Tag Archives: cornwall

Who Needs Mythical Beasts? Rocket Jellies, Snakelocks Anemones and a Dragonet

When my son was younger he thought he saw a kraken. I returned from releasing a crab after an event for the local Cub pack to find him and a friend staring out over the sea, shading their eyes to better spot tentacle tips or unusual splashes among the waves. They were quite sure it was out there.

I watched with them for a long time, until the tide was lapping at our boots, because you never know what might be in the sea. A giant squid would be unusual, but our oceans are full of things that are so weird we are only just beginning to understand them. We sometimes see seals, dolphins and fish feeding frenzies, so why not a kraken?

Since then, my son has grown up a lot and is less sure that there are krakens in Looe. We no longer spend much time hiding in the woods looking for dragons or watching the waves for sea serpents. Junior still loves mythology, Cornish and otherwise, but knows that the real world has as much strangeness as fiction.

We are two minutes into this week’s rock pool expedition when he calls to me urgently to look at a thing he’s found.

Junior at work!

“I think it’s a hydroid medusa,” he says, because there’s not much he doesn’t recognize these days. “Quick, it’s going to get away.”

I grab a pot and wade over to where he is pointing. Staring into the tangle of colourful seaweeds, at first I see nothing.

A flicker of movement has me scooping up the water and when I look in my pot there is a tiny creature zipping from side to side, throwing itself against the edges of the pot like a trapped Trogglehumper. Of course, this creature is not a Roald Dahl creation, but an actual, fabulous marine animal. My books call it a ‘root arm jelly’, although Junior and I know it by a different name.

Whoosh! A rocket jelly. (Cladonema radiatum – aka the root arm jelly).

“Rocket jelly!” we shriek in delight.

With great care, we transfer the jelly into the lid of the pot to see it better.

The underside of the hydroid medusa (Cladonema radiatum – the root arm jelly)

The main part of its body, measuring less than a centimetre, is a perfectly transparent dome, through which we can see its rocket shaped internal parts. Pointing downwards, a mouth fringed with ball-shaped structures is feeling about, moving left and right.

The jelly’s transparent body with dark eyespots around the edge. Root arm jelly (Cladonema radiatum).

At the base of the medusa’s dome there are several dark eyespots. Spreading out at around them, like the fire below a rocket, are the most incredible red tentacles. They are branched, curled and almost feathery. As we watch they expand and contract, feel and reach.

Every time I focus on the medusa, it fires itself off in a new direction. Zooming from one side of the petri dish to another in an instant.

I have never seen a medusa with such expanded tentacles before, but I am sure this is the same species of ‘rocket jelly’ we have seen before (Cladonema radiatum).

Those little tentacles pack a strong sting for their size; it is an efficient little predator. I always find it hard to comprehend is that this free-swimming, speedy jelly is the reproductive stage of a colonial hydroid: an organism which lives attached to rocks or seaweed and doesn’t move from the spot.

Obelia geniculata - a hydroid known as 'sea fir'.
Hydroids like this sea fir, Obelia geniculata, live attached to seaweeds.

While Junior takes photos of the rocket jelly, I notice a young fish glide over the sand, stopping near my feet. It has mottled markings in blue, orange and brown, which look colourful and yet provide the fish with an ideal camouflage among the sand, pebbles and shell fragments. Its eyes are mounted high on its head, giving it a wide field of vision. This is the wonderfully-named dragonet.

Dragonet lying still on the sand. Despite the lovely colours, it is perfectly camouflaged.

These captivating fish have a distinctive way of swimming in short bursts across the seafloor and they have an exceptionally long first dorsal fin. Male dragonets raise this sail-like fin as part of a mating dance, which I would love to see some day! It is perhaps this display, somehow reminiscent of a frill-neck lizard opening its collar, that gives these fish their fabulous name.

Dragonet saying hello to my camera!

The dragonet comes unusually close to my camera before scudding away over the sand, becoming invisible every time it stops.

I take some photos of another striking animal with a mythical name, which seems to abound in this pool: the snakelocks anemone. Just like the Medusa of Roman mythology, this anemone has long, green moving ‘hair’. Instead of being made of snakes, though, the anemone’s locks are its stinging tentacles. They are pretty but deadly, especially if you are a small animal, or even quite a big one. We’ve often seen crab legs hanging out the mouths of these large anemones.

