why do marine animals live deep inside a lake when the surface of the lake freezes?

We know that liquids expand on heating and so density decreases. In water there is an exception and when we heat water above 0°C, water contracts and the volume decreases. However, at 4°C the density of water becomes maximum with less volume and this is called anomalous expansion of water.

In cold countries or regions where oceans freeze the ice remains on the top and thus making non conductors of heat. Thus the aquatic life in the surface below thrive in spite of freezing temperatures on the top.

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Vasantha Sivaraj,

askIITians faculty