French zoologist Henri Marie Ducrotay de Blainville described the leopard seal in Description The skull of the leopard seal The leopard seal has a distinctively long and muscular body shape, when compared to other seals. This species of seal is known for its massive reptilian-like head and jaws that allow it to be one of the top predators in its environment. A notable key feature of leopard seals is its counter-shaded coat.
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French zoologist Henri Marie Ducrotay de Blainville described the leopard seal in Description The skull of the leopard seal The leopard seal has a distinctively long and muscular body shape, when compared to other seals.
This species of seal is known for its massive reptilian-like head and jaws that allow it to be one of the top predators in its environment. A notable key feature of leopard seals is its counter-shaded coat.
A counter-shaded coat is when the dorsal side of the coat is darker than ventral side. Leopard seals have a silver to dark gray blended coat that makes up its distinctive "leopard" coloration with a spotted pattern, whereas the ventral side of the coat is paler in color—ranging from white to light gray. They are about the same length as the northern walrus , but usually less than half the weight.
Leopard seals have an enormous mouth relative to their body size. Since leopard seals are "true" seals, they do not have external pinnae, or ears, but they do have an internal ear canal that leads to an external opening. Sightings of vagrant leopard seals have also been recorded on the coasts of Australia, New Zealand where individuals have been recorded even on the coasts of major cities such as Auckland  and Dunedin  , South America, and South Africa.
Higher densities of leopard seals are seen in the Western Antarctic than in other regions. Some researchers believe this is due to safety concerns for the pups. The estimated population of this species ranges from , to , individuals, which puts leopard seals at "least concern".
This trait of vocalizing underwater for long periods has made them available to acoustic surveys, allowing researchers to gather most of what is known about them. Acoustic behavior Leopard seals are very vocal underwater during the austral summer.
Their back is bent, the neck and cranial thoracic region the chest is inflated and as they call their chest pulses. The male calls can be split into two categories: vocalizing and silencing, in which vocalizing is when they are making noises underwater, and silencing noted as the breathing period at the air surface.
These cadence of calls are believed to be a part of a long range acoustic display for territorial purposes, or the attraction of a potential mate. Where the younger male seals have many different types of variable calls — the adult male seals have only a few, highly stylized calls. In male seals, vocalizing coincides with the timing of their breeding season, which falls between November and the first week of January; captive female seals vocalize when they have elevated reproductive hormones.
Breeding habits A mother leopard seal with her pup. Since leopard seals live in an area difficult for humans to survive in, not much is known on their reproduction and breeding habits. However, it is known that their breeding system is polygynous, meaning that males mate with multiple females during the mating period. A sexually active female ages 3—7 can give birth to a single pup during the summer on the floating ice floes of the Antarctic pack ice, with a sexually active male ages 6—7.
Mating occurs from December to January, shortly after the pups are weaned when the female seal is in estrus. A newborn pup weighs around 66 pounds and are usually with their mother for a month, before they are weaned off.
The male leopard seal does not participate in taking care of the pup, and goes back to its solitary lifestyle after the breeding season. Mating takes place in the water, and then the male leaves the female to care for the pup, which the female gives birth to after an average gestation period of days. Co-operative hunting of leopard seals on Antarctic fur seal pups has been witnessed, which could be a mother helping her older pup, or could also be female-male couple interactions, to increase their hunting productivity.
Young leopard seals will usually eat mostly krill , squid and fish. Leopard seals are also known to take fur seal pups. Other prey include penguins and fish. Antarctic krill Euphausia superba , southern elephant seal Mirounga leonina pups and seabirds other than penguins have also been taken as prey. It kills the swimming bird by grabbing the feet, then shaking the penguin vigorously and beating its body against the surface of the water repeatedly until the penguin is dead.
Previous reports stating the leopard seal skins its prey before feeding have been found to be incorrect. Lacking the teeth necessary to slice its prey into manageable pieces, it flails its prey from side to side tearing and ripping it into smaller pieces. Their large front flippers are used to steer themselves through the water column making them extremely agile while hunting.
They use their front flippers similarly to sea lions otariids  and leopard seal females are larger than males. This layer of blubber also helps to streamline their body making them more hydrodynamic. This is essential when hunting small prey items such as penguins because speed is necessary.
Scientists take blubber thickness, girth, weight, and length measurements of leopard seals to learn about their average weight, health, and population as a whole. They also have incredible diving capabilities. This information can be obtained by scientists by attaching transmitters to the seals after they are tranquilized on the ice. Scientists attach this device usually to the head of the animal and it records depth, bottom time, total dive time, date and time, surface time, haul out time, pitch and roll, and total number of dives.
This is how we are currently learning so much about leopard seals diet and foraging habits. With this information we are able to calculate and better understand their diving physiology. They are primarily shallow divers but they do dive deeper than 80 meters in search for food. This is possible by increasing surfactant which coats the alveoli in the lungs for re-inflation. They also have a reinforced trachea to prevent collapse at great depth pressures.
However, attacks on humans are rare. Most human perceptions of leopard seals are shaped by historic encounters between humans and leopard seals, that have occurred since the Heroic Age of Antarctic exploration. He was saved only when another member of the expedition, Frank Wild , shot the animal.
His companions managed to save him by repeatedly kicking the animal in the head with the spiked crampons on their boots. This was the first recorded human fatality from a leopard seal. Brown and another researcher, Richard Burt, were snorkeling in the water. Burt was snorkeling 15 meters away when the team heard a scream and saw Brown disappear into the water. She was quickly rescued by her team but they were unfortunately unable to resuscitate her. It was later revealed that the seal had held her underwater for six minutes at a depth of up to 70m.
She suffered a total of 45 separate injuries most of which were concentrated around her head and neck. As she was snorkeling at the time she may have seen the seal approaching her. Andrews University stated that the seal may have mistaken her for a fur seal or may have been frightened by her presence and attacked in defense.
Professor Boyd said that Leopard Seal attacks on humans were extremely rare but warned that they may potentially become more common due to increased human presence in Antarctica. The coroner recorded a verdict of an accidental death caused by drowning due to a leopard seal attack. Because of their limited subpolar distribution in the Antarctic, they may be at risk as polar ice caps diminish with global warming. In the wild, leopard seals can live up to 26 years old.
Kenmerken[ bewerken brontekst bewerken ] Het lichaam van de zeeluipaard is sterk gestroomlijnd, waardoor hij hoge snelheden in het water kan bereiken. De kop is sterk afgevlakt en lijkt daardoor wel reptielachtig. Zeeluipaarden bewegen zich met hun lange voorvinnen door het water. Een mannetje is ongeveer 3 m lang en kg zwaar. De vrouwtjes kunnen tot 4 m lang en kg zwaar worden. De kleur is aan de bovenzijde van het lichaam donkergrijs en aan de onderzijde zilverwit. Op de kop en aan de zijkanten komen grijze vlekken voor.