Question

what is anomalous behavior of water? how it is important to aquatic life?

Answer 1

Anamalous behaviour of water is exhibited by water between 0⁰C and 4⁰C in which the volume of given amount of water decrease with increase in temperature from 0⁰C to 4⁰C, and beyond 4⁰C, the volume of given amount of water increase with rise in temperature.
This anomalous behaviour of water plays an important role in the survival of sea animals in cold water, as explained below :-
In winter, the temperature of surroundings falls, the water on the surface of lake cools towards 4⁰C and becomes denser. It attains maximum density at 4⁰C and sinks down. The warmer (i.e., less dense ) water present near the bottom of lake rises up. However, once the colder water on top of lake reaches temperature below 4⁰C, it becomes less dense and remains at the surface of lake, where it freezes. Now the water at the bottom of the lake remains at 4⁰C, in which the water animals can remain safe below the ice.