Weddell Seal

Taxobox
name = Weddell SealMSW3 Wozencraft | pages = | id=14001044]
status = LR/lc
status_system = iucn2.3
status_ref = IUCN2006|assessors=Seal Specialist Group|year=1996|id=11696|title=Leptonychotes weddellii|downloaded=12 May 2006]

---

regnum = Animalia
phylum = Chordata
classis = Mammalia
ordo = Carnivora
subordo = Pinnipedia
familia = Phocidae
genus = "Leptonychotes"
genus_authority = Gill, 1872
species = "L. weddellii"
binomial = "Leptonychotes weddellii"
binomial_authority = (Lesson, 1826)
range_

range_map_caption = Weddell seal range
itis = 180669
ncbi = 9713The Weddell Seal ("Leptonychotes weddellii"), is a true seal that occurs in large numbers and inhabit the circumpolar region of the southern hemisphere, including Antarctica. A weddell seal can grow 9.5 feet (2.88 m) long and weigh between 880 to 1320 lbs (400 to 600 kg)cite book |last=Kindersley |first= Dorling |year=2001,2005 |title=Animal |location=New York City |publisher=DK Publishing |isbn=0-7894-7764-5] . It is estimated that there are approximately 800,000 individuals today. It can regularly be seen in the many seasonally ice-free islands along the Antarctic Peninsula. This pinniped is not thought to migrate, and any local movements are usually the result of changes in ice conditions.

It is named after Sir James Weddell, commander of British sealing expeditions in the Weddell Sea. It is the only species in the genus "Leptonychotes".

Behavior and ecology

The Weddell Seal is known for their very deep dives — which may reach some m to ft|700|abbr=yes|wiki=yes|precision=0. It can also stay underwater for approximately 80 minutes. Such deep dives involve foraging sessions, as well as searching for cracks in the ice sheets that can lead to new breathing holes. The seal can remain submerged for such long periods of time because of high concentrations of myoglobin in the muscles. [cite journal |author=Zapol WM, Hill RD, Qvist J, Falke K, Schneider RC, Liggins GC, Hochachka PW |title=Arterial gas tensions and hemoglobin concentrations of the freely diving Weddell seal |journal=Undersea Biomed Res |volume=16 |issue=5 |pages=363–73 |year=1989 |month=September |pmid=2800051 |doi= |url=http://archive.rubicon-foundation.org/2531 |accessdate=2008-07-22]

Depending on the latitude it inhabits, this marine mammal gives birth from early September through November, with those living at lower latitudes giving birth earlier. It is not very social out of water, even avoiding physical contact at most times.Copulation has only been observed to occur underwater, where the female is often bitten in the neck by her partner. Young Weddell Seals have a gray pelage for the first 3 to 4 weeks; later they turn to a darker color. Play fighting is very common for this animals as it grows. The pups reach maturity at 3 years of age. The color of the adults is very dark brown, lighter ventrally, and mottled with large darker and lighter patches, those on the belly being silvery white. Adult males usually bear scars, most of them around the hind flippers and genital region. The Weddell Seal has a shorter lifespan than most other pinnipeds. On average, the Weddell Seal lives for 20 years, compared to an average life expectancy of 40 years for most other seals. This is because the Weddell Seal winters under the Antarctic sea ice adjacent to continental Antarctica where it is required to constantly grind away at the ice which forms at the edges of their breathing holes. This has the effect of wearing down its teeth over time. Once a Weddell Seal's teeth have worn down to a certain level, the seal is unable to eat and eventually starves to death.

The Weddell Seal lives further south than any other mammal, inhabiting the waters of McMurdo Sound, mi to km|800|abbr=yes|wiki=yes|precision=0 from the South Pole. This relatively meek animal is usually found in large groups on ice attached to the continent and can be easily approached by humans.

Protection

The Weddell Seal is protected by the Antarctic Treaty and the Convention for the Conservation of Antarctic Seals.

References

* [http://seamap.env.duke.edu/species/tsn/180669 OBIS-SEAMAP]
* [http://animaldiversity.ummz.umich.edu/site/accounts/information/Leptonychotes_weddellii.html ADW: Leptonychotes weddellii]
* [http://www.cdli.ca/~dpower/resp/adapt~1.htm Adaptions of Diving Mammals]
* [http://www.animalbehaviorarchive.org/assetSelect.do?assetId=763199&section=summary Audio recording from Macaulay Library at Cornell Lab of Ornithology]
*cite journal | author = Zapol, W. M. | year = 1987 | title = Diving Adaptations of the Weddell Seal | journal = Scientific American | volume = 256 | issue = 6 | pages = 100–105