Elephant seals or sea elephants are very large, oceangoing

earless seal The earless seals, phocids, or true seals are one of the three main groups of mammals within the seal lineage, Pinnipedia. All true seals are members of the family Phocidae (). They are sometimes called crawling seals to distinguish them from th ...

s in the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

''Mirounga''. Both species, the

northern elephant seal The northern elephant seal (''Mirounga angustirostris'') is one of two species of elephant seal (the other is the southern elephant seal). It is a member of the family Phocidae (true seals). Elephant seals derive their name from their great s ...

(''M. angustirostris'') and the

southern elephant seal The southern elephant seal (''Mirounga leonina'') is one of two species of elephant seals. It is the largest member of the clade Pinnipedia and the order Carnivora, as well as the largest extant marine mammal that is not a cetacean. It gets its ...

(''M. leonina''), were hunted to the brink of extinction for lamp oil by the end of the 19th century, but their numbers have since recovered. They can weigh up to . Despite their name, elephant seals are not closely related to

elephant Elephants are the largest living land animals. Three living species are currently recognised: the African bush elephant ('' Loxodonta africana''), the African forest elephant (''L. cyclotis''), and the Asian elephant ('' Elephas maximus ...

s, and the large

proboscis A proboscis () is an elongated appendage from the head of an animal, either a vertebrate or an invertebrate. In invertebrates, the term usually refers to tubular arthropod mouthparts, mouthparts used for feeding and sucking. In vertebrates, a pr ...

or trunk that males of the species possess is an example of

convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last comm ...

. The northern elephant seal, somewhat smaller than its southern relative, ranges over the

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is bounded by the cont ...

coast of the U.S., Canada and Mexico. The most northerly breeding location on the Pacific Coast is at

Race Rocks Marine Protected Area Race Rocks Ecological Reserve is a BC Parks ecological reserve off the southern tip of Vancouver Island in the Strait of Juan de Fuca in Metchosin, British Columbia, Canada. Description Located at a narrow part of the Strait, the area covers ...

, at the southern tip of

Vancouver Island Vancouver Island is an island in the northeastern Pacific Ocean and part of the Canadian province of British Columbia. The island is in length, in width at its widest point, and in total area, while are of land. The island is the largest ...

in the

Strait of Juan de Fuca The Strait of Juan de Fuca (officially named Juan de Fuca Strait in Canada) is a body of water about long that is the Salish Sea's main outlet to the Pacific Ocean. The Canada–United States border, international boundary between Canada and the ...

. The southern elephant seal is found in the Southern Hemisphere on islands such as

South Georgia South Georgia is an island in the Atlantic Ocean, South Atlantic Ocean that is part of the British Overseas Territories, British Overseas Territory of South Georgia and the South Sandwich Islands. It lies around east of the Falkland Islands. ...

and

Macquarie Island Macquarie Island is a subantarctic island in the south-western Pacific Ocean, about halfway between New Zealand and Antarctica. It has been governed as a part of Tasmania, Australia, since 1880. It became a Protected areas of Tasmania, Tasmania ...

, and on the coasts of New Zealand, Tasmania, South Africa, and Argentina in the

Peninsula Valdés A peninsula is a landform that extends from a mainland and is only connected to land on one side. Peninsulas exist on each continent. The largest peninsula in the world is the Arabian Peninsula. Etymology The word ''peninsula'' derives , . ...

. In southern Chile, there is a small colony of 120 animals at Jackson Bay (''Bahía Jackson'') in Admiralty Sound (''Seno Almirantazgo'') on the southern coast of

Isla Grande de Tierra del Fuego Isla Grande de Tierra del Fuego ( English: ''Big Island of the Land of Fire'') also formerly ''Isla de Xátiva'' is an island near the southern tip of South America from which it is separated by the Strait of Magellan. The western portion (61. ...

. The oldest known unambiguous elephant seal fossils are fragmentary fossils of a member of the tribe Miroungini described from the late

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58Petane Formation of New Zealand. Teeth originally identified as representing an unnamed species of ''Mirounga'' have been found in South Africa, and dated to the

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

epoch; however, Boessenecker and Churchill (2016) considered these teeth almost certainly to be misidentified

toothed whale The toothed whales (also called odontocetes, systematic name Odontoceti) are a parvorder of cetaceans that includes dolphins, porpoises, and all other whales with teeth, such as beaked whales and the sperm whales. 73 species of toothed wha ...

(odontocete) teeth. The elephant seals evolved in the Pacific Ocean during the Pliocene period. Elephant seals breed annually and are seemingly habitual to colonies that have established breeding areas.

