Tag Archives: Hermit crab

Rock Pool Highlights in Looe

As anyone who takes notice of the natural world knows, nothing stays the same. I visit my local beaches around East Looe so frequently that I know every rock and every pool. Yet, the more time I spend here, the more I notice.

Sitting by a pool for a long time, I notice more and more detail, like this tiny needle whelk.

Sometimes I learn something new about a familiar animal, sometimes I am treated to fascinating displays of natural behaviour, and sometimes I find species I never seen before. Here are five recent highlights from my local beach.

There’s always something new to see… in this case it’s Other Half in his new waders.

Cushion Star Hatchlings

It took me many years to realise that cushion stars lay eggs and to finally see my first just-hatched babies. Now I know what to look for, I see their eggs everywhere in the summer rock pools.

So many baby cushion starfish (Asterina gibbosa), fresh out of their eggs.

I find a cluster of new, tiny cushion stars and fall in love with their bright orange perfection and impossibly small tube feet.

Cushion stars – these baby starfish have just hatched and are setting out across the pool on their little tube feet.

A Hermit Crab Without a Shell

The thing that everyone knows about hermit crabs is that they live in the empty shell of a sea snail. It’s not entirely true to say that they have no shell of their own though. Hermit crabs have tough claws and shell covering the front part of their body. Just like other crustaceans, they moult their shell each time they grow.

A St Piran’s hermit crab, East Looe. This hermit crab’s rear end is comfortably housed in a shell.
Moulted shell of a St Piran’s hermit crab. Hermit crabs have shell covering the front part of their bodies. When they grow, they moult their old shell, leaving it behind.

Hermit crabs don’t, however, have a shell on their rear end. Instead, they have a long, spiral tail, which is soft and bendy. When the hermit crab finds a suitable shell to live in, it winds its tail up through the internal structure of the shell, clamping its home in place.

If a hermit crab loses its shell to another crab or a predator, it finds itself in a real predicament. That soft tail is vulnerable to attack.

Hermit crab out of its shell
Hermit crab out of its shell, showing its curly tail.

When Junior and I come across a homeless hermit, we locate a suitable empty shell and watch what the crab does.

The whole process is astonishingly quick.

Nudibranch Sea Slug – Eubranchus exiguus

Regular readers will be well aware of my (entirely justified) obsession with sea slugs. If you aren’t already aware of how exquisite these little animals are, you might like my introductory talk for The Shores of South Devon.

Most UK sea slugs are small and some are so tiny that you can barely see them with the naked eye. I spot a speck of jelly on some seaweed and spend the next twenty minutes crouching in the water to try to focus my camera on it.

Eubranchus exiguus – a nudibranch sea slug, Looe, Cornwall.

The slug is moving, the seaweed is moving and my hands are far from steady, but the photos are good enough. Meet a species of nudibranch sea slug that is new to me: Eubranchus exiguus.

Eubranchus exiguus sea slug, showing the distinctive shape of the cerata on the slug’s back.

The long, inflated cerata on the back of this sea slug look like they have been pinched in near the top, giving them a vase-like shape. Scattered white flecks adorn its body. When I can get it in focus, it is a fabulous-looking creature.

The Eubranchus exiguus slug on seaweed with my finger in the background to give an idea of scale. It was around 2mm long.

Rock Goby Eggs

There are few things more mesmerising than fish eggs. They are generally transparent, meaning that you can see the babies’ eyes looking out at you. As the fish grow, they become fidgety, twisting and turning inside the egg. Rock gobies are a very common rock pool fish and their distinctive capsule-shaped eggs are usually well-guarded by the father, who stays close until they hatch.

Rock goby eggs. Looe, Cornwall.
Rock goby eggs

Doto slugs (and a bonus slug)

Finding sea creatures in the pools is a haphazard business; you can rarely be sure of finding even common species. However, if I want to find a Doto sp. slug, I know just where to look.

In places around my local rocks, the brown seaweeds (wracks) are so completely covered in hydroids that they look like they have grown beards. Very close-up, these hydroids (Dynamena pumila) look like stacks of pale triangles. Among them, feeding on the hydroids, are the tiniest splodges of jelly – the Doto slugs.

Doto sp. slug – possibly Doto onusta. Looe.

Out of the water, they are a sorry, squidgy mess. If, however, I can persuade one off the hydroid, I can put it in the water to reveal its towering jelly-mould structure decorated with charming crimson or black dots. The satellite dish rhinophores (antennae) on the slug’s head are an impressive accessory too.

Doto sp. slug – possibly Doto onusta. Looe, Cornwall.

Whether they remind you of cakes or jellies, there’s something gloriously edible-looking about the Doto slugs.

Warning: Slugs are not dessert. Don’t eat rock pool wildlife.

The little spots on the slug’s cerata look so much like cherries on a cake. Doto sp. slug, Looe.

