elephant seal

John Edward Gray established the genus Mirounga in 1827.{{cite book | chapter=Synopsis of the species of the class Mammalia |page=180 |editor= Baron Cuvier | title=The Animal Kingdom Arranged in Conformity with its Organization, by the Baron (G) Cuvier, with additional descriptions by Edward Griffith and others | volume=5 | year=1827 | chapter-url=https://www.biodiversitylibrary.org/page/34790374 |last=Gray | first=John Edward |publisher=Printed for G.B. Whittaker }} The generic name Mirounga is a Latinization of miouroung, which is said to have been a term for the seal in an Australian Aboriginal language. However, it is not known which language this represents.{{cite web |author1=Threatened Species Scientific Committee |title=Conservation Advice: Mirounga leonina, southern elephant seal |url=http://www.environment.gov.au/biodiversity/threatened/species/pubs/26-conservation-advice-07122016.pdf |publisher=Australian Government, Department of Agriculture, Water, and the Environment |access-date=16 May 2020 |date=7 December 2016}}

Elephant seals are marine mammals classified under the order Pinnipedia, which, in Latin, means feather- or fin-footed.{{Cite book|title=Princeton Encyclopedia of Marine Mammals|last=Macdonald|first=David|publisher=Princeton University Press|year=2009}} Elephant seals are considered true seals, and fall under the family Phocidae.{{Cite book|title=Elephant seals|date=1999|publisher=Central Coast Press|isbn=9780965877695|location=San Luis Obispo, Calif.|oclc=44446823|url-access=registration|url=https://archive.org/details/elephantseals0000frie}} Phocids (true seals) are characterized by having no external ear and reduced limbs. The reduction of their limbs helps them be more streamlined and move easily in the water. However, it makes navigating on land more difficult because they cannot turn their hind flippers forward to walk like the otariids. In addition, the hind flippers of elephant seals have a lot of surface area, which helps propel them in the water.

Elephant seals spend the majority of their life (90%) underwater in search of food, and can cover {{convert|100|km|mi|-1|abbr=off}} a day when they head out to sea. When elephant seals are born, they can weigh up to {{convert|36|kg|lb|abbr=off}} and reach lengths up to {{convert|122|cm|ftin|abbr=on}}. Sexual dimorphism is extreme, with male elephant seals weighing up to 10 times more than females,{{Cite book|title=Encyclopedia of Marine Mammals|last1=Thewissen|first1=J.M.|last2=Würsig|first2=B.G.|last3=Perrin|first3=W.F.|publisher=Academic Press|year=2009|location=Amsterdam}} and having a prominent proboscis.

Elephant seals take their name from the large proboscis of the adult male (bull), reminiscent of an elephant's trunk, and considered a secondary sexual characteristic.{{cite web |author=Mirounga |url=http://animals.nationalgeographic.com/animals/mammals/elephant-seal.html |archive-url=https://web.archive.org/web/20070614052623/http://animals.nationalgeographic.com/animals/mammals/elephant-seal.html |url-status=dead |archive-date=June 14, 2007 |title=Elephant Seal, Elephant Seal Profile, Facts, Information, Photos, Pictures, Sounds, Habitats, Reports, News – National Geographic |publisher=Animals.nationalgeographic.com |access-date=2009-01-08}} The bull's proboscis is used in producing extraordinarily loud roaring noises, especially during the mating season. More importantly, however, the nose acts as a sort of rebreather, filled with cavities that reabsorb moisture from their exhalations.{{cite journal |author1=Huntley, A. C. |author2=Costa, D. P. |author3=Rubin, R. D. | year = 1984 | title = The contribution of nasal countercurrent heat exchange to water balance in the northern elephant seal, Mirounga angustirostris|url=http://jeb.biologists.org/content/113/1/447 | journal = Journal of Experimental Biology | volume = 113 | pages = 447–454|doi=10.1242/jeb.113.1.447 |pmid=6527090 |doi-access=free }} This is important during the mating season when the seals do not leave the beach to feed, and must conserve body moisture as there is no incoming source of water.

