Lobodon carcinophaga

Description

The crabeater seal has a slender, streamlined body, a distinct neck, a slim face, and a relatively pointed snout. Females are slightly longer on average than males with a length of 7-8 feet, compared to 6-8 feet for males. Weight ranges from 440 to 660 pounds.

After the summer moult, the crabeater seal is dark brown dorsally and grades to blonde ventrally. It has darker brown markings on the back and sides over the paler brown pelage. The flippers are the darkest parts of the body. Its fur slowly changes to blonde throughout the year, and it is almost entirely blonde by the summer. It often has long scars running along the sides of its body. These are most likely inflicted by its major predator, the leopard seal.

The crabeater seal is probably the fastest pinniped on land, reaching speeds of up to 15 mph. When sprinting, its foreflippers move alternately across the snow and its hind flippers are lifted off the ground and held together.

Distribution and Habitat

With an estimated population of around 15 million individuals, the crabeater seal is by far the most numerous pinniped. It is primarily found on the coast and pack ice of Antarctica. In the winter months, it may be found on the shores of South America, Australia, South Africa, Tasmania, New Zealand, and various islands surrounding Antarctica.

Habits and Behaviors

Crabeater seals may be found in large aggregations of up to 1,000 animals, but are usually solitary or in small groups.

Crabeater seals dive primarily at night and are reported to average 143 daily dives in late February. Once in the water, diving occurs nearly continually for approximately 16 hours. Most dives are for traveling and are less than a minute long and less than 33 feet deep. Foraging dives are slightly deeper and appear to vary throughout the day, with crepuscular dives being deeper. Exploratory dives are the deepest and presumably for navigation as they usually occur just before a traveling or foraging dive.

Crabeater seals may use breathing holes created by Weddell seals. Young Weddell seals may even be chased from breathing holes by adult crabeater seals.

Diet

Despite its common name, this seal's diet is made up primarily of krill, supplemented with cephalopods, fish, and crustaceans. It feeds by swimming through a school of krill with its mouth open, sucking them in and then sieving the water out through its specialized dentition. Its scientific name, Lobodon, is derived from Greek words meaning "lobed teeth." The teeth interlock to form a sieve through which the krill are filtered, and a ridge of bone fills the gap between the teeth and the back of the jaw, stopping prey from escaping from the mouth while feeding. Feeding probably occurs prinicipally at night

Reproduction

Crabeater seals probably mate on the pack ice surrounding Antarctica in the austral spring, from October to December. Gestation lasts about 11 months and probably includes a period of delayed implantation. The following September, the pregnant female occupies a space on the ice floe in which she gives birth and cares for her single pup. A male joins the female in her chosen area just before or just after parturition. He defends the female and the newborn pup from both predators and other males. That male is probably not the father of the pup, hower. Since females come into estrus just after weaning, the male's only apparent interest is in waiting for the female to be sexually receptive.

Pups are born weighing approximately 44 pounds and gain weight while nursing at a rate of about 9 pounds a day. Physical contact between the mother and pup during this period is necessary. If either the pup or the mother strays, the other immediately follows. Pups are weaned at about 3 weeks old.

Crabeater seals become sexually mature between 3 and 4 years of age, and females may have successful pregnancies between 5 and 25 years old.

Scientific Classification

phylum Chordata
subphylum Vertebrata
class Mammalia
order Carnivora
suborder Pinnipedia
family Phocidae
genus & species Lobodon carcinophaga

Animal Diversity Web http://animaldiversity.org/accounts/Lobodon_carcinophaga/
ARKive http://www.arkive.org/crabeater-seal/lobodon-carcinophaga/
Seal Conservation Society http://www.pinnipeds.org/seal-information/species-information-pages/the-phocid-seals/crabeater-seal

Questions or comments about this page?