Tag Archives: sea slugs

From Cornwall to Cornouailles – a dabble in the Breton rock pools

Once the busy summer season of rock pooling events is over, we like to jump on the ferry and get away for a few weeks. We have friends to visit and lots to do, but somehow we always end up on the beach. It’s fascinating to discover the difference it makes to be a few hundred kilometres further south.

Although there are plenty of familiar species here, there are some that are around their northern limit here in Brittany, but might put in appearance in Cornwall one day, especially as the seas warm up.

On a sheltered shore in the lee of the Quiberon peninsula, the beach where our friend Mylene spent her childhood holidays, I find a Pachygrapsus marmoratus crab, a species I saw nearby last year when I didn’t have my camera.

Pachygrapsus marmoratus crab
Pachygrapsus marmoratus crab

The rippled pattern on its carapace and the wide flat edge between its eyes make it unlike any of our native crabs. Originally found further south on the Atlantic coast, it has been working its way northwards in recent years and seems to be firmly established in Brittany now.

The three teeth along each side of the carapace distinguish this species from other rock crabs
The three teeth along each side of the carapace distinguish this species from other rock crabs

Something I didn’t notice last year is how fabulously green its knee joints are, matching its emerald eyes. It’s not afraid to use those leg-joints, scuttling away at high speed at every opportunity to hide among the dense aggregations of the invasive Pacific oyster. I nearly lose it several times before it decides to settle in the corner of a pool, allowing me photograph those hairy legs and green knees.

The fabulous green knees of Pachygrapsus marmoratus!
The wonderful green knees of Pachygrapsus marmoratus!

Junior calls out that he’s found a slug. He thinks. He’s not sure. There are so many living blobs on the shore that it can be hard to tell.

The blob is a plump yellow thing, perhaps four or five centimetres long and from the speed it’s crawling across the rock, it is most definitely a slug. Initially, I assume it’s a sea lemon, but it doesn’t quite look right. It has a more squidgy, unicoloured look and instead of the citrussy bumps of the sea lemon’s skin, this slug has rounded protrusions of varying sizes all over its back. I can’t place it so we call it a ‘Doris might be a sea lemon, species’ and I take plenty of photos to help identify it for sure later.

Doris verrucosa - the 'warty Doris' - exploring a bed of Pacific oysters
Doris verrucosa – the ‘warty Doris’ – exploring a bed of Pacific oysters

It’s over a month after we return from holiday that I remember the photos and transfer them to my computer. On screen it’s obvious that this Doris slug looks nothing like any sea lemon I’ve ever seen. With the help of some extremely geeky books, websites and a forum of fellow nudibranch aficionados, I manage to confirm that it is a Doris verrucosa. The “warty Doris”… not the most charming name, but Junior is rightly thrilled that he found it. This isn’t a species we’ve ever seen in the UK.

Each rhinophore on the slug's head is framed by two pairs of prominent protrusions and the gills are framed by a crown of tall protrusions.
Each rhinophore on the slug’s head is framed by two pairs of prominent protrusions and the gills are framed by a crown of tall protrusions.

We revisit a beach that is the polar opposite of the sheltered shore of Quiberon. Ste Anne de Palud is a west-facing windswept expanse of muddy sand framed by a north-facing rocky headland and pools, which provide an incredible habitat for all sorts of clam shells and colourful anemones as well as a perfect set of conditions for the honeycomb reef worm, which builds its huge beehive-like structures all around the rocks.

A honeycomb worm reef overhanging a pool at Ste Anne la Palud, Brittany
A honeycomb worm reef overhanging a pool at Ste Anne la Palud, Brittany

The anemones are fabulous, but so well tucked under steep overhangs of rock or so well buried in sediment that they are tricky to see, let alone identify.

