The Cornish summers are anything but predictable. One day I’m sweltering in shorts and beach shoes and the next I’m shivering in waders and a thick jumper. Although the showers are back with a vengeance, there’s always something to be found if I can make it across the rocks without breaking an ankle.
My first outing is to the rocks beyond East Looe beach and I’m pleased to come across a new colony of St Piran’s hermit crabs on the mid-shore.
They’re becoming a familiar sight around Cornwall and I’m starting to recognise them from the tips of their red legs, before their chequerboard eyes and equal-sized claws emerge from their shells. Continue reading Wrasse and wrack→
The pools sparkle as the sun finally shoulders its way through the February murk. Beneath the surface, the seaweeds are sprouting up, the first sign of spring in the rock pools, and with them come the sea slugs. Many of these minute molluscs choose to spawn in the shallow waters around the shore, where their favourite foods such as sponges, sea squirts and seaweeds are abundant.
How they travel such distances to find mates and lay their eggs here is something of a mystery to me. They are delicate, squishy little things at best, and mere blobs of jelly out of the water. Once in the water, though, they reveal their colours and shapes, and most rockpoolers delight in finding them. Today, I see mostly pale, blobby ones rather than their spectacular cousins, but they are intriguing nonetheless. Continue reading A Window to the Underwater World→
Next month, 50 years will have passed since the Torrey Canyon tanker ran aground off the Isles of Scilly, releasing a 700 square km oil slick. On the last day of 2016, I visited Porth Mear to learn how a long-term survey has revealed the secrets of the beach’s fragile recovery, and to see if the St Piran’s hermit crab (Clibanarius erythropus)has managed to make more than a temporary comeback.
When the Torrey Canyon hit rocks in February 1967, its cargo of oil ended up on the Cornish, Breton and nearby coasts. The oil, along with huge quantities of solvent emulsifying chemicals used in an attempt to disperse it, decimated seabird populations and marine wildlife.
Concerned by the impact on his local beach, biology teacher, Richard Pearce, decided to monitor the wildlife on the shore three times a year. He’s been doing his survey without fail ever since.
I wasn’t born when Richard first marked out his quadrats on Porth Mear beach, but I grew up hearing stories of the horror people felt at the sight of the thick black tide, the pervasive smell of the oil, and the woefully unprepared volunteers attempting to shift the cloying oil with garden tools. Decades later, lumps of tar were still washing onto our beaches after every storm.
I’ve always wondered what the process of recovery looked like, so I jumped at the chance to join Richard at Porth Mear for survey number 150.
It’s clear, after many surveys, that Richard knows the beach well. So well, in fact, that even when the gouged crosses and splodges of green paint that mark the survey quadrats have worn away or been covered up by seaweed, he still knows exactly where they are.
As he shows me his method, calling out the presence and coverage of seaweeds, barnacles and molluscs to his partner, Richard tells me how after the Torrey Canyon disaster the green seaweeds were the first to flourish. With many of the grazing molluscs wiped out by the oil and the chemicals used to disperse it, the seaweeds soon took over. After this other animals gradually returned.
Over the years, Richard has seen many changes. Some are seasonal or weather related, others are harder to explain but may be due to warming seas. Why one pool that was once crammed with mussels now has almost none and why limpets are doing particularly well this season is hard to say, but the data he is collecting reveals changes that would otherwise go unnoticed.
The tide drops and, while Richard is knee-deep examining a quadrat alongside a long deep pool, I explore the lower shore pools, determined to find out whether the St Piran’s crab is still here. After an absence of more than 30 years, this equal-clawed hermit crab started to reappear around Cornwall in 2016 and we had one record on this beach in the spring. Although past records are too patchy to be sure, it’s thought that pollution from the Torrey Canyon played a role in the loss of this species, so 50 years on it would be lovely to find it re-establishing.
Every time I see a shell move, I leap on it, looking for the red legs and spotty eyes, but every one is a common hermit crab (Pagurus bernhardus).
Rooting around in the pools always reveals some unexpected treasures. I make my first record of a stalked jellyfish (Calvadosia cruxmelitensis) at this site.
This is always a good beach for finding Cornish clingfish, and the rocks of the lower shores don’t disappoint. In one small area I find a dozen of these stunning little duck-faced fish, some with iridescent blue spots on their heads.
As I follow a gully across the shore I find several scorpion fish lurking among the rocks. Brittle stars lurch away into the seaweed and Xantho pilipes crabs close up, pretending to be pebbles.
