Surely a very rare glimpse of the secret life of a Heart Urchin or Sea Potato. These photographs show a specimen of Echinocardium cordatum (Pennant) emerging from its burrow in the wet sand at low tide on the shore at Port Eynon, Gower.
Its movements, as it surfaces, describe a circular path because it can only travel forwards and not backwards or sideways. The spines are coated with a layer of wet sand but you can see a clear channel is maintained for the tube feet or podia to move in and to assist with the passage of water. The channel or tunnel is formed by the spines over-arching the central ambulacral groove.
Revision of a post first published 21 October 2009
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