It isn’t clear what species these slugs are; Doto slugs are notoriously difficult to identify. They were initially thought to be Doto coronata. That species isn’t now believed to feed on Dynamena pumila, so they may be a species known as Doto onusta – or something else. Whatever they are, I absolutely love to see them.

And now for a bonus slug… The orange-clubbed slug, Limacia clavigera, is a frequent find, but is too fabulous to be left out. Enjoy!

The orange-clubbed sea slug, Limacia clavigera. Looe, Cornwall.

Have you found anything new on your local beaches? I love to hear what other people have seen and can often help to identify unusual finds if you’d like to get in touch.

You can also find identification guides to some common rock pool creatures such as crabs, starfish and fish on my Wildlife page.

Whatever the weather, always stay safe in the rock pools. Follow my rockpooling tips to look after yourself and the wildlife on the shore.

This website is a labour of much love and the content is available for free to everyone. My wonderful readers often ask if there is a way to support my work. You can now ‘buy me a coffee’ through my Ko-fi.uk page. (Just click donate and you can set the amount to pay by PayPal). Thank you!

It’s Conger Time! Low Tide Rock Pooling Surprises.

No matter how many times I go rock pooling, something always takes me by surprise. It helps that I’m constantly awestruck by simple things: the blue flash of a kingfisher zipping over the pools; the unfurling tentacles of a fanworm; a seaweed-covered stone that turns into spider crab – sprouting legs and walking off.

Today, Junior and I are looking for little cuttlefish because that’s what we always do in shallow, sandy pools. We won’t find any, but that never matters. Whatever turns up will be the best thing ever.

It can take a while to get your eye in, but seemingly empty rock pools are full of life.

Although the pools look deserted, I know they’re not. I stand still in the water and am reminded of games of ‘Grandmother’s Footsteps’ in the playground. There are flickers of movement at the edges of my vision, yet each time I look towards them there is nothing but clear water covering smooth sand.

A dragonet is the first creature to break cover, gliding noiselessly in short bursts. Every time the fish stops swimming, my eyes struggle to make out its triangular, small-mouthed head or slender tail against the sand. Only the orange glint of its eyes, which protrude from the top of its head like a cartoon drawing, give the dragonet away.

Dragonet resting on gravelly sand. Having eyes on top of its head gives it great vision of what is going on all around.

It takes me several attempts to lower my camera into the water. The fish darts away at the slightest disturbance. Even close-up, the wavy blue patches and dark saddle patterns on the fish’s back blend with the colours of the sand. Sometimes I take a photo and realise afterwards that the fish isn’t in it.

Dragonet in a sandy pool

The sand in the pool is pock-marked with tiny craters. Keeping my camera in the water I wait for the creators of this miniature battlefield to reveal themselves. After a few moments, I am rewarded with a frantic jet of sand shooting out of the bed of the pool to my left. Another erupts to my right.

Zooming in to the source of the sand-flinging I can see a solitary common shrimp, digging like an eager puppy, throwing sand out in every direction as it sinks deeper into the pit it has made.

Brown shrimp digging

A minute later, it moves on to another spot and resumes its endeavours. All around me, other shrimps are digging in earnest to find food. If I move at all, they fling sand over themselves until only their googly eyes are still visible.

Digging brown shrimp

Small, brilliantly camouflaged, gobies also flit about the pool, occasionally photo-bombing my attempts to photograph the shrimps. These may be sand gobies or common gobies; it takes close examination to separate the two species and they have no plans to stay still for long enough.

Brown shrimp – and a young green shore crab (bottom right)

We follow the tide, pulled ever further out through the pools by our curiosity, exploring under rocks and among the seaweed until we are at the seaward edge of the rocks. In the summer we snorkelled just a few metres from here at mid-tide, seeing small spotted catsharks, wrasse and comb jellies over the seagrass and kelp.

Kelp provides a wonderful habitat for other species, including this sea mat bryozoan (Membranipora membranacea).
Membranipora membranacea – even closer-up showing the rectangular autozooids and feeding tentacles extended.

Junior finds a south-clawed hermit crab (Diogenes pugilator) that has been washed in by a wave. We place it in a more sheltered spot and it has disappeared in seconds, burrowing into the soft sand.

Diogenes pugilator hermit crabs have a very long left claw.

By this point my hair is soaked from putting my head close to the dripping-wet seaweed that hangs over the rock faces, looking into every nook and cranny. I can see that Junior is plastered head to toe in sand from building a huge tide fort. It’s a happy sort of look. In any case, there’s nobody here to judge us apart from some whistling oystercatchers and they are too busy impaling limpets to worry about us.

Short video of brown shrimp, sea spider and hermit crab in action.

Crawling up to a small overhang with my chin almost touching the sand, I lift the fringe of sea lettuce aside and meet today’s surprise. A large, amber eye, as big as my own, is looking back at me.

