Species diversity is the most familiar type of biodiversity. In this catagory, every group of organisms that can reproduce among itself is recognized for its environmental niche. A young girl shares moment with a lamb at a children's petting zoo. Photo taken by Barb Aldridge, 1987.

Although it would be nearly impossible to count each one, most scientists estimate that there are at least 10 million unique species of organisms on Earth.

Today, scientists have named and identified more than 1.75 million species but believe this is just 20 percent of the total existing species. We will probably never be able to accurately calculate the total number – species are constantly going extinct, more quickly than we can learn about them. (Encarta, "Biodiversity")

Many local environmental organizations seek to preserve the environment by saving one species at a time. This by itself is insufficient, because species are all interrelated. The outcome of one species determines life for all others in its ecosystem.

Ecological Diversity Species Diversity Genetic Diversity

What is biodiversity? | Global Hotspots | Mass Extinction | Florida Everglades | Bibliography