A day at Kynance Cove on the Lizard Peninsula has become a fixture in the Cornish Rock Pools calendar. The smooth, serpentine cliffs don’t create many hiding places for marine life, but Junior loves the geology and caves. There are always creatures to see too if you look carefully enough, so I take the opportunity to relax in the sun, staring at fish through the clear water.
The funny thing is that, while I stare in, the fish stare back, creeping closer up the sides, over pink encrusting algae and through fronds of the Corallina seaweed to secure a better view. Bold young shannies, prop themselves up on their two-pronged pectoral fins, swivelling their colourful clown eyes to observe me.
In the far corner of the pool, a Montagu’s blenny pops up to say hello. It’s easily recognisable by its pronged head tentacle, which looks like a tiny Christmas tree.
The surrounding rocks are covered in barnacles, which suits these fish well. The Montagu’s blenny likes nothing better than to nibble the feeding legs off barnacles.
I soon start to doubt that this fish is just curious. Unlike the shannies, which are just juveniles, this Montagu’s blenny is full size and sports a fine pattern of turquoise spots on his body. It is the male blenny’s job to guard the eggs, and this fish is taking no prisoners.
He seems determined to chase me out of his territory, repeatedly headbutting my camera. He may only be 7cm long, but I have a feeling that if I put a finger in the water he won’t hesitate to take me on with his sharp little teeth.
The hard rock becomes uncomfortable to lie on after a while, digging into my legs, but I try not to change position. The fish will scatter if I make any sudden movement or noise. Half a dozen shannies are darting around the bottom of the pool, while others are basking in shallow grooves at the edge. The Montagu’s blenny doesn’t take his eye off my camera.
I watch him until the tide turns and the waves begin to sweep in. This may not be the most diverse rock pooling beach, but the fish are a joy to watch and it’s a wonderful spot to while away a sunny morning before enjoying a pasty in the café. Summer starts here!
I should be at home, cracking on with some work, but I’ve heard there are comb jellies about and I could do with some photos for my jellyfish course for ERCCIS.
I cut through overgrown vegetation, down the cliff path to a favourite cove. In the ten minutes it’s taken me to walk here, the grey clouds have lifted and the sea’s looking good enough to dive into.
My progress through the rocky gully is slow. The warm weather has brought an explosion of slippery sea lettuce which blocks my view of my feet as they feel for underwater rocks. Tangles of pink spaghetti, the eggs of sea hares, are wrapped around many of the green fronds and a close inspection reveals that dozens of stalked jellyfish (Haliclystus octoradiatus) have already made their homes here.
As I move into deeper water, something catches my eye, floating below the surface. It’s so transparent it’s barely there, but it shimmers intermittently. With some difficulty, the current swishing the jelly back and forth, I scoop it up and carry it in cupped hands to a sheltered overhang. For a moment I think I’ve dropped it, then it swims out.
I’m treated to a fabulous display of iridescence as the comb jelly beats its tiny combs, sending a trail of light and colour up the lines on its tiny body.
Between the current washing into the pool and the jelly’s own surprisingly speedy swimming efforts, it slips away each time I come close to getting it under the camera. To add to the fun, my camera can’t see it. I take a whole series of photos of nothing. The perfect transparency of the animal means I can only focus on the seaweed below.
When another comb jelly washes into the pool, I’m sure there will be lots more opportunities to attempt photos. Stepping out into the open water, I take some time to accustom my eyes, staring past the surface reflection into the water. Soon, I notice comb jellies everywhere.
There are dozens, hundreds even, and some are large enough to fill the palm of my hand. Even the large jellies pose a challenge to my camera, but amongst the many seaweed shots, I start to take a few that show off the jellies’ light display.
While most are the large species, Beroe cucumis, with their characteristic sack shape, there are a few smaller ones amongst them. These are sea gooseberries, Pleurobrachia pileus. They are barely a couple of centimetres long, spherical, with two trailing tentacles.
Despite their tiny size, they are just as mesmerising as the B. Cucumis, the lines down their sides flickering every colour of the rainbow.
Among all the comb jellies I spot an even smaller interloper, a hydroid medusa. Hydroids are related to jellyfish, but their adult form usually lives attached to seaweeds, stones or shells. This minute creature is a baby hydroid, looking very much like a jellyfish as it actively swims past, beating its bell fringed with short tentacles.
The pattern of the cross on top of it and the fringe of dark spots around the edge of the bell suggest that it is a young Clytia hemispherica.
