They jump from branch to branch very quickly. Meters from the ground, without falling. How do you do that? American biologists have studied the behavior of black eyebrows based on three experiments and slow-motion images. In Science They write Both the distance and curvature of the branches play into split-second trade-off games.
Black eye (Black eye) Lives in eastern North America, body length 25 to 40 cm, larger and heavier than Eurasian red pineapple. But whether or not the pine flees from the mortons or hawks, it jumps from tree to tree.
To analyze these acrobatics biomechanically, Nathaniel Hunt and colleagues built an arrangement in which Annan had to jump from a small platform to a wooden beam. Attached a forged branch to the platform: a horizontal slot where the eyebrows can run to jump into the beam. The flexibility of the false branches was different.
During the experiment, Annan also discovered a new strategy
Thus, they found that branch springs jump faster and faster: in the most flexible false branches, they jump when the distance to the beam is still more than three bodies. At least on the flexible false branch, they only jumped below a body length.
They further challenged the eyebrows by increasing the distance from the beam and the flexibility of the false branch. Each eye made the same jump five times. In this way, they wanted to find out if the animals had improved their jumping. In fact: the number of ‘landing errors’ – swinging too far above or below the beam – decreased. It never went wrong: not a single eye fell to the ground on the first jump.
In the third experiment, the researchers adjusted the beam height compared to the initial platform, and varied the distance. Now the Annans have invented a new strategy: they also used the vertical back wall of the test setup so that by turning their legs, they were able to push half of the jump away from that wall. For longer distances (up to five body lengths), the back wall of the eye is often used. Biologists suspect that animals use extra push-offs to correct their speed, so they do not cross the bar.
In an additional message In Science Neuroscientists Karen Adolph and Jesse Young brought the research of Hunt and colleagues to a broader perspective. An eye baby who learns to jump is not much different from learning to crawl and walk, they write – in both cases there is constant interaction with the environment to calculate proper movements. However, a bigger impact often falls from a tree than from a soft carpet in the living room.
Learning movements are a lifelong process, they conclude. Annan discovering new trees, for example, for female bats who learn to adjust their flight movements during pregnancy.
A version of this article also appeared in the NRC on the morning of August 6, 2021
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