Outdoors: Rockpools provide a world of fascination

If there were a competition to find Scotland's hardiest creatures, then it is likely that those that live on the high tops of the Cairngorms – such as the ptarmigan or snow bunting – would be the immediate front-runners. They do, after all, live in an environment that closely mirrors the Arctic.

But there is a community of plants and animals found in another habitat – the intertidal zone – which survives and thrives in an even greater range of environmental extremes and where the physical forces are just so much greater than on any storm-lashed mountain.

Living part on land and part under the sea, the creatures on a rocky shore are the true stalwarts of the animal world. Almost every conceivable hardship is thrown at them. When it rains the rockpools dilute and lose salinity, which on hot days can increase through evaporation. Whelks, winkles or limpets exposed to the summer noonday sun must positively bake inside their shells, yet in only a few hours' time the cold sea will envelop them again.

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In winter, they will have to endure sharp frosts at low tide, and when the sea does come crashing back in, surging currents and huge waves threaten to dislodge them from their rock homes. If all that weren't enough, hordes of avian predators such as oystercatchers, turnstones and redshanks pick over the ground at low tide, only to be replaced by a new wave of hunters as the sea rushes back, including fish such as winter codling and sea bass.

The variables are huge, but there is plenty of food here carried by planktonic tidal flows, and this is why the intertidal zone on a rocky shore is home to such a diverse array of creatures. It is a fascinating, easily accessible environment, and one which children just love exploring. Rockpooling is a great family day out – and it is free!

The best way to get an insight into the amount of life in and around a rockpool is to pick a reasonably sized one, sit down and look closely. The more you look, the more you will see.

Some of the most colourful creatures are the sea anemones, generally found on the lower shore. The commonest species is the cherry-red coloured beadlet anemone. The body is soft and jelly-like and bears numerous tentacles that are used to catch tiny creatures. If the tentacles are exposed, gently touch them with a finger and they will quickly retract. The tentacles have a sticky feel, an important aid in trapping prey.

Fish are plentiful and the best ploy to seek them out is to carefully turn over large stones at the bottom of a pool. More times than not a fish will dart out.

The variety of fish will increase the further down the shore you go, but a couple of hours' searching should reveal several species. One of the more intriguing species is the butterfish, so called because it is so slimy that it is very difficult to hold without it popping through the fingers. Another remarkable fish is the shanny, which likes nothing better than to bask in the sun half out of the water at the edge of a rockpool.

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But the creature that will generate the most excitement from children is the crab. The most frequently found species is the green-coloured shore crab and even a small one can give a pretty painful nip. The fear factor means it can take a bit of practice to master the technique of holding it from behind with one finger on the top-shell and the thumb underneath.

Another interesting species is the hermit crab. They are common in rockpools and live in empty mollusc shells, such as those of winkles and whelks. The right claw, which is larger than the left, is used to shield the opening of the shell when it retires. In some pools they can be very numerous and their protective armour means they are not so prone to hiding under rocks.

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The golden rules of rockpooling are to return every creature back into the pool from where it was caught and always put lifted stones and rocks back into their original position.

It is all great fun and there can be few activities that beat guddling along a rocky shore on a hot summer's day; the excitement of finding a fish or the shriek of being nipped by a crab. It is the stuff from which childhood memories are made.

• This article was first published in The Scotsman Magazine, April 17, 2010