Editing Northern elephant seal (section)

==Description==
[[File:Northern Elephant Seal Skull.jpg|thumb|left|Northern elephant seal skull on display at the [[Museum of Osteology]], [[Oklahoma City]], [[Oklahoma]]]]
The huge male northern elephant seal typically weighs {{convert|1500|–|2,300|kg|lb|abbr=on}} and measures {{convert|4|–|5|m|ft|abbr=on}}, although some males can weigh up to {{convert|3700|kg|lb|abbr=on}}.<ref>Beer, ''Encyclopedia of North American Mammals: An Essential Guide to Mammals of North America''. Thunder Bay Press (2004), {{ISBN|978-1-59223-191-1}}.</ref> Females are much smaller and can range from {{convert|400|to|900|kg|lb|abbr=on}} in weight, or roughly a third of the male's bulk, and measure from {{convert|2.5|to|3.6|m|ft|abbr=on}}.<ref>[http://www.mnh.si.edu/mna/image_info.cfm?species_id=184 ''Mirounga angustirostris''. Northern Elephant Seal]. A {{convert|22|ft|m|0|abbr=on}} individual was reported by Scammon in 1874. Smithsonian National Museum of Natural History</ref> The bull southern elephant seals are, on average, larger than those in the northern species, but the females in both are around the same size, indicating the even higher level of [[sexual dimorphism]] in the southern species.<ref name = Walker>{{cite book |vauthors=Novak RM |year=1999 |title=Walker's Mammals of the World. |edition=6th |publisher=Johns Hopkins University Press |location=Baltimore |isbn=978-0-8018-5789-8}}</ref> Northern elephant seals typically live for around nine years.<ref>{{cite web |title=Elephant Seals {{!}} National Geographic |website=[[National Geographic Society]] |url=https://www.nationalgeographic.com/animals/mammals/group/elephant-seals/ |archive-url=https://web.archive.org/web/20170223010928/http://www.nationalgeographic.com/animals/mammals/group/elephant-seals/ |url-status=dead |archive-date=23 February 2017 |access-date=7 October 2018 |date=10 May 2011}}</ref>

Pups are born with dark, almost black fur that they shed after [[weaning]] to turn silvery grey. As they develop, both juveniles and adults go through a [[Moulting|molting]] period in which their initially black fur is replaced with a coat that ranges from silver to deep grey, finally fading to tan. Adult males' necks and chests are furless and have a speckled pattern of pink, white, and light brown. This thicker, calloused skin on the neck builds a protective shield in preparation for fights they participate in during the mating season. <ref>{{cite web |title=Northern Elephant Seal |date=19 April 2022 |url=https://www.fisheries.noaa.gov/species/northern-elephant-seal |access-date=2024-04-11 |publisher=NOAA Fisheries}}</ref><ref>{{cite web |title=Lifestyle of Northern Elephant Seals |url=http://earthguide.ucsd.edu/elephantseals/lifestyle/ |access-date=2024-04-11 |publisher=Earthguide at UCSD}}</ref>

The eyes are large, round, and black. The width of the eyes and a high concentration of low-light pigments suggest sight plays an important role in the capture of prey. Like all seals, elephant seals have atrophied hind limbs whose underdeveloped ends form the tail and tail fin. Each of the "feet" can deploy five long, webbed fingers. This agile, dual palm is used to propel water. The pectoral fins are used little while swimming.{{citation needed|date = October 2017}}
While their hind limbs are unfit for locomotion on land, elephant seals use their fins as support to propel their bodies. They are able to propel themselves quickly — as fast as {{convert|8|kph|kn mph}} — in this way for short-distance travel, to return to water, catch up with a female or chase an intruder.{{citation needed|date = October 2017}}

Like other seals, elephant seals' bloodstreams are adapted to the cold in which a mixture of small veins surrounds arteries capturing heat from them. This structure is present in extremities such as the hindlimbs.{{citation needed|date = October 2017}}

A unique characteristic of the northern elephant seal is that it has developed the ability to store oxygenated red blood cells (RBC) within its [[spleen]]. In a 2004 study researchers used [[MRI]] to observe physiological changes of the spleens of five seal pups during simulated dives. By three minutes, the spleens on average contracted to a fifth of their original size, indicating a dive-related sympathetic contraction of the spleen. Also, a delay was observed between contraction of the spleen and increased hematocrit within the circulating blood, and attributed to the hepatic sinus. This fluid-filled structure is initially expanded due to the rush of RBC from the spleen and slowly releases the red blood cells into the circulatory system via a muscular vena caval sphincter found on the cranial aspect of the diaphragm. This ability to slowly introduce RBC into the blood stream is likely to prevent any harmful effects caused by a rapid increase in [[hematocrit]].<ref>{{cite journal | vauthors = Thornton SJ, Hochachka PW | title = Oxygen and the diving seal | journal = Undersea & Hyperbaric Medicine | volume = 31 | issue = 1 | pages = 81–95 | year = 2004 | pmid = 15233163 | url = http://dspace.rubicon-foundation.org/xmlui/bitstream/handle/123456789/6520/15233163.pdf | access-date = 27 August 2015 | archive-url = https://web.archive.org/web/20190714002421/http://dspace.rubicon-foundation.org/xmlui/bitstream/handle/123456789/6520/15233163.pdf | archive-date = 14 July 2019 | url-status = usurped }}</ref>