Conger eel
Conger eel

It belongs to a sharp-nosed brown fish whose body is hidden by the deep, dark hollow beneath the rock. I move my own nose back a little from its long, sharp jaw.

If this is what I think it is, that body will be long and the jaws contain a powerful set of teeth that make it an efficient predator.

Junior knows I only call him away from his work when there’s something truly exciting to see and I am massively excited. I’m pretty sure this is the first conger eel we have ever found on the shore.

Do-do-do…. Conger eel under an overhang exposed by the low tide.

For a moment, we wonder if it is alive. There is hardly any water under the overhang and the fish doesn’t move. I sloosh some water from the pool through the gap in the rock and the fish repositions its head to take in the oxygen. The tide is already on the turn so it will be fine.

I take a couple of photos, pour some more water into the overhang and leave our fish-friend in peace.

It’s a good thing there is no-one to see the pair of us, covered in sand, dripping wet, dancing and singing our way back off the beach with the waves at our heels. It isn’t most people’s idea of a beach party and the pun is terrible, but we couldn’t care less.

“Do-do-do. Come on and do the conger!”

Happy New Year! Here’s to all of you who have done your bit to help wildlife and make the world a better place in 2021.

With thanks to the experts on Facebook groups who confirmed I was correct in my feeling that the fish looked ‘congerish’.

Some other finds from this expedition…

Blue-rayed limpets
Sea slug! The first time I have found Palio nothus in this location. This nudibranch slug has wonderful tall helter-skelter rhinophores on its head and a circlet of fluffy gills on its back.
‘Kelp fir’. Obelia geniculata hydroids on the kelp, looking like a wintery forest.
A sea spider – probably Nymphon sp. Look at the little spidery shadow it’s casting on my hand.
Crouching rockpooler, hidden dragonets

Whatever the weather, always stay safe in the rock pools. Follow my rockpooling tips to look after yourself and the wildlife on the shore.

This website is a labour of much love and the content is available for free to everyone. My wonderful readers often ask if there is a way to support my work. You can now ‘buy me a coffee’ through my Ko-fi.uk page. (Just click donate and you can set the amount to pay by PayPal). Thank you!

Staycation Safari

After many days of getting drenched every time we step outside, Junior and I decide to make the most of the warmer weather and have a lazy day pootling about our local area. If everyone else is taking a holiday in Cornwall, so can we! The rocks between Plaidy and Millendreath are perfect for clambering and exploring, and I promise Junior a spot of wave jumping when we reach the sand beyond.

‘Slug alley’ at Millendreath

“I’ve found a blob,” Junior calls over to me.

I am kneeling among some seaweed at the top of a deep rocky gully. My head is almost pressed against the minute Dynamene pumila hydroids that grow on this seaweed, looking at what I’m sure is Doto sea slug spawn. “What kind of blob?” I ask.

“I think it’s a slug,” he says, and I’m up and at his side in a second.

The blob is bigger than I expect, almost like a small anemone on the rock. We stare at it closely, our heads touching. It looks as though it is tipped with blue.

“Oh my word,” I say. “I think you’ve done it.”

We hug and cheer and do a little slug dance, because every slug deserves a dance and this one is especially special. For weeks now, we have been looking for Antiopella cristata, a slug which ought to be found here but which I have never seen.

Taking great care not to harm the slug, we transfer it to a pot of seawater and watch it floof up.

The fully ‘floofed’ Antiopella cristata nudibranch sea slug.

The slug’s body is yellowish, but its back is covered in large waving cerata, each tipped in pale, frosted blue. The effect is like opening a geode to find tall, pointed blue crystals inside.

Close-up Antiopella cristata’s cerata remind me of peacock feathers.

We call the slug ‘Aunty Crystal’ to help remember its scientific name.

Antiopella cristata – or Aunty Crystal as we named this stunning sea slug.

We have named this gully ‘slug alley’ for a reason and plenty more creatures, slugs and others, are hiding on the tall, shady rock face. I find several bright red Rostanga rubra slugs munching on the red sponges.

The Rostranga rubra slug, which gets its incredible colour from the sponges it eats.

A tiny ghost-white slug has been laying its eggs nearby. In the water it takes on a frilly appearance, making it look ever more spectral.

Goniodoris nodosa, looking frilly and ghost-like.

Sea cucumbers adore this area and are to be found everywhere, with their bodies hidden in holes in the rock and just their black and yellow mouths protruding. The two main species I see are Pawsonia saxicola and Aslia lefevrei.

Sea cucumber at Millendreath.

When submerged, they will open a wide fuzz of frilly tentacles to feed.

We clamber over the rocks onto the sand, helping a stranded rockling back into a pool on the way, and splash in the waves for a while.

This rockling had ended up out of the water at low tide, so we helped it back into a pool.

