快猫短视频

How salamanders manage to move around on uneven, vertical tree surfaces with such dexterity has long baffled scientists. A new discovery suggests they use a trick out of a horror movie: filling their toes with pools of blood.

While at Washington State University was observing wandering salamanders (Aneides vagrans) through a close-up camera in 2021 in a coastal redwood forest, he noticed blood moving in a rhythmic pattern under their translucent skin. Before lifting their foot to take a step, blood inundated the tips of the salamanders鈥� 18 toes. Once they placed their foot, the blood dissipated, and they kept their toes drained while clinging to the surface.

In the lab, Brown鈥檚 team filmed three tip-toeing salamanders on a clear platform and examined their internal structures. They found that the salamanders can control the flow of blood to each toe via two blood pathways called sinuses. Blood is always flowing throughout the animal鈥檚 feet, but when the salamander extends its toe tip, it allows more blood to rush in.

The inflation-then-deflation move changes the toe鈥檚 stiffness, which probably 鈥渉as huge implications鈥� for its grip, says Brown. Like an inflated basketball bouncing off the floor versus a flat one sticking, the blood-filled toes appear to help release the animal from a surface.

The move makes sense, especially when you are covered in sticky mucus, says at the New York Institute of Technology, who was not involved in the study. It probably takes wandering salamanders less energy to inflate off a surface rather than to unstick themselves using muscular force.

Toes with two blood sinuses seem to be widespread among salamanders, so similar blood inflating and deflating tricks might be the basis for good grip across a variety of species, says Brown, who plans to study other salamanders to investigate.