2.4.3. Pyramid of Energy

To compare the functional roles of the trophic levels in an ecosystem, an energy pyramid is most suitable. An energy pyramid, reflects the laws of thermodynamics, with conversion of solar energy to chemical energy and heat energy at each trophic level and with loss of energy being depicted at each transfer to another trophic level. Hence the pyramid is always upward, with a large energy base at the bottom.

Let us explain this with an example. Suppose an ecosystem receives 1000 calories of light energy in a given day. Most of the energy is not absorbed; some is reflected back to space; of the energy absorbed only a small portion is

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All snakes smell with their tongues. When a snake sticks out its tongue it smells its surroundings. The moist tongue collects scents and small organisms from whatever it touches and from the air around it. When the tongue goes back into the mouth the forks touch a special sensory spot called the Jacobson’s organ on the roof of the mouth and tells the snake what it smells. Snakes have a small notch in their lips that they can stick their tongues through so they don’t need to open their mouths. Some snakes can smell with their noses.

utilised by green plants, out of which the plant uses up some for respiration and of the 1000 calories, therefore only 100 calories are stored as energy rich materials.

Pyramid of energy

Now suppose an animal, say a deer, eats the plant containing 100 cal of food energy. The deer uses some of it for its own metabolism and stores only 10 cal as food energy. A lion that eats the deer gets an even smaller amount of energy. Thus usable energy decreases from sunlight to producer to herbivore to carnivore. Therefore, the energy pyramid will always be upright.

Energy pyramid concept helps to explain the phenomenon of biological magnification-the tendency for toxic substances to increase in concentration progressively at higher levels of the food chain.