The incredible fish-scaled geckos of Madagascar that tear off their own SKIN as a defense mechanism

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When Madagascar's fish-scale geckos perceive a threat, they resort to an extremes to protect themselves - tearing out of their own skin.

The geckos have large, overlapping scales that flake off so easily that when a biologist in the late 1800's tried collecting them with cotton and handling them carefully, few specimens were preserved with all scales intact.

However, researchers have now made a baffling discovery - the scales are actually a strong armour similar to a crocodile's skin.

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When Madagascar's fish-scale geckos (pictured) perceive a threat, they resort to an extremes to protect themselves - tearing out of their own skin. New research has revealed that the fragile scales have a hidden strength - bony deposits called osteoderms - which is the same material that makes up crocodilian scales

They contain bony deposits called osteoderms, the same material that makes up crocodilian scales. 

Fish-scale geckos (Geckolepis maculata) have large scales, large legs and are cream in color with black bands. 

According to the IUCN, the species is widely distributed in Madagascar and thought to occur from northern to southeastern Madagascar including the offshore island of Nosy Be. 

New research, published in the African Journal of Herpetology, found that osteoderms in fish-scale gecko scales are the same material that make up the tough scales and plates of crocodilians and aramadillos.

This led the researches to wonder: If these geckos have armor, why do they shed it? 

'The big question is why there are these conflicting defense strategies,' said Daniel Paluh, the study's lead author and a doctoral student at the Florida Museum of Natural History. 

'This gecko can actually drop its skin as a defense mechanism, but it also has these mineralizations - usually thought of as body armor - that it's just leaving behind.'

However, Paluh says that the osteoderms might not necessarily serve as a defensive shield - they could contribute calcium for egg development in female geckos or even help regulate body temperature.  

HOW THEY DID THE STUDY  

When Madagascar's fish-scale geckos perceive a threat, they resort to an extremes to protect themselves - tearing out of their own skin.

Now, new research has revealed that the fragile scales have a hidden strength - bony deposits called osteoderms - which is the same material that makes up crocodilian scales, but researchers still aren't sure why the geckos shed their skin.

To conduct the study into the geckos' scales, Paluh studied hundred of geckos using X-ray computed tomography (CT) technology, which uses thousands of X-rays to create high-resolution, multilayered 3-D images of specimens. 

The CT scan of the gecko revealed dense, bony material inside the skin - a feature Paluh hadn't noticed in most other geckos. 

CT scans produced these reconstructions of the skulls and osteoderms of the species Gekko gecko (left), Tarentola mauritanica (middle) and Geckolepis maculata (right) showing the relative thickness and density of their osteoderms

To conduct the study into the geckos' scales, Paluh studied hundred of geckos using X-ray computed tomography (CT) technology, which uses thousands of X-rays to create high-resolution, multilayered 3-D images of specimens. 

The CT scan of the gecko revealed dense, bony material inside the skin - a feature Paluh hadn't noticed in most other geckos. 

'I thought, "Wow, this is really strange,"' said Paluh.

'We started diving deeper to verify that what we were seeing in the CT scan were actually these mineralized elements.' 

While osteoderms are found in some lizards, they are rare in geckos - a group that includes more than 1,600 species. 

Before Paluh's study, only wall geckos (Tarentola) and the tokay gecko (Gecko gecko) were known to have this particular kind of protective outer armor. 

Courtesy of SciNews 

New research, published in the African Journal of Herpetology , found that osteoderms in fish-scale gecko scales are the same material that make up the tough scales and plates of crocodilians and aramadillos. This led the researches to wonder: If these geckos have armor, why do they shed it?

Most geckos have thin skin covered in tiny, granular scales - and they tend to rely on camouflage and the cover of the night to hide from predators. 

But some groups, such as Geckolepis, to which the fish-scale gecko belongs to, have evolved weak skin as a form of defense. said Dr Aaron Bauer, a researcher at Villanova University and co-author of the study. 

When a predators strike them, the geckos can rip out of their skin to escape, 'like the tear-away football jerseys of the 1970s,' he said. 

However, the paradox of the concept of 'sheddable armor' contributed to the widespread questioning of a 1911 study by biologist W.J. Schmidt, who published his observations of osteoderms in the scales of Geckolepis polyepis. 

Researchers were skeptical about his findings until Paluh's CT scan showed that Schmidt was right. 

'Schmidt had to illustrate what he saw, which could have contributed to his work being questioned,' Paluh said. 

Fish-scale geckos (Geckolepis maculata) have large scales, large legs and are cream in color with black bands. The species is widely distributed in Madagascar and thought to occur from northern to southeastern Madagascar including the offshore island of Nosy Be

'It was unclear whether he was replicating the histology accurately. 

'The advantage we have today is that we can combine newer, innovative tools with traditional methods than have been used for hundreds of years. 

'It provides a new perspective to some of the classical anatomical observations.'

To verify that the fish-scale geckos did indeed osteoderms, Paluh also used techniques similar to Schmidt's. 

He cleared and stained excised patches of skin containing multiple scales to determine if the tissue was mineralized, and this revealed tiny, interlocking osteoderms - just like those Schmidt described and drew more than a century earlier.

The inset, left, shows the tightly interlocking osteoderms in a Geckolepis maculata scale magnified 100 times. On the right is biologist W.J. Schmidt's 1911 illustration of the osteoderms he observed in the species Geckolepis polyepis

'Schmidt was a great anatomist, and I'm sure that he was confident in what he saw,' Said Dr Bauer. 

'Indeed, anatomists of his time, working with much less technically advanced equipment than we have today, were pretty good about getting animal anatomy right.' 

The researchers think that osteoderms evolved independently in Geckolepis, Tarentola and Gekko gecko because they are not close relatives, and CT scans showed osteoderm structure and density vary among the three. 

G. gecko and Tarentola mauritanica have plate-like and granular osteoderms, while in G. maculata, the deposits resemble the small irregular pieces of a mosaic. 

According to Paluh, further research is needed to determine how the bony deposits develop in Geckolepis and whether they can be regenerated after scales have torn away. 

'There are plenty of interesting questions left to answer,' said Paluh.

'Clearly, our understanding of gecko anatomy isn't yet complete.' 

Fish-scale geckos shed their skin when threatened. But CT scans (pictured) reveal bony deposits - essentially body armor - in their scales, raising the question of why the geckos seem to have conflicting defense strategies