Mirounga leonina (southern elephant seals) are found along the coast of Antarctica and on sub-Antarctic islands when breeding or molting. However, before human exploitation they were more common farther north. The largest present population occurs on the island of South Georgia, in the South Atlantic Ocean. Southern elephant seals are also common on Macquarie Island, Heard Island, Kerguelen Island, and the Peninsula Valdez in Argentina. When at sea, M. leonina often journey thousands of miles from their breeding grounds. Despite the occasional sighting, not much is known about their range outside of the breeding season.
Biogeographic Regions: antarctica (Native ); oceanic islands (Native ); indian ocean (Native ); atlantic ocean (Native ); pacific ocean (Native )
Some pups are also born on the Antarctic continent. Southern elephant seals prefer sandy and cobble beaches, but will haul-out on sea ice, snow and rocky terraces and regularly rest above the beach in tussock grass, other vegetation, and mud wallows. At sea, females and males tend to disperse to different feeding grounds. Wandering and vagrant southern elephant seals reach southern Africa, southern Australia, New Zealand and Brazil in South America. An Indian Ocean record at Oman on the Arabian Peninsula represents a northernmost record.
Male southern elephant seals are the largest pinnipeds, larger even than northern elephant seals, Mirounga angustirostris, their closest relatives. Mirounga leonina males have been documented reaching over six meters long and weighing over 4000 kg. This is in sharp contrast to females, which are rarely over 800 kg or four meters long. In fact, both species of the genus Mirounga are more sexually dimorphic than any other mammal. This dimorphism stretches beyond just size. Males also have a large, inflatable proboscis, which enhances vocalizations used to challenge other males for mating rights. The southern elephant seal proboscis is slightly smaller than the proboscis of northern elephant seals, overhanging the mouth by only about 10 centimeters compared to 30 centimeters in their northern relatives.
Breeding populations vary in size. In the South Georgian population, males average 450 cm in length and weigh 4,000 kg. Females average 280 cm and weigh 900 kg. The seals from Macquarie Island population are somewhat smaller, with males averaging 420 cm in length and 3,000 kg and females averaging 260 cm and 400 kg.
Despite the large difference in size, male and female southern elephant seals do share many physical traits. They have a similar body type. This includes short front flippers used primarily for steering in the water, and very strong, fully webbed, rear flippers that can propel them through the water with remarkable speed and agility. They also have a layer of short, stiff hair covering their bodies. At birth this fur is very dark in color, but lightens after the first molt. New fur after a molt is typically a dark gray/brown with lighter underside and lightens over the course of the year. It is also common for the bodies of both sexes to have scars, usually around the neck, from fighting and mating.
Range mass: 300 to 4000 kg.
Average mass: 2000 (male) 500 (female) kg.
Range length: 260 to 600 cm.
Average length: 500 (male) 300 (female) cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger; sexes shaped differently; ornamentation
When southern elephant seals are on land, they are typically found along the coast of sub-Antarctic islands on smooth beaches of sand or small rocks. Although they used to breed well into temperate regions, M. leonina are now only found farther south. They are found on land during the breeding season, from August to November, and the molting season, which lasts 3 to 5 weeks in the spring. The rest of the year is spent entirely at sea. During this time they can be found from sub-Antarctic waters to almost as far north as the equator, often venturing thousands of kilometers from their breeding grounds. While males typically forage on the Antarctic continental shelf, females travel farther into open waters. During their time at sea, southern elephant seals can sustain dives for up to two hours, but most dives last only around thirty minutes. Amazingly, they only spend 2 to 3 minutes on the surface between dives. During most trips at sea, they are underwater for 90% of the time, day and night. While most dives are only between 300 and 800 m, dives of over 1500 m have been recorded, nearing depths only surpassed in mammals by sperm whales.
Range depth: 1500+ to surface m.
Average depth: 300-800 m.
Habitat Regions: polar ; terrestrial ; saltwater or marine
Aquatic Biomes: pelagic ; coastal
Other Habitat Features: intertidal or littoral
Habitat and Ecology
Females reach sexual maturity between 3 and 5 years and males reach sexual maturity at an age of 4 years. However, few males breed until they reach the age of least 10 years (Jones 1981). Ninety percent of males die before the age of 10 years while 90% of females die before the age of 14 years (McCann 1980, Reijnders et al. 1993).
