Today’s the last day of term for my kids. Their little heads are full of an endless, sun-soaked holiday, and I am madly searching for coastal campsites, desperately seeking anywhere that can squeeze us all in at short notice.
One of the joys of a family trip to the beach is the rockpooling. I’ve been fascinated by it since I was small. My mum would take my sister and I down to the south-west most summers, which was probably her only opportunity to stretch out and read, while we entertained ourselves. After some industrious sandcastling, we’d clamber onto the intertidal rocks, thwarting barnacles with our jelly shoes, to see what the falling tide had left behind. We occasionally scooped the trapped residents into our bucket for closer inspection, but were just as happy peering through a snorkel mask into this unique, temporarily captive underwater world.
Hours of holiday fun (can you spot six from my list at this rockpool?)... Illustration: Chris Shields (rspb-images.com)
Super-speedy fish and shrimps were exciting finds and so were crabs, because you had to look really hard to find them, parting fringes of bladderwrack and sea lettuce, lifting stones, looking for scuttling movements or frantic self-burying. Occasionally we’d spot a starfish, which merited dragging our poor mother over for a look. We never handled those; they looked too delicate – and a bit alien.
But my favourites were the red-brown beadlet anemones. Reliably found pretty much everywhere, they looked like giant jelly sweets out of water, but below the waterline they’d unfurl a frilly mass of pinkish-brown tentacles into the swell. I’d lean in and offer up a fingertip, which they’d latch onto and gently try to pull into their digestive tract - always giving me a slight thrill that they might succeed.
I’ll be no less enthusiastic as I take my own kids rockpooling this summer - but rock pools aren’t just for kids. They’re fascinating, temporary habitats, and such harsh environments that it seems incredible that so much aquatic life survives there.
Water trapped in rock pools heats up in the sun, becoming warmer, shallower and saltier. Wildlife has to withstand that - along with crashing waves, dwindling headroom and browsing predators, with hiding as their only means of evasion.
And yet rockpools remain a thriving microcosm of our shoreline species, conveniently packaged into a small space that any naturalist can investigate and identify. Over 100 species of crustaceans, anemones, fish, bivalves, molluscs, starfish, even sponges - not to mention the myriad seaweeds. Few rock poolers will be able to name everything they see, so it’s lots of fun to learn as you go.
To which end, here are my top 10 rockpool favourites…
1. Hermit crab (Pagurus bernhardus)
These property-ladder climbing little masters of disguise are fun and fascinating to watch - so it’s little wonder that we find hermit crabs so beguiling. I’m putting them at number one for sheer personality. Look for shells moving in a jerkier way than you’d expect from a mollusc.
2. Common limpet (Patella vulgata)
Vacant limpet shell. Photo: Kirstie Duhig
It’s the king of the clingers, the rock-pool VIP… Limpets boast the strongest muscle tissue of any animal, holding on with an incredible force of 75 lbs per square inch! I’ve only managed to successfully prise one off a rock once, after sneaking slowly up and catching it unawares. They use a sharp, rasp-like tongue, hidden somewhere under there, to graze algae off the rocks, along with seaweed seedlings. Their shell shape is affected by wave flow, how long they spend out of water and how stressed they are - a relaxed and well-fed limpet has shallower contours. See? They’re fascinating!
3. Beadlet anemone (Actinia equina)
Out of water, they’re a strange mound of reddish jelly up to 5 cm across. But those below the waterline send forth an impressive crown of 192 waving, fluttering, sticky-tipped tentacles, arranged in six circles. It can sting its tiny prey, but is harmless to humans. It can tolerate very warm water and can even survive being temporarily dried out - and its mouth is also its bottom, and ejects ready-made babies out into the water, where they land on the rocks and set up home. I adore everything about this bizarre animal.
4 Common starfish (Asterias rubens)
Starfish! Photo: Carolyn Merrett (rspb-images.com)
Our most common starfish has five arms covered with white pimples, and can reach 30 cm across. Its suckery little feet can prise a mollusc shell apart enough to slip a bit of its own stomach in and secrete enzymes to liquefy the shellfish inside... but if needs be, they can survive several months without food (though they'll shrink).
5. Shanny (common blenny) (Lipophrys pholis)
Shannies love a rockpool, being creatures of the intertidal zone. They’re great not just for their cute, frog-like faces but because they’re almost amphibious… As the tide recedes, if they can’t find a rockpool they’ll walk across the rocks in search of a rocky crevice, out of water but cocooned among damp seaweeds, where they’ll survive until the tide returns. Look out for a chunky, bumpy, mottled little fish with a long, spiny dorsal fin along its back, usually sitting at the bottom propped up on its clawed front fins.
6. Shore crab (Carcinus maenas)
No mollusc-shell hideaways for these guys - so they must resort to lurking under rocks, hiding in weeds or burying themselves in sand. These are the most common crab found in rockpools - usually as juveniles. After mating (belly to belly, if you’re interested), females release developed larvae in the open sea as plankton, which gradually morph into tiny crabs and head to shore, often settling in rockpools. A 2 cm wide crab is about a year old, and has already moulted about 10 times. Most are greenish-brown, though bright green and red/orange shells are not unknown.
7 Dog whelk (Nucella lapillus)
Pointy-shelled molluscs are predators, and dog whelks will happily feast on the mussels and barnacles that line British rockpools. They come in a variety of attractive pastel hues, rippled with ivory, making them the rockpool equivalent of the dolly mixture - irresistible to my childish hands. Their tough, thick shell and choice of mid-tidal refuge offer them some protection from both crabs and seabirds.
8 Common prawn (Palaemon serrates)
Prettier than the brown shrimp they share rockpools with, these attractive, striped translucent crustaceans seem to test the waters with their whip-like antennae. They’ll eat pretty much anything: sea-carrion, algae, any old organic gloop, and even hunt smaller crustaceans. Those in rockpools are the same species that are hauled from the Atlantic by trawlers, but are likely to be a little smaller. Stay safe, little prawns!
9. Common goby (Pomatoschistus microps)
Several goby species can turn up in rockpools. Common gobies are sand-coloured with brownish markings and two separate dorsal fins. They rely on camouflage against fine gravel, and will seek this out in rockpools and lurk a few millimetres above it, looking out for tiny prey to eat.
10. Bladderwrack (Fucus vesiculosus)
Bladderwrack. Photo: Andy Hay (rspb-images.com)
Rockpools are underwater gardens, ablaze with colourful foliage in red, green and copper. Bladderwrack is not the most colourful of these, but it’s a favourite of mine for two reasons: first, it’s the first one I learned to identify and name, when I was a small child, and secondly, it still looks pretty good out of water, retaining its thick, leathery form and beguiling blister-like baubles. Interestingly, it yields more bladders (and smoother ones) in calm water than in choppy water. And it’s edible, albeit not particularly pleasant!
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What will you find?
Rockpooling isn’t just a wonderful way to enjoy the beach – kids can even go rockpooling to earn points towards our Wild Challenge award… Completing three ‘help nature’ activities plus three ‘experience nature’ activities (such as rockpooling), you can upload your photos to achieve a bronze award, earning stickers and personalised certificates. How’s that for a summer challenge? Register and find out more at the RSPB Wild Challenge page.