Snakelocks anemones in the rock pool.

Some snakelocks anemones are neon green with purple tips, while others are a muted beige colour. Out of the water, they are a sorry squidgy mess of jelly but in the pools their tentacles move and flow, sometimes with the current, sometimes reaching and grabbing for prey they have sensed.

Snakelocks anemone – some are green and some are beige.

The chug of a boat makes us look up. Unusually for this area, there is a dive boat close to the rocks. Two-by-two, people in Scuba gear pop up on the surface and clamber aboard. I wonder what they have seen and whether they have noticed the tiny rocket jellies, lurking dragonets or even the medusa-haired snakelocks anemones.

Dive boat close in to shore.

Perhaps the divers have seen the kraken as they’ve explored the sea just beyond our reach. Even if they have, we don’t feel we have missed out by being confined to the land. The rock pools are full of truly magical beasts. You just have to look.

Snakelocks tentacles waving in the current.

paddle–swimming And fish-whispering: Summer rock pooling in Cornwall

The sun is back and, for once, it has coincided with some big tides. Beach shoes at the ready, Junior and I scramble across the rocks, the clamour of the busy beaches far behind us, heading for our local pools. With Covid levels higher than ever in Cornwall at the moment, we’re hiding away from the crowds as much as we can.

The view to Downderry from East Looe.

We are so used to having to put on layers, waterproofs and wellies that it feels quite decadent to be able to wander about comfortably in shorts. The water is sparkling and the sun’s reflection on my camera screen is so strong that I can’t see the image properly, even when I adjust it to maximum brightness.

I might not be able to see much at first, but the pools are full of life. We cross the rocks to a wide pool fringed with oarweed and sugar kelp. We slip and slide over thongweed and step carefully into the cool water to avoid disturbing the wildlife.

Gorgeous blue-rayed limpets are everywhere on the kelp.

A small movement reveals the presence of a well-camouflaged dragonet. Knowing how hard it is for anyone to detect it, the fish takes its time, gliding a short distance across the sand then taking a break, seeming to disappear each time it stops.

The dragonet blends in perfectly with the sand, pebbles and shells.
Dragonet

Among the delicate red seaweeds, there are plenty of stalked jellyfish (Haliclystus octoradiatus). Their colour range is the same as that of the seaweeds, so although they are bright and attractive, they are not easy to spot.

Stalked jellyfish: Haliclystus octoradiatus

With every step I am getting deeper into the pool, but for once it doesn’t matter. Soon I am right in the middle, with water lapping up to my waist. A blue dragonfly zigzags past me, swooping low before turning back and disappearing towards the cliff.

I wade over to a tall rocky overhang while Junior enjoys a swim across the pool. There are several large fish flitting in and out of the kelp so I lower my camera a little at a time to see how they react. When this is successful, I decide to make the very best of the summer conditions. I pull my swim goggles on and lower my head into the water.

The fish (juvenile pollock) are stand-offish at first

There is a nursery shoal of juvenile pollock down here.  They hesitate at first. Winding their slender bodies through the kelp fronds, they watch me through wide yellow-rimmed eyes.

The young pollock get ever closer to take a look at me.

I’ve always thought of pollock as a silver coloured fish, but these youngsters are golden-green with shimmering blue stripes running from their head to their tail. Their jutting bottom lip makes them look open-mouthed, mid-conversation.

Hello fish friends! The young pollock are keen to take a close look at my camera.

They are certainly a friendly bunch, swimming ever closer to the camera until their tails are brushing the lens. I have to keep lifting my head to breathe, but they don’t seem to mind.

Video: Hello fish!

After a while, I leave the pollock to talk among themselves and move on to an adjoining pool. A shoal of sand eels is patrolling here. These fish are of a more nervous disposition, turning, balling and flashing with silver at the slightest disturbance. If they spotted a predator, they would flee head-downwards, burying themselves in the sand in an instant.

Sand eel swim-past.

I move slowly and give the sand eels space, turning my attention to the sea squirts and snails on the rocks.

An especially pretty yellow star-ascidian surrounded by pink algae and red seaweeds.

