Flips, flops and cartwheels
Scientists discover gecko tail has mind of its own
Anthony Russell holds a Leopard Gecko, tail still in place. / Photos: David Fairbanks
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
Anthony Russell of the University of
Calgary and Tim Higham of Clemson University in South Carolina are
closer to solving this mystery as outlined in a paper they co-authored
published in the journal Biology Letters.
The scientists demonstrate that tails exhibit not only rhythmic but
also complex movements, including flips, jumps and lunges, after the
tails are shed. 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.
The new findings are significant because Higham and Russell’s
discoveries indicate that the lizard tail can provide a model for
studying the complex functions of the spinal cord and the effects of
spinal cord injuries.
is known about the ecological ramifications of tail loss, such as
distracting predators, storing energy reserves and establishing social
status but little is known about the pattern and control of movement of
autotomized gecko tails,” says Russell a biological sciences professor
at the U of C.
“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 3 centimetres height.”
Higham, a former U of C student and now an assistant professor of
biological sciences at Clemson, says more study needs to be done.
“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?” says Higham.
The Leopard Gecko can sheds its tail to avoid predators.
“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.”
The ability of an animal, or part of an animal, to move without the
active control of higher centres 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
behaviour 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 autotomized gecko tail may be an excellent model for understanding
the spontaneous activity that is sometimes observed following partial
or complete spinal cord injury,” says Russell.
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 centre located there that is likely overridden by higher
centres until the tail is shed, at which point its potential is
The scientists’ paper can be found online at: http://rsbl.royalsocietypublishing.org/