Friday, March 16, 2012
I noticed this limpet's conspicuous feeding tracks when I visited the North Yorkshire coast earlier this week.
When the tide turns and begins to go out limpets return to their resting place on the rocks, where they fidget with their shells to grind a groove that their shell will fit into with a water-tight seal, trapping water inside the shell between tides.
When the tide comes in again they wander around to feed in a very efficient way, zig-zagging from side to side so they can rasp as much alga as possible from the rocks without straying too far from home. The length of the feeding trails depends on the state of the tides; during spring tides when they're covered with sea water for longer they have time to stray further from home before they need to retreat to their resting niche.
The most recent feeding trail here runs from top left to bottom right, while older ones have faded because the covering of algae on the rocks has had a chance to regrow.
You can find some impressive scanning electron microscope images of a limpet's file like radula by clicking here and read more about the biology of limpets here.
Here there's a time lapse movie showing 6 hours of limpet feeding compressed into 5 seconds.