Sagartia elegans anemone, Ste Anne la Palud
Sagartia elegans anemone, Ste Anne la Palud
Strawberry amemone showing its blue beadlet fighting tentacles
Strawberry amemone showing its blue beadlet fighting tentacles
Another colour variation of Sagartia elegans
Another colour variation of Sagartia elegans

Junior is digging holes in the sand and discovers just how packed with life the sand is as he uncovers dozens of thin tellin shells, which burrow their way back down as he watches. The tideline is strewn with evidence of the diversity of life beneath our feet, with spiny cockles, sea potato urchins, the delicate tubes of the worm Pectinaria belgica and necklace shells.

Spiny cockles and their relatives are common here
Spiny cockles and their relatives are common here
Pectinaria belgica worm tube
Pectinaria belgica worm tube
Necklace shell. Euspina catena
Necklace shell. Euspina catena

There’s a good chance that some of the less familiar animals we’ve seen will show up on the Cornish coast at some point. The St Piran’s hermit crab has already successfully made the crossing and I saw them first here.

A trip to Brittany feels like the perfect way to familiarise myself with creatures that I might need to identify in future. It’s also a good excuse to eat lots of pancakes and put my feet up. Both make me happy!

The vast, rich sands of Ste Anne la Palud
The vast, rich sands of Ste Anne la Palud
A juvenile sea hare
A juvenile sea hare

Secret Beach Day

Although no beach in Cornwall is a complete secret, there is no shortage of inaccessible bays, without car parks, cafes and many of these are perfect for rock pooling. The extra effort of walking (in my case sliding) down a steep field and hauling back up it at the end of the day pays off. This secret beach, one of several between Falmouth and the Helford river is a complete gem, just as diverse as I remember it.

Cornish Rock Pools Junior’s friends who appeared on Countryfile  with us have joined us today. Unlike Portreath, the north coast beach we filmed at, it’s incredibly easy to find creatures on this sheltered shore.

Our first discovery is that a population of St Piran’s hermit crabs has established here, probably new since my last visit several years back. I spot the tell-tale red antennae poking out of a shell.

St Piran's hermit crabs reappeared in Cornwall a few years ago after a long absence. The red antennae and chequerboard eyes make it instantly recognisable.
St Piran’s hermit crabs reappeared in Cornwall a few years ago after a long absence. The red antennae and chequerboard eyes make them instantly recognisable.

We haven’t gone far before we come across a lovely long pool with plenty of loose boulders to provide protection to sea creatures. As I turn a rock, Junior spots a large fish that shoots out and noses into a clump of seaweed at the edge of the pool to hide. I put Other Half on the case. He skillfully coaxes it into a corner of the pool in the hope it will swim into his big bucket, which it obligingly does.

The underside of the rock I’ve turned is crowded with life. There are colourful patches of sponges and sea squirts. A clutch of yellow eggs coats part of the surface.

Close up of Cornish clingfish (Lepadogaster purpurea) eggs showing the eyes and spotty tails
Close up of Cornish clingfish (Lepadogaster purpurea) eggs showing the eyes and spotty tails

These are clingfish eggs and the parent will be nearby. Within them, the babies are developing fast. A pair of eyes gazes out of each egg and the tails, wrapped tightly round the little heads are visible too. Something close by catches my attention, a colourful slug.

Calma glaucoides sea slug
Calma glaucoides sea slug

The slug’s long, yellow-tipped cerata sway like hair in the current, giving it a puffed-up appearance. It’s an attractive animal, a pale blue colour when it catches the light. This slug, Calma glaucoides, specialises in eating fish eggs, and especially likes those of the clingfish.

Calma glaucoides sea slug, found near its favourite prey, clingfish eggs.
Calma glaucoides sea slug, found near its favourite prey, clingfish eggs.

Meanwhile, Other Half and Junior are excited about the fish in their bucket. Junior reckons it’s a giant goby and I think he may be right. I try to pick it up to try to confirm the species by taking a look at the fin under its belly, but the fish is very lively.

