Plants utilize sunlight, chlorophyll, water, nutrients, and carbon dioxide to manufacture glucose and release oxygen. We call plants primary producers. Animals consume these plants. We call these consumers. Another name for plant eaters is herbivore.
Carnivores eat herbivores.
Omnivores eat both herbivores and carnivores. Man is an omnivore. Energy flow in an ecosystem is one way. Much energy is lost in the form of heat. The higher the trophic level, the less energy is available to the consumer.