$A$ characteristic which enables an organism to live in an environment is called

Organisms occupying similar ecological niche but different geographical areas of distribution are called as

Despite variations in external environment,organisms try to maintain constancy of its internal environment which is called . . . . . . .

The organism which tolerates a wide range of salinity is called ...$A$...
$II.$ The organism which tolerates a narrow range of salinity is called ...$B$...
Choose the correct option for $A$ and $B$.

Animals that move about or swim about in the sea are known as:

In desert grasslands,which type of animals are relatively more abundant?