
Preface
“I shall not pretend to assert that they are as numerous as land snakes; but it is very likely that one hundred species at least of this tribe exist in the waters of the ocean, lakes, and rivers.”
C. S. Rafinesque 1817. Dissertation on water snakes, sea snakes and sea serpents. Philosophical Transaction
When Rafinesque wrote this, 14 species of snakes were considered water snakes. The idea for a global overview of aquatic snakes has attracted my attention since I finished the Homalopsid Snakes, Evolution in the Mud in 2007. Books on sea snakes are available: Malcolm Smith’s classic The Sea-Snakes, William Dunson’s The Biology of the Sea Snakes, Harold Heatwole’s Sea Snakes, and Ivan Ineich and Pierre Laboutes’ Sea Snakes of New Caledonia, to name a few. However, most information on aquatic snakes remains scattered in hundreds of journals and books.

Snakes living in fresh and brackish waters had been mostly overlooked. Snakes inhabiting marine environments were restricted to a relatively few lineages, while snakes using freshwater were found in many more lineages. Furthermore, snakes use aquatic habitats in many ways that may not cause them to be easily recognized as aquatic. For example, some North American snakes spend the winter in water-filled crayfish burrows and are terrestrial or semi-aquatic the rest of the year.

This volume is perhaps best considered an illustrated, annotated checklist of aquatic and semi-aquatic snakes in marine and freshwater environments. The biggest challenge was deciding what species to include and which to exclude. While the intent was to have accounts for all aquatic snakes, where do you draw the line on the continuum? How much evidence do you need to label a species semi-aquatic? I am confident this volume covers the range of snakes that are traditionally considered semi-aquatic. However, knowledge of some of these animals is poor or absent, while others are some of the best-studied reptiles.

Snakes are derived from lizards, but surprisingly few saurians are semi-aquatic, and no extant lizards are known to be aquatic. Bauer and Jackman (2007) found 73 species in 11 families using freshwater habitats. They found no aquatic lizards inhabiting the Nearctic or Palearctic regions. Still, the Neotropics, the Oriental, and Australian regions support the greatest diversities of freshwater forms, particularly in the families Gymnophthalmidae, Scincidae, and Varanidae. Pauwels et al. (2008) listed 153 snakes (about 5% of all snakes recognized at the time) that inhabit freshwater. This number covers 44 genera in six families (Acrochordidae, Boidae, Colubridae, Elapidae, Homalopsidae, and Viperidae), with the greatest numbers in the Oriental (64 species) and Neotropical Regions (39 species).
Aquatic Snake Diversity and Natural History is a survey of the aquatic and semi-aquatic snakes of the world
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