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Friday, August 29, 2014


Do you recognize the animal below in its distinctive position at sea?

Sometimes the front flipper is also held downward in an arc towards the hindflipper, leading to a classic shape and an informal term for this behavior — "jughandling."  The next picture will reveal more of the animal.

Note the small head and snout, prominent whiskers, and long ear flaps.  The image above also emphasizes the impressive length of the flippers (and note that the flippers lack fur).

This is a Northern Fur Seal (Callorhinus ursinus), photographed in Monterey Bay on 22 August 2014.  They can also be found offshore of Bodega Head on trips to Cordell Bank.

Northern Fur Seals spend up to 300 days of the year at sea, coming to shore only during the pupping season.  The reason for the jughandling position is unknown.  A thermoregulatory function has been proposed, e.g., in cold water, removing the flippers from the water may prevent heat loss; or in warm water, it may allow heat dissipation.  Other possible explanations for the behavior have involved creating a stable position for sleeping and generating a silhouette that's less conspicuous to predators from below.

Here are two more pictures so you can appreciate this pinniped and ponder this behavior: 

P.S.  Jughandling facts and ideas from Liwanag, H.E.M.  2010.  Energetic costs and thermoregulation in Northern Fur Seal (Callorhinus ursinus) pups: The importance of behavioral strategies for thermal balance in furred marine mammals.  Physiological and Biochemical Zoology 83: 898-91.  

1 comment:

Anonymous said...

most interesting !! c