A couple of shells roll past my feet, tumbled by the waves over the silty sand. I make a quick grab for them and, sure enough, they both contain hermit crabs. At low tide, I occasionally find this species here, easily recognised by its enormously long left claw. These crabs are both south-clawed hermit crabs, also known by their gladiatorial sounding scientific name, Diogenes pugilator.

Diogenes pugilator, the south-clawed hermit crab.

They are ready for battle, almost falling out their shells in their attempts to dislodge my grip, unaware that I am saving them from the herring gulls that are lurking at the water’s edge.

The south-clawed hermit crab has long hairs on its antennae.

Junior and I kneel at the edge of a sandy pool and pop the hermit crabs in. We watch one emerge without hesitation. The tips of its claws come first, then the stalked eyes and finally its long hairy antennae. The hermit crab hoists its shell up and runs a few paces.

With a furtive glance about it, the crab swings its vast left claw inwards, shoveling sand into a pile while simultaneously flicking the sand over its back with its little right claw. Grains of sand are flung up through the water and by the time they have settled, only the back of the shell and the tops of the hermit crab’s eyes are visible. It is buried out of sight.

We take the hermit crabs back to the sea, leave them as far out as possible – safe from predators – and carry on wave hopping until the tide turns, when we too must head for home.

Here’s a little video of this week’s highlights from the Cornish rock pools. Sit back and enjoy!

If you would like to find out more about rock pool wildlife or go on your own rock pooling adventures, be sure to pick up my books Rock Pool and Beach Explorer. Out now with September Publishing and available from all book shops and online.

A Shore In Recovery on St Piran’s Day

We tread extra-carefully around the pool, even though we’ve already guessed the St Piran’s hermit crabs won’t be here. The trail of destruction left by the powerful easterly gales is evident: boulders have been lifted by the waves and tossed far from their usual positions, the rich coatings of sponges, squirts and hydroids on their undersides gone. Life is still going on but not as before.

Junior finds a rock goby and some pipefish, but the pool feels like a shadow of its former self. The signs are not good for the nursery of young St Piran’s hermit crabs* (Clibanarius erythropus) that we have been monitoring for the last year.

One thing we have learned from watching these starry eyed, red-whiskered, bristly-legged hermit crabs is that they tend to huddle together. Unlike our common ‘Bernard’ hermits, we usually find the St Piran’s crabs congregated in just two pools on the beach. In this particular pool, there is a central rocky island where all the tiny young crabs like to hang out under a sponge-coated rock, scuttling around like a bunch of kids at the soft play, while the adults are normally found quietly feeding in an adjacent pool.

The St Piran’s hermit crab nursery last year. Every shell has a juvenile St Piran’s crab in it.

We haven’t seen a single St Piran’s hermit crab in the adult pool. They are easily distinguished from the common hermit by their equal-sized claws and bright red antennae, which are visible at a quick glance, even if most of the crab is well-hidden in the shell.

A fully grown St Piran’s crab with the distinctive red antennae, equal sized claws, black and white-spotted eyes and blue-striped leg tips.

As we approach the nursery area I almost don’t want to look. I see a common periwinkle shell sprout legs and my heart jumps. I kneel on a rock to look closely, but it is a common hermit crab, using its oversized right pincer to explore the coral weed, searching for food.

The common ‘Bernard’ hermit crab has yellow-green eyes, a right claw that is bigger than the left and pale antennae.

Among the nursery rocks, there is nothing.

Last time we were here, before the storms hit, every little shell had a St Piran’s hermit crab inside. Now, apart from a broad clawed porcelain crab clinging to the underside of a stone, the area is eerily quiet.

Cornwall’s shores are no strangers to fierce weather and, in places, there are signs of a recovery already, with new seaweed growth and newly-forming sea squirts. St Piran’s hermit crabs, on the other hand, are already at the northern limit of their range here, so they may not cope well with cold winter gales and dips in the sea temperature.

At the far end of the pool I find a chiton on the rock and stop to take a photo. These animals are molluscs but look more like woodlice than snails with their plate-armour shells. Unlike their crustacean look-alikes they have no legs and live firmly attached to the rock.

The colours of the chiton (Lepidochitona cinerea) blend in with the rock.

A flat periwinkle shell on the sand behind the chiton catches my eye. It’s not an unusual shell, but the living shells are usually found feeding on the seaweed and most of the loose shells have been swept away by the storm. There are other small shells close by and they are likely to all be hermit crabs.

My instincts are good. Just as I turn the flat periwinkle shell and glimpse the red antennae deep inside, Junior crouches next to me and shouts that he thinks he can see a St Piran’s crab.

Our first glimpse of a your St Piran’s hermit crab in the pool.

We soon discover that every little shell in this part of the pool is a St Piran’s. Our nursery crabs are still here and have upgraded to bigger shells. There are dozens of them.

Our St Piran’s crab emerges to check us out. It still has some growing to do but is far bigger than last year. It now has the classic colours of the adult crab.
We soon discover lots more shells, all with St Piran’s hermit crabs inside.

