Amputated gecko tails jump and move around long after their bodies are gone

As a last-ditch effort to distract predators and escape, some animals will remove a limb or organ from their body. Geckos take this already hardcore survival strategy to insane new levels — their tails effectively remain alive long after amputation.

A ton of species are known to jettison appendages in a desperate attempt to save the rest of themselves. It's a list that includes everything from snakes to spiders to octopuses to even fellow mammals like Culver's spiny rat. Mostly, this is just meant to give the predator a second target, and that moment of hesitation is usually enough for the now somewhat reduced animal to escape. With their connections to the animals' nervous system severed, the appendages usually stop working more or less immediately.

Leopard geckos, however, are a major exception, as researchers at UC Riverside and the University of Calgary discovered. Their tails can actually keep moving for a full thirty minutes after being shed. The tails are able to swing back and forth in a simple rhythm, and even more amazingly they can flip and jump about an inch in the air. Researchers Timothy Higham and Anthony Russell put these gecko tails to the test by charting the electircal activity some freshly shed specimens. Writing for New Scientist, Michael Marshall details what the researchers discovered:

The two types of movement followed different patterns of electrical activity. The tail jumped or flipped when both sides were activated simultaneously, whereas – not surprisingly – it swung from side to side when first one side then the other was activated.

Jumps and flips were triggered by bursts of pulses that varied much more in length than those triggering rhythmic swinging. Higham says this suggests they are controlled by separate neural circuits, rather than a single circuit that can send out different signals. The swinging seems to be controlled by an automatic process, but the jumps and flips are far more erratic. Higham says the circuit controlling them may be linked to the tail's touch receptors, so the jumps and flips could be a response to external stimuli.

Although exactly how the leopard gecko evolved this bizarre ability is still a mystery, its purpose is pretty clear. It's one thing to shed an appendage that just sits there motionless on the ground - that isn't going to fool a predator for very long. But a tail that can actually move and even jump about? That's a far more tempting target, and that flipping tail is much more likely to allow the leopard gecko to escape.

Original paper at The Journal of Experimental Biology via New Scientist. Image by Ryan Somma on Flickr.