Pregnant females arrive from September to October, and usually give birth within five days of their return. Pups are nursed for an average of 23 days and then are abruptly weaned when the female departs to sea. Females come into estrous about four days before they wean their pup and mate, starting a new reproductive cycle before completing their current effort. Pups remain on the breeding beaches for eight to ten weeks, during which time they complete the moult of their lanugo coat, before departing to sea.
Elephant seals have an annual cycle with two well-defined pelagic phases, with transitions being marked by moult and reproduction. Adult males and females come ashore to reproduce from August to October. This species provide one of the most extreme examples of polygyny among mammals. The social units are harems, each held by a single dominant male that monopolizes access to up to 120-150 sexually receptive females for a period of approximately two months. Early in the breeding season males establish dominance hierarchies on beaches via impressive displays, which include rearing up on the hindquarters and lifting almost two-thirds of the body straight up to fight with a peer or issue vocal challenges to nearby bulls.
Vocalizations include a booming, loud call of the adult male in the breeding season, variously called a bubbling roar, a harsh rattling sound, and a low pitched series of pulses with little variation in frequency. Adult females have a high-pitched yodeling call which they use when distressed, and to call their pups. They will also utter a low pitch, sputtering growl. Pups call to their mothers with a sharp bark or yap, which is also used when interacting with other seals.
Southern elephant seals spend a large percentage of their lives at sea and only return to land to give birth, breed and moult. At sea, they range far from their rookeries and predominantly feed between the Subantarctic convergence and the northern edge of the pack ice, south of the Antarctic convergence. Adult males typically venture further south than females, and are known to forage at the seaward edge of the Antarctic continental shelf.
Foraging elephant seals combine exceptionally deep diving with long-distance traveling, covering millions of square kilometers while traversing a wide range of oceanographic regions during periods of up to seven months at sea. The seals spend most of their at-sea time in particular water masses that include frontal systems, currents and shifting marginal ice-edge zones. Studies of foraging locations suggest that seals are sensitive to fine-scale variation in bathymetry and ocean surface properties (sea-ice concentration, sea surface temperature).
Southern elephant seals are prodigious divers and routinely reach the same depths as their northern counterparts. Dive depth and duration vary during the year and between the sexes, but normally range from 300 to 500 m deep and from 20 to just over 30 minutes in duration. A maximum depth of 1430 m was recorded for a female, following her return to sea after the moult. Another post-moult female dove for an astonishing 120 minutes, which is by far the longest dive ever recorded for a pinniped.
Prey consists of approximately 75% squid and 25% fish. Antarctic Notothenia fishes are thought to be important prey when these seals are near the Antarctic continental shelf. Most feeding by females occurs in deep ocean areas at mid-water depths. Adult males pass through female feeding areas on their way south to Antarctic continental slope and shelf waters, where their diving activity suggests they pursue more benthic prey.
Killer whales, and in lower latitudes, large sharks are predators on this species. Leopard seals are also known to kill southern elephant seals.
Water temperature and chemistry ranges based on 16344 samples.
Depth range (m): 0 - 0
Temperature range (°C): -1.726 - 13.900
Nitrate (umol/L): 1.714 - 30.651
Salinity (PPS): 33.556 - 34.912
Oxygen (ml/l): 5.959 - 8.248
Phosphate (umol/l): 0.278 - 2.131
Silicate (umol/l): 1.783 - 78.870
Temperature range (°C): -1.726 - 13.900
Nitrate (umol/L): 1.714 - 30.651
Salinity (PPS): 33.556 - 34.912
Oxygen (ml/l): 5.959 - 8.248
Phosphate (umol/l): 0.278 - 2.131
Silicate (umol/l): 1.783 - 78.870
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.
Southern elephant seals feed exclusively when they are at sea. For this reason not much is known about what they eat. The main known sources of food are squid, crabs, shrimp, fish, and sharks. This prey is obtained both near the surface and also during very deep dives. They have been known to eat bottom dwelling fish.
Animal Foods: fish; mollusks; aquatic crustaceans
Primary Diet: carnivore (Eats non-insect arthropods, Molluscivore )
Not much is known of the roles of southern elephant seals while they are at sea. However, they are known to be important to their ecosystem as predators of fish, sharks, squid, crabs, and shrimp and as prey for large sharks, killer whales, and leopard seals. Another important role they play in the ecosystem is as a host for many kinds of parasites. Some of the known parasites include tapeworms, acanthocephalans, and the louse Lepidophthirus macrorhini.
