A recent study from Washington State University (WSU) found that wandering salamanders (Aneides vagrans), known for their agility when it comes to traversing the high canopies of redwoods in their native north-west California, may have blood-powered toes that enable them to both stick to and take off from trees with ease.
Previously, just how these small, mottled amphibians were able to leap and land so assuredly was something of a mystery. The tips of salamanders' square-shaped toes are covered with translucent skin that encases visible blood 'lakes’ and it was assumed that these lakes merely aided oxygenation.
However, new research, published in the Journal of Morphology, found that to the surprise of experts, salamanders actually fill, trap and drain blood in the tips of their toes, giving them far more control when it comes to attaching, detaching and general locomotion (movement) in their leafy surroundings.
The study was initiated by Christian Brown, lead author and an integrative physiology and neuroscience postdoctoral researcher at WSU.
Brown’s interest was piqued while assisting as the salamander expert during the production of a documentary when he noticed through the high-spec cameras that their toes were filling with blood before detaching from the surface.
In collaboration with the camera assistant William Goldenberg, they conducted high-resolution video trials and witnessed how wandering salamanders finely control and regulate blood flow to each side of their toe tips. This allows them to adjust pressure asymmetrically, improving grip on irregular surfaces like tree bark.
It appeared to show that blood rushing into the toe seems to help salamanders detach rather than attach.
By slightly inflating the toe tip, the salamanders reduce the surface area in contact with the surface they are on, minimising the energy required to let go.
This dexterity is crucial for navigating the uneven and slippery surfaces of the redwood canopy, and for safe landings when parachuting between branches.
While Brown plans to expand the research to include other salamander species and habitats, it’s also hoped that this previously unknown physiological mechanism in salamanders may aid bio-inspired designs such as prosthetics and even robotic appendages.
Speaking of the research, Brown said: “If you’re climbing a redwood and have 18 toes gripping bark, being able to detach efficiently without damaging your toe tips makes a huge difference." He continued: “This could redefine our understanding of how salamanders move across diverse habitats.”
He added: “Gecko-inspired adhesives already allow surfaces to be reused without losing stickiness. Understanding salamander toes could lead to similar breakthroughs in attachment technologies.”
Main image: Wandering salamanda/William P. Goldenberg
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