A few examples of well-known primary consumers are cows, deer and rabbits. These animals are strict herbivores, meaning that they only eat plant-based food sources. Other examples of primary producers include elk, moose, impalas, gazelles, wildebeest, hippopotamuses, giraffes, elephants and many insects.
Biologists place organisms in one of several categories, called trophic levels, depending upon what they eat. For example, green plants manufacture their own food via the process of photosynthesis; accordingly, scientists call them “producers.” Whereas producers make their own food, organisms at the next trophic level consume the producers. This leads biologists to classify most animals as “consumers.”
Biologists recognize a key difference between the types of consumers. Some subsist exclusively on plants, so they earn the name “primary consumers.” Other animals, such as lions, tigers and snakes, subsist exclusively on primary producers, so they bear the title “secondary consumers.”
Eventually, all animals die, and organisms called “decomposers” break down the dead animals, and release the chemicals and resources within the animal into the environment. Plants draw these resources from the soil via their roots, and begin the process anew.
Inefficiencies in the food chain cause each trophic level to have less energy than the preceding one. As a general rule, only 10 percent of the energy in any level is passed on to subsequent trophic levels.