A new study is shedding fresh light into the incredible world of California’s temperate forests, and the daring survival techniques of one of its inhabitants: parachuting salamanders.
研究, published on Monday in the journal Current Biology, shows how salamanders living in the canopy are able to parachute consistently, slowing their speed and controlling their movements.
Salamanders aren’t exactly known for their agility and their dexterity – people associate them with rotting logs and streams, said Christian Brown, a doctoral student in biology at the University of South Florida. But the study shows the counterintuitive nature of these creatures, and has implications for other organisms that may not look cool but have special abilities.
“This is a five-gram salamander that climbs the world’s highest trees and isn’t afraid to take a leap of faith,” said Brown.
Scientists knew before that wandering salamanders lived in redwoods, and in dense numbers – sometimes 30 或者 40 individuals in the crown of one tree.
The amphibians are lungless: they breathe through their skin and the tissue surrounding their mouth. The forest’s damp fern mats in the canopy helped prevent them from drying out, and offer a safe haven.
在 2020, Brown and colleagues had published a detailed description of how the salamanders jump. Unlike other species, they used two feet instead of one. They don’t take off as quickly in a horizontal way, hinting at something: jumping with less power might be contributing to stability after the jump, said Brown. “It’s better to be in control after the jump than to jump really powerfully.”
毕竟, if you’re going to jump from the world’s tallest trees, you’ll need to parachute and glide.
To test their skydiving abilities, Brown put the five-inch-long salamanders into tiny wind tunnels – the same type you might see at an indoor skydiving park, just in a salamander’s size. And just like human skydivers, the salamanders moved their bodies and limbs to slow their descent, successfully slowing their velocity by 10%, the researchers found.
They dropped three other species of salamanders into the wind tunnels. The wandering salamanders, Brown says, “slowed themselves down the best”. They also pumped their tails and moved their limbs to change direction horizontally.
Why did the species evolve this special trick, since salamanders don’t seem to be very aerodynamic or prone to fly? Because salamanders can’t answer that question themselves, scientists have to use what we know about the ecosystem and come up with hypotheses to test, Brown said.
One idea is that they use jumping and dropping to quickly escape predation. 在实验室, just tickling a wandering salamander’s tail will cause it to jump.
Another idea is that the salamanders’ moves are a form of locomotion – an elevator up and down the forest canopy. Brown thinks most of the jumps take place from tree to tree 40 到 80 feet above the ground – far enough where a fall might not be fatal, but it would put a salamander in danger during a long trek home. Another study showed it would take the salamanders hours to days to get back up to the crown from the ground. Pacific giant salamanders stalk the forest floor and prey on the wanderers, while all their resources – food, dampness, mates – would be far up in the labyrinth of mats and ferns. So jumping would be an easy way to get around. “It’s more efficient and minimizes the risks,” said Brown. “Ultimately we think the jumps are a prevention for falling all the way to the forest floor.”
The researchers now want to assess in more detail how the salamanders sail through the air in their natural environment, at the tops of trees. They are using ladders to drop them a few meters outdoors paired with onsite observations from up to 200 feet high to test this behavior in the field. They are also taking the glide patterns observed in the lab and overlaying them with maps of redwood crowns and salamander locations to better visualize the effectiveness of gliding at steep angles in their habitat.
The study has shown that salamanders can move their bodies in completely unexpected ways – turning, parachuting, gliding to the next branch. “The level of control is kind of exceptional, so that’s exciting,“ 他说. “This is an animal that can leap around with dexterity to navigate its habitat … and they just might surprise you.”