Most of us think of energy as electricity from a plug or gasoline from our favorite station. These forms of energy run our tools, toys and keep our homes at a temperature that we like. For fish and all other living things energy takes the form of food or direct conversion of sunlight. These forms of energy come from only one place, directly or indirectly, and that’s the sun. The oil and coal we use to make electricity and gasoline comes from plants that used the sun to grow and fermented for eon’s underground – kind of like an energy bank. We have been withdrawing from that energy bank pretty heavily for the last 100 years and it will be empty in another 50 years. To understand how energy is used in nature an understanding of the laws of thermodynamics is required. Continue reading