Question

A blue whale lives in water , a bat can fly and man can walk on two feet , still these animals are grouped together . Name the group and state the basis of their grouping by giving four points

Answer 1

Blue  whales  , Bats and humans are grouped under the class Mammals.

This is because :-
<> They are viviparous [ give birth to young ones ]

<> Have mammary glands to nourish their young ones

<>They have sweat glands

<>They have hair all over their body

Answer 2

Hey friend,
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These animals are grouped together as they all are mammals. 

Their group name is Mammalia.

Basis of their grouping :-

1. They are warm-blooded animals.

2. They have four-chambered hearts.

3. They contain mammary glands for the formation of milk to feed their young. 

4. Their skin contains hairs and sweat as well as oil glands.

5. They give birth to young ones. ( except:- platypus and echidna )

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Hope it helps ^_^