Question

How is a whale different from a fish even through they r both aquatic animals????

Answer 1

because a whale has lungs instead of gills and comes to the surface to breathe.
also, they give birth to live young instead of laying eggs.
all these are the characteristics of mammals and hence a whale isn't a fish but a mammal

Answer 2

Fishes and whales are both vertebrates, and live in similar aquatic environments. Except for a few species, whales only live in the ocean water, whereas fishes inhabit in both fresh and salt water. Whales are classified in the class ‘mammalia’ and order Cetacea in the animal kingdom. The term ‘whale’ is sometimes used to refer to all cetaceans, which include the sperm whale, killer whale, pilot whale, and beluga whale. On the other hand, fishes are the members of paraphyletic group, which includes all gill-bearing aquatic animals. This group includes all cartilaginous and bony fishes, lampreys and living hagfishes, etc.Whales are said to be the largest animals on Earth, and there are some fishes which can be among the smallest of other animals. Being mammals, whales are warm-blooded, and are required to maintain a constant warm body temperature. Fishes, on the other hand, are cold blooded, which means their body temperature changes according to their surrounding water.

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