When the tide turns, Junior and I retreat to the first pool, swimming and bobbing in the water, watching butterflies tumble past and swallows circling high above. There are boats, people and a whole world out there, but, like the pollock, we are happy in our rock pool refuge.

Even the seaweeds are shining in the sun. Forkweed, Looe, Cornwall.

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!

Neap Tide Adventures

Days like this don’t seem ideal for rock pooling; the tide is nowhere near low enough to expose my favourite pools and the weather is iffy. Despite this, I am convinced that there is plenty to see on the mid-shore. Cameras and rock pooling super-crew (Other Half and Junior) at the ready, we set out to uncover marine treasures.

One advantage of neap tides, when the sea doesn’t go out very far, is that it won’t rush back in either. We can take our time. Junior soon locates lots of gem anemones with their tentacles wide open.

Gem anemone

Under a stone further down the shore, I spot a beautifully camouflaged anemone. It’s too small to see properly, so I have to wait until I get home to confirm that it’s a Sagartia troglodytes anemone.

Sagartia trogladytes anemone

The B shape at the base of the tentacles is a useful identifying feature, although I’ve always thought they look more like Scooby Doo ghost eyes than letters.

Other Half calls me over to look at a blob. He’s becoming quite an expert blob finder.

We look together at the tiny brown jelly-spot on the seaweed. At first, we think it is an anemone because it seems to have a circle of retracted tentacles. As soon as I dunk it in the water though, I can see the pale lumps of primary tentacles around the edge. It must be a stalked jellyfish.

Is it just me or does this stalked jelly not look pleased to see me? Haliclystus octoradiatus.

Gradually, the stalked jelly unfurls each arm until it looks much less blob-like.

Haliclystus octoradiatus -starting to look more like a stalked jellyfish than a blob.

The rain seems to be holding off now, and I make myself comfortable by a calm pool to watch the little world go by. My camera has barely entered the water before a bold prawn trots out of the seaweed, its legs working at top speed in its eagerness to check out what I’m up to.

Common prawn coming to take a look at my camera.
Common prawn

A head pops up between the fronds of saw wrack at the back of the pool. The young Montagu’s blenny swivels an eye back and forth beneath its jaunty headgear. I feel a larger blenny move through the seaweed near my hand and lift my camera out of the water before I get a nip from the territorial shanny.

Peek-a-boo! Montagu’s blenny taking a look above the serrated wrack.
Montagu’s blenny.

A dinky starfish in the coral weed catches my eye. I see several species of starfish on this beach, but this is a mid-shore specialist: Asterina phylactica. The colours of the tiny pincers on its back (the pedicellariae) form an orange star shape. Under the camera, I can see its tube feet reaching out and exploring its surroundings as it glides along.

Asterina phylactica – cushion starfish

Other Half brings passes me a tiny shell he has found. He thinks it might be a wentletrap, a shell we sometimes find. I have never seen one so small and assume it is probably a different species. I take a look with the camera and realise he was right. The bold sculpture of ribs over the rounded whorls of the long spire are striking, even in this tiny juvenile. Best of all, the shell is occupied.

Juvenile wentletrap

I watch the snail emerge and set off across the pool.

This makes me think of a unicorn and a rainbow – juvenile wentletrap.

Sea squirts are something of an enigma to me. They are hugely varied in their colours, shapes and sizes. Aplidium turbinatum, in particular, seems to me to look different every time I find it. When I first see this one, I am convinced that the white, spiky-looking set of openings under the coral weed is a bryozoan.

I know this looks familiar, but takes me a long time to work out that it is Aplidium turbinatum, a sea squirt.

Yet, after a while watching it, I realise it is opening and closing like a squirt, puffing water in and out. It bears little resemblance to the orange gelatinous Aplidium turbinatum I usually see further down this beach, but the jutting triangular crowns around the edge of each opening are the same.

Aplidium turbinatum sea squirts

Fortunately, I can turn to the incredible Aphotomarine website for confirmation and, sure enough, it has some photos of very similar specimens (thanks David!).

While the tide seeps back into the pools, we chat with a fellow rock pooler whose photos I have often seen online, and who I eventually realise I have met before in real life through another conservation group.

Chthamalus sp barnacles starting to open as the tide comes in.

