The wonders of rockpooling

As the twice-daily ebb of the tide drains from the foreshore, a remarkably rich world is exposed. Where scrunching shingle beaches give way to rugged rocky shores, a veritable oasis of miniature ecosystems await discovery, each containing a treasure-trove of organisms that lurk within the still waters.

Rockpooling is one of those activities that reverts you back to a child-like state of mind: you become absorbed in unearthing a myriad of fascinating creatures, derive excitement from prodding around after crabs and shrimps; each new pool presents a plethora of species to be scrutinised and investigated. The air of discovery is ever-present, as you never know what you might find in the next rockpool: there is always something different, some bizarre animal that you’ve not encountered before. And here in Cornwall, we’re very much blessed with one of the county’s most diverse intertidal communities of seashore wildlife.

the superb rockpooling habitat along Castle Beach in Falmouth

There have been some particularly low tides over the past few weeks, in tune with the waxing and waning of the moon and its associated pull on the ocean. This has presented ample opportunity to don the wellies and head down to the beach in search of some rockpooling action, which has rewarded with some fantastic discoveries. I’ve been meaning to write this blog for a good week or so, but it as been somewhat manic with uni deadlines and coursework of late. I thought I’d take a brief lull in the barrage of work to detail some of the highlights from recent visits to the seashore, although I’d thoroughly recommend you check out a an eloquently-written post on the joys of rockpooling by Jack Barton, fellow student on the zoology course with University of Exeter.

One of the on-going photography projects I’m carrying out alongside fellow wildlife photographer Max Thompson is capturing many of these rockpool creatures on a white background (in a shallow covering of sea water in a white tray). Using a combination of post editing and flash to really make the subjects stand out, you can then create brilliant collages of the various inhabitants, such as the one above. Species pictured (top left clockwise): Arch-fronted Swimming Crab, Spiny Starfish, Common Hermit Crab, Cushion Star, Cornish Sucker and Brittle Star

When presented with your first rockpool, it’s hard to know where to start! There is so much diversity contained within such a small area, particularly if you venture to the seaward reaches of the intertidal zone at low water. The colourful assortment of different algae and seaweeds is a good place to start, from the bright pink and segmented Pink Coralweed, through to the edible Peppered Dulce and remarkably iridescent Rainbow Weed, which shimmers blue and purple as it catches the light.

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Rainbow Weed

Next up you might appreciate the peppering of gastropods clinging to the stone and rocks within: the wrinkled limpets holding fast via an immensely strong sucker-like foot; clusters of periwinkles, grey topshells and dog whelks, and perhaps the colourful painted and flat topshells too. A keen eye may reveal that some of these mollusc shells have been commandeered by a species of a very different kind…the characterful hermit crab. Once discovered, these innovative crustaceans rapidly retreat into their adopted home; a bit of patience will reward as the eyes, antenna, and then tightly curled appendages emerge tentatively, and the whole shell tips on its side as it trundles off across the substrate.

common hermit crab emerging from its adopted netted whelk
three common species of limpet – in the Patella genus – can be found along most of Britain’s rocky shore, although their separation is very tricky. This particular limpet has been encrusted with Lithophyllum incrustans algae
the common squat lobster is an odd-looking beast, sort of half way between a lobster and a crab. This species is in actual fact more closely related to hermit crabs, and prefers to remain hidden in crevices or beneath stones whilst ‘marooned’ in rock pools at low tide

The underside a rewarding rock can harbour a dazzling array of organisms: the shuffling hairy porcelain crabs edge sideways upon exposure; the incredibly delicate-looking brittle stars flair their arms as they topple into the water; crabs and various fish scuttle away in a puff of sand a flick of their tail. Crustacean species can vary from velvet swimming crabs through to edible, Montagu’s , shore and brown crabs. The three-bearded rockling, the pipefish, the common blenny, butterfish and bizarre Cornish sucker are amongst the fish that we’ve encountered along Falmouth’s rockpools. The underside of over-turned rocks themselves can present some cool species too: a close scrutiny might reveal the well-camouflage Chitons (gastropods) or perhaps the flower-like Star Ascidians

An amazingly-coloured chiton that I believe to be Tonicella rubra, and then a miniature brittle star

star ascidians are members of the Tunicate family, otherwise referred to as sea squirts. This describes their action upon contact, often expelling water through their excurrent siphon in response. This is a colony of zooids connected together in a jelly-like substance called the ‘test’

I think the most enjoyable aspect of rockpooling is simply the feeling of discovery and seeking the unknown. There is such a broad diversity of species to be found within these island oases that you can easily spend a few hours slowly rummaging around the foreshore, totally absorbed in the activity. The advancing tide is often the limiting factor that eventually brings rockpooling to a premature end, as the shore is claimed once again by the sea and the rockpools are re-submerged.

snakelocks anemones are amongst a handful of different anemone species that can encountered in rockpools. The bright green and purple colouration is derived from a symbiotic algae called Zooxanthellae, which reside in the tentacles. The algae photosynthesise and provide the host with additional energy
common prawns can often be found darting about in the deeper rockpools, sporting immense antenna and sensory appendages for detecting and subsequently handling morsels of food and prey
this bizarre creature is a sea slug, or Nudibranch: a gastropod that is essentially ‘naked’ and shell-less. This particular individual is of the species Aeolidia papillosa, with a wavy mane of protuberances that give the impression of a rather unkempt dog

So there is just a bit of a taste of Cornish rockpooling – it’s certainly a great way to brighten up many a dull winter’s day. However, as the sea temperature edge higher through spring and the weather (hopefully!) settles, snorkelling will definitely be my next port of call for exploring the rich marine life around our coast here in Falmouth.

a common seastar washed ashore after a recent storm

Thanks for reading! As ever, you can keep up to date with my photography and activities through Facebook and twitter.


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