It is still early days for this hermit crab that returned to Cornwall’s shores relatively recently after a long absence. In the past it was only an intermittent resident but warming seas may enable these hermit crabs to breed successfully here. On the other hand, an increase in storm events or a weakening of the Gulf Stream could have the opposite effect. A changing climate risks heavier rain bringing more pollution from our rivers and changes in marine oxygen levels and in the plankton on which the food chain depends.

The marine ecosystem is sensitive to our changing climate and so complex that it is extremely hard to predict the exact impacts of changes. (If you’re interested to find out more, check out the Marine Climate Change Impacts Partnership 2020 Report Card).

Further down the shore we find slightly less storm damage and some of the rock pool residents in their usual places. A young topknot flatfish demonstrates its ability to sucker onto the rocks and glide across the seabed, moulding its body to every contour.

Topknot flatfish suckering onto the rock.

In what feels like a reward for our persistence, we find a fabulous Geitodoris planata slug on the lower shore. This time of year, lots of slugs are beginning to spawn.

Geitodoris planata (formerly known by the wonderful name Discodoris planata). The white patches on its back are acid glands used as a defence against predators.

We find a second G. planata in another pool. I am tempted to do some matchmaking, but we leave the slugs where we found them and let nature take its course.

The second Geitodoris planata, looking especially flat and starry.
A close-up of those acid glands (the white stars).

The sun is shining, the St Piran’s crabs are still here, we have seen our favourite nudibranch slug and we have every reason to think that the shore will recover well from the impact of the storms as the spring arrives.

All that is left to do is to head home to prepare our pasties and saffron buns for St Piran’s Day. I would share photos of them, but they were gone too fast!

Gool Peran Lowen!

* I understand that some our lovely neighbours in Devon aren’t so keen on the use of the common name ‘St Piran’s’ for the Clibanarius erythropus hermit crab, which has returned to parts of West Devon as well as to Cornwall. I am completely biased, but the name seems a good fit and it saves me from attempting to pronounce the scientific name. The legend of St Piran says that he was thrown into the sea in his native Ireland with a millstone tied to him, but floated across the sea to Cornwall. The hermit crabs also arrived floating in the plankton from somewhere, most likely Brittany, which also has connections with St Piran. The hermit crab’s striking black and white eyes match the colours of the Cornish flag. I’ve heard plenty of other common names for this crab and anyone can invent their own. In other parts of Europe Clibanarius erythropus has names meaning ‘Little Hermit Crab’, ‘Devil’s Hand Crab’ and ‘Antisocial Crab’, among others.

Bottoms-up! Wildlife Recording on the Last Spring Tides Before Lockdown

There’s no collective noun, as far as I am aware, for a group of rock poolers, but if there was it would refer to bottoms in the air as that’s our standard position – head down, bottom up, searching for marine life. On the best tides it’s not unusual to find other rock pool fanatics on my local shore, drawn by the promise of rarely accessible habitats. So, during the spring tides of early March, I found myself in the company of the bottoms-up brigade at Hannafore, exploring one of our favourite shores.

Junior and his friends were with me, enjoying one of the endless field trips that usually make up our home educating life. Around us, life was churning along as usual despite the first Coronavirus cases being recorded in Cornwall a day or two before. With so many of good friends living elsewhere in Europe, we were only too aware of how quickly the situation might deteriorate, but while we were already starting to avoid indoor events and gatherings as far as we could, the open shore felt as good a place to be as any.

A beautifully marked Xantho pillipes crab – one of many lovely finds at Hannafore.

While the kids were building stone citadels and warring rocky villages at the top of the beach, I gave them vague instructions to come and find me soon and set off down the shore, following the receding tide over slippery rocks and frothing seaweed. I was joined by a friend from north Devon making a special guest appearance at Hannafore.

Among the boulders we discovered a tiny Montagu’s sea snail; a small tadpole-like fish with tiny eyes that tends to curl its tail round its head, looking more like a sleeping cat to me than a snail. These fish were soon turning up everywhere, with more than half-a dozen down a single gully.

A Montagu’s sea snail (fish) in its classic curled-up position. The fish suckers onto rocks.

Further along, a topknot flatfish was clinging to the rock with its sucker-fin, so perfectly blended with the colours of the stones and weed that only its fluttering gills and swivelling eyes gave it away.

Topknots sucker onto rocks and stay still to avoid being seen. Like many other intertidal fish, they can change colour to match their surroundings.

A head popped up from a neighbouring gully, another marine biologist friend from the Marine Biological Association  (MBA) was busy exploring, and across the lagoon, other friends from Bude Marine Group were approaching. Junior and his friends also abandoned their construction works and set out to explore the exposed reef armed with cameras to capture their adventures.

A dahlia anemone. These anemones have a sticky column and are often covered in gravel.

