Lasso snake

The brown tree snake can climb trees and power poles by looping itself into a lasso.

Brown tree snake looking at you
Pavel Kirillov, CC BY-SA 2.0, via Wikimedia Commons

Snakes don’t have legs. To get around, they have to get creative. Historically that means one of four different tactics. Undulation, the most common means of locomotion, involves the snake shaping its body into waves and pushing off bits sticking up off the ground to move forward. Sidewinding has similar waves but the snake also lifts off the ground in a rolling motion – so the waves are both side-to-side and up-and-down. Concertina motion is that classic coil, brace, and release, a surprise spring. Finally, there’s rectilinear motion, in which the snake creeps directly forwards rather than forming coils or waves.

That was the state of scientific knowledge of snake locomotion… up until this year. A research team in Guam was monitoring and protecting an endangered species of bird, the Micronesian starling. It’s endangered because of the brown tree snake, an invasive species that has demolished the local bird population. This snake climbs trees to get the birds, using the concertina motion described above. But, it turns out, not just the concertina.

The scientists attempted to block this climbing snake with a big metal cylinder below the birds’ nests. Here in New Zealand we do the same thing to stop possums, stoats, and weasels. It’s normally very effective, because it’s near-impossible to climb a smooth metal pole. But, somehow, the brown tree snake found a way.

Video footage revealed the mystery. It also showed an entirely new method of snake locomotion. A snake coiled itself around the base of the cylinder, gripping its own body and forming a lasso. Then it began to creep upwards:

Impressive. Terrifying and impressive.

[Thanks to Gareth E.]

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