A 3D-Printed Rattlesnake Reveals How the Rattle Stirs Fear, Even in Animals Unfamiliar with the Sound
The distinct rattle of a rattlesnake is one of the most well-known defensive sounds in nature. As humans, we know that sound means “stay away” even if we don’t live in areas where rattlesnakes are prevalent. This can be said of most animals that commonly interact with rattlesnakes, such as mountain lions.
But can the same be said for animals that don’t cross paths with these snakes? This was the question of a group of researchers from the University of Texas at El Paso. Their findings, published in the journal PLOS One, dive into that question and reveal why the rattle is such a prominent deterrent.
“This research is an effective demonstration of scientific creativity and interdisciplinary innovation,” said Liz Walsh, interim dean of UTEP’s College of Science, in a press release.
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3D-Printing Custom Rattlesnakes
For this study, the El Paso research team, with the help of Fab Lab El Paso, 3D-printed a nearly life-like robotic rattlesnake and tested how 38 different species at the El Paso Zoo would interact with it.
The 3D model displayed a rattlesnake’s typical posture, with the rattles actually taken from deceased snakes found on the road near El Paso.
The snake models were then presented to the zoo animals across three trials. For the first trial, the team placed a food reward in the animal’s enclosure, then released the animal to claim it. For the second trial, the team did the same thing, except they placed the snake model next to the food reward, but did not activate the rattle. In the third trial, the food reward was again placed next to the snake, but when the animal approached for the reward, the rattle was switched on.
How Animals React to Rattlesnakes
The researchers found that when the rattle was switched on, all the animals tested showed some form of adverse reaction. This, according to the research team, demonstrates that the snake’s rattle is an effective deterrent regardless of species.
However, what surprised the research team was that species that typically share their ecosystems with rattlesnakes, like mountain lions and collared peccaries (javelinas), showed a much stronger fear response than animals that don’t have these snakes in their natural ecosystems. Even more surprising is that all of the animals were born in captivity, and therefore could not have learned this behavior in the wild.
“These results suggest the rattlesnake rattle serves a dual purpose,” said Océane Da Cunha, lecturer and graduate student coordinator in UTEP’s College of Science, in a press release. “Animals with no prior exposure to rattlesnakes still reacted strongly, which supports the idea that rattling acts as a deimatic, or startle, signal. But the amplified response in species that share their present distribution with rattlesnakes points to an evolved, innate sensitivity to the rattle.”
A Better Understanding of Rattlesnakes
The team also notes that the rattlesnake rattle is a rare example of multimodal defensive display, as the snake combines body posture, sound, visual cues, and tail vibration. Thanks to the team’s snake model, they can test this type of combined display in a controlled environment, something that has been difficult to do with live snakes in the past.
“By combining engineering, behavioral ecology, and evolutionary biology, Dr. Da Cunha and her team have advanced our understanding of how signaling systems evolve and why they persist,” said Walsh in the release. “Their findings not only illuminate rattlesnake behavior but also contribute broadly to our knowledge of animal communication and predator–prey interactions.”
The results add to a long-standing hypothesis that the rattle originated as a simple startle behavior and then evolved into a deeper warning. These results also raise further questions about how animals develop innate fears and how those traits evolve.
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