- the louse Lepidophthirus macrorhini
Knowledge of predation of M. leonina is limited due to their deep ocean habitat. Known predators include large sharks, specifically great white sharks, and killer whales. Leopard seals are also known to prey on pups. In order to avoid predation, southern elephant seals have dark dorsal surfaces with lighter undersides. This allows some camouflage by blending in with the lighter water when viewed from below and the darker water when seen from above.
- large sharks, specifically great white shark
- killer whale
- leopard seal
Anti-predator Adaptations: cryptic
Based on studies in:
This list may not be complete but is based on published studies.
Known prey organisms
Based on studies in:
This list may not be complete but is based on published studies.
Life History and Behavior
When at sea, Mirounga leonina rarely encounter each other and thus have no need for communication. The only time communication is used is during breeding. Males use their large proboscis as a sound chamber for amplifying their bellows. These sounds are made to establish territories and challenge males for established harems. Upright posturing often accompanies these vocalizations and males are known to visually assess their competitor before fighting. Lesser males will also exhibit a flattened posture without inflating their proboscis when near another male’s harem to demonstrate that they are not threats.
A threat vocalization is a low-pitched harsh vocalization. While the seal is doing this it will raise its head and forequarters off of the ground, supporting itself without fore flippers. A lunge from an animal is a rapid movement of the head towards an opponent or invader. This is done with an open mouth. A high rear is the raising of the front half of the body then delivering blows to another animal with the neck or chin. A bite may also be used, mainly from a low rear or a high rear position.
Females are known to communicate with newborn pups through vocalizations. Females and pups recognize each other through these vocal cues and through their individual smells.
Communication Channels: visual ; acoustic ; chemical
Perception Channels: visual ; tactile ; acoustic ; chemical
There is little known about lifespan in southern elephant seals. This is largely due to the lack of substantial information concerning the periods of the year when they are at sea. Average life expectancy in the wild, as seen during the breeding season, is about 23 years. However, about 30% of pups die in their first year. Captive M. leonina have lived to 15 years of age. Not much is known concerning the deaths of these mammals but, in addition to predation, weather and disease may play a large role in limiting their lifespan.
Status: captivity: 15 (high) years.
Status: wild: 23 years.
Status: wild: 20.0 years.
Status: wild: 18.0 years.
Status: wild: 23.0 years.
Status: wild: 20.0 years.
Lifespan, longevity, and ageing
Male southern elephant seals arrive at breeding grounds several weeks before females and, through vocalizations, body positions, and occasional fighting, claim territories on the beach. The best and largest territories go to the largest and strongest males. These “alpha” males become the head of a harem when the females arrive, often mating with up to 60 females in their harem. If harems exceed this size, additional “beta” males may be present, each claiming as many females as they can. Females become a part of a harem simply through their position on the beach and may move from one harem to another incidentally.
In addition to their mating duties, alpha males are responsible for keeping unwanted males away from the harems. This is done through the same vocalizations and aggressive body postures that were used originally to claim their harem. Males must remain on their territory to defend it and, therefore, go for periods of months without eating. This, and the stress of aggressive encounters with other males and the energy expense of mating with multiple females, can take a significant toll on male physical condition. Only males in the best physical condition at the beginning of breeding season will successfully defend their territory and breed with multiple females. Subordinate males attempt to copulate with females on the edges of territories or in the surf as they leave the beach.
Females that were pregnant from the previous year’s mating give birth to one pup shortly after arriving on land. A period of lactation follows the birth. Then, several days before the pups are weaned from their mother’s milk, females enter estrus and mate with the alpha male or a successful beta male. Shortly following mating, males return to sea. Females return to the sea immediately after the pups are weaned.
