Blood-powered toes give salamanders an arboreal edge

A new study in the Journal of Morphology reveals the answer may have a lot to do with a surprising mechanism: blood-powered toes. The Washington State University-led research team discovered that wandering salamanders (Aneides vagrans) can rapidly fill, trap, and drain the blood in their toe tips to optimize attachment, detachment and general locomotion through their arboreal environment.

The research not only uncovers a previously unknown physiological mechanism in salamanders but also has implications for bioinspired design. Insights into salamander toe mechanics could ultimately inform the development of adhesives, prosthetics, and even robotic appendages.

"Gecko-inspired adhesives already allow surfaces to be reused without losing stickiness," said Christian Brown, lead author of the study and an integrative physiology and neuroscience postdoctoral researcher at WSU. "Understanding salamander toes could lead to similar breakthroughs in attachment technologies."

Discovery sparked by a documentary shoot

Salamanders of the Aneides genus have long puzzled scientists with their square-shaped toe tips and bright red blood "lakes" that can be seen just beneath their translucent skin. Historically, these features were thought to aid oxygenation, but no evidence supported that claim.

Still frame image showing the hindfoot of a live Wandering Salamander (Aneides vagrans) from a ventral perspective just before the salamander takes a step forward. This image shows the large digital blood sinuses and the points at which they connect near the distal-most joint. Credit: William P. Goldenberg

A Wandering Salamander (Aneides vagrans) clings to a camera lens with a single forelimb after leaping onto the lens during scientific investigation of their jumping, parachuting, and gliding behaviors. Credit: Christian Brown

A Wandering Salamander (Aneides vagrans) stands/clings to a horizontal/vertical surface while a camera and high-powered lens capture the blood activity within the toes. Credit: Christian Brown