Fish-scale gecko in Madagascar evades predators by getting naked – Los Angeles Times
Talk about escaping by the skin of your teeth! Scientists have discovered a new type of gecko — an evasive little lizard who can escape predators’ grip not just by dropping its tail, but by shedding the scales on its skin.
The new species Geckolepis megalepis, described in the journal PeerJ, has big, fish-like scales, larger than any of the other gecko species in its genus. It’s also the first new Geckolepis species to be described in 75 years, and the first currently recognized species in 123 years.
G. megalepis lives in northern Madagascar, where it appears to be found only around the limestone karst of the Ankarana massif. While other geckos do have scales that can slip off passively, Geckolepis seems to have a certain amount of control over the process.
This has created problems for scientists trying to study the genus Geckolepis; capturing the lizards without losing their scales in the process has been a total pain for more than 120 years.
“Indeed, the process of collection often damages even the most intact specimens,” the study authors wrote. “Voeltzkow (1893) captured his specimens with bundles of cotton (‘Wattebäuschen’), and even this was not sufficient to prevent some scale loss.”
Among its scale-shedding brethren, however, G. megalepis’s scales are king. The oversized scales seem to come off at the slightest perturbation, leaving smooth, pink skin beneath.
These scales can be torn off so easily partly because of their size, the scientists said. Bigger scales have much more surface area relative to the edge where they’re attached to the skin than smaller scales do, which makes it easier for the bigger scales to be ripped away.
But the scientists think there’s also a control mechanism at play, in which the gecko contracts a layer of connective tissue beneath the skin to help release the scales, and the skin’s uppermost blood vessels are squeezed to prevent bleeding.
A partly naked gecko looks kind of like a half-picked scab, but at least the look doesn’t last forever.
“The scarless regeneration of the whole integument occurs within a few weeks, apparently starting from stem cells of the deeper layers of the connecting tissue and is considered as unique among vertebrates,” the study authors wrote.
That stem-cell-fueled regenerative power could be of interest to scientists studying applications in human medicine.
Scientists think that these scales are meant as a defensive measure, but they’ve only documented their use as a means of escape a handful of times in the literature: from a scorpion (Grosphus flavopiceus), a bird (Dicrurus forficatus) and a large nocturnal Blaesodactylus gecko. For that last case, the G. megalepis lizard actually slipped out of the predator’s mouth about 30 seconds after it had been caught.
Perhaps these slippery little lizards could teach Houdini a thing or two. In the meantime, scientists say they hope to keep studying how this remarkable gecko skin works.
“Further studies on the role of dermolytic scale autotomy by Geckolepis are clearly needed, in order to understand its functionality with a range of predators (its function against snakes, for instance, has not yet been observed), and to understand the pressures driving the evolution of greater scale size in this particular lineage of Geckolepis,” the authors wrote.
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