The Unusual Soft Anatomy of Snakes

This year I had the opportunity to help my friend Lori Neuman-Lee dissect a number of Wandering Gartersnakes (Thamnophis elegans) for her research on the effect of toxic chemicals on reptile physiology. During my Master's, I had the opportunity to help teach a Comparative Anatomy course, during which I learned a great deal about the internal anatomy of vertebrates. However, dissecting an animal for research requires greater accuracy and precision than dissecting for teaching, and we decided to read up on snake anatomy before we got started. Because we found few resources to aid us in our work, we video-taped one of the dissections to help future would-be snake anatomists locate and identify snake organs, several of which can be a little tricky. Check out the video below and learn to dissect a snake! Lori is doing the dissection in the video, and like many things, she makes it look easy. I would recommend some pretty intense practice first if you want to become as accomplished as she is. Salvaged, all-too-common road-killed specimens often make for ideal practice if you don't mind bits of them being smashed, and they sometimes have interesting things in their stomachs.

A few notes: Snakes are long - it's in the blog title. But the implications of being long for the internal anatomy of an animal are not usually considered. For example, in humans and most other animals, paired organs, such as kidneys, lungs, and gonads, are found next to one another, across the body's plane of symmetry. This is not so in snakes; there simply isn't room. Add to their body shape the fact that a great deal of the body cavity must sometimes be filled with eggs or prey items, and there's little room left for the vital organs: heart, lungs, liver, kidneys, spleen and pancreas. That's why snakes have A) evolved elongate organs, B) evolved staggered paired organs, and C) lost some organs or members of paired organs.

Many snake organs are similar in shape to their overall body form. The liver, stomach, gonads, kidneys, and lung are all elongate. Those that come in pairs are either staggered, such as the kidneys and gonads (right always anterior to left), or asymmetrical, such as the lungs. See the tiny left lung near the heart? In a real snake it's almost impossible to find. It is a vestigial organ, meaning it does not function in breathing any more, although in some sea snakes it does have a co-opted function: it helps regulate buoyancy much like the swim bladder of a fish. These adaptations are part of what makes snakes so amazing and unique.

Finally, because 2013 has been designated the Year of the Snake by non-profit conservation group Partners in Amphibian and Reptile Conservation, I hope to help them promote snake research and snake conservation through frequent writing and outreach. As always, thanks for your comments and your readership. Life is Short but Snakes are Long received over 22,000 hits in 2012 and I'm looking forward to an even bigger 2013!

Life is Short, but Snakes are Long by Andrew M. Durso is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.