I am currently on holiday in South Wales, the coastline here is famously scenic and geologically complex and most of the beaches here have fabulous rocky platforms full of marine life. Beach-combing and rock-pooling are two of my favourite things to do whenever I happen to be near the coast; I find that searching the salty shore for interesting and unusual sea-creatures (alive or dead – as they often are) is both great fun and relaxing to the mind. You may think that there can’t be much life to find in our freezing, murky waters and compared to a tropical reef you would be correct, yet cold waters harbor different organisms to warm ones and the diverse life of the ocean is much more resilient to low temperatures than land animals are.
In British waters alone can be found Jellyfish of various sorts, Seahorses, Urchins, Star-fish, many different crustaceans, Dolphins, Octopuses, Whales, Sharks (including the Basking shark), cold-water corals and thousands of species of Molluscs. Rock pools are an unstable and sometimes hazardous habitat; the sea washes over them twice a day but leaves them high and exposed twice a day too. When they are covered by the waves they are at risk of damage when a storm arrives and huge waves pound the rocks – ripping off seaweed, stirring up sediment, destroying nests and eggs and dashing creatures to death. When they are exposed the animals and plants trapped in these small pools risk extreme heat from the sun, evaporation resulting in desiccation, increasing salinity, and are at great risk from land predators.
For the naturalist rock-pools present a fantastic opportunity to observe organisms that would otherwise be hidden by the ocean, care and respect should always be the motto of the rock-pooler however, as many of these creatures are delicate, shy or even legally protected so contact with them should be minimised. I find rock-pools to be a lucky-dip as each one may hold different things and the cut-off nature of them sometimes results in larger or more unusual marine animals becoming trapped – so you never know what you may find.
I recently spent some hours rock-pooling on Newgale beach not far from where I am staying in Pembrokeshire, the pools were not extensive but they nonetheless held a few interesting things. The first thing of interest I found was a small Common Starfish (Asterias rubens) that seemed to be drying out in the sun and far from water, I plopped him (or her, difficult to tell with echinoderms) into a large pool and he soon crawled off rather faster than you might expect. Next my friend managed to net a good-sized Shanny (Blennius pholis) which is a common denizen of rock-pools, these wedge-shaped fish make a nest in the sand and the male guards the eggs jealously.
One of the best ways of finding interesting rock-pool organisms is to turn over large stones in or around the pools as they will often have many small but curious things stuck to the bottom or hiding beneath. Upon lifting one stone I found a Chiton (a mollusc that resembles an armor-plated fingernail) and a pretty Brittle-star (Ophiothrix fragilis); these delicate things move in a strange way by waving and twisting their thin arms sideways – they are echinoderms like starfish but are not as closely related as you would think. To continue with the echinoderms I lifted another rock and found a very small Green Sea-urchin (Psammechinus miliaris) that was clutching a bit of shell seemingly as protection or camouflage.
These animals were among the less-often seen ones that can be found on the shore but along with these I did come across many commoner species that are widespread around Britain. Sea Anemones come in many colours and should be familiar to everyone, shrimps abound and multitudinous sea-snails or bivalves are colourful and varied but often prove tricky to identify. Lobsters are rare to find in a rock-pool but crabs can be easily found; both Shore crabs and Velvet-swimming crabs are common but many other smaller species can be encountered. At Newgale beach I discovered a young but quite dead Edible crab (adults live deep at sea but young develop in the shallows), part of a very dead Spider-crab and a couple of large Shore crabs which put up a fight when I tried to net them. I also came across one of my favourite seashore animals – a Hermit Crab – tucked shyly away in a large winkle shell, these little nomads just seem so cool to me, cute too.
Rock-pooling can be done at any time of the year (though there are some things only found in summer) and pretty much any shoreline around Britain with rocks can turn up something for those with an interest and a good eye.