The three terms that are used to describe organisms such as lions are third order heterotrophs, tertiary consumers and top carnivores. Lions are also known as apex or top predators.
Lions do not have any enemies other than humans and belong to the very top of the food chain in a grassland ecosystem. Lions are known as tertiary consumers since they eat secondary consumers, which are plant eaters or primary consumers. Heterotrophs are organisms that are not self-sustaining and eat other living organisms. Lions are third order heterotrophs since they eat secondary consumers or second order heterotrophs. Carnivores are animals that eat other animals.