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Common Seal (Phoca vitulina)

Pinnipeds [1] are the seals and their relatives, a group of semi-aquatic marine mammals. The Pinnipedia is in the Order Carnivora. There are three seal families: Odobenidae (walruses), Otariidae (eared seals, including sea lions and fur seals), and Phocidae (true seals).[2]

Seals are sleek-bodied and barrel-shaped. Their bodies are well adapted to the aquatic habitat where they spend most of their lives. Pinnipeds have flippers for hands, big bulky bodies, doggish faces, and big eyes. Unlike cetaceans, pinnipeds have their noses on their face, and each nostril of the nose closes when the pinniped goes under water. Like cetaceans, pinnipeds have a thick layer of blubber (fat) just under their skin: this blubber keeps them warm in cold waters and keeps them fed during times when food is not easily found. When they cannot find food, they live off the fat in the blubber.

Pinnipeds are carnivorous. This means they eat only meat (such as fish or squid) and not plants. However, almost all pinnipeds can be eaten by sharks or orca whales.

Seals are often trained in zoos or aquariums to put on shows. However, in Sweden, it is illegal to train a seal to balance a ball on its nose.[3]

Sleep[change | change source]

Pinnipedes sleep in the water.[4] They may also sleep on land. In both environments, there is danger. At least in the northern hemisphere, there is danger from polar bears on land; and in the water there is danger from sharks.[5] While sleeping in water, the animals go through different stages of sleep. They do some behaviours during sleep: they come to the surface occasionally to breathe, and they now and then open an eye for a period of time.[4] The details vary in different species or group. Similar adaptations are found in cetaceans like dolphins.

Taxonomy[change | change source]

  • Family Phocidae (Earless seals or true seals)
    • Subfamily Monachinae
      • Tribe Monachini
        • Genus Monachus
      • Tribe Mirungaini
      • Tribe Lobodontini
    • Subfamily Phocinae
      • (placed here)
      • Tribe Phocini
        • Genus Histriophoca
        • Genus Phoca
        • Genus Pusa
          • Ringed Seal (Pusa hispida, formerly Phoca hispida)
          • Caspian Seal (Pusa caspica, formerly Phoca caspica)
          • Nerpa or Baikal Seal (Pusa sibirica, formerly Phoca sibirica)
        • Genus Halichoerus

References[change | change source]

  1. From Latin pinna, wing or fin, and ped-, foot.
  2. Jeff W Higdon, Olaf RP Bininda-Emonds, Robin MD Beck, and Steven H Ferguson (2007). "Phylogeny and divergence of the pinnipeds (Carnivora: Mammalia) assessed using a multigene dataset". BMC Evol Biol. 2007 7: 216. doi:10.1186/1471-2148-7-216. PMC 2245807. PMID 17996107. 
  3. Gifford, Clive; Lisa Clayden (2002). Family Flip Quiz Geography. Bardfield Centre, Great Bardfield, Essex, CM7 4SL: Miles Kelly Publishing. ISBN 1-84236-146-5.
  4. 4.0 4.1 Lyamin et al 2004. Relationship between sleep and eye movement in cetaceans and pinnipeds. Archives Italliennes de Biologie 142: 557–568.
  5. Gill, Victoria 2012. Slowest Greenland shark hunts sleeping prey. BBC Nature [1]