Elephant seals 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 ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

''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 siz ...

(''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 oil by the end of the 19th century, but their numbers have since recovered. They are the largest extant

carnivorans Carnivora is a monophyletic order of placental mammals consisting of the most recent common ancestor of all cat-like and dog-like animals, and all descendants of that ancestor. Members of this group are formally referred to as carnivorans, ...

, weighing up to . 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 definition, to Antarctica) in the south, and is bounded by the contine ...

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

Race Rocks 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 o ...

, 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 by ...

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 outlet to the Pacific Ocean. The international boundary between Canada and the United States runs down the centre ...

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

Macquarie Island Macquarie Island is an island in the southwestern Pacific Ocean, about halfway between New Zealand and Antarctica. Regionally part of Oceania and politically a part of Tasmania, Australia, since 1900, it became a Tasmanian State Reserve in 197 ...

, and on the coasts of New Zealand, South Africa, and Argentina in the Peninsula Valdés. In southern Chile, there is a small colony of 120 animals at Jackson Bay (''Bahía Jackson'') in Admiralty Sound (''Seno Almirantazgo'') at 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''Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million 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 to be almost certainly misidentified

odontocete The toothed whales (also called odontocetes, systematic name Odontoceti) are a parvorder of cetaceans that includes dolphins, porpoises, and all other whales possessing teeth, such as the beaked whales and sperm whales. Seventy-three species of t ...

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

Taxonomy

John Edward Gray John Edward Gray, FRS (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 ...

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

Description

Elephant seals are marine mammals 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 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 t ...

(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 or otariid or otary is any member of the marine mammal family Otariidae, one of three groupings of pinnipeds. They comprise 15 extant species in seven genera (another species became extinct in the 1950s) and are commonly known eit ...

. 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 the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most an ...

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

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 mouthparts used for feeding and sucking. In vertebrates, a proboscis is an elong ...

. 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 reprod ...

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 breathing, exhaled breath to permit the rebreathing (recycling) of the substantially unused oxygen content, and unused inert content when present, of each breath. ...

, filled with cavities designed to 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 mammal, marine mammals. They comprise the extant taxon, extant family (biology ...

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

skate Skate or Skates may refer to: Fish *Skate (fish), several genera of fish belonging to the family Rajidae * Pygmy skates, several genera of fish belonging to the family Gurgesiellidae * Smooth skates or leg skates, several genera of fish belongin ...

rays Ray may refer to: Fish * Ray (fish), any cartilaginous fish of the superorder Batoidea * Ray (fish fin anatomy), a bony or horny spine on a fin Science and mathematics * Ray (geometry), half of a line proceeding from an initial point * Ray (gra ...

, squid,

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

eel Eels are ray-finned fish belonging to the order Anguilliformes (), which consists of eight suborders, 19 families, 111 genera, and about 800 species. Eels undergo considerable development from the early larval stage to the eventual adult stage ...

s, small

shark Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachi ...

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 oth ...

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 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 the manner in which an animal routinely casts off a part of its body (often, but not always, an outer ...

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 The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. ...

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 cell Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek ''erythros'' for "red" and ''kytos'' for "holl ...

s. These adaptations allow elephant seals to dive to such depths and remain underwater for up to two hours. Elephant seals 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 An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the pu ...

and

vein Veins are blood vessels in 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 the pulmonary and umbilical veins, both of which carry oxygenat ...

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 Butterfat or milkfat is the fatty portion of milk. Milk and cream are often sold according to the amount of butterfat they contain. Composition Butterfat is mainly composed of triglycerides. Each triglyceride contains three fatty acids. But ...

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 ''tapetum lucidum'' ( ; ; ) 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 reflects visible light back through the retina, increasing the light a ...

, 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. 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

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 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 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 in the northeastern Pacific Ocean. 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 The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or w ...

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 In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is the manner in which an animal routinely casts off a part of its body (often, but not always, an outer ...

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 where 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 th ...

of elephant seals are

killer whales The orca or killer whale (''Orcinus orca'') is a toothed whale belonging to the oceanic dolphin family, of which it is the largest member. It is the only extant species in the genus ''Orcinus'' and is recognizable by its black-and-white pat ...

and

great white sharks The great white shark (''Carcharodon carcharias''), also known as the white shark, white pointer, or simply great white, is a species of large Lamniformes, mackerel shark which can be found in the coastal surface waters of all the major ocean ...

. Cookie cutter sharks can take bites from their skin.

Milk stealing

Sheathbills,

Skuas The skuas are a group of predatory seabirds with seven species forming the genus ''Stercorarius'', the only genus in the family Stercorariidae. The three smaller skuas, the long-tailed skua, the Arctic skua, and the pomarine skua are called jae ...

, Western Gulls, and African feral cats have been reported to directly pilfer milk from the

elephant seals Elephant seals are very large, oceangoing earless seals in the genus ''Mirounga''. Both species, the northern elephant seal (''M. angustirostris'') and the southern elephant seal (''M. leonina''), were hunted to the brink of extinction for oil ...

' teats.

Status

The IUCN lists both species of elephant seal as being of

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

, 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. The animal is protected in most countries where it lives. In Mexico, the northern elephant seal is protected in the

Guadalupe Island Biosphere Reserve The Guadalupe Island Biosphere Reserve, (Reserva de la Biosfera Isla Guadalupe in Spanish), is located in the Pacific Ocean and is part of Baja California state of Mexico. The Reserve consists of Guadalupe Island and several small islands nearby ...

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 a village and Census-designated place on the Pacific coast of San Luis Obispo County, California, United States. Its position along State Route 1 is about halfway between Los Angeles ...

, 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 state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

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, Beachmasters, the 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