Despite a brisk, cold wind that was welding my fingers to my camera, the excitement of the finds stopped me from worrying about anything except what was in front of me. Sea slugs, quirky hydroids, and beautiful clingfish kept me occupied and there was still a little time before the tide would turn.

A small clingfish, possibly a two-spot. These fish also have a sucker to help them stick to rocks.

The egg cases of the larger of our two catshark species were plentiful on the rainbow wrack and a shout from my MBA friend brought the children running back – a newly-hatched baby Greater spotted catshark (Scyliorhinus stellaris).

Greater spotted catshark egg cases, often called mermaid’s purses.

Baby Greater spotted cat shark (Scyliorhinus stellaris).

Time always feels desperately short to explore this fabulous environment, but every second is full of wonder. Finding a hairy hermit crab made my day, if it wasn’t already made by just being there with so many fantastic and knowledgeable people.

Hairy hermit crab. It’s easy to see how it gets its name!

The hairy hermit crab isn’t a common find on our local shores and this particular crab was exceptionally co-operative, emerging from its hiding place without hesitation which meant I could take photos and video of its incredibly hairy claws, its pale blue eyes and its stunning violet antennae.

Hairy hermit crab.

This week I published the paperback of my book and shared the celebrations through video interviews and a recorded book reading.

Like all children, my son is doing his best to adapt to keeping in touch with friends and family from a distance and my other half is working from home. Some friends have been desperately ill and others still are putting their lives on the line every day as nurses and critical workers. Writing has felt pointless at times, impossible at other time and yet it seems important to share the beautiful things, because these will return.

Stalked jellyfish, Calvadosia cruxmelitensis.

The happy moments shared with my bottoms-up brigade of rock poolers, the exploration and the freedom may just be a memory at the moment, but I am reassured to know that life carries out there beneath the waves as it will here above. The wild creatures that make me catch my breath will still be there when all this is over. Friendships remain and my little community is showing strength, compassion and ingenuity to make sure we carry each other through.

European 3-spot cowrie (Trivia monacha) on star ascidian (Botryllus schlosseri).

Stay safe and watch this space for more colourful creatures to brighten your days, whatever they may bring.

Spot the spider crab! (Macropodia sp.)
Spider crab (Macropodia sp.)
A well-decorated spider crab (Macropodia sp.) in the water. This crab deliberately covers itself in seaweed as camouflage.
Aeolidia filomena – The great grey sea slug or ‘sheep’ slug. These common sea slugs feed on sea anemones.

Rock Pool Bingo – Searching for Southerly Species (Part 1)

It’s always wonderful to spend time with other rock pooling obsessives, so I was popping with excitement at the prospect of three whole days one the shore with friends from North Wales.

Welsh coasts are wonderfully rich in marine life, but I was looking forward to showing my friends some species that I see in Cornwall which aren’t found in most of the rest of the British Isles. I also had a new camera to try out. We wasted no time in drawing up a bingo card of what we hoped to find.

On day 1 we explored the shore at Hannafore in Looe. Junior knew exactly where to look to cross off the first species on our bingo card: the St Piran’s hermit crab (Clibanarius erythropus). He scrambled over rocks on the mid-shore to a pool where these crabs tend to congregate and within a minute he had located the first one.

Sometimes these hermit crabs, with their red antennae and equal-sized claws are barely visible, hiding deep in their borrowed shells. Today they were less shy. This one seemed to almost fall out of its shell as it investigated my camera, while another nipped boldly at my friend’s fingers as he photographed the crab’s distinctive black and white chequerboard eyes.

St Piran's crab almost out of its shell, showing its short back legs
St Piran’s crab almost out of its shell, showing its short back legs

As we followed the tide further down the shore, we looked for sea slugs in some of the usual places but with no luck. I soon realised that I was the only one feeling disappointed. With his head hidden from sight under an overhang, one of my friends was gasping in delight at the sight of a painted top shell. They might be common on the shore here, but apparently that’s not the case in Anglesey.

Although painted topshells are a common sight on my local shores, I never tire of photographing them.
Although painted topshells are a common sight on my local shores, I never tire of photographing them.

Despite the keen breeze that was preventing the tide running out as much as I’d hoped, we soon ticked off another item from the wish list.

I’ll admit that I hadn’t realised that rainbow wrack (Cystoseira tamariscifolia) is mainly a south westerly species. This bushy seaweed is one of our most unmistakeable plants and is a common sight all around Cornwall. In the water its fronds display a turquoise-green  iridescent sheen that is arrestingly beautiful. Out of the water, rainbow wrack loses its magic, appearing brown or dull-green. For some reason I find it impossible to fully capture the colours in photos.

Rainbow wrack - a southerly species on our 'bingo card'.
Rainbow wrack – a southerly species on our ‘bingo card’.