By the time we leave, the sun is low in the sky. I am more than satisfied with all the wonderful creatures I have found on the neap tide, and it is high time I had some birthday cake.

Strawberry anemone

Whatever the tide, 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!

A Swim Over The Rock Pools

“Quick, I need the camera. There’s a jelly.”

Junior’s enthusiasm takes me aback. He has a healthy aversion to getting close to jellyfish. We have already changed course many times on today’s high tide swim to avoid the trailing tentacles of compass jellyfish.

Compass jellyfish. Also known as sea nettles as they pack quite a little sting, these jellyfish have beautiful markings.
The distinctive markings of the compass jellyfish.

These common summer visitors have striking brown V-shaped markings around their edges, like the points of a compass. Although their sting is rarely serious, somewhere in the region of a stinging nettle in strength, it isn’t much fun if you swim face-first into one as I have done on a few occasions.

Crystal jelly. This is a hydroid medusa rather than a ‘true’ jellyfish. It has short tentacles around the edges rather than long trailing tentacles.

Some other species we have seen this week, like the moon jellyfish and crystal jellyfish, are harmless but today only the compass jellies are out.

One of many moon jellyfish washed up by the strong swell. This species is harmless.
Moon jellyfish only have a very weak sting so are usually harmless to people. Never touch a jelly if you’re not sure of the species and wash your hands well before touching your eyes.

Incredible numbers of sand eels fill the water in every direction, flashing silver as they turn, before melding into the green sea. Junior notices a small spotted catshark (Scyliorhinus canicula) – also known as dogfish – swimming through a rocky gully beneath us. Alongside submerged rocks, several species of wrasse flit among the kelp.

This sand eel is speeding along – photo by Junior

I unclip the camera from the safety float and pass it to Junior who is pointing excitedly at something I can’t see.

I dip under the water and look at where he’s pointing. Still nothing. I bob up for air and try again.

This time I see something much smaller than I was expecting, or half see it – it’s mostly transparent with just the faintest pink hue.

Comb jelly – photo by Junior

“Is it a comb jelly?” Junior asks. This is the first one he’s seen and much excitement ensues as he tries to photograph a barely visible tiny swimming thing while holding his breath and floating in water 5 metres deep.

Comb jelly by Junior. The transparency of the animal and its movement in the water make it hard to focus, but you can see the shining light of the combs.

Mostly we just enjoy the incredible coloured light show this Beroe cucumis comb jelly is putting on for us. The iridescent disco-light effect is created by lines of beating hair-like cilia (the combs) that run the length of the comb jelly’s body.

This species looks like a simple hollow tube or sack, but it is an efficient predator, known to feed on other comb jellies.

The different colours of the lights around the edges of the comb jelly are incredible to watch. Photo by Junior.

How Junior spotted this little speck in the ocean, I have no idea. We look around for more but find none.

Comb jelly by Junior.

Eventually we have to head back to shore, drifting over all of our familiar rock pools on the way. Hermit crabs and netted dog whelks are out in force and as we near the beach, we see shannies basking on sunny rocks in the shallows.

There are lots of these ‘south clawed’ hermit crabs (Diogenes pugilator) on the sand. Their left claw is much longer and larger than their right.

This might not be rock pooling in the usual sense, swimming on a high tide gives us a whole new perspective on life here. You don’t need to be a billionaire to become weightless and take a soundless flight over the rock pools. There is no better way to see how this environment looks for most of each day, when the wider ocean and the shore cross over and become one.

Swimming in the sea in Cornwall is a wonderful experience but is very different from swimming in a pool and can be dangerous. Always consider the conditions and stay well within your limits. Check the weather, tides and currents, enter the water slowly and adjust to the temperature. Choose a lifeguarded beach if possible and a place where you know how to safely enter and exit the water. Swim alongside the shore. A tow float makes you more visible and beach shoes can protect you from weever fish and sharp rocks. Don’t swim alone and let someone know where you are. In any emergency at sea or on the shore, call the Coastguard on 999.

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!

May Half-Term Rock Pooling

Who doesn’t need a week off at the moment? Whether you’re visiting your local beach or holidaying in Cornwall, rock pooling is a free and fun experience for all the family.

Read on for links to events, rock pooling tips and my guide to what you might find.

