UNC Professor Details How Prairie Rattlesnakes Survive in Yellowstone for Discovery Channel

Research supports hypothesis that the answer lies in the snake’s venom

Screen shot of Professor Stephen Mackessy from TV program

UNC Professor Stephen Mackessy discusses his experiment in this screenshot from the Discovery Channel program "X-Ray Yellowstone." Related: Watch video of the segment below.

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Research by University of Northern Colorado Professor Stephen Mackessy provides evidence that a protein in their venom has allowed prairie rattlesnakes to adapt and survive in harsh environments, such as those in Yellowstone National Park.

The presence of the venomous North American snake in Yellowstone has been considered a scientific mystery.

"We've long hypothesized that venom has allowed prairie rattlesnakes to expand their behavioral repertoire that's typically been out of reach," Mackessy said.

It typically takes snakes, which are cold blooded, about five days in normal 75-degree temperatures to digest their prey. If the process takes longer, deadly bacteria from the decaying meal can build up and the toxins can kill the snake. Furthermore, digestion typically shuts down below 55 degrees, Mackessy said.

In "unprecedented" experiments in his lab, Mackessy replicated Yellowstone's extreme temperatures in the snake's habitat and took a series of X-rays of prairie rattlesnakes that ingested mice. It took the snake much longer to digest the mouse that had not been injected with venom. Mackessy ended the experiment before it became lethal for the snake. When venom was introduced into the prey before being consumed, X-rays confirmed that digestion was nearly complete after five days.

"One of the major components of prairie rattlesnake venoms is what we call proteolytic enzymes, and these are proteins that chop up other proteins," Mackessy said on the program "X-Ray Yellowstone" for the Discovery Channel series Curiosity, whose producers approached him to conduct the experiments.

The program initially aired on the Discovery Channel last month and was then re-broadcast multiple times on the Science Channel.

"This is an area that encapsulates an interest since I began doing research: what are the venoms doing for the snakes themselves," he said, adding that prairie rattlesnakes make it the farthest north of large-bodied snakes. Their habitats stretch from southern Canada to northern Mexico.

Mackessy, a UNC biology professor internationally known for his research on venomous snakes, has received $1.3 million supporting his research and scholarship since 1991. He has published more than 50 research articles, one book and six book chapters, and has presented at more than 50 local, national and international scientific meetings. During his 21 years at UNC, he's involved nearly 50 undergraduate students in his research, which focuses on how compounds in snake venom can be used in cancer-fighting drugs.

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