Freshwater mussels of the family Unionidae, also known as naiads, have inhabited fresh waters around the world for the last 400 million years. Here in Texas, the presence of these unique mollusks ensures our water quality, helps support the worldwide pearl industry, and, in a quirk of history, influenced the founding of San Angelo. Yet their continued survival is by no means certain, due to overharvesting, environmental degradation, and the rapid spread of exotic mussel species.

To help professional biologists and amateur naturalists know and preserve these mollusks, this book provides baseline reference material for all 52 species of freshwater mussels in Texas. It focuses particularly on the unionids, with brief descriptions of other freshwater bivalves. A typical entry includes the following information:

• Scientific and common names
• Distribution (with a range map)
• Size / Shell / Shell teeth
• External color / Internal color
• Soft tissues / Habitat / Spawning
• Glochidia / Hosts
• Economic importance
• Comments

Color photos illustrate each species. In addition to the descriptions, the authors offer general discussions of freshwater mussel anatomy, biology, ecology, and commercial uses.