Some lizard species can ‘drop’ their tails if they are threatened or captured by predators. The predator is distracted by the twitching tail, allowing the lizard to make its escape.
But can a tailless lizard survive as well as an intact one? New research carried out at the University of California, Riverside, suggests that western banded geckos are just as good at hunting insects whether or not they still have their tail.
“Other studies have documented the negative effects of tail loss on lizards' ability to run, jump, mate and reproduce,” said lead author Marina Vollin. “However, few have examined their ability to capture food when they lose their tails, which is critical for regenerating the tail and for overall survival.”
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To establish whether a tail helps geckos to hunt more successfully, the researchers studied intact and newly tailless geckos as they hunted crickets in an artificial enclosure.
The tailless geckos seemed to struggle more with their balance before and during a strike. The maximum strike velocity of the tailless geckos was also lower, highlighting the importance of the tail during prey capture. Nonetheless, the tailless geckos still captured crickets about 77 per of the time, which was the same success rate as the intact geckos.
However, the researchers say that geckos in the wild may perform differently to those in captivity.
“It is very possible that geckos suffer a loss in feeding performance and success following autotomy in nature given the complexity of the habitat and more room for the prey to escape,” said co-author Dr Tim Higham. “It’s important to get a sense of how they operate in nature, where additional elements could affect whether they have more difficulty capturing prey.”
It can take a western banded gecko up to a month to regenerate its tail, so the team are keen to find out if the lizards regain their agility once the limb has grown back. These lizards are an important part of the ecosystem in Mexico and the southwestern US, as they eat insects and help control the scorpion population, but they are also key prey for birds, snakes and mammals.
“I’ve heard them referred to as ‘nature’s popcorn’, because other animals can eat a bunch of them at once, they’re abundant, and easy to acquire,” Vollin said. “They’re a big part of the base of the food chain.”
Tail loss in lizards
The scientific name for the process by which animals shed a body part is called ‘autotomy’. Tail autotomy is really common in lizards, and is found in 13 of the 20 lizard families.
There are two methods that lizards use to shed their tails: intervertebral autotomy and intravertebral autotomy. In intervertebral autotomy the tail will break off between the vertebrae. With intravertebral autotomy, there are perforated fracture points across the centre of each vertebra in the mid-point of the tail. Blood vessel sphincters will contract after tail loss, to minimise blood loss.
Some lizard species, such as the five-lined skink, have brightly coloured tails to attract the attention of predators, therefore directing attacks away from the head and body and towards the tail, which they can afford to lose if they are captured.
Most lizards that lose their tail can regenerate it over a period of weeks or months. However, the new tail will be made of cartilage rather than bone. The new tail doesn’t tend to be as 'nice' as the original, and may differ in texture, length or thickness.
Most lizards can only regenerate their tail a certain number of times before it no longer grows back. And some species, such as the crested gecko, will never get a new tail.
