Key ideas1 of 3
Count kinds, not just individuals
Biodiversity describes the variety of species in an ecosystem or across Earth. A species is a kind of organism. Counting organisms alone does not tell us how many species are present. In the diagram, both habitats contain 12 individuals. Habitat A contains only one species; habitat B contains four species, with three individuals of each. B has greater biodiversity by this measure, even though the total number of organisms is the same.
