From SCIENCE NEWS
A deep-sea snail wears a multi-layered suit of armor, complete with iron, new research shows. Dissecting details of the shells structure could inspire tough new materials for use in everything from body armor to scratch-free paint.
The snail, called the scaly-foot gastropod, was discovered nearly a decade ago living in a hydrothermal vent field in the Indian Ocean. In its daily life, the snail encounters extreme temperatures, high pressures and high acidity levels that threaten to dissolve its protective shell. Worse, it is hunted by crabs that try to crush the mollusk between strong claws.
The scaly-foot snails shell employs a structure unlike any other known mollusk or any other known natural armor, the researchers report January 19 in Proceedings of the National Academy of Sciences. Ortiz and her colleagues found that the shell consists of a 250-micrometer-thick inner layer of aragonite, a common shell material, sheathed in a 150-micrometer-thick layer of squishy organic materials. The organic layer is encased in a thin, stiff outer layer (about 30 micrometers thick) made of hard iron sulfidebased scales. The gastropod wears larger versions of the scales on its exposed foot.
The model showed that the outer layer, the shells first line of defense, sacrificed itself by cracking slightly under pressure. But the cracks were branched and jagged, dissipating energy widely through the shell and keeping any one crack from spreading too far. The iron-based scales could shift and roughen the shells surface during a crab attack, which in turn would grind down the attacking claw, the researchers suggest.
The soft organic middle layer changed shape in response to pressure, keeping the brittle inner layer from feeling too much of the pinch. Organic material could also insert itself in any cracks that formed in either sandwiching layer and keep the crack from spreading. Plus, the middle layer together with the outer layer protects against acidic waters and may also help shield the snail from high temperatures.
The shells curvature also helped reduce stress on the calcified inner layer. The inner layers rigidity provided structural support, to keep the whole shell from caving in.
A deep-sea snail wears a multi-layered suit of armor, complete with iron, new research shows. Dissecting details of the shells structure could inspire tough new materials for use in everything from body armor to scratch-free paint.
The snail, called the scaly-foot gastropod, was discovered nearly a decade ago living in a hydrothermal vent field in the Indian Ocean. In its daily life, the snail encounters extreme temperatures, high pressures and high acidity levels that threaten to dissolve its protective shell. Worse, it is hunted by crabs that try to crush the mollusk between strong claws.
The scaly-foot snails shell employs a structure unlike any other known mollusk or any other known natural armor, the researchers report January 19 in Proceedings of the National Academy of Sciences. Ortiz and her colleagues found that the shell consists of a 250-micrometer-thick inner layer of aragonite, a common shell material, sheathed in a 150-micrometer-thick layer of squishy organic materials. The organic layer is encased in a thin, stiff outer layer (about 30 micrometers thick) made of hard iron sulfidebased scales. The gastropod wears larger versions of the scales on its exposed foot.
The model showed that the outer layer, the shells first line of defense, sacrificed itself by cracking slightly under pressure. But the cracks were branched and jagged, dissipating energy widely through the shell and keeping any one crack from spreading too far. The iron-based scales could shift and roughen the shells surface during a crab attack, which in turn would grind down the attacking claw, the researchers suggest.
The soft organic middle layer changed shape in response to pressure, keeping the brittle inner layer from feeling too much of the pinch. Organic material could also insert itself in any cracks that formed in either sandwiching layer and keep the crack from spreading. Plus, the middle layer together with the outer layer protects against acidic waters and may also help shield the snail from high temperatures.
The shells curvature also helped reduce stress on the calcified inner layer. The inner layers rigidity provided structural support, to keep the whole shell from caving in.