Mating System: polygynous
Once a year, from August to November, southern elephant seals return to land to breed. Amazingly, most return to the very same breeding grounds on which they were born. Five to seven days after pregnant females arrive on the beaches, they give birth to one pup. Occasionally twin pups are born but one typically dies soon afterwards. The mothers then nurse their young for about 23 days. Females may nurse longer if their energy reserves allow them to do so. During their time on the breeding grounds females eat little or not at all. Towards the end of this time, females enter estrus and mate with a male. Shortly after mating, females wean their young. At this point, they abandon their young and return to the ocean. Pups then forage on their own for several weeks before venturing out to sea in small groups. Female southern elephant seals typically reach sexual maturity by the age of 3 and participate in the annual breeding cycle by age 6. Males reach sexual maturity by age 5 or 6, but rarely are developed enough to compete for mates until they reach 10 to 12 years of age. The gestation period of female M. leonina is about eight months. There is a period of several weeks during late October when all mature females mate. In order to maintain the yearly birthing cycle with an eight-month gestation period, there is delayed implantation of the fertilized egg for about three months. After the three-month delay, the egg implants and begins to develop to become mature enough for birth during the next breeding season.
Breeding interval: Southern elephant seals mate once each year.
Breeding season: Breeding season lasts from August to November.
Range number of offspring: 1 to 2.
Average number of offspring: 1.
Range gestation period: 9 to 7 months.
Range weaning age: 20 to 35 days.
Average weaning age: 23 days.
Range time to independence: 20 to 25 days.
Average time to independence: 23 days.
Range age at sexual or reproductive maturity (female): 2 to 4 years.
Range age at sexual or reproductive maturity (male): 5 to 6 years.
Average age at sexual or reproductive maturity (male): 6 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; viviparous ; delayed implantation
Average birth mass: 42500 g.
Average number of offspring: 1.
Female southern elephant seals are the sole caregivers for their young from the moment of conception until weaning, a period that lasts around one year. After delayed implantation, which follows mating, the nine-month gestation period of the pregnancy begins. During this time, the pup develops inside the mother as she is diving and feeding in sub-Antarctic waters. Shortly after coming to land, females give birth to their pups, typically weighing between 25 and 50 kg at birth. Following birth, mothers bond vocally and through smell with their pup. For the next 20 to 25 days (sometimes as long as 35 days) mothers are responsible for providing milk and protecting pups. Mothers are typically less than one-meter from their pups during the stage of suckling, regardless of tide, the position in the harem, or the time in the breeding season. A pup might get separated from its mother due to male harassment and herding of females. This can result in an abandoned pup. Once a pup is separated from its mother the results are fatal. Alien suckling (nursing between unrelated cows and pups) isn't tolerated in this species. If an orphan pup attempts to steal milk from a sleeping or resting cow, it usually is bitten and will succumb to starvation or the effects of the bites. The most dire threat to young pups is adult males who crush pups as they travel and fight on beach territories. During lactation, mothers do not return to the water to feed and instead live on fat reserves built up during the previous foraging season. At weaning pups weigh from 120 to 130 kg, a weight gain of as much as 105 kg in a few weeks!
Immediately following weaning, female southern elephant seals return to sea, leaving their pups alone on the beach. Eventually the pups begin to get hungry and find their way to the ocean, learning to feed and swim on their own. After weaning, there is no interaction between parents and pups. Approximately 30% of these pups will not live through their first year.
Parental Investment: no parental involvement; precocial ; female parental care ; pre-fertilization (Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)
Evolution and Systematics
The proboscis of the male elephant seal amplifies calls by bulging using a combination of air, blood, and muscle.
"Another species in which the male sports an exaggerated nose is the elephant seal, largest of all seals at 5-6 m long and up to 3500 kg in weight. The huge, bulging nose of the mature male is used during the breeding season, when the seals gather in vast herds on the shores of California or the South Atlantic islands. The proboscis of the mature male bulges with the combined efforts of blood, muscle and air, and amplifies his defiant bellowing at other males." (Foy and Oxford Scientific Films 1982:136)
Learn more about this functional adaptation.
Molecular Biology and Genetics
Barcode data: Mirounga leonina
Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.
See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
Statistics of barcoding coverage: Mirounga leonina
Public Records: 3
Specimens with Barcodes: 3
Species With Barcodes: 1
Although once hunted by humans, southern elephant seals were never near extinction like northern elephant seals. This is largely because most of the breeding grounds of M. leonina were out of reach of hunting boats. Hunting did have some impact, but numbers have recovered since hunting has ceased. Some populations are are experiencing declines. This may be normal population fluctuations, however.
