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Science!: Snail Armor, Dino Deathtraps and Beer

Lauren Admire | 25 Jan 2010 21:00
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Military Looks to Scaly-Footed Snail for Future Troop Armor

Undersea chimneys, nicknamed "black smokers," belch out superheated water from below the Earth's crust. The waters surrounding the smokers are teeming with toxic compounds - sulfur and other compounds make this water incredibly acidic. Located in the deeper, benthic layers of the ocean (around 2100 m), these environments are completely devoid of sunlight - but not of life.

Despite this being one of the harshest and cruelest of oceanic environments, life has an uncanny way of prevailing against all odds. Take the Crysomalion squamiferum, a species of underwater scaly-footed snail that was just discovered in 2001. Its three-layered shell has different materials that form the toughest covering ever discovered. Even the military has turned its eager eyes towards replicating a combat version for humans. The exterior of this gastropod is so tough that it can withstand pressures of up to 300 atmospheres (equivalent to 4,400 pounds per inch), searing temperatures of 752ยบ F, and the piercing claws of predatory crabs.

Haimin Yao of MIT discovered the secrets behind the snail's sturdy shell by studying its cross-sections and simulating various predatory attacks that the shell would normally withstand. Made of iron sulphide compounds, the outer layer is the thinnest yet toughest layer. When "attacked" by a diamond tipped probe (simulating a crab attacking with its claw), it cracked - which is all part of the master plan. The cracks were tiny and jagged, effectively dissipating the energy from the attack and preventing larger cracks from forming. The iron in the shell would also erode the crab's claw, so if it continues to attack these scaly snails, it may find its main mode of attack rendered ineffective.

The middle layer of the shell is thicker than the outer shell, but has a spongy consistency. Like a football helmet, it helps to absorb the force from the crab's attacks. The inner layer is made of calcium carbonate, a common compound found in most seafaring animal shells. However, in this particular environment, an uncovered calcium carbonate shell would quickly erode away. The outer and middle layers protect the vulnerable snail, and also provide additional structural support, preventing the shell from bending. Again, the crab is foiled. With each layer supporting the other, they can't be peeled away individually.

Source: Science Blogs

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