Was It Designed?

The Shell of the Scaly-Foot Snail

● It has one of the strongest exoskeletons ever discovered in nature. The scaly-foot snail, found at the floor of the Indian Ocean, can withstand the water pressure occurring at a depth of some 8,000 feet (2,400 m). Furthermore, this little 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.

Consider: The shell of the scaly-foot snail has three layers. The first is composed of iron sulfides; the second resembles the protein coating found on 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 attack by predator 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.

Using a diamond-tipped device called an indenter, researchers learned 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 sulphide 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 bulletproof vests, as well as ship and aircraft hulls. “Even Arctic oil pipelines that are buffeted by icebergs could benefit,” says Discover.

What do you think? Did the shell of the scaly-foot snail come about by chance? Or was it designed?

[Diagram on page 23]

(For fully formatted text, see publication)

Indenter

Outer layer

Middle layer

Inner layer

[Picture Credit Line on page 23]

Courtesy Anders Warén