The gecko tail literally has a mind of its own, as it exhibits not only rhythmic but also complex movements, including flips, jumps and lunges, after it is shed, finds a new study.
Anthony Russell of the University of Calgary (U of C) and Tim Higham of Clemson University in South Carolina carried out the study.
Geckos and other lizards have long been known for their incredible ability to shed their tails as a decoy for predators, but little is known about the movements and what controls the tail once it separates from the lizard's body.
Although one previous study has looked at movement of the tail after it is severed, no study up to this point has quantified movement patterns of the tail by examining the relationship between such patterns and muscular activity.
"What we've discovered is that the tail does not simply oscillate in a repetitive fashion, but has an intricate repertoire of varied and highly complex movements, including acrobatic flips up to three centimeters in height," said Russell, a biological sciences professor at the U of C.
"An intriguing, and as yet unanswered, question is what is the source of the stimulus is that initiates complex movements in the shed tails of leopard geckos," said Higham.
"The most plausible explanation is that the tail relies on sensory feedback from the environment. Sensors on its surface may tell it to jump, pivot or travel in a certain direction," he added.
The ability of an animal, or part of an animal, to move without the active control of higher centers in the brain is well known, but this generally occurs as a result of traumatic physical injury.
Tails of lizards are shed under the animal's own control.
Because of this, the behavior of the shed part has adaptive evolutionary importance and its actions are programmed to assist in the owner's survival.
The movements are coordinated by the part of the spinal cord that is housed in the tail.
The isolated tail serves as a vehicle for studying the ways that nerves and muscles act together to generate controlled but complex outputs in the absence of the influence of the brain.
The new study shows that the signals responsible for movements of the shed tail begin at the very far end of the tail, indicating that there is a control center located there that is likely overridden by higher centers until the tail is shed, at which point its potential is realized.