A Vixen and her cub had been out along the tideline before me, their tracks stitched closely side by side, crisp and dainty in the frosty sand. Beyond them, where the sea had retreated, my boots sank into drifts of unseasonable, fresh-laid sand, soft and fluffy as snow, writes Michael Viney.
ANOTHER LIFE: In the long calm before Christmas, the reach of each high tide was measured precisely: a succession of parallel, wobbly graph-lines etched across the strand. On a shore so open to ocean swells and breakers, the tidal surge in winter is more usually chaotic, its final limits blurred by heavy surf. But for days (and wondrous, starry nights) the quiet lap of the furthest wavelet, the slow swirl of the last few bubbles in the dark, was remembered in a lacy, scalloped edge along the strand.
Each of these was further hemmed with sea-shells, heaped together like leaves. A less quiescent sea would have pounded them to fragments as the raw material of sand, but here they had been lifted, tumbled, hustled gently shorewards: drifts of limpets, mounds of mussels (or rather, the glazed and vacant grottoes of their lives).
To look closely at any square foot of jumbled limpet shells, their porcelain interiors turned up to the sun, is to marvel at the subtle variation that selection brings about in one simple, functional design.
The half-dozen limpet species that stick around our rocky shores all live in conical, toughly-ribbed shells, proof against the sea's hammer-blows. Even the beautiful and fragile-seeming blue-rayed limpet, Patina pellucida, translucent as a fingernail, clings to kelp in the same basic form.
The limpet cone is asymmetrical, its apex often tilted like a Kentish hop-kiln and highest towards the head of the snail crouched within.
According to position on the shore and exposure to the wave, it may be flattened, or drawn up into a pointed "Chinaman's hat" with sharply fluted ribs. Colours change, too: oranges, greens, ivory whites and rims of tortoiseshell.
Least glamorous, perhaps, are the big, blunt-headed shells of the common limpet, Patella vulgata that monopolise the higher reaches of the rocks. This is the bairneach, long considered the lowliest of desperate peasant foods (yet, as Seamas Mac an Iomaire remarks in The Shores of Connemara: "Don't mind them, a batch of limpets is a sweet healthy food beside the hearth on a cold spring afternoon when one is hungry").
No shore animal, it seems, has excited greater interest from science. Its shell is clearly storm-proof, and its secure adhesion to the rock can be tested by the slightest tap of warning. The grip is not, as I once thought, achieved solely by suction, but also by an adhesive produced on the sole of the animal's foot. As long ago as the 18th century, an entomologist hung weights from limpets stuck to the underside of a rock and found that it took one of 30 lbs to break their hold.
Nothing could be better designed to take the pounding of Atlantic swells.
But, looking at a limpet left high and dry on seemingly bare rock, how do they feed and on what? Aristotle was first to record that limpets go on grazing excursions, like land-snails, but the means of navigation to and from their "home scar" is still not fully proven.
The margins of the limpet's shell have to make perfect contact with the rock, so that it holds enough seawater inside its mantle through the hours while the tide has withdrawn. Pulled tight to the rock, the edges of the shell slowly grind a depression, and when the limpet comes home, it turns its shell round to achieve the best fit, like a dog in a basket.
The animals feed on microalgae coating the rock and the sound they make while their teeth rasp the surface (they are toughened with iron and silica) can actually be heard on still nights. A research team at West Cork's Lough Hyne have recorded the noise by sticking gramophone transducers on limpet shells and listening through headphones.
Volume of noise is a guide to feeding intensity, and the impact of limpets on shore vegetation is considerable (rocks that are cleared of them promptly turn green with seaweed sporelings). The limpets may spend up to two hours off base, especially at spring tides in the night hours, feeding for most of the time, over a wide range, before returning home.
How do they do it? Not, apparently, by celestial navigation, since they home just as well in a fog, or under water, or when the rock they have arrived at is turned around experimentally. Not by dead reckoning, since they only sometimes go home the same way they went and are only partly confused by deliberate upheavals in the rockscape. The answer seems to lie in the limpets' mucus trails. Even when these are scrubbed away with detergent, the animals seem to be able to follow their noses, sorting out the trails to arrive at their correct home address, with its perfect fit.
Do you need to know all this to take the dog for a walk on the strand? Probably not: but suitable New Year's resolutions about awareness of the natural world may suggest themselves.
Meanwhile, limpets get concise and proper mention in a new book that tells everything any nature-lover could reasonably wish to know about the habitats and wildlife of 19 sq km of the coast of Waterford. Tramore: Bay, Dunes and Backstrand is a model of fact-packed local scholarship, attractively presented by Declan McGrath, who teaches in the Waterford Institute of Technology.
The association of Tramore with holiday crowds has led me to avoid what is obviously a supremely varied corner of the south-east, with remarkable dunes and saltmarsh, and strands big enough to offer proper solitude in most months of the year. Walking the shore has led McGrath into thinking about the dynamics of sand and ocean, and his pages on the future local impact of rising sea level will be read with special interest.
More than 350 species crowd into his book. Some are well-known, such as the hundreds of brent geese that winter along the Backstrand, but they also number the many less-appreciated plants of Tramore's great dunes, now under threat from several kinds of erosion. This knowledgeable book shows what an asset a naturalist can be in planning for a durable landscape.