A team of American researchers has discovered a new mode of locomotion in snakes that allows them to climb long smooth cylinders without problems. This unexpected behavior, never seen before, has been discovered in a species from the island of Guam, in Micronesia. Thanks to the new movement, similar to a loop, this snake is capable of climb an electric pole and even cause power outages.
For a hundred years, the ways in which snakes crawl have been categorized into four: serpentine, the most characteristic movement by which the snake moves its body sinuously; concertina, which implies the contraction of the body as a spring or accordion; lateral or side displacement, typical of the species that inhabit the desert to minimize the areas of contact with the burning sand; and rectilinear, characteristic of large and voluminous species that crawl in a straight line.
But the brown tree snake shows a fifth type of locomotion hitherto unknown, as explained by the study authors in the journal «Current Biology». The find was an unexpected result of a project led by a team from Colorado State University to protect the nests of starlings in Micronesia, one of only two native forest species still left on Guam.
The nocturnal brown tree snake has decimated bird populations on the island, where it was accidentally introduced in the late 1940s or early 1950s. The animal has caused extensive damage and is responsible for numerous power outages. all over the island every year.
The team was trying to use a meter-long metal deflector to prevent these snakes from climbing into the birds’ nest boxes. These same deflectors have been used by bird watchers to keep other snakes and raccoons away from birds. But the new study suggests that for this species that is not an obstacle.
The researchers observed on video how a snake formed what looked like a loop around the cylinder and moved its body upward. The biologists were so surprised that we “almost fell out of our chair,” by their own admission. “We saw that part of the video about 15 times,” admits co-author Martin Kastner. Nothing I’ve ever seen compares to that.
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Tree snakes were already known to be very good climbers. They can climb vertically using the smallest projections of a surface and push themselves up more than two-thirds of their body length. They use a movement called accordion locomotion in which the snake bends sideways to grab at least two regions. But loop locomotion is different in that it forms a single grip region and is more physically demanding. So much so that snakes must stop for long periods to rest.
This loop locomotion can contribute to the success and impact of this highly invasive species. It allows these animals to access potential prey that would otherwise be unreachable and can also explain how you scale power poles.
The researchers hope their findings will help bring back starlings and other endangered birds, as they can now design more difficult baffles for snakes. Also, this completely new way of snakes getting around may not be the last to be discovered.