They are very much larger than other pinnipeds, with southern elephant seal bulls typically reaching a length of {{convert|5|m|ft|0|abbr=on}} and a weight of {{convert|3000|kg|lb|sigfig=1|abbr=on}}, and are much larger than the adult females (cows), with some exceptionally large males reaching up to {{convert|6|m|ft|sigfig=1|abbr=on}} in length and weighing {{convert|4000|kg|lb|sigfig=1|abbr=on}}; cows typically measure about {{convert|3|m|ft|0|abbr=on}} and {{convert|900|kg|lb|sigfig=1|abbr=on}}. Northern elephant seal bulls reach a length of {{convert|4.3|to|4.8|m|abbr=on}} and the heaviest weigh about {{convert|2500|kg|lb|sigfig=2|abbr=on}}.{{cite web|url=http://www.parks.ca.gov/?page_id=1115 |title=Elephant Seals |publisher=Parks.ca.gov |date=2007-05-23 |access-date=2009-01-08}}{{cite web|url=http://encarta.msn.com/encnet/features/dictionary/DictionaryResults.aspx?lextype=3&search=Elephant%20Seal |title=Elephant Seal – MSN Encarta |publisher=Encarta.msn.com |access-date=2009-12-29 |archive-url=https://web.archive.org/web/20091028024826/http://encarta.msn.com/encyclopedia_761572126/Elephant_Seal.html |archive-date=2009-10-28 |url-status=dead }}

The northern and southern elephant seal can be distinguished by various external features. On average, the southern elephant seal tends to be larger than the northern species. Adult male elephant seals belonging to the northern species tend to have a larger proboscis, and thick chest area with a red coloration compared to the southern species. Females do not have the large proboscis and can be distinguished between species by looking at their nose characteristics. Southern females tend to have a smaller, blunt nose compared to northern females.

{{Species table |genus=Mirounga |authority-name= Gray |authority-year= 1827 |species-count=two|no-note=y|narrow-percent=75}}

{{Species table/row

|name=Northern elephant seal|binomial=Mirounga angustirostris

|image=File:Mirounga angustirostris, Point Reyes.jpg|image-size=180px |image-alt=

