Venom Research in Colorado

​If you’ve ever bumped into a rattlesnake in Colorado during a summer hike, chances are it was a Prairie rattlesnake (Crotalus viridis). These snakes are the widest ranging venomous snake in Colorado and are sometimes encountered by hikers on trails in the plains and the foothills. Just like people, snakes tend to be more active during the warm summer months, as they rely on higher temperatures to be able to capture prey, migrate and reproduce. With rattlesnake season in full swing, our venom analysis lab at the University of Northern Colorado is hard at work collecting Prairie rattlesnakes from new locations in Colorado. After we capture snakes, we extract venom, dry it down, and process it to understand its composition and properties.

​Venoms are complex mixtures containing different toxins that can cause a huge variety of symptoms when a person is bitten. Different species of snakes and even populations of the same species can have different types of toxins because they live in different environments and eat different kinds of prey. Our lab is interested in determining both how and why venom composition varies between species of rattlesnakes found in the western United States. 

Most people bitten by venomous snakes in the United States survive because of the effectiveness of antivenom and the fact that medical help is usually readily available. However, it’s important to know the composition of venoms from snakes throughout the country because the effects of their toxins can vary widely. For example, knowing which snakes possess potent toxins that affect the nervous system or those that contain tissue digesting enzymes can help inform snake bite treatment as well as make anti-venom production more effective. 

Understanding venom variation can also tell scientists a lot about the history and ecology of a particular snake species. To answer these kinds of questions we need to have a good understanding of what types of animals are typically prey items for a certain species or population. For example, sea snakes primarily feed on fish which is reflected in the toxins present in their venoms that are very effective at killing fish. Rattlesnakes in general tend to feed on small mammals like mice, but will eat whatever they can get, leading to venoms with many different kinds of toxins that can kill prey in a variety of different ways. 

​The Prairie rattlesnake is not only common in Colorado, it’s range spreads from southern Canada to northern Mexico. Though it has such a large range, we still don’t understand how or why its venom varies. Because of this our lab is interested in studying geographic variation in venom composition since this species lives in many different environments with many different prey items. By separating and purifying the main toxins that make up venoms from snakes in geographically distinct areas, we now know that this species varies in levels of medically significant toxins throughout its range. We see snakes in certain areas with higher amounts of tissue digesting enzymes, while snakes in other areas primarily have potent toxins that affect the nervous system. Knowing these differences can help medical professionals give better medical care to people bitten in different areas. Our study will be ongoing for the next few years, and we hope that our research can answer questions about snake ecology as well as help with snake bite treatment. 

-Cara Smith
PhD student, Venom Analysis Lab
Curator, UNC Museum of Natural History
University of Northern Colorado