US Federal List: no special status
CITES: appendix ii
IUCN Red List of Threatened Species: least concern
IUCN Red List Assessment
Red List Category
Red List Criteria
IUCN Evaluation of the Southern Elephant Sea, Mirounga leonina
Prepared by the Pinniped Specialist Group
A. Population reduction Declines measured over the longer of 10 years or 3 generations
A1 CR > 90%; EN > 70%; VU > 50%
Al. Population reduction observed, estimated, inferred, or suspected in the past where the causes of the reduction are clearly reversible AND understood AND have ceased, based on and specifying any of the following:
(a) direct observation
(b) an index of abundance appropriate to the taxon
(c) a decline in area of occupancy (AOO), extent of occurrence (EOO) and/or habitat quality
(d) actual or potential levels of exploitation
(e) effects of introduced taxa, hybridization, pathogens, pollutants, competitors or parasites.
Generation time is approximately 9-10 years. Some populations decreased markedly in the last 50 years to levels that meet the CR criterion locally. But, in the last 30 years (assuming a generation time of 10 years), some stopped declining while others are increasing but have not as yet recovered to baseline numbers.
The most recent information available for the largest population (South Georgia) is that it is stable. One of the five most important populations (Península Valdés) has been growing and it is now apparently stable. Based on best available information, the combined size of the declining colonies do not in combination bring the global status into a vulnerable condition according to IUCN criteria.
A2, A3 & A4 CR > 80%; EN > 50%; VU > 30%
A2. Population reduction observed, estimated, inferred, or suspected in the past where the causes of reduction may not have ceased OR may not be understood OR may not be reversible, based on (a) to (e) under A1.
Local population reductions have been observed in the past 30 years for not well-understood reasons.
A3. Population reduction projected or suspected to be met in the future (up to a maximum of 100 years) based on (b) to (e) under A1.
Predicted reduction in sea ice habitats due to continued climate warming will impact the distribution of food and breeding habitat for the species. Predictions are not clear yet regarding how these effects will impact the size of the populations.
A4. An observed, estimated, inferred, projected or suspected population reduction (up to a maximum of 100 years) where the time period must include both the past and the future, and where the causes of reduction may not have ceased OR may not be understood OR may not be reversible, based on (a) to (e) under A1.
A global population reduction for the species has not occurred in the past 30 years.
B. Geographic range in the form of either B1 (extent of occurrence) AND/OR B2 (area of occupancy)
B1. Extent of occurrence (EOO): CR < 100 km²; EN < 5,000 km²; VU < 20,000 km²
Elephant Seals reproduce in colonies where harems are dispersed over a few km of coastline. Colonies may be thousands of km away from each other. Distribution at sea is over millions of square km.
B2. Area of occupancy (AOO): CR < 10 km²; EN < 500 km²; VU < 2,000 km²
See above for B1. The AOO on land is relatively small for each stock but significantly larger than the above numbers during the pelagic phases (when animals are apparently solitary and disperse widely away from breeding sites).
AND at least 2 of the following:
(a) Severely fragmented, OR number of locations: CR = 1; EN < 5; VU < 10
(b) Continuing decline in any of: (i) extent of occurrence; (ii) area of occupancy; (iii) area, extent and/or quality of habitat; (iv) number of locations or subpopulations; (v) number of mature individuals.
(c) Extreme fluctuations in any of: (i) extent of occurrence; (ii) area of occupancy; (iii) number of locations or subpopulations; (iv) number of mature individuals.
Besides a few colonies in the Antarctic and the temperate SW Atlantic, subpopulations are distributed among sub-Antarctic islands around the Antarctic continent, but this is the normal pattern, not the result of induced fragmentation of the population(s).
C. Small population size and decline
Number of mature individuals: CR < 250; EN < 2,500; VU < 10,000
The current abundance is > 10,000.
AND either C1 or C2:
C1. An estimated continuing decline of at least: CR = 25% in 3 years or 1 generation; EN = 20% in 5 years or 2 generations; VU = 10% in 10 years or 3 generations (up to a max. of 100 years in future)
C2. A continuing decline AND (a) and/or (b):
(a i) Number of mature individuals in each subpopulation: CR < 50; EN < 250; VU < 1,000
(a ii) % individuals in one subpopulation: CR = 90–100%; EN = 95–100%; VU = 100%
(b) Extreme fluctuations in the number of mature individuals.