My other half and Junior join me, hunting for crabs and fish. Every thirty seconds I remind them that we need to look for little hermit crabs and they ignore me as they should. They’re used to me and my missions.
Junior at least keeps pointing out suitable pools. He knows they like the ones with pink coralline seaweed and there are lots here. I barely have time to glance at one before he’s trying to drag me to the next.
And then it happens. A shell moves and as soon as I pick it up I know. The legs are red, the shape’s wrong for the common hermit crab.When the crab extends its claws there can be no doubt, they’re hairy and pretty much equal sized. This is a St Piran’s crab.
I yell like I’ve won a golden ticket. Under my camera it’s easy to see the black and white spotty eyes of the crab. We all gather to look and as I take an underwater photo, I see other shells moving.
Sure enough, this next shell has a St Piran’s crab in it, and the next, and the next. While I’m taking photos in the pool, Richard is examining shells on the rock by a small overhang. “There are nine more here,” he says. Soon we’ve counted at least fourteen. They’re all larger than the one found here earlier in 2016.
Whether there are other groups of St Piran’s crabs on this beach is hard to say. The tide is surging in now so we’ve run out of time to search.
The existence of the St Piran’s crab is a fragile one; storms, temperature change, pollution and disturbance threaten our shore wildlife now more than ever. Richard’s survey provides an incredible conservation tool with its wealth of data about what’s here and how it changes.
50 years on from the Torrey Canyon disaster, the confirmation of the St Piran’s crab’s comeback is an uplifting way to complete this survey (and the year).
Things have been quiet on this page the last couple of months. Cornish Rock Pools Junior, Other Half and I took an extended holiday to visit the towns and beaches of Brittany. As always our travels had a bit of a marine theme…
“Est-ce que c’est un anémone?” the eager child in the dark-rimmed spectacles asks. We explain what a ‘stalked jellyfish’ is to the class of seven-year-olds. “Jellyfish!” they chant.
Between fascinating excursions to the fire station and the sardine factory, we are giving impromptu English lessons to a class of primary school students during our twinning visit to Quiberon in Brittany.
It’s funny how the summer days float by. The house has been practically bursting with people for weeks now and I haven’t found the space to write about our many beach trips, but August still feels like a lazy month.
It reminds me of my childhood summers; a jumble of paddling, swimming, rockpooling and finds. Only I’ve just turned 40 and now I’m the one remembering hats and towels, preparing picnics and being called on constantly to help build dams or identify creatures. Every few days I realise that I’ve failed to take many photos and still haven’t blogged anything I’ve found. It’s just the way August goes.
The warm waters are drawing in all sorts of creatures at the moment. The north coast especially is teeming with jellyfish. Harmless Moon jellyfish have washed up in their thousands. These transparent little jellies have four mauve circles in their centre in a pattern that reminds me of cucumber slices (OK, that’s probably just me).
Other jellyfish that have mild stings, like the compass jellyfish are also washing in and I think my thigh met with one of the many blue jellies in the water at Mawgan Porth a couple of weeks ago from the unattractive rash I developed! On the plus side, some friends found a spiny starfish in a pool at the top of the mid-shore pools, which looked like it might be feeding on the stranded jellies.Continue reading Summer Lazing in Cornwall’s Rock Pools→
As you might imagine, we’re fans of nature documentaries in this house and we’re all looking forward to watching Steve Backshall’s new series, Fierce. It’s got me and Cornish Rockpools Junior thinking about opportunities to meet ‘fierce’ wild creatures closer to home.
Of course, these animals aren’t exactly fierce, they’re just equipped to survive the evolutionary arms race with attitudes, weapons and chemicals that aren’t very human-friendly.
You don’t need a plane, a film crew and a ton of equipment to seek out an encounter with a well-armed rockpool ninja. This weekend’s massive low tides are the perfect opportunity to head out onto the shore and check out our top 5 fierce(ish) rockpool creatures.
So, check the tide times, grab a bucket, put on your wellies and take a look…
5. Small spotted catshark
These small sharks, often known as dogfish, sometimes become stranded in pools during the very lowest of tides. They’re not at all aggressive, but it’ll sound impressive that you’ve met one. They have incredibly rough skin that used to be used as sandpaper. In some places you can also find their egg cases and those of their larger cousin, the nursehound, attached to seaweed. They take around 7-9 months to hatch out so never detach the egg case from the weed.
