Monday, 14 November 2011

The Protective Shell of The Scaly–Foot Snail

The scaly-foot snail found at the floor of the Indian Ocean has one of the strongest exoskeletons ever discovered in nature. It can withstand the water pressure occurring at a depth of some 2,400 metres.
This mollusk is unaffected by both the high acidity of the water and its fluctuating temperature – Including the hot water that gushes forth from hydrothermal vents. The shell also shields it from attack by predators.

The scaly-foot snail’s shell has three layers. The first is composed of iron sulfides, the second resembles the protein coating found in other snail species and the third is made up of a calcium mineral called aragonite. With its triple layer of defense, the scaly-foot snail is impervious to attacks by predators crabs, which try to crush the shell with their powerful claws. The crab may grip the snail for days at a time, but the shell holds fast.

Researchers with the use of a diamond-tipped device called an indenter, discovered that “the outer shell is designed to crack in a way that absorbs energy” reports Discover Magazine. “Cracks spread only by fanning out around the iron sulfide particles. This “microcracking” not only absorbs energy, it also ensures that larger cracks do not form.

Meanwhile the middle layer absorbs the mechanical energy exerted during an attack.

Researchers hope to copy the structure of the scaly-foot snail’s shell in order to produce stronger helmets and bullet proof vests as well as ship and aircraft hulls and Arctic oil pipelines that are buffeted by iceburgs.

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