The glare of sunlight on my screen combined with the transparency of all the animals I’m trying to photograph make it impossible to tell how I am doing. I give up taking photos and simply enjoy the spectacle until the tide calls time and forces me back up the beach.
Comb jellies are supposed to phosphoresce, which would be amazing to see. I’m wondering if I can sneak in a little night time rockpooling this weekend. Although the jellies are here in huge numbers today, they may disappear as quickly as they arrived. I should be working, but some things are just too exciting.
The sun shone, which is always a good start, and I couldn’t have asked for a more enthusiastic group. After the morning’s presentation and a lot of work on topshell identification, we enjoyed a perfect picnic on Gyllingvase beach, taking care to protect our sandwiches from the herring gulls, before setting out to explore the rocks.
I was showing some of the group the different topshells, winkles and other shells found near the top of the shore, when someone found a coil of eggs under a stone. It was a perfect start – the eggs of a great grey sea slug (Aeolidia filomenae). We looked all around the area and couldn’t see the slug that had laid them, but it was probably still close by.
Inspired by our early success, we carried on down the shore and one of the group found some codium seaweed. Remembering that I’d mentioned that the photosynthesising sea slug, Elysia viridis, is often found on this seaweed, she called me over.
The lump on the codium she’d hoped might be a slug was seaweed, but we examined the codium some more and soon found two photosynthesising slugs on it. The shout of, ‘Slug’, went up so that everyone could gather to take a look.
Gyllingvase has all sorts of seaweeds, lots of pools and steep rocky overhangs, which makes it a perfect habitat for snails. We found the egg capsules of the netted dog whelk and the European sting winkle among many other things.
‘Slug!’ The shout went up again, this time for a big brown sea hare (Aplysia punctata) and before long we’d seen several of them. They love the sea lettuce and other seaweeds that are growing rapidly in the pools this time of year. They were congregating all over the beach to lay their pink spaghetti egg strings on the seaweed.
We had another shout, that turned out to be this beautiful candy-striped flatworm. It’s not a mollusc of course, but was still a great find.
It was clear there were plenty of creatures to be found and the entire group took the search seriously, crawling on the rocks, staring into pools, lifting seaweed and bringing all sorts of finds to me.
In a kelp-strewn gully at the edge of the sea, we found more snail eggs of various sorts and some live sting winkles. A sea lemon was sheltering in a small hole in the rock, our fourth sea slug species of the day.
We put it in a pot of water to watch its rhinophores emerge from its head and its gill feathers unfurl on its back.
By now the tide was starting to turn, so I placed the sea lemon back on its rock and hurried to take a look down another promising gully. There were some anemones about, the favourite food of the great grey sea slug whose eggs we’d seen at the beginning, so I hoped I might find one hanging about there somewhere.
After a few minutes of examining an overhang and taking a look under stones I’d drawn a blank and stopped to take a look at some finds people had brought to me. I was about to haul myself back up the rocks when I spotted a long stone that was half-wedged against the rounded overhang at the back of the pool. It looked like a sluggy sort of stone, one that wouldn’t move easily and might have all sorts of sponges, squirts and other things slugs like to eat growing on or near it.
As soon as I turned the stone, I could see the colourful cerrata of a little slug. It most definitely wasn’t a great grey sea slug with its bright reds and blues. I screamed, ‘Slug!’ loudly enough for most of Falmouth to hear and fumbled with a petri dish, scared I might drop the slug in the water and lose it.
The great thing about teaching a workshop is that everyone there is just as excited by marine creatures as me, and this one, a Facelina auriculata, is one of the most beautiful slugs I’ve seen on the shore. It caused a lot of excitement and photo taking.
After returning the Facelina auriculata, which we nicknamed ‘the patriotic slug’ due to its red, white and blue colours, I turned my attention to a deep pool to look at some rainbow wrack. Lovely though the turquoise iridescence of rainbow wrack is, it wasn’t the seaweed itself that interested me, but the colony of various hydroids growing on it. These colonial animals are relatives of the jellyfish and anemones and are a favourite food of many sea slugs.
I was hoping to find a Eubranchus farrani, a colourful slug with fat cerrata and orange markings on its body, which loves to eat hydroids. I soon spotted a tiny slug, but it was something different. It was so small I could barely see it, but in the petri dish when it came out fully I could see under my camera’s magnification that it was a Polycera quadrilineata, a pretty white slug with yellow markings and yellow-tipped tentacles.
It was hard to see much with the naked eye, but we all had hand lenses and cameras to get a close look.
