Features:

1. The image illustrates that energy analysis (making use of conservation of energy principle during energy transformations) often gives partial information easily while getting full information is often very hard. This boon of energy analysis is why it finds so much use in physics and many other fields.

2. To explicate the image: the food web in the image can be analyzed in terms of energy transfers and transformations. One aspect of the analysis is that biota need so much energy to live and can only get so much from their environment (i.e., the Sun and other biota). You can put limits on their behavior from energy analysis without knowing what ATP actually does. Of course, for full information you need to know about the details of the energy transfers.

3. To follow the energy flow in the image: electromagnetic radiation (EMR) from the Sun mainly in visible band (fiducial range 0.4--0.7 μm) → chemical energy and macroscopic mechanical energy (i.e., kinetic energy and gravitational potential energy) in biota → dissipation to waste heat energy all along the way → ultimately re-radiation to space as infrared radiation EMR mainly in the near infrared band (∼ 0.750--1.4 μm).

   In physics, we follow the energy rather than "follow the money".

4. For a definition and general explication of energy, see Physics file: energy_explication_4.html. For an explication of the only physics formula everyone knows E=mc², see Relativity file: e_mc2_4.html.