D. Very small or restricted population
Number of mature individuals: CR < 50; EN < 250; VU < 1,000 AND/OR restricted area of occupancy typically: AOO < 20 km² or number of locations < 5
E. Quantitative analysis
Indicating the probability of extinction in the wild to be: CR > 50% in 10 years or 3 generations (100 years max.); EN > 20% in 20 years or 5 generations (100 years max.); VU > 10% in 100 years
There has been no quantitative analysis of the probability of extinction. It is unlikely that the species will meet any of the above criteria, although the effects of global warming are unknown.
Listing recommendation — The Southern Elephant Sea should be classified as Least Concern. No serious threats have been affecting the land breeding colonies of the species in the last 30 years. The foraging areas may be affected by the impact on the distribution of prey by climate change effects, although it is unknown how this may actually influence the species distribution and numbers. Some local declines are a cause for concern and should be assessed at the level of populations by the IUCN SSC Pinniped Specialist Group
Traditionally, three distinct populations have been distinguished: South Georgia, Macquarie and Iles Kerguelen. However, elephant seals breeding at Península Valdes on the mainland of South America and at the Falkland (Malvinas) Islands are thought to be a distinct population from those at South Georgia. Similarly, the elephant seal populations at the Prince Edward Islands and Iles Crozet are also considered to be distinct from those at Iles Kerguelen and Heard Island, and the small populations in the Tristan de Cunha Islands and Gough Island may also be distinct. Additionally, some colonies have unknown affiliations (e.g. Bouvet). Thus, there may be at least five and perhaps more, distinct breeding populations, although their foraging areas overlap quite extensively at sea (SCAR 1991, Reijnders et al. 1993, Bailleaul 2007, Biuw 2007).
The most important southern elephant seal populations in the world have been either stable or decreasing sharply in the last 50 years (Hindell and Burton 1987, Guinet et al. 1992, Pistorius et al. 2004). Today, some of those that were in decline are apparently returning to a positive trend (Boyd et al. 1996, Guinet et al. 1999).The Valdés population has grown and now is stable (Campagna and Lewis 1992, Lewis et al. 1998). The reason for the differences in the trends in various areas is not known with certainty, but different levels of food availability associated with various oceanographic features seems to have played a role.
There are few threats and conflicts today, as southern elephant seals live far from human population centres and have minimal interactions with commercial fisheries. Intensive fishing could potentially deplete important prey stocks. However, relatively little is known about their feeding habits. There is no evidence that recent declines for animals breeding in the Indian and Pacific Oceans are related to fisheries in the Southern Ocean (SCAR 1991). However, development of new fisheries at high latitudes in the future could have a significant impact on elephant seal populations (SCAR 1991, Reijnders et al. 1993).
In the South Orkney Islands a few young male elephant seals were killed for dog food in the 1950s and early 1960s when they were ashore moulting. Southern elephant seals that haul out at mainland sites could come in contact with feral dogs and other terrestrial carnivores and be exposed to a variety of diseases including morbiliviruses.
The possible effects of global climate change on southern elephant seals are not well known. Learmonth et al. (2006) suggest that while the effects of global climate change are uncertain, that the species is likely to decline as a result of habitat and ecosystem changes.
Relevance to Humans and Ecosystems
Southern elephant seals may occasionally compete with some fisheries, but this is unlikely. Southern elephant seals live in remote regions where they have few interactions with humans.
In the past, southern elephant seals were hunted for their blubber that was boiled down into oil. A typical male could produce about 350 liters of oil. Some aboriginal people also hunted them for food and skins. This activity has ceased and killing is now controlled by the Convention for the Conservation of Antarctic Seals. The only use of M. leonina to man today is for purely scientific purposes.
Positive Impacts: body parts are source of valuable material; research and education
Southern elephant seal
The southern elephant seal (Mirounga leonina) is one of the two extant species of elephant seals. It is both the largest pinniped and member of the order Carnivora living today, as well as the largest Antarctic seal. The seal gets its name from its great size and the large proboscis of the adult males, which is used to make extraordinarily loud roaring noises, especially during the mating season. Rather larger at average than the male northern elephant seal (Mirounga angustirostris) (which is 40% lighter) and male walrus (Odobenus rosmarus) (the average North Pacific bull, of the larger race, is 2.5 times lighter), the adult bull southern elephant seal is without rival the largest carnivoran alive. An average adult male southern elephant seal weighs six to seven times more than the largest terrestrial carnivorans, the polar bear (Ursus maritimus) and Kodiak bear (Ursus arctos middendorffi).
