Introduction to freshwater invertebrates / James H. Thorp and Alan P. Covich -- An overview of freshwater habitats / James H. Thorp and Alan P. Covich -- Protozoa / William D. Taylor and Robert W.

Introduction to invertebrates of inland waters / James H. Thorp, Walter W. Dimmick, and Alan P. Covich -- An overview of inland aquatic habitats / James H. Thorp and Alan P. Covich -- Protozoa / ...

There are millions of different types of living things on Earth. In order to keep track of them all, scientists put living things into groups based on characteristics that they have that are the same.