Air-Breathing Fishes : Evolution, Diversity, and Adaptation

Rating:
Summary: Fish lung is quite ancient
Review: Although this book is a detailed survey and synthesis of air-breathing fishes, it is clearly written, and provides introductory background information on the subject. As is pointed out several times, while air-breathing fishes are often considered as the fishes which evolved the ability to breathe in the air, and then invaded the land to evolve into the land vertebrates, this is not entirely correct. The fish lung evolved in the ancestor to both the ray-finned fishes and the lobe-finned fishes, many millions of years prior to transition to land. In the Upper Devonian one of many different fishes with lungs, a group belonging the lobe-finned fishes, became amphibious and eventually evolved into the tetrapods. While the fish lung was conserved and exists in the modern lungfish, in the bulk of fishes, such as modern teleosts, the fish lung evolved into a non-respiratory gas bladder, used largely for buoyancy control. Nonetheless, for more than three hundred different species of modern freshwater, shallow fishes, air breathing is a valuable mechanism to cope with hypoxic water conditions, and was conserved or re-evolved.