Make every beach trip an adventure with my children’s book, Beach Explorer: 50 Things to See and Discover. It’s packed with hands-on activities, facts and quizzes.

EVENTS

Organised rock pooling events are perfect for learning about marine wildlife with the experts. Due to current restrictions, booking is essential for most activities and plans may change. At the time of writing, the following groups and organisations are planning events in the half term:

If you’re not able to attend an event, don’t worry. It’s easy to rock pool safely and to look after the wildlife with a little preparation.

ROCK POOLING TIPS

All you need for successful rock pooling is a pair of wellies or sturdy shoes and a little patience. There are many fascinating species to see, so go slowly, look carefully, leave everything as you found it and have fun!

  • The European 3-spot cowrie (Trivia monacha)
  • St Piran's Hermit Crab at Hannafore, Looe
  • A colourful Xantho pilipes crab.
  • A dahlia anemone.
  • Watching fish at Kynance Cove with Junior (photo by Other Half)
  • Green shore urchin, Hannafore, Looe
  • Passing round a spiny starfish
  • Junior getting to know our wrasse-friend
  • A juvenile turbot at Lundy Bay
  • Cornish Rock Pools junior drying off in the sunshine at Port Nadler, near Looe.
  • Plaidy near Looe
  • Just one more rock... exploring the Cornish rock pools
  • Flat periwinkles and other shells washed up on Looe Beach
  • Montagu's blenny with its distinctive head crest
  • Although painted topshells are a common sight on my local shores, I never tire of photographing them.
  • Always check the tide times, stay clear of cliffs and waves and dress for the weather.
  • Nets can harm delicate sea creatures so are best left at home. A bucket or tub is ideal if you want to scoop up an animal to look at, but be sure to put it back.
  • Why not finish up with a beach clean to help look after the wildlife?

Find out more about rock pooling with my top tips and guides.

BEACHES

The choice is endless! Cornwall has over 300 beaches and they are all fantastic. Any beach with rock pools will have crabs, snails, anemones, fish and more.

Find out about some of my favourite rock pooling beaches here.

WHAT TO SEE

May and June are fabulous rock pooling months. The pools are bursting with new life from baby fish to brightly coloured seaweeds and stunning starfish.

Sit quietly and look closely at the pools to watch prawns, crabs and sea snails going about their business. Gently lift seaweed and look under stones to reveal the secret hiding places underneath (be sure to put them back as you found them).

Here are some of my favourite treasures to find in the pools …

Cushion Stars

These puffy little starfish are common in the pools. Did you know that they can re-grow their arms?

Shannies

The common blenny (or shanny) is perfectly adapted to shore life and can even breathe through its skin when out of the water. It also has a great smile.
The common blenny (or shanny) is perfectly adapted to shore life and can even breathe through its skin when out of the water. It also has a goofy smile.

Sea lemons

In the water the sea lemon's rhinophores and frilly gills emerge and we can see its wonderful colours
Sea lemons a type of sea slug. They eat sponges and breathe through the frilly gills on their backs.

Green Shore Crabs

Green shore crab with eggs - Christmas eve 2018 in Looe
Green shore crabs can survive in lots of different conditions and can eat almost anything – even each other. This female has eggs under her tail.

Common Prawns

Prawns are curious and will often swim over to investigate anything new in their pool. You can see right through their bodies!

Strawberry anemones

Strawberry anemones are red with yellow flecks, just like a strawberry. Their tentacles are packed with stinging cells to catch their prey.

Star Ascidians

Star ascidians might look like flowers but they are simple animals called sea squirts. They form colonies – each ‘petal’ of the flower shapes is an individual animal. They can be yellow, blue, purple, red or white.

Flat Periwinkles

Flat periwinkle in the Cornish rock pools
Flat periwinkles feed on seaweed and come in lots of colours. Look out for their eggs on the seaweed – they look like little circles of jelly.

These are just a few of the creatures you might find. Discover more with my guides to the wildlife in the rock pools and my blog.

Happy rock pooling! Be sure to get in touch to let me know what you find this half-term.

A Year of Cornish Marine Life

Like everything else about 2020, this is a strange New Year’s Eve. Many have lost loved ones this year, and most of us have spent the festive season apart from friends and family. Whatever the year ahead brings, it will be made better by connecting with the natural world and doing the small (or large) things that we can to build a better society and environment.

