Biodiversity is short for biological diversity—the variety of living things on Earth. Our planet is so rich with life that scientists don’t even know for sure how many different kinds of organisms may exist.

So far, they’ve identified and named more than 1.7 million species, including:

Mushrooms photo: Rob Bierregaard

• 950,000 species of insects
• 270,000 species of plants
• 19,000 species of fish
• 10,500 species of reptiles and amphibians
• 9,000 species of birds
• 4,000 species of mammals.

The rest includes mollusks, worms, spiders,
fungi, algae, and microorganisms.

But scientists think that millions more species, mostly microorganisms and invertebrates, such as insects and worms, are yet to be discovered.