‘’I found something on the beach the other day, maybe you’d know what it is? ´´ is something I hear a lot, especially in these, the longer days of the year. This week’s query grabbed me more than most would however, primarily as it was presented more elegantly than most would bother. In a box which once held an expensive wine glass and wrapped so carefully in the soft foam which once cosseted that same delicate crystal were seven gleaming nuggets, brilliantly white and alluringly fragile.
´´Urchin shells’’ I said, but puzzled at how white they had been bleached. Could they really have caught that much sun, and all the while lying intact on a windy West Mayo shore? ‘’Domestos’’ she confessed, explaining that she thought they would improve a shelf or windowsill somewhere in her new house. They probably will, especially as they are not found so much around here, certainly less than the whelks, limpets and clamshells which line mantle pieces and bring beach thoughts to living rooms around Ireland.
About the size and shape of a small spud, the Sea Potato (as it is called in the West of Ireland) or Heart Urchin (as it is called by the rest of the world) is an echinoderm, that group of species which, in basic terms, are all quite round such as starfish, sea cucumbers and sand dollars. The animal lives inside the exceptionally thin shell which contains an elaborate configuration of tiny holes, allowing soft spines to stick out and defend against predators. Other urchins, like the once abundant but now overfished purple urchin, live on rocks and graze algae but the sea potato spends its life covered in soft sand, feeding on detritus.
How did this sand dwelling subtidal species come then, in numbers, to meet such an elegant end as a polished ornament at the hands of a beach walker? The sea potato breeds in summer and it is at this time that large numbers of juveniles are found on the sediment surface. An out of season large swell, which we received last week, would be their certain shoreward transporter. Or, more likely, they could have recently taken up an unwelcome residence in a lobster pot, as they are reputed to do, and found themselves subsequently evicted by a fisherman whose windowsill and mantelpiece collections are already quite complete.