On the eve of 2021, I am struggling personally to come to terms with losing EU citizenship and all of the opportunity, discovery and connections it has brought me. International cooperation is essential to tackling the global issues that face our wildlife and we will have to work harder than ever to build understanding and find solutions to problems that cannot wait.

Life will go on and I am super-excited about my new children’s book, Beach Explorer, due to be published in the spring. As ever, I will continue to bring you the very best of the Cornish rock pools straight to your computer through my blog.

To bring a little cheer to myself and to you, here are a few of my favourite rock pool wildlife photos from my encounters this year. I hope you will be inspired to get outside and meet your own local wildlife, and to join all of us who are working to protect and restore nature.

A Happy and Healthy New Year to All! Bonne Année 2021!

A painted top shell – January 2020

Xantho pilipes crab – February 2020.
Pagurus cuanensis, the hairy hermit crab. March 2020
Bright coloured sponge (Prob Oscarella sp.) April 2020.
“Cedric the spider crab”. Photo by Cornish Rock Pools Junior. May 2020.
Juvenile masked crab moult. June 2020.
Cladonema radiatum – an athecate hydroid medusa. July 2020.
Calma glaucoides sea slug with its spawn. August 2020.
Star ascidian growing on seaweed. September 2020.
Dahlia anemone. October 2020.
Facelina auriculata – October 2020.
My first ever Xaiva biguttata crab! October 2020.

Migrating Prawns and Blue-Rayed Limpets

Junior normally keeps a low profile on this blog, but for several years now, he has been taking his own photos and videos of marine life. He recently put together this lovely video for Cornwall Wildlife Trust’s Your Shore Beach Rangers project. It showcased alongside other amazing videos by local young people last weekend at the virtual See You at the Sea Festival and he would love to share it with all our Cornish Rock Pools friends.

My favourite part of the video shows something Junior discovered in Looe a couple of months ago: a prawn migration. I was crawling around in waders with my head under a rocky overhang at the time, so I only saw the tail end of the procession as it advanced with the incoming tide. Fortunately, Junior managed to capture some fantastic footage of hundreds of prawns galloping along the seabed, all heading in the same direction in their hunt for food.

Junior’s photo of a common prawn (not migrating!).

Also featured in the video are Junior’s top photographic subjects – the blue-rayed limpet and sea slugs. He’s even coded an animation showing a day in the life of a corkwing wrasse family. We hope you enjoy his work.

Blue-rayed limpets by Cornish Rock Pools Junior

Junior’s friend, Rowen, has also created a video for the festival showing her beautiful marine artwork and how she creates it, all accompanied by incredible facts about the animals she draws and paints. She would love you to take a look.

All of the videos are available to view on the Cornwall Wildlife Trust Marine channel on YouTube. The three with the most likes and views and that catch the judges eye will win prizes this weekend!

I have been writing my new children’s book this year (due to publish spring 2021), but with that nearly ready, I’m looking forward to sharing lots of the fabulous creatures I’ve been seeing in the rock pools over the last few months. Watch this space!

Summer is acome unto day… May Rock Pool Gallery

Summer arrives early in Cornwall, with festivals around the county singing in the new season on the first of May every year.  Except, this year the Padstow Obby Osses have stayed in their stables, the Calstock Giant hasn’t set sail down the Tamar to re-join his love, and there has been none of the usual dancing through the streets of Helston.

Oblivious to all of this, the natural world is carrying on. Swifts are screaming past the window,  the herring gulls are nestled on their mossy rooftop nests and in rockpools everywhere, there will be tangles of new-growing seaweed, father fish guarding their eggs and all manner of colourful creatures going about their usual business.

Scroll through the gallery below for a glimpse of what will be happening right now beneath the waves in rock pools around Cornwall. And if you’d like to find out more about our amazing marine life, explore my blog, or take a look at the fantastic video workshops that Cornwall Wildlife Trust has been busy creating. Happy virtual rockpooling!

