Tree-dwelling salamanders control their fall as they float down from trees by stretching out their limbs like human skydivers do
Salamanders that live in the world’s tallest trees use an outstretched skydiving posture to slow their descent when they jump or fall to the ground.
These wandering salamanders (Aneides vagrans) seek out moisture in the canopy of California redwoods, and thrive in damp fern platforms 60 metres off the ground.
“The fern mats are a refuge up there that allow them to survive, but it’s a harsh world,” says Christian Brown at the University of South Florida. “There are obstacles and dangers, including possibly falling out of the tree.”
While working with the salamanders in a lab, Brown noticed the amphibians willingly leapt from his hand with their limbs splayed. “After they jumped, we realised that they assumed this parachuting posture,” says Brown. “They seemed to have control, but in real time, it’s impossible to tell.”
So, Brown and his colleagues designed an experiment that would let them watch the action in slow motion. After ruling out the possibility of dropping the salamanders from treetops or buildings, they had an ingenious idea: plopping the amphibians in a vertical wind tunnel. The machine, which resembles a miniature indoor skydiving facility, allowed the researchers to record the nuances of the salamander’s motion for a few seconds on camera.
“We dropped them in the wind tunnel, and everybody was kind of floored initially,” says Brown. By outstretching their legs, the salamanders slowed their vertical speed by up to 10 per cent, and they used their tails as rudders to glide horizontally. “We were a bit shocked by just how adept they are at controlling their aerial behaviours.”
To see if this ability was limited to wandering salamanders, the team also put three other species through the same trial: arboreal salamanders (A. lugubris), speckled black salamanders (A. flavipunctatus) and ensatina salamanders (Ensatina eschscholtzii). Arboreal and speckled black salamanders are known to climb trees, while ensatina salamanders live on the ground. Some of the other tree-dwelling species adopted a splayed posture on occasion, but the wandering salamander, which lives furthest from the forest floor, assumed the skydiving position every time.
“They could not only keep themselves upright, but they could manoeuvre, bank turns, and right themselves when they went upside down,” says Brown.
Journal reference: Current Biology, DOI: 10.1016/j.cub.2022.04.033
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