|authority-name=Gill |authority-year= 1866 |authority-not-original=yes

|range=Eastern Pacific Ocean

|range-image=File:Mirounga angustirostris distribution map.svg

|range-image-size=180px

|size=

|habitat=

|hunting=

|iucn-status= LC

|population=

|direction=

|subspecies=

}}

{{Species table/row

|name= Southern elephant seal|binomial=Mirounga leonina

|image=File:Southern Elephant Seal (5797958581).jpg|image-size=180px |image-alt=

|authority-name=Linnaeus |authority-year= 1758 |authority-not-original=yes

|range=Southern Ocean

|range-image=File:Southern Elephant Seal area.png

|range-image-size=180px

|size=

|habitat=

|hunting=

|iucn-status= LC

|population=

|direction=

|subspecies=

}}

{{Species table/end}}

File:Miroungaskull.jpg

Elephant seals spend up to 80% of their lives in the ocean. They can hold their breath for more than 100 minutes{{cite news|last=Amos|first=Jonathan|title=Elephant seals dive for science|url=http://news.bbc.co.uk/1/hi/sci/tech/4736196.stm|work=2006|publisher=BBC News|access-date=23 April 2013|date=2006-02-21}}{{cite web |url= http://www.eleseal.org/pdf_lay/book_2004.pdf |title= Southern Elephant Seals of Sea Lion Island – A Long-term Research Project |website=Eleseal.org |access-date=2010-05-21}} – longer than any other noncetacean mammal. Elephant seals dive to {{convert|1550|m|ft|abbr=on}} beneath the ocean's surface (the deepest recorded dive of an elephant seal is {{convert|2388|m|ft|abbr=on}} by a southern elephant seal, while the record for the northern elephant seal is {{convert|1735|m|ft|abbr=on}}).{{cite journal |author1=Gregory S. Schorr |author2=Erin A. Falcone |author3=David J. Moretti |author4=Russel D. Andrews |year=2014 |title=First long-term behavioral records from Cuvier's beaked whales (Ziphius cavirostris) reveal record-breaking dives |journal=PLOS ONE |volume=9 |issue=3 |page=e92633 |doi=10.1371/journal.pone.0092633 |pmid=24670984 |ref=Schorr |pmc=3966784|bibcode=2014PLoSO...992633S |doi-access=free }}{{cite web |url= http://www.coml.org/comlfiles/press/CoML_Beyond_Sunlight_11.17.2009_Public.pdf |title= Census of Marine Life – From the Edge of Darkness to the Black Abyss |publisher=Coml.org |access-date=2009-12-15}}{{cite journal | vauthors = Robinson PW, Costa DP, Crocker DE, Gallo-Reynoso JP, Champagne CD, Fowler MA, Goetsch C, Goetz KT, Hassrick JL, Hückstädt LA, Kuhn CE, Maresh JL, Maxwell SM, McDonald BI, Peterson SH, Simmons SE, Teutschel NM, Villegas-Amtmann S, Yoda K | title = Foraging behavior and success of a mesopelagic predator in the northeast Pacific Ocean: insights from a data-rich species, the northern elephant seal | journal = PLOS ONE | volume = 7 | issue = 5 | pages = e36728 | date = 2012-05-15 | pmid = 22615801 | pmc = 3352920 | doi = 10.1371/journal.pone.0036728 | bibcode = 2012PLoSO...736728R | doi-access = free }} The average depth of their dives is about {{convert|300|to|600|m|ft|sigfig=1|abbr=on}}, typically for around 20 minutes for females and 60 minutes for males, as they search for their favorite foods, which are skates, rays, squid, octopuses, eels, small sharks and large fish. Their stomachs also often contain gastroliths. They spend only brief amounts of time at the surface to rest between dives (2–3 minutes). Females tend to dive a bit deeper due to their prey source.

File:Northern elephant seals fighting.webm

Elephant seals are shielded from extreme cold more by their blubber than by fur. Their hair and outer layers of skin molt in large patches. The skin has to be regrown by blood vessels reaching through the blubber. When molting occurs, the seal is susceptible to the cold, and must rest on land, in a safe place called a "haul out". Northern males and young adults haul out during June to July to molt; northern females and immature seals during April to May.

Elephant seals have a very large volume of blood, allowing them to hold a large amount of oxygen for use when diving. They have large sinuses in their abdomens to hold blood and can also store oxygen in their muscles with increased myoglobin concentrations in muscle. In addition, they have a larger proportion of oxygen-carrying red blood cells. These adaptations allow elephant seals to dive to such depths and remain underwater for up to two hours.{{Cite web | title = 5.4 Seals | publisher = Classroom Antarctica | url = http://www.classroom.antarctica.gov.au/5-southern-life/5-4-seals | url-status = dead | archive-url = https://web.archive.org/web/20110601184942/http://www.classroom.antarctica.gov.au/5-southern-life/5-4-seals/ | archive-date = 2011-06-01 }}

Unlike some other marine mammals, such as dolphins, elephant seals do not have unihemispheric slow-wave sleep. Instead they sleep deeply for a little less than 20 minutes at the time while sinking through the water to depths that has been measured to 377 meters. When being near the continental shelf, where the ocean is less deep, they will often reach bottom, which sometimes wakes them up. But more often they continue to sleep on the seabed. On average, they get about two hours of sleep a day over a period of seven months, which is among the lowest amount of sleep of any mammal.[https://www.abc.net.au/news/science/2023-04-21/sleeping-elephant-seals-plummet-hundreds-of-metres-in-ocean/102232320 Sleeping elephant seals fall through ocean's depths, and some even nap on the sea floor]

They are able to slow down their heartbeat (bradycardia) and divert blood flow from the external areas of the body to important core organs. They can also slow down their metabolism while performing deep dives.

