Weddell seal

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Weddell seal
WeddellSeal2.jpg
Scientific classification
Kingdom Information
Domain Eukaryota
Kingdom Animalia
Subkingdom Bilateria
Branch Deuterostomia
Phylum Information
Phylum Chordata
Sub-phylum Vertebrata
Infraphylum Gnathostomata
Class Information
Superclass Tetrapoda
Class Mammalia
Sub-class Theriiformes
Infra-class Holotheria
Order Information
Superorder Preptotheria
Order Carnivora
Sub-order Pinnipedia
Infraorder Arctoidea
Family Information
Superfamily Phocoidea
Family Phocidae
Sub-family Monachinae
Tribe Information
Tribe Lobodontini
Genus Information
Genus Leptonychotes
Species Information
Species L. weddellii
Population statistics
Conservation status least concern[1]

The Weddell seal (Leptonychotes weddellii) is a species of seal of the family Phocidae, and one of the most common seals found in Antarctica. It is named after its discoverer, the English sailor and seal hunter James Weddell.

Description

Weddell seals are large, with a body length of 8.2 feet to 11.5 feet, and weigh 880 to 1,320 pounds; males, although just as long, weigh considerably less than females. Adults are dark gray in color, and bears light white or yellowish patches throughout, which fade during the summer molts. Young animals are light gray in color and unspotted. The relatively small head and short muzzle distinguish them from other Antarctic seals.

Range and habitat

The Weddell seal is found around the entire Antarctic continent, living in the waters off the shoreline to the edge of the pack ice; it is found further south than any other mammal[2]. A small population also exists further north on the South Georgia Islands. In winter, many Weddell seals do not migrate northward, but keep near an ice hole to which they dive into, either to forage, or to avoid harsh winter weather; if thin enough, ice holes are created by chewing through with their canine teeth[3]. Wandering and stray Weddell seals are sometimes seen on the shores of the Falkland Islands, Australia and New Zealand, indicating an extensive foraging range over much of the Southern Ocean.

Diet

The food consists almost exclusively of fish, with cephalopods and crustaceans taken in small quantities. When diving for food Weddell seals have been recorded as the deepest-diving seal, reaching depths of up to 2,000 feet, and can stay under water for up to one hour, covering a foraging area of up to 7.5 miles[4].

Reproduction

Weddell seals are solitary as adults, with some fighting occurring when forced to share an ice hole or defending a small shore area. Younger animals are more tolerant with each other. A single pup is born in the Antarctic spring (September / October) on the ice, and nursed for up to six weeks. Then it is left by the mother, who then mates again in the water. At the age of two, these seals become sexually mature, and have a life expectancy of 25 years.

Threats

Weddell seals are slow and sluggish on the ice. Since they have no enemies to fear outside the water, they show no escape behavior and can be touched by people[5], and this trust led them in the past to be killed by sealers or by personnel at research stations as food for sled dogs. Despite this, the population of Weddell seals is estimated at 500,000 to 1 million animals (the ICUN estimates a minimum of 300,000, while admitting difficulty in making a proper assessment[6]), making it the most common seal of Antarctica after the crabeater. The Ross Sea area has been cited as having a high density Weddell seal population[7]. Natural threats include orcas and leopard seals.

References

  1. https://www.iucnredlist.org/species/11696/45226713
  2. https://oceanwide-expeditions.com/to-do/wildlife/weddell-seal
  3. https://animaldiversity.org/accounts/Leptonychotes_weddellii/
  4. https://www.afsc.noaa.gov/nmml/education/pinnipeds/weddell.php
  5. http://www.antarctica.gov.au/about-antarctica/wildlife/animals/seals-and-sea-lions/weddell-seals
  6. https://www.iucnredlist.org/species/11696/45226713#population
  7. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0182922