Wild Harris

Link to Rocky Shore Animals

Limpets are cone-shaped sea snails which have a great talent for clinging to the rock. Unlike barnacles, they can crawl around, and do so when the tide is in, scraping weed off the rocks with their tongue. This tongue, called a radula, is like a ribbon covered in hard teeth. As it wears away new radula grows to replace it. Limpets are so good at grazing weed that they can keep a patch of rock completely clear. The only place they can't reach is the back of their shell - if you look carefully you will often find weed growing on a limpet's shell and nowhere else.

Seaweed on limpet shell    (Photo: Paul Tyler)

Weed grows on the back of a limpet shell - the only place that's out of reach!

You may have noticed that it is very hard to dislodge a limpet from its resting place. There are 2 reasons for this - the limpet has a strong sucker-like muscle which pulls the shell down very firmly, especially if it senses danger. The other reason is that, remarkably, the shell fits the rock perfectly, leaving no gaps round the edges. This perfect fit stops the limpet from drying out, makes it much harder for a crab or bird to lever it off the rock, and holds it down tight when waves wash over it. (Link to:  How does a limpet make its shell a perfect fit to the rock it lives on?)

 limpets with grey topshell    (Photo: Paul Tyler)

Limpets firmly attached to the rock at low tide. The patterned sea snail in the middle is a grey topshell. 

by Paul Tyler

Link to Rocky Shore Animals