4. Snakelocks anemone
This anemone is common in rockpools all around Cornwall. It’s easy to see how it gets its name from its long snake-like tentacles, which are usually green with purple tips, but sometimes a dull-brown. They’re from the same family as jellyfish and have stinging cells which shoot poisonous harpoons into anything that touches their tentacles. It’s best not to touch this anemone as some people have a reaction to the sting. If you do touch one be sure not to rub your eyes because stinging cells can attach to your skin – wash your hands as soon as you can.
Cornish Rock Pools Junior is convinced snakelocks anemones can eat your foot. That’s unlikely, but watch what they do to this fly…
An unlikely contender, but there are several species of worm on the shore that can be pretty fearsome, especially the larger ragworms. These animals have an extendible jaw that can shoot out and deliver a painful bite. Others, like the bootlace worm secrete a toxic mucus. Handle with care!
2. Compass jellyfish
Like the anemone, this jellyfish is armed with lots of nematocysts (stinging cells), but far more powerful. These jellies with their distinctive V-shape compass markings can give you a painful sting. Jellyfish don’t live in the rockpools but are often washed in by the winds and tides, especially in the summer and autumn months. They’re beautiful creatures and well worth a look, but remember not to get close or to put your hands in the water – their tentacles can be hard to see, very long and can become detatched from the main jellyfish, so it’s not worth the risk (yes, that’s talking from experience… I’m a slow learner). There are lots of different species of jellyfish and some, including the massive barrel jellyfish, are harmless, but if you’re not sure, stay clear!
1. Devil crab (Velvet Swimming Crab)
The top fierce creature award, as voted by Cornish Rock Pools Junior who will not go near them, is [insert fanfare of your choice here]… the velvet swimming crab. This crab, known by Junior and many others who’ve met it as the ‘devil crab’, is afraid of nothing and is always quick to use its pincers. Their dark shells and gleaming red eyes give these crabs a sinister look to match their temperament. They’re brilliantly suited to hunting in the rockpools and shallow seas. If you dare to look closely at one (see ‘How to pick up a crab’), you’ll see that their stripy back legs are flattened into paddles, making them excellent swimmers. Watch out for them lurking buried in the sand, with only those red eyes showing.
There are plenty more dangerous creatures, such as the weever fish and the Portuguese man o’ war, that didn’t make our list because we so rarely see them in the rock pools.
It almost goes without saying that by far the most dangerous creature on the shore is us humans. Marine litter, warming seas, pollutants, overfishing and habitat destruction all threaten our amazing marine life. Please do your bit every time you visit the shore:
If you turn any rocks replace them gently, the right way up.
Avoid using nets that can harm creatures and tread carefully.
If you catch any creatures, keep them in plenty of sea water and return them quickly to where you found them.
Don’t leave any litter behind and be aware that sun cream isn’t good for wildlife.
Every time you visit a beach take 2 minutes to pick up any rubbish you see.
Have fun and please do let me know what creatures you meet (fierce or otherwise) in the Cornish rock pools.
As soon as I heard the yell of excitement, I guessed what it might be. This is the species that everyone recording rockpool wildlife in Cornwall has been watching out for. For me, it was especially exciting that this one, found by Jan of Coastwise North Devon, had just turned up in one of my favourite coves, Porth Mear.
Meet Clibanarius erythropus. Nope, none of us could remember that name either, though we knew it certainly was one. Jan decided to name little hermit crab Sydney to make things easier.
Clibanarius erythropus is a distinctive (if unpronounceable) crab. Most species of hermit crab have one claw that is considerably larger than the other – most are ‘right clawed’. This species is almost unique in having two fairly equal sized claws.
The white spots on its eyes and its striking red legs are also a good aid to identification.
If you find one, please take a photo and send your record to ORKS, the Cornwall and Isles of Scilly online recording system -it’s quick and easy to do.
This warm-water species, relatively common in the Channel Islands and around the French coast, is at its northerly limit in Cornwall. It used to be found occasionally on our shores, but has rarely been recorded here since the 1967 Torrey Canyon oil spill in 1967. The last recorded sighting was in 1985.
But this year it has reappeared. There have already been at least three records from various locations around Cornwall in 2016. Could these hermit crabs be making a comeback?
One explanation for the reappearance is the high water temperatures of the last couple of years. In 2015 warm currents arrived early in the year bringing a massive bloom of the giant barrel jellyfish. These conditions could have been right for the hermit crab plankton to survive and settle on our shores.
So now we have to wait and find out whether the conditions remain favourable for this little hermit crab to become a long-term resident in our rock pools.
For everyone who loves Cornwall's rock pools. Information about great beaches, marine wildlife and conservation.