Online Class: Snakes of the Western Hemisphere

Snakes, also known as serpents, are the focus of this course, with heavy emphasis on snakes of the Americas. Topics include snake history, biology, lifestyle, and more along with detailed understanding of each major type of snake. Prevention and treatment of snake bites and attacks, along with snake-related activities and hobbies close out this course, leaving students empowered and equipped in both knowledge and practical application. 

Snakes are part of the order squamates, which includes snakes and lizards, but also belong to the suborder serpentes -- the reason they are also called serpents.

There are almost 3,000 species of snakes that range widely in size, capability, and location. Antarctica is the only continent on which no snakes have been found due to its extremely cold temperatures and snakes' ectothermic nature. Snakes also live in both the Indian and Pacific Oceans, as these tend to have more mild temperatures than some other bodies of water. Although snakes do live on many smaller land masses, there are some sizable islands (such as New Zealand and Ireland) where snakes exist only in zoos.

Historically speaking, the fossil record of snakes tends to be inadequate and largely unknown. Snake skeletons are usually fragile and small, making fossilization more difficult. Earliest fossils have been found in Algeria and Utah from the Cretaceous period. It is widely accepted that prior to these early recognizable snake fossils, snakes descended from lizards. During the Paleocene Era, however, modern snakes became tremendously diversified following the extinction of dinosaurs. Nonetheless, snake origins are somewhat unknown, although there are two primary hypotheses:

• The Aquatic Mosasaur – This theory presents the idea that snakes evolved from mosasaurs -- aquatic reptiles from the Cretaceous period that are now extinct. Mososaurs, in turn, evolved from varanid lizards (carnivorous and generally intelligent reptiles). This hypothesis holds that the need to combat marine conditions, such as osmosis-related corneal water loss and disuse of ears, resulted in the fused, transparent eyelids and lack of external ears found in snakes. During the Cretaceous period, many of these reptiles became terrestrial.

• The Burrowing Lizard – Some fossil evidence indicates that snakes may have evolved from burrowing lizards. There were both terrestrial and semi-aquatic burrowing lizards; the theory is that their bodies evolved to primarily burrow, which caused them to eventually lose their limbs. Due to the nature of burrowing in the ground, the corneas of the eyes would become continuously scratched and the ears would be filled with dirt, thus resulting in a loss of the external ears and the development of the fused eyelids.

Scientists are continually discovering new fossils and the debate over snakes' origin continues; either hypothesis could be accurate, but it is also very possible for both to be wrong or incomplete.