Catsharks favour rainbow wrack when they come inshore to lay their distinctive egg cases often known as “mermaid’s purses”. Despite my hopes of ticking off the egg cases of the greater spotted catshark (Scyliorhinus stellaris) on day 1, the breezy conditions meant we struggled to see into the water. The only eggcases I found were from the smaller species (Scyliorhinus canicula).

A small-spotted catshark eggcase with a baby shark starting to develop inside
A small-spotted catshark eggcase with a baby shark starting to develop inside.

The small patch of seagrass that appeared last year was looking denser and wider than before. The length and width of the fronds suggested that it might be Dwarf seagrass (Zostera noltii), a different species from the other seagrass bed I know of on the site.

The seagrass on this part of the site looked like it might be Zostera noltii, the dwarf eelgrass.
The seagrass on this part of the site looked like it might be Zostera noltii, the dwarf eelgrass.

We embarked on the usual fruitless look for seahorses, which like to live in or near seagrass. I know they’re unlikely to turn up on the shore, but it never stops me looking.

With two species of stalked jellyfish on our bingo card, I was feeling confident of finding them. Instead I kept finding a species that my visitors had already seen, Calvadosia campanulata. These lovely bell-shaped jellies often have brilliant turquoise spots on the bell and and are very photogenic.

Turquoise spots on the bell of a stalked jellyfish (Calvadosia campanulata).
Turquoise spots on the bell of a stalked jellyfish (Calvadosia campanulata).

Despite the less-than-perfect conditions, we had ticked off some new species and amassed a huge collection of photos by the time the tide turned. With two days still to go and better weather on the way, we were off to an excellent start.

Blue-rayed limpet on kelp at Hannafore, Looe
Blue-rayed limpet on kelp at Hannafore, Looe

Junior knew to look for photosynthesising sea slugs on codium seaweed. He found us this lovely solar powered slug, Elysia viridis.
Junior knew to look for photosynthesising sea slugs on codium seaweed. He found us this lovely solar powered slug, Elysia viridis.

A carpet of yellow star ascidian (Botryllus schlosseri) at Hannafore, Looe
A carpet of yellow star ascidian (Botryllus schlosseri) at Hannafore, Looe

One of the strangest finds of the day. Green shore urchins often camouflage themselfs with bits of seaweed or small pieces of gravel, but this one had completely barricaded itself in with chunky stones.
One of the strangest finds of the day. Green shore urchins often camouflage themselfs with bits of seaweed or small pieces of gravel, but this one had completely barricaded itself in with chunky stones.

A bright-coloured pheasant shell at Hannafore, West Looe.
A bright-coloured pheasant shell at Hannafore, West Looe.

The Legendary Slug Formerly Known as Discodoris

The tide has turned and I am reluctantly preparing to leave one of best rock pooling beaches in Cornwall after a fabulous few hours in perfect conditions in the company of great friends. As you’d expect, the day has been full of interesting finds, from sponge-covered spider crabs to golden clutches of clingfish eggs. My camera batteries are running low and my hair is dripping with seawater from all the time I’ve spent poking my head under seaweed-festooned overhangs. The kids migrated up the beach a while back to investigate the picnic bag but us adults can’t bear to leave the pools. As the water creeps up my wellies, I gently turn one last rock, and then another for luck.

This small species of spider crab (Inachus sp.) was so completely covered in sponges that I couldn't see her shell at all.
This small species of spider crab (Inachus sp.) was so completely covered in sponges that I couldn’t see her shell at all.

I let out gasp so loud that it would make most people think I’d just broken a bone, but my friend knows better. She moves closer to ask what I’ve discovered, but I’m so overwhelmed with excitement that I can only babble about having, “finally found one”.

I point a trembling finger at the rock. “It’s a Disco…a Discodoris planata,” I stutter, before launching into a garbled explanation of how it used to be a Discodoris has been renamed Geitodoris, but I use Discodoris because I love that name and…

I take a few photos of the cause of my breathless wonder, straighten up and fling my arms over my head and shout at the top of my lungs to attract the children’s attention. It takes me a minute to realise that the distant child I have in my sights is not mine, but  Junior has noticed my flailing and comes scrambling across the rocks with his friends.

We crowd in the fast-filling pool and peer down at my rock. Even Junior is a bit confused by my excitement over the small, brown lump I’m indicating.

Not just a brown lump... Geitodoris planata (the slug formerly known as Discodoris planata)
Not just a brown lump… Geitodoris planata (the slug formerly known as Discodoris planata)

“It’s Discodoris,” I explain, breathlessly. Instantly, he joins my paroxysms of delight, shrieking out the great news to his friends and going through the same Geitodoris speech as me, for this unassuming slug has become something of a legend in our household.

This isn’t the first time I’ve ever seen one, but it’s the first time I’ve had a working camera with me and it’s the first “Discodoris” that Junior has seen. He is especially impressed with the white star patches on the slug’s back. These are glands which secrete a powerful acid, ideal for seeing off predators.

