Southern Elephant Seal
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| Southern Elephant Seal | ||||||||||||||||
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| Mirounga leonina Linnaeus,, 1758 |
The Southern Elephant Seal (Mirounga leonina) is one of two species of elephant seal (the other is the Northern Elephant Seal). It is a member of the family Phocidae or "true seals".
The elephant seals get their name from their great size and the fact that the adult males have a large proboscis, which is used in making extraordinarily loud roaring noises, especially during the mating season. Males can attain lengths up to 6.5 metres and weights up to 4 tonnes. There is a great sexual dimorphism in size, with the males very much bigger than the females (they are called bulls and cows), and correspondingly there is a highly polygynous mating system, with a successful male able to impregnate up to 40 females in one season.
Southern Elephant Seals are found throughout the Sub-Antarctic regions, coming ashore to breed in the summer but wintering at sea. They used to live in large numbers around Tasmania, but were wiped out by the sealing industry and are now only seen there a few times a year. They are occasionally seen off the coasts of New Zealand and South Africa. They breed on the subantarctic islands, with the population at South Georgia being the largest (it includes about half of the entire species population). Other important populations are at Macquarie Island (over 80,000 individuals), Heard Island and the Kerguelen Islands.
After their near extinction due to hunting in the 19th century, total population is about 600,000, but all the populations seem to be declining at present. The reasons for this are unclear, but it may simply be that once protection from hunting was established, the species recovered so fast that it overshot its equilibrium numbers.
Elephant seals feed in deep water, and can dive to great depths, up to 1700 metres. Dives lasting up to two hours have been recorded. They feed on cephalopods such as squid and cuttlefish, and large fish including sharks. When at sea, they spend a high proportion of their time underwater, and they only need to spend a few minutes on the surface between dives.