  • Our brown Geitodoris planata and its much paler yellow mate getting friendly in the Cornish rock pools!
  • This small species of spider crab (Inachus sp.) was so completely covered in sponges that I couldn't see her shell at all.
  • Another species of stalked jellyfish - Haliclystus octoradiatus - near Penzance
  • Facelina auriculata sea slug
  • Polycera quadrilineata sea slug at Gyllingvase, Falmouth

The Surprising Mini-World of Rock Pool Insects

If my blog posts have seemed a bit thin on the ground the last few months, it’s fair to put the blame on Atiyah, Brendan, Ciara and Dennis.

Even on the good days the lighting and conditions have been less than ideal so, to make the best of a mediocre tide, I enlisted the help of Other Half. Together, we could look under the sort of rock I usually see but leave alone, knowing it weighs far more than I do.

This short video shows you some of the animals living there…. read on to find out more.

Other Half was pleased with the strawberry anemones, which were enormously plump with all their tentacles retracted.

Strawberry anemone
Strawberry anemone

Under a carefully constructed shelter made of small stones and pieces of kelp we could also see the purple-tipped spines of a green shore urchin. Among its many disc-topped tube feet, a long polychaete worm was exploring.

Green shore urchin
Green shore urchin

What drew my eye most, though, were the holes in the rock. These were scattered across the surface of the rock and about the circumference of a pencil. I caught the tiniest glimpse of movement as I looked into one of them.

Piddock holes underneath the boulder.

If I were the BBC Natural History Unit, I’d have filmed inside with an endoscope or transported the rock to deeper water so I could photograph the gaping shells emerging to feed.  Instead, you will have to take my word for it that there were piddocks in those holes!

Piddocks are bivalve molluscs (clam shells), which burrow into the rock and spend their entire lives in their holes.

A rock with this many cracks and holes in it is bound to contain some good hiding places for other animals and also some air pockets, which enable some of our most unlikely rock pool wildlife to survive being submerged twice a day. Some insects and other arthropods that breathe air live here, but you have to be patient to see them.

I settled down with my camera and before long, the first waggling antennae of a springtail poked over the rim.

The end of a piddock protruding from a hole. (Taken on another occasion).

I often see rafts of blue-grey Anurida maritima springtails floating on the surface tension of pools in the summer, but these were smaller still and so pale they looked almost transparent. They are clearly visible in the video but I could only take very blurred still photos.

The fabulous Essential Guide to Rock Pooling by Steve Trewhella and Julie Hatcher was my first port of call in trying to identify them. The book has great photos and plenty of clear information on what to look for. Steve kindly identified these springtails as Axelsonia littorlis – a new species to me. It’s amazing what you find when you stop to look.

The best shots I could get were of a larger bug called Aepophilus bonnairei, a beetle-like creature with red eyes and a spiky coat of hairs around its back and legs. These hairs trap air bubbles, which help the insect to breathe when it is submerged.

Aeopophilus bonnairei bug on a rock
Aepophilus bonnairei bug on a rock
A juvenile Aepophilus bonnarirei.

Time was short as the tide was already turning and the waves were pounding in. I tried to photograph as many species as I could so that I could put records together afterwards. Some, like the painted top shells and the various crabs, are easy to identify.

This image has an empty alt attribute; its file name is between-plaidy-and-millendreath-january-2020-painted-topshell.jpg
Painted top shell.

One of the most striking sponges I see on the shore is the vivid blue Terpios gelatinosus. Many other sponges are harder to identify confidently.

Blue sponge - Terpios gelatinosus with keel worm
Blue sponge – Terpios gelatinosus – with keel worm

It seemed that no part of this valuable habitat was left unoccupied. To avoid any of these creatures coming to harm, we gently manoeuvred the rock back in place well before the surging waves reached us.

Different coloured patches of star ascidian among spirorbid worms, keel worms and other life on the boulder.

As always, I was left in utter awe of the fragile little creatures we saw.

It is remarkable that these animals will cling onto life here no matter how much the wind howls and the sea roars around them, while we head home to bring the plant pots in out of the wind, check the fences and put the kettle on.

Broad-clawed porcelain crab
A grey and windy day on the shore. It’s incredible that anything can survive in these pools, especially insects.

Gem anemone hunt

We weren’t really rock pooling, just going for a walk to the beach, or so we said. Junior packed his hammer and chisel in case there were fossils and I packed my camera, because you never know.

