Wednesday 14 November 2012

Creature Feature: Fin Whale


Fin Whales (Balaenoptera physalus), also sometimes referred to as the Finback whale or common rorqual, is the second largest whale in the world, second only to the Blue whale. The Fin whale can weigh up to 80 tones and stretch up to 26 meters long.  It has a v-shaped head with asymmetrical colouring.  The left jaw is dark coloured, usually grey and the right side is white. The rest of the whale is usually white on the ventral side and dark coloured on the dorsal side. The Fin whale has a very stream-lined body with a tall dorsal fin rising at a shallow angle about two-thirds of the way along the back.  It is part of the rorqual family of whales and therefore has distinctive throat grooves.  These horizontally running grooves allow the whale to open its mouth very wide in order to take in large amounts of water which it then pushes back out through the numerous, large baleen plates hanging in its jaw, to filter out the plankton, krill and small schooling fish that make up its diet. 
The Fin whale lives in social groups of 2 to 7 individuals as well as being often seen feeding near other groups of whales such as the Humpback or Minke whales.  The only non human predator of the Fin whale is the Killer whale or Orca.  Female Fin whales are mature at around 7 to 12 years, while males mature slightly faster at 6 to 12 years. A female Fin whale will give birth to a live calf after 11 to 12 months gestation.  The calf is approximately 6 meters long and 2 tones when it is born.  Fin whales are believed to live as long as 90 years.  Another interesting fact is that in some rare cases Fin whales have been known to breed with Blue whales as a few hybrids, believed to be sterile, have been located.

 
Fin Whale surfacing.
 

 
Diagram of the Fin Whale. (courtesy of EnchantedLearning.com)
 
 

 
Pictures showing the way in which the rorqual grooves allow for expansion of the mouth.

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