Thursday, 15 October 2015

Overachieving Lizard Grows Three Tails - via Herp Digest

By James Owen, National Geographic,  September 30, 2015
If the ability of some animals to regrow lost tails isn’t weird enough, a lizard has been found with three new tails in the place of one.
Spotted in June in the Metohija region of Kosovo, the adult blue-throated keeled lizard (Algyroides nigropunctatus) had tails that measured 30, 15, and 10 millimeters in length.
The freak individual, besides being a first known in the species, is among only a handful of triple-tailed lizards documented worldwide, according to its co-discoverer Daniel Jablonski, a biologist at Comenius University in Bratislava, Slovakia. Two-tailed specimens are more often seen—though are still relatively rare.
“I have been studying reptiles for a long time and examined hundreds or maybe thousands of specimens, but this was my very first” three-tailed lizard, he said via email.
The three tails are likely glitches in the lizard's autotomy, a self-amputation process in which species shed their tails to escape predators. The animals then regenerate a new tail by replacing the missing bone with cartilage.
Other vertebrates, including salamanders and tuataras—a reptile native to New Zealand—have replaceable tails, though they mostly occur in lizards. 
Past studies of multi-tailed lizards suggest that an extra tail usually happens when the original tail is only partially severed and remains attached.   
But in some cases, the extra appendages are formed after the entire tail is gone—as likely occurred with the Kosovo specimen.
A crushing force likely fractured the base of the lizard's spine, causing a new tail to grow from each separated vertebra, according to the study, published in August in the journal Ecologica Montenegrina. A bird of prey or a dog may have attacked the animal—feral dogs “are pretty common in the Balkans,” notes Jablonski.
Supporting the theory that the lizard lost its old tail completely, its new tails have different colors and scaling patterns than the skin where the break occurred.
“What is cool here is that the original tail has been lost, rather than being damaged and retained,” says Bill Bateman, a biologist at Curtin University in Perth, Australia.
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Autotomy is an important escape tactic for many species, he said, “so it’s not surprising that odd events like this one occur," says Bateman, who wasn't involved in the study.
Even so, the Kosovo lizard is “pretty dramatic, as all three tails look like they have generated from a stump, and all of them look quite big.” 
Bateman once saw specimens of brown anole lizards (Anolis sagrei) in the U.S. with three tails, but "they [had] very short and undeveloped ‘tail-lets'” attached to the original tail, he says.
Having multiple tails may affect balance and pose other handicaps, but the newfound specimen was in good condition, according to the study, and released unharmed.
It's possible the lizard compensates for its abnormality by changing its behavior—ie. becoming more wary of predators and maintaining a smaller territory, Bateman suggests. 
“I doubt there are any health costs associated with having extra tails,” he adds.
And after all, it's a pretty incredible offer: Three tails for the price of one.

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