New insights about the scaly-foot gastropod, a tiny snail that lives near thermal vents on the floor of the indian ocean, could help scientists design better armor for soldiers and military vehicles, according to a new study appearing in PNAS.

MIT materials scientists report that the snail's shell is unlike any other naturally occurring or man made armor. Their study suggests that its unique structure dissipates energy that would cause weaker shells to fracture.

When a crab attacks a snail, it grasps the snail's shell with its claws and squeezes it until it breaks — for days if necessary. The claws generate mechanical energy that eventually fractures the shell, unless it is strong enough to resist.


photo: wikipedia commons

In the new paper, researchers report that the shell of the hot vent gastropod has several features that help dissipate mechanical energy from a potential penetrating predatory attack. Of particular importance is its tri-layered shell structure, which consists of an outer layer
embedded with iron sulfide granules, a thick organic middle layer, and a calcified inner layer.

The team measured the mechanical properties of the snail shell using a machine called an indenter, which has a diamond tip. By measuring the force applied to the shell, and the shell's
resulting displacement, they can calculate its mechanical properties.

Most other snail shells have a calcified layer with a thin organic coating on the outside. In the
scaly foot gastropod, simulations suggest that the relatively thick organic middle layer can absorb much energy during a penetrating attack. It may also help to dissipate heat and thermal fluctuations exhibited near hydrothermal vents.





Citation: Haimin Yao et al., 'Protection mechanisms of the iron-plated armor of a deep-sea hydrothermal vent gastropod', Proceedings of the National Academy of Sciences, Jan. 2010