| Summary: | Ringed seals Phoca hispida, the smallest of the marine arctic pinnipeds, are one of only two seal species in the world adapted to life in the land-fast sea ice. The habitat is characterized by a stable ice platform forming in early winter and lies at latitudes subject to extreme low temperatures. The small body size of adults and semi-altricial pups are an unusual adaptation to cold, allowing ringed seals to use shelters that they construct in the snow overlying their breathing holes. These small subnivean structures act to hide adults and pups from predators, especially polar bears, Ursus maritimus, and arctic foxes, Alopex lagopus. It appears that dry lanugal pups could withstand the arctic cold without shelter, but pups that have been wetted become hypothermic and require shelter to regain thermoneutrality. Since female seals actively swim away with their pups from attacks on their birth lairs by foxes and bears, both the physical and the thermal protection of alternate subnivean lairs are important for the survival of the neonate. Weddell seals, Leptonychotes weddelli, resident in the land-fast ice of the Antarctic, are the ecological counterpart of the ringed seal. Their large body size is typical of the usual cold adaptive strategy of other polar phocid seals.Key words: ringed seal, behaviour, development, physiology, adaptations, arctic winter, Phoca hispida Mots clés: phoque annelé, comportement, développement, physiologie, adaptations, hiver arctique, Phoca hispida
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