Wetlands have been called "biological supermarkets." Besides animals that live there permanently, many nonwetland animals, such as opossums, raccoons, and skunks, visit for food and water. Wetlands also provide shelter for mammals such as minks, moose, and muskrats. Wetland conditions make it necessary for the animals that live there permanently to adapt in special ways.

Microorganisms

Microorganisms cannot be seen by the human eye. Those found in wetlands include protozoa and bacteria. Protozoa are single-celled animals that can use the Sun's energy to make their own food. Other protozoa are parasites that live on aquatic plants, on damp ground, or inside animals or plants. Bacteria are also single celled, but they cannot make their own food and must obtain it from the environment.

Some protozoa infect mosquitoes with malaria, a disease characterized by chills, fever, and sweating. The mosquitoes then spread the disease to humans. Malaria...