On my last wander at our local beach I had hoped to find some gem anemones to photograph, but didn’t succeed. It was worth another look for these tiny creatures, which have stripy tentacles and bright colours around their mouths when they are open, but at low tide most of them are retracted into white-striped blobs.

When retracted gem anemones look rather like an urchin test with a warty surface and white stripes down their sides.
When retracted ,gem anemones look rather like an urchin test with a warty surface and white stripes down their sides.

I left the sounds of hammering and splitting rocks behind me at the edge of the shore, where Junior was happily amusing himself on a fossil hunt, and headed towards an unseasonably glassy sea, pausing to look for anemones in the small pools on the way.

At the water’s edge, I reached a large pool too deep for gem anemones, but in the middle of the pool a submerged boulder was covered in Irish moss seaweed, providing the perfect habitat for stalked jellyfish. I looked so closely among the tangles of weed, hunting for tiny jellies, that I almost missed the huge stalked jellyfish right under my nose.

Haliclystus octoradiatus stalked jelly near Looe, Cornwall
Haliclystus octoradiatus stalked jelly near Looe, Cornwall

This was an unusually large Haliclystus octoradiatus stalked jellyfish, easily distinguished from the other species we see in Cornwall by the presence of blob-shaped primary tentacles in between its arms.

Most stalked jellyfish of this species have just one primary tentacle blob between each pair of arms, but this one had far more blobs than usual. The jelly can use these primary tentacles as anchors to grip onto the seaweed if it chooses to move, using a looping, cartwheeling motion.

I've sometimes seen a stalked jelly with one extra primary tentacle blob between its arms, but this one had lots of extras.
I’ve sometimes seen a stalked jelly with one extra primary tentacle blob between its arms, but this one had lots of extras.

In another nearby pool I spotted this colourful Calvadosia cruxmelitensis stalked jellyfish, well decorated with white nematocysts, which are its stinging cells.

Calvadosia cruxmelitensis stalked jellyfish
Calvadosia cruxmelitensis stalked jellyfish

Junior joined me at this point, wanting to show me a blenny he’d found. We scrambled nearly to the top of a high rocky outcrop in which some small pools had formed. There was no sign of his little fish, and there were no gem anemones, but there was this daisy anemone.

Daisy anemones have many layered tentacles, like daisy petals and come in all sorts of colours.
Daisy anemones have many layered tentacles, like daisy petals and come in all sorts of colours.

We carried on our expedition through a gap in the rocks to the adjoining beach where clear, shallow pools lined with pink encrusting seaweed nestled under a towering overhang carved out by the sea into the shape of a breaking wave.

Strawberry anemone
Strawberry anemone

These pools were full of anemones too and we stopped to take photos of clusters of snakelocks anemones and a rather flattened-looking strawberry anemone before I noticed the first gem anemone. It was closed up, forming a diminutive pink blob that blended perfectly into the colours of the pool. Close to it was another.

As we moved among the chain of pools we found dozens, but not a single one was open. Junior stared determinedly into every cranny, excited that the pools he had found were proving so interesting.

“There are some open anemones here,” he called out, “maybe Dahlia anemones? What do gem anemones look like when they’re open?”

I knelt on the rock beside him. At the far edge of the pool, tucked under a small ledge, I could see the white stripes of the gem anemone tentacles. Much cheering and hugging ensued.

The open gem anemones Junior found near Looe
The open gem anemones Junior found near Looe

Soon I was able to show Junior my up-close photos of the anemones so he could see why I was so obsessed with finding them. Each one had a vivid, almost fluorescent green mouth tinged with bright pink spots at its corners. The anemone’s mouths were framed in deep red and grey rays that stretched to the base of the zebra striped tentacles, some of which had flashes of green at their bases.

The mouth of the gem anemone
The mouth of the gem anemone

Truly one of our most spectacular anemones, people rarely notice the gem anemone because it is only a few centimetres across even when fully grown.

Gem anemone near Looe, Cornwall
Gem anemone near Looe, Cornwall

Junior is already planning a night time return to these pools to investigate whether these anemones will glow under the light of our ultra-violet torch. Watch this space!

Gem anemone -winter colour in the Cornish rock pools
Gem anemone -winter colour in the Cornish rock pools