Elephant seals (Mirounga angustirostris) are large, oceangoing mammals of the order Pinnipedia. They get their name from their great size and from the male’s large proboscis, which resembles an elephant’s trunk. Elephant seals live in the Southern Hemisphere and breed on subantarctic islands and coasts. The largest males weigh as much as 6,000 kg (13,200 lb) and measure up to 7 m (23 ft) in length; females are about one-third smaller.
Elephant seals spend most of their lives at sea, coming ashore only to mate and give birth every 2–3 years. They are excellent swimmers and divers; they can stay submerged for more than an hour at depths greater than 1 km (0.6 mi). When they do come ashore, it is usually onto sandy beaches or rocky shores where there is little vegetation.
During the breeding season (December to February), adult male elephant seals battle for dominance of coastal ” harems” containing 10–100 females with whom they mate. Females give birth to a single pup weighing 80–90 kg (180–200 lb) after a gestation period of 11 months; pups grow rapidly on their mothers’ milk, gaining almost 600 kg (1,300 lb) in their first year. At weaning, pups are around 3 m long and weigh 400 kg (880 lb). Adult males rarely interact with females or pups outside of the breeding season; during this time they fast and molt their haircoat on land before returning to sea.
The diet of elephant seals consists mainly of squid and fishes; however because these animals must dive so deep to find food—up to 1 km—their stomachs often contain sand eels, crabs, shrimp, starfish, sponges, cephalopods such as octopus and cuttlefish bones found on the ocean floor. Because squid beaks accumulate in gastric folds lining their stomachs over time causing irritation leading eventually to death by infection if not regurgitated periodically through vomiting , researchers believe that squid form a significant part of the diet but whole specimens are seldom observed in scat samples . Consequently most information about prey items comes from analysis of stomach contents . Studies have shown that although larger individuals target bigger prey items , all age groups eat similar proportions by weight . There is also evidence that different populations feed on distinct suites of species indicating dietary specialization . For example M . angustirostris feeding off Peru consume lanternfishes while those nearer Antarctica take krill indicating resource partitioning between neighboring populations . Where seal numbers are high competition for food resources may lead some animals especially young adults away from preferred areas close inshore towards waters further offshore where conditions such as temperature may be less favorable but fish stocks higher due largely to lower predation rates caused by distance from land based predators such as gulls skuas sheathbills penguins etcetera In general though it appears that food availability rather than intra specific competition regulates population dynamics within groups of southern elephant seals since growth rates do not appear limited by access to resources even when large aggregations occur Although energy dense blubber provides reserves against lean times body mass can fall quickly when fasting during extended periods at sea Between dives lasting up two minutes air is forced out lungs expelling carbon dioxide which diffuses into surrounding tissue forcing oxygen rich blood back into circulation Myoglobin stored in muscle cells provides oxygen during strenuous activity allowing elephants seals stay underwater far longer than would otherwise be possible To avoid decompression sickness nitrogen bubbles released from solution in tissues during ascent must be eliminated slowly over several days This explains why hauled out animals spend considerable time ‘grooming’ themselves : scratching vigorously with hind flippers apparently helps remove loose skin scales parasites etcetera expediting gas exchange Post weaning pups remain relatively stationary spending prolonged periods either basking haul out or swimming close shore whereas adults undertake long distance migrations circumnavigating entire continents Although movements patterns vary considerably between sexes tracking data suggests both follow similar broad strategies staying within familiar ranges except when seeking mates then returning regardless successful mating encounter occurs or not Calves born late summer tend make shorter trips close shore whereas those born early winter venture well offshore covering greater distances probably associated with learning how best exploit local resources During non breeding season southern elephant seal congregate sub Antarctic islands including Macquarie Island South Georgia Heard Island Falkland Islands Crozet Prince Edward Marion Gough Nightingale Tristan da Cunha Amsterdam Saint Paul Ile Amsterdam Kerguelen Bouvet Island along continental shelves particularly ice free areas adjacent pack ice While typically dispersed solitary animals will sometimes form temporary associations other conspecifics often related parties These social interactions serve various purposes including thermoregulation predator avoidance reproductive opportunities information sharing involving behaviors such as vocalizations olfactory cues tactile contact allomothering Perhaps most striking feature vocalisations produced these creatures what known epiglottal clicks unique sound made using larynx clicking action opening closing glottis very rapidly Clicks rates vary depending context anywhere between once per second ten seconds apart faster sequences used communicate excitement fear aggression slower ones identification purposes Pitch also changes according loudness needed carry given distance whether animal surface underwater low notes travel better water higher air Calls produce three main types sounds: moans grunts snores Moans constant low amplitude signal modulated frequency used indicate distress solicit assistance calling lost offspring Grunts series pulses emitted irregular intervals generally louder amplitude than moans thought represent contentment appeasement Snores produced regularity varying duration typically loudest calls signals relaxation contentment Vocalisations play important role regulating social structure enabling space use conflicts avoided minimized facilitating breeding success Although capable surviving prolonged periods isolation prefer company others Individual home ranges widely variable determined sex age reproductivity experience presence competitors etcetera Males maintain territories along coastlines which overlap those many other bulls often quite substantially Females raise young remote quiet sites inaccessible land predators typically located inland among tussock grasses rock crevices Bulls establish dominance hierarchies fighting fiercely rivals win rights mate herds cows Youngsters mostly fend themselves small family groups led experienced matriarch until old enough join mixed sex herd bachelor group Despite formidable arsenal weaponry consisting sharp canine teeth powerful jaws shaggy mane thick skin trunks bulls seldom seriously injure kill each competitor Instead physical contests serve intimidate opponents assert authority determine pecking order Major injuries sustained result accidental collisions waves rocks ice Serious fights broken off submission signalled lowering head rolling onto side exposing ventral region After copulation takes place bull leaves immediately rejoins bachelor group does interact calves nursing mothers any longer Meanwhile cow returns secluded spot gives birth wean pup Several weeks post parturition mother ready mate again cycle begins anew