The southern elephant seal is distinguished from the northern elephant seal (which does not overlap in range with this species) by its greater body mass and a shorter proboscis. The southern males also appear taller when fighting, due to their tendency to bend their backs more strongly than the northern species. This seal shows extreme sexual dimorphism in size, seemingly the largest of any mammal by mass, with the males typically five to six times heavier than the females. In comparison, in two other very large marine mammals with high size sexual dimorphism, the northern elephant seal and the sperm whale (Physeter macrocephalus), the males weigh on average about three times as much as the females, and only more than four times as heavy in exceptionally heavy bull specimens. While the females southern elephant seal typically weighs 400 to 900 kg (880 to 1,980 lb) and measures 2.6 to 3 m (8.5 to 9.8 ft) long, the bulls typically weigh 2,200 to 4,000 kg (4,900 to 8,800 lb) and measure from 4.2 to 5.8 m (14 to 19 ft) long. An adult female averages 771 kg (1,700 lb) in mass, while a mature bull averages about 3,175 kg (7,000 lb). Studies have indicated elephant seals from South Georgia are around 30% heavier and 10% longer on average than those from Macquarie Island. The record-sized bull, shot in Possession Bay, South Georgia, on 28 February 1913, measured 6.85 m (22.5 ft) long and was estimated to weigh a hulking 5,000 kg (11,000 lb), although it was only partially weighed piecemeal. The maximum size of a female is 1,000 kg (2,200 lb) and 3.7 m (12 ft). 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 hind limbs whose 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. 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 8 km/h (5.0 mph)) in this way for short-distance travel, to return to water, to catch up with a female, or to chase an intruder.
Pups are born with fur and are completely black. Their coats are unsuited to water, but protect infants by insulating them from the cold air. The first moulting accompanies weaning. After moulting, the coats may turn grey and brown, depending on the thickness and moisture of hair. Among older males, the skin takes the form of a thick leather which is often scarred.
Like other seals, the vascular system of elephant seals is adapted to the cold; a mixture of small veins surround arteries, capturing heat from them. This structure is present in extremities such as the hind legs.
Range and population
The world population was estimated at 650,000 animals in the mid-1990s, and was estimated in 2005 at between 664,000 and 740,000 animals. Studies have shown the existence of three geographic subpopulations, one in each of the three oceans.
Tracking studies have indicated the routes traveled by elephant seals, demonstrating their main feeding area is at the edge of the Antarctic continent. While elephant seals may come ashore in Antarctica occasionally to rest or to mate, they gather to breed in subantarctic locations.
The largest subpopulation is in the South Atlantic, with more than 400,000 individuals, including about 113,000 breeding females on South Georgia; the other breeding colonies of the Atlantic subpopulation are located on the Falkland Islands and Valdes Peninsula in Argentina (the only continental breeding population).
The second subpopulation, in the south Indian Ocean, consist of up to 200,000 individuals, three-quarters of which breed in the Kerguelen Islands and the rest in the Crozet Islands, Marion and Prince Edward Islands, and Heard Island. Some individuals also breed on Amsterdam Island.
Colonies once existed in Tasmania, Saint Helena, and the Juan Fernández Islands off the coast of Chile. Some individuals at the time of moulting have been found in South Africa or Australia. Lost animals have also been reported from time to time on the shores of Mauritius, with two reports from the Río Guayas estuary area in Ecuador.
After the end of large-scale seal hunting in the 19th century, the southern elephant seal recovered to a sizable population in the 1950s; since then, an unexplained decline in the subpopulations of the Indian Ocean and Pacific Ocean has occurred. The population now seems to be stable; the reasons for the fluctuation are unknown. Suggested explanations include a phenomenon of depression following a rapid demographic rebound that depletes vital resources, a change in climate, competition with other species whose numbers also varied, or even an adverse influence of scientific monitoring techniques.
Social behavior and reproduction
Elephant seals are among the seals that can stay on land for the longest periods of time, as they can stay dry for several consecutive weeks each year. Males arrive in the colonies earlier than the females and fight for control of harems when they arrive. Large body size confers advantages in fighting and the agonistic relationships of the bulls gives rise to a dominance hierarchy with access to harems and activity within harems, being determined by rank. The dominant bulls (“harem masters”) establish harems of several dozen females. The least successful males have no harems, but may try to copulate with a harem male's females when the male is not looking. The majority of primiparous females and a significant proportion of multiparous females mate at sea with roaming males away from harems.
