SDSU researchers blindfold rattlesnakes to study night navigation

SAN DIEGO — A San Diego State University doctoral student has discovered that rattlesnakes primarily use their eyes to see at night rather than their heat-sensing abilities used to hunt prey, the university announced Tuesday.

Doctoral students Hannes Schraft and SDSU biologist Rulon Clark sought to test a group of rattlesnakes at the Barry M. Goldwater Air Force Range in Yuma, Ariz. The two researchers used a small strip of duct tape to blind some snakes and a small amount of beeswax on other snakes to block the heat- sensitive membrane on their faces. A control group of snakes received neither blocking mechanism.

“I was expecting to see that when they were blindfolded, but had their infrared organs that they would still be just fine,” Schraft said. “Because they could `see’ those warm bushes with infrared. When snakes hunt, that’s what they can do.”

The two researchers released the test subject snakes into a 10 meter wide area with four bladder sage bushes. The snakes without blindfolds who had their membranes blocked easily found the bushes while the blindfolded snakes had a much harder time trying to find them.

“When you cover a snake’s eyes, its movements immediately become a lot more erratic,” Schraft said. “They don’t find the bushes at all.”

According to SDSU, no snakes were harmed during the study. The university’s Institutional Animal Care and Use Committee signed off on the study’s method before Schraft and Clark proceeded.

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