Question
Mon October 29, 2012 By:
 

Why whales are not grouped in the class pisces......???

Expert Reply
Tue October 30, 2012
This is because whales are mammals and not fishes.

Although whales and fish both live in water, this is the only way in which they are the same. There are a multitude of features which determine the difference between a fish and a whale.

  • Whales give birth to live young which are gestated inside the womb of the animal from the moment of fertilisation. Fish, however, mostly lay eggs, which are fertilised and gestate outside the mother's body.
  • Fish are cold-blooded whereas whales maintain a warm, constant body temp
  • Further, whales, like all mammals, breath air. Fish cannot survive by breathing air. They absorb air out of the water they take in through their gills. (Whales take in air through a blowhole in the top of the head and this air travels to the lungs, which then aerate the blood.)  These methods of respiration are quite clearly very different.

When whales are examined closely in terms of biology, social structure and communication, they are found to be remarkably different from fish. Whales are much closer to mammals in every way, other than their habitat, which is the one commonality they share with fish.

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