A population is defined as a group of individual organisms that occupy the same habitat and are of the same species. This means that they interbreed and produce fertile offspring, supporting each other and maintaining the balance of their ecosystem. Pictured above is a school of fish that live together and interbreed, which fits the definition of a population. Several species find ecological advantages to living in groups. In the case of these fish, it can be observed that traveling in large numbers reduces the amount of friction working against each individual. There’s also the well-known dogma of “safety in numbers,” in which a school of fish can appear more intimidating to potential predators when they swim as a population.