Taxonomy

John Edward Gray John Edward Gray (12 February 1800 – 7 March 1875) was a British zoologist. He was the elder brother of zoologist George Robert Gray and son of the pharmacologist and botanist Samuel Frederick Gray (1766–1828). The same is used for a z ...

established the genus ''Mirounga'' in 1827. 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 The Indigenous languages of Australia number in the hundreds, the precise number being quite uncertain, although there is a range of estimates from a minimum of around 250 (using the technical definition of 'language' as non-mutually intellig ...

. However, it is not known which language this represents.

Description

Elephant seals are

marine mammals Marine mammals are mammals that rely on marine ecosystems for their existence. They include animals such as cetaceans, pinnipeds, sirenians, sea otters and polar bears. They are an informal group, unified only by their reliance on marine env ...

classified under the order Pinnipedia, which, in Latin, means feather- or fin-footed. Elephant seals are considered true seals, and fall under the family Phocidae. 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 An eared seal, otariid, or otary is any member of the marine mammal family Otariidae, one of three groupings of pinnipeds. They comprise 15 extant taxon, extant species in seven genus, genera (another species became extinct in the 1950s) and are ...

. 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 a day when they head out to sea. When elephant seals are born, they can weigh up to and reach lengths up to .

Sexual dimorphism Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...

is extreme, with male elephant seals weighing up to 10 times more than females, and having a prominent

. Elephant seals take their name from the large

of the adult male (bull), reminiscent of an elephant's trunk, and considered a secondary sexual characteristic. The bull's proboscis is used in producing extraordinarily loud roaring noises, especially during the

mating In biology, mating is the pairing of either opposite-sex or hermaphroditic organisms for the purposes of sexual reproduction. ''Fertilization'' is the fusion of two gametes. '' Copulation'' is the union of the sex organs of two sexually repr ...

season. More importantly, however, the nose acts as a sort of

rebreather A rebreather is a breathing apparatus that absorbs the carbon dioxide of a user's exhaled breath to permit the rebreathing (recycling) of the substantial unused oxygen content, and unused inert content when present, of each breath. Oxygen is a ...

, filled with cavities that reabsorb moisture from their exhalations. 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

pinniped Pinnipeds (pronounced ), commonly known as seals, are a widely range (biology), distributed and diverse clade of carnivorous, fin-footed, semiaquatic, mostly marine mammals. They comprise the extant taxon, extant families Odobenidae (whose onl ...

s, with southern elephant seal bulls typically reaching a length of and a weight of , and are much larger than the adult females (cows), with some exceptionally large males reaching up to in length and weighing ; cows typically measure about and . Northern elephant seal bulls reach a length of and the heaviest weigh about . 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.

Extant species distributions

Physiology

Elephant seals spend up to 80% of their lives in the ocean. They can hold their breath for more than 100 minutes – longer than any other noncetacean mammal. Elephant seals dive to beneath the ocean's surface (the deepest recorded dive of an elephant seal is by a southern elephant seal, while the record for the northern elephant seal is ). The average depth of their dives is about , typically for around 20 minutes for females and 60 minutes for males, as they search for their favorite foods, which are skates, rays,

squid A squid (: squid) is a mollusc with an elongated soft body, large eyes, eight cephalopod limb, arms, and two tentacles in the orders Myopsida, Oegopsida, and Bathyteuthida (though many other molluscs within the broader Neocoleoidea are also ...

octopuses An octopus (: octopuses or octopodes) is a soft-bodied, eight-limbed Mollusca, mollusc of the order (biology), order Octopoda (, ). The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttlefish, ...

, eels, small

shark Sharks are a group of elasmobranch cartilaginous fish characterized by a ribless endoskeleton, dermal denticles, five to seven gill slits on each side, and pectoral fins that are not fused to the head. Modern sharks are classified within the ...

s and large fish. Their stomachs also often contain

gastrolith A gastrolith, also called a stomach stone or gizzard stone, is a rock held inside a gastrointestinal tract. Gastroliths in some species are retained in the muscular gizzard and used to grind food in animals lacking suitable grinding teeth. In ...

s. 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. Elephant seals are shielded from extreme cold more by their

blubber Blubber is a thick layer of Blood vessel, vascularized adipose tissue under the skin of all cetaceans, pinnipeds, penguins, and sirenians. It was present in many marine reptiles, such as Ichthyosauria, ichthyosaurs and plesiosaurs. Description ...

than by fur. Their hair and outer layers of skin

molt In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is a process by which an animal casts off parts of its body to serve some beneficial purpose, either at ...

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 Hauling out is a behaviour associated with pinnipeds ( true seals, sea lions, fur seals and walruses) temporarily leaving the water. Hauling-out typically occurs between periods of foraging activity. Rather than remain in the water, pinniped ...