Elephant seals have a helpful feature in their bodies known as the countercurrent heat exchanger to help conserve energy and prevent heat loss. In this system, arteries and veins are organized in a way to maintain a constant body temperature by having the cool blood flowing to the heart warmed by blood going to external areas of the animal.

Milk produced by elephant seals is remarkably high in milkfat compared to other mammals. After an initially lower state, it rises to over 50% milkfat (human breast milk is about 4% milkfat, and cow milk is about 3.5% milkfat).{{cite web|url=http://www.coastsidestateparks.org/pdfs/Elephant%20Seal%20Fact%20Sheet.pdf |title=Northern Elephant Seal Fact Sheet |publisher=Coastside State Parks Association |access-date=26 March 2013 |url-status=dead |archive-url=https://web.archive.org/web/20130513045204/http://www.coastsidestateparks.org/pdfs/Elephant%20Seal%20Fact%20Sheet.pdf |archive-date=13 May 2013 }}

Elephant seals have large circular eyes that have more rods than cones to help them see in low light conditions when they are diving. These seals also possess a structure called the tapetum lucidum, which helps their vision by having light reflected back to the retina to allow more chances for photoreceptors to detect light.

Their body is covered in blubber, which helps them keep warm and reduce drag while they are swimming. The shape of their body also helps them maneuver well in the water, but limits their movement on land. Also, elephant seals have the ability to fast for long periods of time while breeding or molting. The turbinate process, another unique adaptation, is very beneficial when these seals are fasting, breeding, molting, or hauling out.{{Explain|date=January 2023|reason=The turbinate process is not explained, this seems to assume expert knowledge}} This unique nasal structure recycles moisture when they breathe and helps prevent water loss.

Elephant seals have external whiskers called vibrissae to help them locate prey and navigate their environment. The vibrissae are connected to blood vessels, nerves, and muscles making them an important sensing tool.

Due to evolutionary changes, their ear has been modified to work extremely well underwater. The structure of the inner ear helps amplify incoming sounds, and allows these seals to have good directional hearing due to the isolation of the inner ear. In addition to these adaptations, tissues in the ear canal allow the pressure in the ear to be adjusted while these seals perform their deep dives.

File:Northern Elephant Seal rookery at San Simeon.jpg

Males arrive at potential breeding sites in spring, and fast to ensure that they can mate with as many females as possible. Male elephant seals use fighting, vocalisations, and different positions to determine the dominant males.{{Cite journal|last=Laws|first=R|date=1956|title=The Elephant Seal: General, Social, and Reproductive Behavior|journal=Falkland Islands Dependencies Survey|volume=13}} By the time males reach eight to nine years of age, they have developed a pronounced long nose, in addition to a chest shield, which is thickened skin in their chest area. They display their dominance by showing their noses, making loud vocalisations, and altering their postures. They fight each other by raising themselves and ramming each other with their chests and teeth.

By the time females arrive, each dominating male has already established his territory on the beach. Females cluster in groups called harems, which consist of up to 50 females surrounding one alpha male. Outside of these groups, a beta bull is normally roaming around on the beach. The beta bull helps the alpha by preventing other males accessing the females. In return, the beta bull might have an opportunity to mate with one of the females while the alpha is occupied.

Birth on average only takes a few minutes, and the mother and pup have a connection due to each other's unique smell and sound. The mothers will fast and nurse up to 28 days, providing their pups with rich milk. The last two to three days, however, females will be ready to mate, and the dominant males will pounce on the opportunity. Males and females lose up to a third of their body weight during the breeding season. The gestation period for females is 11 months, and the pupping seasons lasts from mid to late summer. The new pups will spend up to 10 additional weeks on land learning how to swim and dive.

