell seals can reach depths of over 600 m (1,950 ft.), and can undertake dives of at least 82 minutes, feeding primarily at depths of 100 to 350 m (325 to 1,138 ft.), with a diurnal feeding pattern.

Ecology and Conservation

Weddell seals do not migrate very far and will often be found within a few miles of where they were born.
Weddell seals that remain in fast ice areas abrade and grind the ice to maintain access to and from the water. They bite at the ice and then rapidly swing the head from side to side to grind away the ice with their teeth. Such behavior, though, comes at a cost, as seals living in areas where extensive grinding of ice is necessary have accelerated wearing down of their teeth and decreased life expectancy.
Although Weddell seals in fast ice areas are relatively protected, animals in the pack ice are vulnerable to predation by Killer Whales and Leopard Seals (Stirling 1969a, Visser et al. 2008).
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.

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

Hückstädt, L. 2015. Leptonychotes weddellii. The IUCN Red List of Threatened Species 2015: e.T11696A45226713. http://dx.doi.org/10.2305/IUCN.UK.2015-4.RLTS.T11696A45226713.en. Downloaded on 26 September 2018.

NOAA Fisheries – Weddell Seal Species Profile. https://www.afsc.noaa.gov/nmml/education/pinnipeds/weddell.php/. Downloaded on 26 September 2018.