The sun. It affects all organisms, whether directly or indirectly. It helps and affects the whole food chain. The sun helps plants grow, which feeds animals and other predators, and finally when the animals die, decomposers break up the organisms and release nutrients back into the environment.

It also affects other food chains, depending on what animals, the prey and predators, etc.

But the sun is an energy source that affects all organisms in a certain way.

Yes indeed..The sun is the source of energy for "All Livng Things On Earth". But...The question still remains... Is solar energy required for lifeforms we have yet to discover elsewhere in the cosmos.

I ask that simply because here on earth so little solar energy is required for life as we know it.

From the "TOTAL SOLAR OUTPUT OF ENERGY" from our local star (The Sun) only one millionth of one billionth of 1% strikes the earth at any given moment. And consider the solar output of the largest star known....One "Billion" of our sun's will fit inside. The "Solar" energy in the cosmos is not infinite but that amount of energy is beyond my compression .

For almost all organisms it's the sun.

The sun.

The only exception are the life forms that live around hydrothermal vent.

http://www.ceoe.udel.edu/deepsea/level-2...