The white patches are powerful acid glands.
The white patches are powerful acid glands.

On close inspection, there’s a pale-yellow blob alongside our “Discodoris” (Geitodoris planata): another slug. At first, I assume from its colour that it must be a Jorunna tomentosa, a slug I often see on this shore. Indeed, there is another Jorunna tomentosa on the same rock. However, this one seems to be getting very cosy with Discodoris. In fact, it looks to me as though they are mating. The yellow slug also has a far flatter profile than any Jorunna tomentosa I’ve seen before.

Our brown Geitodoris planata and its much paler yellow mate getting friendly in the Cornish rock pools!
Our brown Geitodoris planata and its much paler yellow mate getting friendly in the Cornish rock pools!

If the tide wasn’t coming in, and if I wasn’t called away by someone further up the beach finding a giant goby, I might have been able to check the slug’s underside. If I’d done that I could have seen without doubt that this was a second “Discodoris”, a two-for-one package. The underside of Geitodoris planata is fringed in brown spots, unlike the very similar sea lemon, which is all one colour.

The fish found by some holidaymakers was indeed a giant goby. These fish are a protected species so must not be caught or disturbed without a licence. We left it hiding in its surprisingly small pool.
The fish found by some holidaymakers was indeed a giant goby. These fish are a protected species so must not be caught or disturbed without a licence. We left it hiding in its surprisingly small pool.

Fortunately, social media now enables geeks like me to swap photos with other slug-loving types and sure enough, Geitodoris planata, though usually brown with distinct white acid glands, can sometimes be pale.

Although I will record the slug as Geitodoris planata and there are important scientific reasons for the name change, this little animal will always conjure up glitter balls and platform shoes in my mind. To take photos of the fabled Discodoris, and a mating pair at that, has to be the perfect end to a perfect day.

Geitodoris planata pair
Geitodoris planata pair

Shining like pure gold - the eggs of the Cornish clingfish (Lepadogaster purpurea).
Shining like pure gold – the eggs of the Cornish clingfish (Lepadogaster purpurea).

Jorunna tomentosa slug
Jorunna tomentosa slug

One pool on the mid-shore was home to scores of colourful St Piran's hermit crabs.
One pool on the mid-shore was home to scores of colourful St Piran’s hermit crabs.

Another species of hermit crab - the tiny Anapagurus hyndmanni
Another species of hermit crab – the tiny Anapagurus hyndmanni

Sarah's common eel - our last find of the day before my wellies overtopped!
Sarah’s common eel – our last find of the day before my wellies overtopped!

“The slug formerly known as Discodoris” and a host of other rock pool creatures feature in my book Rock Pool: Extraordinary Encounters Between the Tides. Out now online and in book shops nationwide from September Publishing. If only I’d found one in time to include a photo in the book…

Discoveries on my Doorstep – Rockpooling with the experts in Looe (Day 1)

There’s a questionable theory that 10 000 hours of practice makes you an expert and I may be close to ‘doing my time’ in the Cornish rock pools by now. However, I often feel I’m only scratching the surface of what’s out there. What better then, than to spend a few days on the shore with the genius that is David Fenwick, creator of Aphotomarine together with a fabulous group of fellow rockpool fanatics from Coastwise North Devon?

With layers and waterproofs aplenty, Junior and I joined them at Hannafore Beach, a site I know intimately, to see what new discoveries might await us.

 I realised within minutes that I should have brought a notebook. David’s knowledge of marine species is immense and he wasted no time in finding signs of nematode worms living inside seaweed, reeling off their names. It was windy, drizzling and cold and to make matters worse Junior sprung a leak in his wellies, but there was no doubt this is going to be a fascinating day. Leaving Junior playing at reconstructing ancient ruined cities from the rocks of a mid-shore ridge, we waded across the lower shore.

Sea hares (Aplysia punctata) were everywhere munching on the seaweed.
Sea hares (Aplysia punctata) were everywhere munching on the seaweed.

Some species were familiar. The sea hares were everywhere and so abundant that it was impossible to avoid them. This swirling cloud of purple ink in the water was a sign we’d accidentally disturbed one of them. Continue reading Discoveries on my Doorstep – Rockpooling with the experts in Looe (Day 1)

Home from Home: Quiberon in Brittany

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.


Stalked jellyfish - a Lucernariopsis cruxmelitensis.
Stalked jellyfish – a Lucernariopsis cruxmelitensis.

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.


We have covered the words goby, crab, jellyfish and shark so far and there’s still a sea of raised hands. The children seem desperate to tell us about their finds around the shores of Quiberon. Continue reading Home from Home: Quiberon in Brittany

Rare Hermit Crab Making a Comeback

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.

Clibanarius erythropus - A red legged hermit crab making a comeback in the Cornish rock pools this year.
Clibanarius erythropus – A red legged hermit crab making a comeback in the Cornish rock pools this year.

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.