When I was in college, a fellow student bought several “flying” geckos to look into how much they actually steered while in the air. I honestly don’t recall what the verdict was, but I think they did fall differently when blindfolded. Helping with this research project also gave me a small insight into the exotic pet trade. These geckos were all wild-caught, and they all had worms when they arrived. In the end, seven of ten died before an effective treatment was found, and one not long after that. I’m sure that the stress of capture and transportation made everything worse. At the end, I took the two surviving geckos as pets, and they lived with me for about another year before dying.
It was always fun to see them catching the moths I gave them, and to watch them seemingly teleport from one side of the terrarium to the other, and it was fascinating to watch them steer towards the best landing spot (either the slanted sheet that was used as a net below the balcony, or the person holding that sheet). The way various lizards and frogs have evolved to be able to glide and navigate in the air has always fascinated me, but I have to admit that I never expected to hear of an arboreal, gliding salamander.
Salamanders that live their entire lives in the crowns of the world’s tallest trees, California’s coast redwoods, have evolved a behavior well-adapted to the dangers of falling from high places: the ability to parachute, glide and maneuver in mid-air.
Flying squirrels, not to mention numerous species of gliding frogs, geckos, and ants and other insects, are known to use similar aerial maneuvers when jumping from tree to tree or when falling, so as to remain in the trees and avoid landing on the ground.
Similarly, the researchers suspect that this salamander’s skydiving skills are a way to steer back to a tree it’s fallen or jumped from, the better to avoid terrestrial predators.
“While they’re parachuting, they have an exquisite amount of maneuverable control,” said Christian Brown, a doctoral candidate at the University of South Florida (USF) in Tampa and first author of a paper about these behaviors. “They are able to turn. They are able to flip themselves over if they go upside down. They’re able to maintain that skydiving posture and kind of pump their tail up and down to make horizontal maneuvers. The level of control is just impressive.”
The aerial dexterity of the so-called wandering salamander (Aneides vagrans) was revealed by high-speed video footage taken in a wind tunnel at the University of California, Berkeley, where the salamanders were nudged off a perch into an upward moving column of air simulating free fall.
“What struck me when I first saw the videos is that they (the salamanders) are so smooth — there’s no discontinuity or noise in their motions, they’re just totally surfing in the air,” said Robert Dudley, UC Berkeley professor of integrative biology and an expert on animal flight. “That, to me, implies that this behavior is something deeply embedded in their motor response, that it (falling) must happen at reasonably high frequencies so as to effect selection on this behavior. And it’s not just passive parachuting, they’re not just skydiving downwards. They’re also clearly doing the lateral motion, as well, which is what we would call gliding.”
I always love it when scientists discover something new about a species they thought they knew. I also love discovering animals with cool metallic coloring – just look at this little amphibious gold nugget!
I think this story is really cool, and there’s more in the article I linked. I wanted to focus on one bit in particular. See, I’ve noticed that when it comes to discerning the evolutionary purpose for a given trait, I feel like one of the questions on any dichotomous key would have to be “does this conserve energy?”
Brown suspects that their aerial skills evolved to deal with falls, but have become part of their behavioral repertoire and perhaps their default method of descent. He and USF undergraduate Jessalyn Aretz found, for example, that walking downward was much harder for the salamander than walking on a horizontal branch or up a trunk.
“That suggests that when they’re wandering, they’re likely walking on flat surfaces, or they’re walking upward. And when they run out of habitat, as the upper canopy becomes drier and drier, and there’s nothing else for them up there, they could just drop back down to those better habitats,” he said. “Why walk back down? You’re already probably exhausted. You’ve burned all your energy, you’re a little 5 gram salamander, and you’ve just climbed the tallest tree on Earth. You’re not going to turn around and walk down — you’re going to take the gravity elevator.”
I’m of the opinion that life exists because it’s better at breaking things down than non-life. On a cosmic time scale, the entropy “lost” in the development of life is “regained” as we break down our environment to survive. That said, conserving energy is still a big concern for most organisms, so if there’s gonna be an arboreal salamander, it absolutely makes sense that controlled falling would be preferable to all that bothersome climbing.