Facts about leopard seals
A leopard seal at Lyall Bay, Wellington
The leopard seal (Hydrurga leptonyx) is built for speed. They are easily identified by their long slim body, comparatively large fore-flippers. The disproportionately large head, massive jaws, impressive teeth and tremendous gape give it a snake-like appearance.
In colour, the leopard seal shades from almost black to almost blue on the flanks. The muzzle, throat and belly are light grey scattered with dark grey and black spots. The demarcation between dorsal and ventral colouration is distinct but diffuse. Pup appearance is very similar to that of the adults.
Newborn pups are more than 1 m long and may weigh close to 30kg. Females grow faster than males and very large individuals can weigh up to 450 kg.
Adult females: length 3.6 m, weight more than 300 kg
Adult males: length 3 m, weight 270 kg
Range
Adult leopard seals are normally found along the edge of the Antarctic pack ice but in winter, young animals move throughout the southern ocean visiting New Zealand. Auckland and Campbell islands are known to have leopard seals annually and the mainland regularly receives visitors.
Population
A population estimate in 1977 put the total number at 222,000.
Diet and foraging
A leopard seal shows its teeth, Antipodes
Island
Leopard seals prey on a variety of species, including krill, penguins, fish, seals, cephalopods. It is likely that they are opportunistic in that they prey on whatever is readily available. They are the only seals known to regularly hunt and kill warm-blooded prey, including other seals. Large adults have attacked humans.
These seals frequent ice-floes and waters adjacent to Adelie penguin rookeries and are adept at catching penguins after underwater pursuits or as they fall back into the water after missing their footing on the ice. Penguins are skinned by the seal gripping the skin with its incisor teeth and shaking the bird until the skin tears away.
Life history
Leopard seals are usually solitary animals. Males are sexually mature at 3-6 years of age and females at 2-7 years. Mating has never been observed in the wild. Adults moult between January and June.
Leopard seals appear to have low productivity compared to other seals, with only 50-60 per cent pupping annually. Pups are born mainly in the pack ice in November and the reproductive season ends in late December. Lactation lasts for one month. Males are rarely seen near pupping and nursing sites.
Underwater vocalisations are of low to medium frequency and long duration. The leopard seal's lowest frequency call is particularly powerful and can be heard at the surface and felt through the ice.
Killer whales are known to occasionally predate upon leopard seals.
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