Question

In what way in the anomolas behabiour of water advantage to aquatic anomals

Answer 1

Let me start with what is anomalous expansion of water.

Water contracts till it reaches a temperature of 4 degree Celsius, but expands after that unlike any other compound.

Now, during winters when the atmosphere's temperature drops, the temperature of water drops and say the temperature of the whole water body drops to 4 degree Celsius. Below that temperature when water starts to freeze it expands and hence it's density decreases which makes the colder liquid to remain on top and the temperature of water below it does not drop. The ice starts forming from top and acts as an insulator.

Now, lets say water does not show anomalous expansion, then the colder water being heavier will sink and the whole water body will freeze.

Considering the two cases above, the first one, i.e. 4 degree Celsius is better for survival rather