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The knight who sheds his armour

Last Updated 28 May 2022, 08:15 IST

In nature, there are many knights with armours. The pangolin’s keratinous overlapping scales, the turtle’s bony shell, and the armadillo’s bony plates and keratinous scutes are all examples of animals evolving means to escape from predators. The fish scale gecko, found in Madagascar’s forests, also has scales but with a critical difference. Instead of using the scales to deter its predator when danger strikes, it opts to lose it. The predator, who possibly dreamt of a yummy dinner, is left with the distaste of hard scales in its mouth.

The scales are deposits of bony tissue within the skin, called osteoderm, which also makes up crocodile scales. When grasped by a predator, the fish scale geckos lose patches of their skin along with the scales—a mechanism called autotomy. This defence mechanism to voluntarily lose body parts is also found in other lizards—many lose their tail when attacked. However, fish-scale geckos lose their skin only after the predator has made contact.

The skin of the geckos has a conducive bilayered structure. Each layer is separated by a network of loose connective tissue. The inner layer is tough, while the outer layer, which is much thicker, is weak and comes off easily. When predators attack, the lizards can shed patches of their looser, weaker outer skin. Scientists believe that the attacking mechanisms of island predators, like snakes and primates, could have led to these geckos evolving the unique ability to lose their skin in defence. While it’s fascinating to lose shining armours and grow them back again, the bald exposed skin patches are vulnerable to elements and pathogens attacking the skin.

Fish scale geckos belong to the genus Geckolepis.So far, scientists have discovered five species of these geckos, with the newest species, Geckolepis megalepis, found in the limestone karst of northern Madagascar in 2017. This gecko has the largest-known body scales of any gecko and loses them with exceptional ease. Spoorthy Raman

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(Published 28 May 2022, 08:13 IST)

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