By this time the tide was rushing in. A last foray along a higher gully produced a cowrie shell and a perfectly orange common starfish, which isn’t a mollusc but made us happy nonetheless.
By the end of the day we’d seen five species of sea slug, the egg spiral of the great grey sea slug and all sorts of snails. It was the kind of fantastic result that comes from lots of dedicated people searching and a good dose of luck.
I can only hope that my run of workshop luck holds for my jellyfish course later in the year. Who knows what might turn up?
Nights out tend to become a distant memory when you’re a parent. For the most part I don’t miss them. I have, however, been looking forward to Junior being old enough to join me for night time rock pooling. Towards the end of last year, we tried it for the first time and, although the conditions weren’t ideal, he’s been asking to go again ever since.
The best low tides always happen around the middle of the day, and the middle of the night, but we compromise for this first family expedition of the year, choosing a reasonable low tide at around 10.30pm. The warm, calm weather provides good opportunities for seeing nocturnal activity and tonight I’m trying out my ultraviolet (UV) torch.
It doesn’t disappoint.
I’ve always known that certain species glow under UV light, but I had no idea how much. We’ve barely taken ten paces out across the rocks when we see our first snakelocks anemone, shining from the darkness like an eerie green beacon. The colour is wonderfully alien.
This fluorescence is caused by certain proteins within the animals that take in light of one colour and emit it as another. Some deeper water species can use these properties to appear red, even though red light is filtered out as it passes through the water, meaning the only light available to underwater creatures is UV or blue.
It’s not clear why snakelocks anemones and other sea creatures might want to fluoresce in this way. It seems there may be some benefit in it for their symbiotic algae or it might give them sun protection. It may just be a by-product of a protein that’s useful in other ways. Whatever the reasons, it produces an incredible glow. Junior is already talking of coming back at Halloween.
It’s not just the anemones that take our breath away. If you’re used to rock pooling in daylight when most animals are hiding away under rocks and seaweed, the sheer level of activity in after dark takes you by surprise.
A scratching, crackling sound stops us in our tracks. It’s coming from the rocks. I lift the seaweed to show Junior a group of limpets. Some are feeding, their strong radulas scouring seaweed off the rock and chipping bits of rock. Others are setting into their home scars, grinding their shells into their grooves to create a perfect fit. Close-up, their activities make a surprising amount of noise.
Most rockpool animals are largely nocturnal. Pools that seem empty in daytime become bustling cities of activity. We watch hermit crabs milling around in large numbers, crabs marauding through the pool and across the rocks, fish floating in plain sight. Prawns come towards the light and watch us before shooting away backwards.
Other Half spots a small species of spider crab (Macropodia sp.) decorated with long fronds of seaweed edging sideways across the pool. It’s moving too fast to take a clear photo in the poor light. The blurring makes it look even more alien.
A scorpion fish lies still on the sand, watching out for prey.
One surprise is the stunning colours of the seaweeds under the UV light. Some of the dark red seaweeds take on a far more intense, bright colour, glowing red, pink and orange. Where the top shells have worn spires, their tips glow pink.
After an hour, tiredness and cold begin to set in. We switch off our torches and take a moment to gaze at the stars before we head home to bed. Junior is already asking if we can come again the next night, and the next.
It looks like I’ll be having a few more nights out this summer.
Steve has recently been specialising in finding and studying marine insects and other air-breathing invertebrates that live on the shore, hiding in cracks in the rocks. It seems improbable that beetles and acrachnids can survive out here in the marine environment, but Steve tells me that they’re everywhere, and just get overlooked.
He prises away a piece of rock and points to a minute ant-like insect that’s scurrying across the stone. A rove beetle. It doesn’t take him long to find what he’s been searching for, a pseudoscorpion.
I borrow Steve’s headband magnifier, which is a must-have item for anyone who wants to look like a mad scientist.
It takes me a few seconds to find what I’m looking for and under the magnifier, with its pincers raised towards me, it looks alarmingly like a real scorpion. Pseudoscorpions lack the stinging tail typical of the true scorpions, but they have another way of capturing their prey; they use a poisonous gland in their claws.
Neobisium maritimum is the only species of pseudoscorpion that can live out here on the shore, although others may be found at the top of the beach above the strandline or on cliffs and many species are found in gardens and houses, with one species (Cheridium museorum) even specialising in eating book mites.
This pseudoscorpion seems quite at home exploring the back of Steve’s hand, but its favourite hideouts are deep in the joints of the rocks, where it lurks, hunting for springtails and other tiny prey.