An elephant seal must stay in his territory to defend it, which could mean months without eating, having to live on his blubber storage. Two fighting males use their weight and canine teeth against each other. The outcome is rarely fatal, and the defeated bull will flee; however, bulls can suffer severe tears and cuts. Some males can stay ashore for more than three months without food. Males commonly vocalize with a coughing roar that serves in both individual recognition and size assessment. Conflicts between high-ranking males are more often resolved with posturing and vocalizing than with physical contact.
Generally, pups are born rather quickly in the breeding season. After being born, a newborn will bark or yap and its mother will respond with a high-pitched moan. The newborn begins to suckle immediately. Lactation lasts an average of 23 days. Throughout this period, the female fasts. Newborns weigh about 40 kg (88 lb) at birth, and reach 120 to 130 kg (260 to 290 lb) by the time they are weaned. The mother loses significant weight during this time. Young weaned seals gather in nurseries until they lose their birth coats. They enter the water to practice swimming, generally starting their apprenticeship in estuaries or ponds. In summer, the elephant seals come ashore to moult. This sometimes happens directly after reproduction.
Feeding and diving
Satellite tracking revealed the seals spend very little time on the surface, usually a few minutes for breathing. They dive repeatedly, each time for more than 20 minutes, to hunt their prey—squid and fish—at depths of 400 to 1,000 m (1,300 to 3,300 ft). They are the deepest diving air-breathing non-cetaceans and have been recorded at a maximum of 2,133 m (6,998 ft) in depth.
As far as duration, depth, and the sequence of dives, the southern elephant seal is the best performing seal. In many regards, they exceed even most cetaceans. These capabilities result from nonstandard physiological adaptations, common to marine mammals, but particularly developed in elephant seals. The coping strategy is based on increased oxygen storage and reduced oxygen consumption.
In the ocean, the seals apparently live alone. Most females dive in pelagic zones for foraging, while males dive in both pelagic and benthic zones. Individuals will return annually to the same hunting areas. Due to the inaccessibility of their deep-water foraging areas, no comprehensive information has been obtained about their dietary preferences, although some observation of hunting behavior and prey selection has occurred.
While hunting in the dark depths, elephant seals seem to locate their prey, at least in part, using vision; the bioluminescence of some prey animals can facilitate their capture. Elephant seals do not have a developed system of echolocation in the manner of cetaceans, but their vibrissae (facial whiskers), which are sensitive to vibrations, are assumed to play a role in search of food. When at the subantarctic or Antarctic coasts, the seals can also consume molluscs, crustaceans, nothothens, lanternfish, krill, cephalopods or even algae.
Weaned pups may be prey for killer whales or orcas (Orcinus orca) while juveniles and even adults of up to adult male size may also fall prey to orcas. Cases where weaned pups have been attacked and killed by leopard seals (Hydrurga leptonyx) and New Zealand sea lions (Phocarctos hookeri), exclusively small pups in the latter case, have been recorded. Great white sharks (Carcharodon carcharias) have hunted elephant seals near Campbell Island, while bite marks from a southern sleeper shark (Somniosus antarcticus) have been found on surviving elephant seals in the Macquarie Islands.
After their near extinction due to hunting in the 19th century, the total population was estimated at between 664,000 and 740,000 animals in 2005, but as of 2002, two of the three major populations were declining. The reasons for this are unclear, but are thought to be related to the distribution and declining levels of the seals' primary food sources. Most of their most important breeding sites are now protected by international treaty, as UNESCO World Heritage Sites, or by national legislation.
One of the most famous southern elephant seals is Minazo, who lived in Japan's Enoshima Aquarium from when he was a half-year old until his death in 2005 at age 11. Minazo became popular for his signature bucket-holding, tongue-lolling pose. In 2006, Minazo was memorialized by the Japanese noise musician Masami Akita, also known as Merzbow, in a two-volume album, with artwork by Jenny Akita showing Minazo holding his beloved bucket.
In 2007, Minazo became the subject of an image macro similar to lolcat called "lolrus". In his liner notes, Masami Akita suggested Minazo's frequent and demanding performances left him exhausted, contributing ultimately to his death. Akita's intention in celebrating Minazo was to highlight the plight of captive animals used for performance before public audiences. Minazo has also featured on several T-shirt designs.
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