". 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 Myoglobin (symbol Mb or MB) is an iron- and oxygen-binding protein found in the cardiac and skeletal muscle, skeletal Muscle, muscle tissue of vertebrates in general and in almost all mammals. Myoglobin is distantly related to hemoglobin. Compar ...

concentrations in muscle. In addition, they have a larger proportion of oxygen-carrying

red blood cell Red blood cells (RBCs), referred to as erythrocytes (, with -''cyte'' translated as 'cell' in modern usage) in academia and medical publishing, also known as red cells, erythroid cells, and rarely haematids, are the most common type of blood cel ...

s. These adaptations allow elephant seals to dive to such depths and remain underwater for up to two hours. 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. They are able to slow down their heartbeat (

bradycardia Bradycardia, also called bradyarrhythmia, is a resting heart rate under 60 beats per minute (BPM). While bradycardia can result from various pathological processes, it is commonly a physiological response to cardiovascular conditioning or due ...

) 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 An artery () is a blood vessel in humans and most other animals that takes oxygenated blood away from the heart in the systemic circulation to one or more parts of the body. Exceptions that carry deoxygenated blood are the pulmonary arteries in ...

and

vein Veins () are blood vessels in the circulatory system of humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are those of the pulmonary and feta ...

s 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).

Adaptations

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 The ; ; : tapeta lucida) is a layer of tissue in the eye of many vertebrates and some other animals. Lying immediately behind the retina, it is a retroreflector. It Reflection (physics), reflects visible light back through the retina, increas ...

, 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 In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the p ...

, is very beneficial when these seals are fasting, breeding, molting, or hauling out. 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.

Breeding season

Northern Elephant Seal rookery at San Simeon

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. 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 Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). It is typical for mammals, but also occurs for some non-mammals. Mammals during pregn ...

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.

Life history

The average lifespan of a northern elephant seal is 9 years, while the average lifespan of a southern elephant seal is 21 years. Males reach maturity at five to six years, but generally do not achieve

alpha Alpha (uppercase , lowercase ) is the first letter of the Greek alphabet. In the system of Greek numerals, it has a value of one. Alpha is derived from the Phoenician letter ''aleph'' , whose name comes from the West Semitic word for ' ...

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. Most adult females breed each year. 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 Sea surface temperature (or ocean surface temperature) is the ocean temperature, temperature of ocean water close to the surface. The exact meaning of ''surface'' varies in the literature and in practice. It is usually between and below the sea ...

in the northeastern Pacific Ocean. Females and males utilize different feeding strategies in order to maximize their reproductive success. Males feed in

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word (), meaning "the depths". ...

regions with more abundant food sources, but also more abundant predators. Females feed in

pelagic The pelagic zone consists of the water column of the open ocean and can be further divided into regions by depth. The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or water column between the sur ...

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.

Molting

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.

Predators

The main

predators Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill ...

of elephant seals are killer whales and great white sharks.

Cookiecutter shark The cookiecutter shark (''Isistius brasiliensis''), also called the cigar shark, is a species of small squaliform shark in the family Dalatiidae. This shark lives in warm, oceanic waters worldwide, particularly near islands, and has been reco ...

s can take bites from their skin.

Milk stealing

Sheathbills, Skuas, Western Gulls, and African feral cats have been reported to steal milk from the elephant seals' teats.

Status

The

IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...

lists both species of elephant seal as being of

least concern A least-concern species is a species that has been evaluated and categorized by the International Union for Conservation of Nature (IUCN) as not being a focus of wildlife conservation because the specific species is still plentiful in the wil ...

, although they are still threatened by entanglement in

marine debris Marine debris, also known as marine litter, is human-created solid material that has deliberately or accidentally been released in seas or the ocean. Floating oceanic debris tends to accumulate at the center of gyres and on coastlines, freque ...

, 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. 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.

Gallery

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 San Simeon ( Spanish: ''San Simeón'', meaning "St. Simon") is an unincorporated community on the Pacific coast of San Luis Obispo County, California, United States. Its position along State Route 1 is about halfway between Los Angeles and San ...

, 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 California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

File:Elephant_seals_fighting.jpg, Two northern elephant seal bulls fighting File:An elephant seal from NOAA.jpg, Male northern elephant seal

snout A snout is the protruding portion of an animal's face, consisting of its nose, mouth, and jaw. In many animals, the structure is called a muzzle, Rostrum (anatomy), rostrum, beak or proboscis. The wet furless surface around the nostrils of the n ...

File:Mirounga leonina.jpg, Juvenile southern elephant seal File:MacquarieIslandElephantSeal.JPG, Dominant southern elephant seal bulls fighting at

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

References

External links

Tagging of Pacific Predators, Elephant Seals

Friends of the Elephant seal

Elephant Seal Research Group

Elephant seals -California State Parks

Dr. Daniel Costa's Research Laboratory

Teen Spots Hagfish-Slurping Elephant Seal – YouTube
(2:11)
Elephant Seals - National Geographic
{{DEFAULTSORT:Elephant Seal Mirounga Articles containing video clips Taxa named by John Edward Gray