The average lifespan of a northern elephant seal is 9 years, while the average lifespan of a southern elephant seal is 21 years.{{Cite web|url=http://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=February 23, 2017|title = Elephant Seals | National Geographic|website = National Geographic Society|date = 10 May 2011}} Males reach maturity at five to six years, but generally do not achieve alpha status until the age of eight, with the prime breeding years being between ages 9 and 12. The longest life expectancy of a male northern elephant seal is approximately 14 years.

Females begin breeding at age 3–6, and have one pup per breeding attempt.{{Cite journal|last=Huber|first=Harriet R.|date=1987-06-01|title=Natality and weaning success in relation to age of first reproduction in northern elephant seals|journal=Canadian Journal of Zoology|volume=65|issue=6|pages=1311–1316|doi=10.1139/z87-207|issn=0008-4301}} Most adult females breed each year.{{Cite journal|last=Lee|first=Derek E.|date=2011-06-09|title=Effects of environmental variability and breeding experience on northern elephant seal demography|journal=Journal of Mammalogy|volume=92|issue=3|pages=517–526|doi=10.1644/10-MAMM-A-042.1|issn=0022-2372|doi-access=free}} Breeding success is much lower for first-time mothers relative to experienced breeders. Annual survival probability of adult females is 0.83 for experienced breeding females, but only 0.66 for first-time breeders indicating a significant cost of reproduction. More male pups are produced than female pups in years with warmer sea surface temperature in the northeastern Pacific Ocean.{{Cite journal|last1=Lee|first1=Derek E.|last2=Sydeman|first2=William J.|date=2009|title=North Pacific Climate Mediates Offspring Sex Ratio in Northern Elephant Seals|journal=Journal of Mammalogy|language=en|volume=90|issue=1|pages=1–8|doi=10.1644/08-MAMM-A-130.1|issn=0022-2372|doi-access=free}}

Females and males utilize different feeding strategies in order to maximize their reproductive success. Males feed in benthic regions with more abundant food sources, but also more abundant predators. Females feed in pelagic regions where they are less likely to find prey, but also less likely to be preyed upon. They employ these different strategies because females are smaller, requiring less food, and it is also most important for them to have as many breeding seasons as possible in order to maximize reproductive success. On the other hand, males can adopt a riskier strategy in the hopes of gaining as much mass as possible, and thus being able to have one extremely successful breeding season.{{Cite journal |last1=Kienle |first1=Sarah S. |last2=Friedlaender |first2=Ari S. |last3=Crocker |first3=Daniel E. |last4=Mehta |first4=Rita S. |last5=Costa |first5=Daniel P. |date=January 2022 |title=Trade-offs between foraging reward and mortality risk drive sex-specific foraging strategies in sexually dimorphic northern elephant seals |journal=Royal Society Open Science |volume=9 |issue=1 |page=210522 |doi=10.1098/rsos.210522 |pmid=35116140 |pmc=8767210 |bibcode=2022RSOS....910522K |s2cid=246018225 |issn=2054-5703|doi-access=free }}

File:Animal warning sign, Onrus Beach (South Africa).jpg

Once a year, elephant seals go through a process called molting where they shed the outer layer of hair and skin. This molting process takes up to a month to complete. When it comes time to molt, they will haul out on land to shed their outer layer, and will not consume any food during this time. The females and juveniles will molt first, followed by the sub adult males, and finally the large mature males.

The main predators of elephant seals are killer whales and great white sharks. Cookiecutter sharks can take bites from their skin.

Sheathbills, Skuas, Western Gulls, and African feral cats have been reported to steal milk from the elephant seals' teats.{{cite journal |last1=Sazima |title=Cleaner birds: an overview for the Neotropics |journal=Museu de Zoologia, Universidade Estadual de Campinas |volume=10 |issue=4 |url=https://www.scielo.br/j/bn/a/cx4vzMJnKQMKjDftsVXb5sp/?format=pdf&lang=en}}{{cite book |last1=Chester |title=Antarctic birds and seals |date=1993 |url=https://www.abebooks.com/Antarctic-Birds-Seals-Pocket-Guide-Chester/769351226/bd}}{{cite journal |last1=Gallo-Reynoso |title=Feral cats steal milk from northern Elephant Seals |journal=Therya |date=2010 |volume=1 |issue=3 |pages=207–212 |doi=10.12933/therya-10-14 |doi-access=free }}{{cite journal |title=Antarctica's Milk-Stealing, Grudge-Holding Seabirds |journal=Boston NPR |date=2016 |url=http://archives.wbur.org/thewildlife/2016/03/29/antarcticas-milk-stealing-grudge-holding-seabirds/}}

