Crashlanding geckos rely on their tails to get a grip

Crash landings are quite normal for geckos – it is their habit to launch themselves into leaps between trees to traverse new territory. So how do they stick their landings on impact? They stabilise themselves with their tails, according to a study published in Communications Biology.

A gecko on a leaf
A gecko on a rainforest leaf. Credit: Ardian Jusufi.

Geckos use tails to stabalise a crashlanding

Researchers, led by Ardian Jusufi of the Max Planck Institute for Intelligent Systems, Germany, captured high-speed video recordings of wild Asian flat-tailed geckos (Hemidactylus platyurus) as they glided and landed on tree trunks.

They found that the geckos often crashed headfirst into the trees, losing grip with their forearms and rebounding backwards. Thankfully, the geckos stabilised themselves by using their tails and back legs to reorient themselves.

An illustration. The gecko is moving towards a tree. He geckos front legs land on the tree, the tail swings down on the tree, the head falls back and the front legs let go.
An image sequence of the fall arresting response. Credit: Andre Wee.

Unfortunately, two tailless geckos weren’t able to stabilise themselves when they crash-landed, and fell.

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Gecko robots also use their tails

To test why this happened, the researchers developed two gecko-like robots. One had a long tail and the other had no tail. To simulate gecko feet landing on tree bark, the researchers put Velcro on the walls and feet of the gecko-bots.

Understandably, the robot geckos couldn’t leap and glide like real geckos, so how did the researchers get around this issue? They devised catapults to launch the robots into walls.

The researchers found that the tailed robot was successful in sticking to the wall around 55% of the time, but the tailless bot was only successful 15% of the time.

A black robot gecko on a velcro wall
Gecko robot. Credit: Ardian Jusufi lab

This raised another question for the researchers – what if the gecko only lost some of its tail?

To answer this, the team shortened the gecko-bot’s tail to 25% of its original length. Here, the gecko-bot could still stick a successful landing, but it required a lot more force in its foot-grip to hold on.

Based on these results, the authors concluded that the gecko tails helped the creatures crash-land without falling by decreasing the amount of grip-force needed to hold on. They suggest that this may be useful for stabilising robots and drones that are required to land on vertical surfaces.

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