I’m meant to be helping Steve and Julie find spiny starfish and bull huss shark egg cases, but it’s too windy to access the best areas. Undeterred we see what turns up and this beach never disappoints.
A blob gets me excited (as blobs often do). I frequently see Lamellaria perspicua here – it’s a kind of cross between a snail and a slug and has a syphon tube sticking out the front, which makes them look like mini daleks. This one is different. It’s paler, flatter and doesn’t have the usual crusty appearance. Finally, I’ve found a Lamellaria latens.
Having failed to find any eggs when filming with Countryfile looking for signs of spring, I’m now seeing them everywhere. Every other crab I find seems to be in berry and there’s a wonderful variety in the colour of the eggs between species.
This long-clawed porcelain crab is around the size of my thumb nail and has a small clutch of eggs to match. I don’t remember ever seeing the eggs of this species before. They’re a rich lemon colour, visible under the female’s tail even when she’s upright because they’re so bright.
Also sporting colourful eggs, this Xantho pilipes crab is wandering near a patch of sea grass I’ve not seen on this beach before. This time, the eggs are a deep burgundy red and there are so many of them it’s amazing the crab can still walk.
Steve finds an unusual crab with an arched front, but otherwise like a Green shore crab. We think it might be a species we’ve not seen before and take lots of photos but decide in the end it’s probably just a weirdly shaped shore crab.
It’s quite late in the season now for scorpion fish eggs, and the clutch that Julie finds are looking dried out and generally unhealthy, although there are still eyes visible in there. The dead eggs are being scavenged by hordes of hungry springtails (Anurida maritima).
It makes me wonder if there’s a pseudoscorpion nearby, waiting to guzzle the springtails up.
Everywhere I step there seem to be sea hares, roaming the sea floor and feasting on the freshly sprouted seaweeds. I even find my first tangle of ‘pink spaghetti’ of the season – these are the eggs of the sea hare.
Other-Half, who has been specialising in fish catching recently, manages to scoop up a topknot flatfish. This one is a good size and has the classic highwayman-style dark mask pattern across its eyes.
These fish specialise in living on the shore and have a specially adapted sucker fin allowing them to cling on to the underside of rocks.
The finds come in thick and fast. Julie and Other-Half both come across fully-grown spider crabs covered in seaweeds, pretending to be rocks.
Junior discovers a Green shore crab with a classic clutch of orange eggs under her tail, to complete our kaleidoscope of crab egg colours.
Not to outdone, there are mollusc eggs everywhere too. I see clutches of sting-winkle eggs under every overhang and there are plenty of netted dog-whelk eggs on the seaweed too.
It’s almost a given that you never find what you’re looking for. There’s not a spiny starfish in sight when normally I see them everywhere. We manage to find some catshark egg cases, but most of them are already hatched. It doesn’t matter. What we do find is incredible and I’m so excited to have seen my first pseudoscorpion. As Louis said on Countryfile the other week, there’s always something!
When the BBC approached me about filming a Countryfile episode with Matt Baker on the signs of spring, I reeled off all the exciting things we might find in the Cornish rock pools. By mid-April there would be male pipefish with eggs on their bellies, scorpion fish babies already hatched, crabs with egg masses under their tails and so much more. No problem.
What I hadn’t considered was that the TV crew’s packed schedule would require us to film on an exposed north coast beach on small tide. All I could do was to hope for good weather and some luck.
The West Cornwall episode of Countryfile is available on BBC iPlayer here. (Available at the time of writing).
Portreath, near Redruth, has wide, golden sands and magical craggy cliffs. Like many other beaches in Cornwall, it has a fantastic community group working to conserve wildlife and keep it clean – Love Portreath.
To the east of the bay lies what used to be an important mining port, sheltered by a long harbour wall with a stretch of rocks alongside.
The pools here are a great habitat, but the fierce waves sweep any small stones away, leaving only large boulders and deep overhangs as hiding places for the rock pool creatures. Great for wildlife, but tricky for rock poolers, especially with a strong swell rolling in.
Fortunately, I had help in the form of Cornish Rock Pools Junior and two of his friends, Ashley and Rowen. Without their keen eyes and amazing patience, it would have been an impossible task to find as much as we did in just fifteen minutes. Louis led Matt Baker crashing surf, assuring him there would be more to find on the lower shore, while Ashley plunged waist-deep into pools trying to catch a goby. Rowen spotted a cushion star at the back of a crevice in the rock. Needless to say I was prepared to risk getting my hand stuck to retrieve it (and nearly did).
