National Trust Purbeck Wildlife


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Seashore Safari

A keyhole limpet on Studland Beach

A keyhole limpet on Studland Beach

A group of keen-eyed and eager primary school children on a Studland ‘seashore safari’ found a fantastic variety of marine life along the strandline and, amongst the seaweeds, shells and various bits of crab, there were a few surprises.

A small, unfamiliar crab with attractive sand-particle colouration, was identified as a Pennant’s Crab.  This species has flattened back legs for swimming.

Small sea gooseberries, or comb jellies, were spotted in the shallows even though they are almost invisible apart from rows of delicate hairs called cilia that resemble tiny combs.  These propel the sea gooseberry through the water and, in sunlight, their regular, beating motion generates bands of iridescent colours.

Best of all was a keyhole limpet.  Unlike the common limpet, this species has an oval-shaped hole at the top of the shell that allows more efficient circulation of water over the gills and faster removal of waste products.

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Small is Beautiful

cowrie1aMonstrous, ‘big as a dustbin lid’, barrel jellyfish may be taking centre stage, but for me, the star of the seashore show is the tiny, but very lovely, cowrie. These lemon-shaped, finely ridged sea snails grow to a length of only one centimetre though some tropical cowries can reach 15 centimetres.
When active, the brightly coloured mantle (the outer wall of a mollusc’s body) wraps around the shell so that it is almost totally covered. Their target is sea squirts, as cowries both eat them and lay their eggs inside them.
Two species occur around the UK, the European cowrie, with three dark spots on the shell, and the plain Arctic cowrie. Look for their empty shells along the strandline in patches of coarse gravel.