The IUCN lists both species of elephant seal as being of least concern, although they are still threatened by entanglement in marine debris, fishery interactions, and boat collisions. Though a complete population count of elephant seals is not possible because all age classes are not ashore at the same time, a 2005 study of the California breeding stock estimated approximately 124,000 individuals.{{cite web|url=https://media.fisheries.noaa.gov/dam-migration/po2007sene-ca_508.pdf|title=NORTHERN ELEPHANT SEAL (Mirounga angustirostris) : California Breeding Stock |website=Media.fisheries.noaa.gov|access-date=19 March 2022}} The animal is protected in most countries where it lives. In Mexico, the northern elephant seal is protected in the Guadalupe Island Biosphere Reserve where it was rediscovered after being believed to be extinct.{{Cite web |last=Krieger |first=Lisa M. |date=2024-01-20 |title=Once nearly extinct, Elephant seals staking claims |url=https://www.columbian.com/news/2024/mar/05/once-nearly-extinct-elephant-seals-staking-claims/ |access-date=2024-04-01 |website=The Columbian |language=en-US}}

File:Pink Tongue Elephant Seal Photo by Sascha Grabow.jpg|Southern elephant seal

File:Elephant seals piedras blancas.jpg|Northern elephant seals on Piedras Blancas beach, near San Simeon, California

File:Male,_female_and_pup_Mirounga_angustirostris_10.jpg|Northern elephant seal male, female and pup

File:Elephant seal colony edit.jpg|Northern elephant seals during molting season at Piedras Blancas beach, near San Simeon, California

File:Elephant_seals_fighting.jpg|Two northern elephant seal bulls fighting

File:An elephant seal from NOAA.jpg|Male northern elephant seal snout

File:Mirounga leonina.jpg|Juvenile southern elephant seal

File:MacquarieIslandElephantSeal.JPG|Dominant southern elephant seal bulls fighting at Macquarie Island

File:Elephant Seals at Piedras Blancas, California.jpg|Northern elephant seals at Piedras Blancas, California

• Marine Mammal Center
• Penelope Seal
• Marine Life
• Super weaner
• Neil the Seal

{{Reflist}}

{{Commons category|Mirounga}}

• [https://web.archive.org/web/20090215031553/http://topp.org/species/elephant_seals Tagging of Pacific Predators, Elephant Seals]
• [http://www.elephantseal.org Friends of the Elephant seal]
• [http://www.eleseal.org Elephant Seal Research Group]
• [http://www.parks.ca.gov/default.asp?page_id=1115 Elephant seals -California State Parks]
• [http://bio.research.ucsc.edu/people/costa/ Dr. Daniel Costa's Research Laboratory] {{Webarchive|url=https://web.archive.org/web/20110716165022/http://bio.research.ucsc.edu/people/costa/ |date=2011-07-16 }}
• [https://web.archive.org/web/20080705033249/http://www.racerocks.com/racerock/eco/taxalab/ashleyc.htm Elephant Seals at Race Rocks, Canada]
• [https://www.youtube.com/watch?v=nzMB8jqioV0 Teen Spots Hagfish-Slurping Elephant Seal – YouTube] (2:11)
• [https://web.archive.org/web/20170223010928/http://www.nationalgeographic.com/animals/mammals/group/elephant-seals/ Elephant Seals - National Geographic]

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Category:Mirounga

Category:Articles containing video clips

Category:Taxa named by John Edward Gray