Consumers are heterotrophs, mostly animals which feed on other organisms. Herbivores feed on producers. This is because the herbivores obtain their food directly from plants. The carnivores which feed on herbivores are called as primary carnivores or second order consumers. The animals which feed on primary carnivores are called secondary carnivores. Omnivores eat both plants and animals therefore they are called third order consumers. Detritivores or scavengers are animals which feed on dead bodies of other organisms.