1. Photo by Brocken Inaglory

4. Water Vapor Air Minerals Light

5. Photo by Tomas Castelazo Photo by Edwin Olson Photo by B. Navez

6. Animals and plants in the desert compete over water that is scarce.

11. Photo by "Mike" Michael L. Baird Photo by Brocken Inaglory

12. Photo by Kobako Photo by Zephyris

14. Rabbit are herbivores that eat plants. They live in burrows they dig in the ground. They are preyed on by several carnivores, and they reproduces quickly which reduces competition among predators.

17. Native Introduced

18. 24 European rabbits were released into Australia. The population now numbers in the tens of millions.

20. Green water in the Potomac River due to increased levels of cyanobacteria. Photo by Sasha Trubetskoy