Limpet sticking power down to mucus
Limpets, those coin-sized, suction-cup critters with conical caps, have had the experts fooled all along.
For more than a century, scientists have assumed that their outsized ability to clamp onto tide pool rocks in defiance of bare-handed attempts to pry them off was due mostly to muscle power.
Some South African limpets, one study showed, could withstand up to 100kg of force.
“If you managed to convince a limpet like that to attach to your ceiling, it could probably hold your weight,” said Victor Kang, a doctoral candidate in the department of zoology at the University of Cambridge.
But that bonding power does not come primarily from suction (muscle contraction), or clamping (muscles forcing the animal’s thin hard shell against the rock to provide added friction).
The secret, according to a study published yesterday in the Royal Society journal Open Science, is a superglue slime secreted from a limpet’s pedal sole, the bottom of its rubbery body.
“It is normally difficult to adhere strongly to wet and slippery surfaces, but limpets and some other marine animals manage to do just that using special bio-adhesives,” said Kang, lead author of the study.
“The amount of muscle-driven suction is small and cannot account for their high attachment strength.”
Kang’s study is the first to exhaustively catalogue all the ingredients of the mucus secreted by nine glands found in the pedal sole of the common limpet.
He and his team found no less than 171 protein sequences, along with a lesser number of sugar molecules.
Figuring out what these gluelike substances are made of and how they work could one day inspire synthetic adhesives – for medicine or food – that keep their sticking power in water and are biodegradable, Kang said.
Limpets have been around for about 450 million years, and chances are they will still be clinging to rocks and foraging for tiny bits of algae long after our species has moved on. –