Crabeater Seal

Crabeater Seal
Conservation status
Least Concern (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Carnivora
Family:	Phocidae
Genus:	Lobodon
Species:	L. carcinophagus
Binomial name
Lobodon carcinophagus Hombron & Jacquinot, 1842
Distribution of Crabeater Seal

The Crabeater Seal, Lobodon carcinophagus, is a little-known mammal. At a population of 8 to 50 million (LAWS 1973), among wild animals it is perhaps the "second most numerous large species of mammal on Earth, after humans,"^[2] though this population is far smaller than the 1.3 billion domesticated cattle in the world.^[3] More than one in every two seals in the world is a Crabeater Seal and the population biomass of Crabeaters is about four times that of all other pinnipeds put together ^[4]. It is also one of the fastest seals; a crabeater seal can swim 16 mph ^[5].

Description

Males grow to about 2.2 m to about 2.6 m (7.26 to 8.6 ft) and weigh roughly between 200 and 300 kg (440 to 660 lbs). After molting seasons the fur of the crab eater seal is dark brown fading to blonde on its belly. These seals also have dark brown mailings along the back and sides. The fur lightens through out the year, becoming completely blonde in summer. Crabeaters have long snouts and slender bodies. They have distinctive and complex teeth. Each tooth has tubercles, or bony protuberances with spaces between them. The upper and lower jaws fit together so that when the mouth closes the teeth and the tubercles can strain krill.

Females grow up to 3.6 m (142 in) in length and 230 kg (500 lb) in weight. Crabeater Seals colonized Antarctica during the late Miocene or early Pliocene (15 - 25 million years ago), at a time when the region was much warmer than today. The evolution of this strange, successful and abundant animal can be taken as a token of the bounty and continuous availability of krill.

Pups are born about 1.2 metres in length and weigh between 20 and 30 kilograms. While nursing, pups grow at a rate of about 4.2 kilograms a day. They are weaned after 2–3 weeks.

The seal's background colour is mainly silvery-grey when newly moulted, or golden to creamy white when the coat has faded. Older animals become progressively paler, even when freshly moulted, and may appear almost white. In younger animals, there are net-like, chocolate-brown markings and flecks on the shoulders, sides and flanks, shading into the predominantly dark hind and fore flippers and head.

Diet

Schematic of the skull, showing the unusual shape of the teeth.

Despite its name, its diet does not include crabs. Instead, a crabeater seal's unusual multilobed teeth enable this species to sieve krill from the water. Its dentition looks like a perfect strainer, but how it operates in detail is still unknown. 98% of the Crabeater Seal's food consists of Antarctic krill, Euphausia superba. The seals consume over 80 million tons of krill each year. They live and reproduce in the pack ice zone around Antarctica.

Behavior

Explorer and naturalist E.A. Wilson, who accompanied British explorer Robert Falcon Scott on the 1910-1913 Terra Nova Expedition to the South Pole, recorded that the Crabeater seal will, when close to death, leave the pack and travel far up glaciers to die. He observed Crabeater carcasses on a number of occasions, "thirty miles from the seashore and 3,000 feet (910 m) above sea-level".^[6]

References

Photo gallery