In just a few minutes we managed to assemble a good collection of common rock pool creatures: a green shore crab, a common blenny, some top shells and, of course, the cushion starfish.
Inevitably, I made my television debut by telling the nation that starfish feed by pushing their stomachs out of their mouths and dissolving their prey. You’re welcome!
Although we failed to find many signs of spring other than the large amounts of seaweed sprouting all around us, the magic of television went to work and the final programme included some fabulous footage of green shore crab eggs hatching out into the plankton.
It’s incredible how all the snippets we filmed on the day were woven together into the final programme. Huge thanks go to the all of the Countryfile crew for putting us at ease and doing their TV magic, and to Matt Baker in particular for taking the time to chat and take photos with the children.
Even though conditions weren’t ideal, it was a wonderful opportunity to showcase the Cornish beaches and the creatures that survive in this extreme environment.
Rock pooling can be an emotional experience and I’ve experienced everything from happiness to horror in the last couple of weeks. The arrival of warmer weather has brought out a joyous burst of extraordinary colours in the pools and plenty of surprises too.
I’ve picked out some of the best below, but I’d suggest you put down your food before you read the last one.
It’s never easy to run in knee-deep water and across slippery rocks wearing wellies, but I came close to setting a new land-speed record after hearing the cry of, ‘Octopus!’ from across the shore at Lee Bay.
The timing couldn’t have been better. I was teaching a Coastal Creatures workshop on molluscs in North Devon and here was the mollusc I’d been hoping to find for decades.
Experienced local rock pooler, Rob Durrant of Coastwise North Devon, found the Curled octopus (Eledone cirrhosa) hiding under a rock. With quick thinking, he scooped it into a transparent pot where it demonstrated its great ability to change shape and colour, blanching almost to white when we placed it in a white bucket.
Octopi are natural escape artists. Because they have no bones, they can squeeze into incredibly tight spots. This one seemed to enjoy the safety of its pot and it took some effort to persuade it to swim free in the pool.
One of the volunteers asked me to verify what species of pipefish a participant had found. The fish did have a long snout like a pipefish, but on closer inspection I could see its body was thickened in the middle, and in front of its dorsal fin was a row of flattened spines.
The fifteen-spined stickleback (Spinachia spinachia) is a species I’ve only seen a couple of times before. It’s elusive and easily overlooked, but it is a remarkable fish. In addition to having the most beautiful, tiny mouth, it also has an fascinating life cycle. The male fish builds a nest, arranging fronds of seaweed just-so before the female lays her eggs in it. The female fish dies soon after laying, leaving her mate to guard the nest of eggs until they hatch.
On the same day, we had another surprise, a corkwing wrasse swam straight into Other Half’s bucket.
‘There’s something weird on it,’ he said, thrusting the bucket towards me.
Inside the bucket, a fish with bold turquoise stripes across its face was swimming at an awkward angle, looking at me through a wide orange eye. Pretty though it was, it was something just behind its eye that Other Half was pointing at. He needn’t have bothered: I was already staring at it.
I wasn’t sure I wanted to see it, but I couldn’t help looking.
No doubt, like me, you’ve heard of fish lice. They’re generally tiny copepods, a kind of swimming baked bean, that attach to a fish and suck its blood. They’re the sort of thing that can put you off your lunch, but you accept it’s part of nature.
This thing, on the other hand, was straight out of an alien movie.
Far from tiny, this parasite was at least a quarter of the length of the fish.
It was a giant, woodlouse-like animal, a marine isopod, clamped onto the fish by its jaws. On closer inspection, there were other, smaller isopods of the same sort on the fish.
I’d never seen anything like it – and would be happy not to again. I’ve come across many grim feeding habits on the shore, but never imagined that I’d see a parasite this large.
It was the find of the day, even if it did make me feel a touch nauseous.
Several people at the ramble asked if we should remove the parasite. However horrific it looks to us, all these animals are part of the ecosystem and they have to feed, so it’s best not to interfere.
It turns out that there are a couple of species of isopod that target wrasse. This one is Anilocra physodes, confirmed by David Fenwick of Aphotomarine. David suggests looking out for another isopod that replaces the tongue in weever fish. Yes, you read that right! I have no idea how to go about looking in the mouths of weever fish.
It goes to show that there’s no end of surprises on the shore.
To allow you to get back to your food, here are some less alarming rock pool finds from the recent spring tides.
Happy rock pooling!
For everyone who loves Cornwall's rock pools. Information about great beaches, marine wildlife and conservation.