Each step of the food chain in the energy pyramid is called a trophic level. Plants or other photosynthetic organisms (autotrophs) are found on the first trophic level, at the bottom of the pyramid. The next level will be the herbivores, and then the carnivores that eat the herbivores.

chemical energy

The 10% rule states that between one trophic level to the next only 10% of the energy is passed on to the next. So if producers have 10,000 J of energy stored through photosynthesis, then only 1000 J is passed on to primary consumers.

Four Main Levels of Energy Pyramid

• Producers. The producers and the energy available within them occupy the first level of the energy pyramid.
• Primary Consumers. The second level of the energy pyramid is represented by primary consumers, which are usually herbivores.
• Secondary Consumers.
• Tertiary Consumers.

Least to most: fewest items at the top and greatest at the bottom. For example, the USDA food pyramid shows that fats, oils and sweets (at the top, in the smallest piece) should be eaten less than other foods in larger sections below, like bread, cereal, rice and pasta (at the bottom, in the biggest piece).

Profits are critically important for ventures targeting the bottom of the economic pyramid—the more than 4 billion people who individually earn less than $1,500 per year. Compared with a social responsibility project, a profitable business stands a better chance of being able to increase its scale and impact.

The amount of energy at each trophic level decreases as it moves through an ecosystem. As little as 10 percent of the energy at any trophic level is transferred to the next level; the rest is lost largely through metabolic processes as heat.