Giant goby
Giant goby

Junior deploys his best trout tickling skills to persuade the fish to lie still in his hands, which it eventually more or less does. The sucker-fin underneath has a thick, pointed lobe at the front.

The fleshy sucker fin underneath the giant goby has a point at the front - but the fish isn't keen on staying still for me to get a better photo.
The fleshy sucker fin underneath the giant goby has a point at the front – but the fish isn’t keen on staying still for me to get a better photo.

The fish has the small eyes and the salt-and-pepper colouring typical of a giant goby and lacks the yellow band on the top of the first dorsal fin which identified the more common rock goby. Its fins are tipped with grey instead. This fish is highly protected and it’s important not to disturb or trap them without a licence, so, Junior carefully lowers the bucket into the pool allowing his goby friend to swim straight back to its favourite hiding place.

Other finds come in so fast, it’s hard to keep up with them. We come close to catching a huge mystery fish, which thrashes through the seaweed but escapes without being seen. I find a small yellow slug which I initially assume is Jorunna tomentosa, which I often see on the shore. It’s only when I look at the photos at home that I realise my mistake. This slug has lumpy protrusions all over its body that have a sandy, almost warty appearance.

Doris ocilligera - a species I've never seen before, but which seems to be having a good year in southern UK and northern France.
Doris ocelligera – a species I’ve never seen before, but which seems to be having a good year in southern UK and northern France.

I’ve never seen anything like it, the reason being that this slug has only rarely been recorded in the UK. Doris ocelligera tends to occur further south but seems to be becoming more established in the south of the UK and northern France, with several records coming in over the last few weeks. An exciting find and one I’ll have to look out for more carefully in future.

Thanks go to David Fenwick of Aphotomarine for confirming this slug’s identity.

Doris ocelligera
Doris ocelligera

One of Louis’s friends finds this fabulous spider crab.

It's hard to tell that this is a spider crab and not a lump of seaweed!
It’s hard to tell that this is a spider crab and not a lump of seaweed!

It’s a female which has decorated herself in so much seaweed that, unless she moves, it’s impossible to tell she’s not just another rock. We have a good look at her amazing stalked eyes and spiny shell before returning her safely into the seaweed.

Spider crab
Spider crab

The children’s mums aren’t to be outdone. They get stuck in and bring me all sorts of lovely things. This Ophiothrix fragilis common brittle star has a wonderful bright orange centre.

Brittle star with a lovely orange central disk - Ophiothrix fragilis
Brittle star with a lovely orange central disk – Ophiothrix fragilis

Another mum finds brilliant yellow Berthella plumula slugs, paired together under a stone ready to spawn.

Berthella plumula sea slugs
Berthella plumula sea slugs

This white-ruffed sea slug (Aeolidella alderi) was another lovely find.

Aeolidella alderi - the white-ruffed sea slug
Aeolidella alderi – the white-ruffed sea slug

The rocks of the lower shore are covered in all sorts of colourful wildlife. Ciona intestinalis sea squirts tipped with bright yellow rings, blue star ascidian sea squirts and lots of variegated scallops decked out in marbled patterns of brilliant orange and pink.

Ciona intestinalis sea squirt
Ciona intestinalis sea squirt

One variegated scallop opens its shell and swims away in jerking side to side movements, like a leaf falling from a tree.

A variegated scallop prepares to swim away
A variegated scallop prepares to swim away

Before we know it, the tide is pushing in and we slip and slide our way across the seaweed-covered rocks back to the sand. The time between the tides is short, just enough to give us a glimpse into this extraordinary marine community before the sea rolls in to cover everything once more. We sit and watch oystercatchers, herons and even a pair of swans fly across the sea, while the children set off into the distance with a metal detector, onto new adventures already.

Visiting a beach like this is an extraordinary privilege. We make sure to leave everything unharmed, to pick up any litter we see and to leave nothing behind. I’m already looking forward to my next visit.

Light bulb sea squirts - and some mystery orange eggs
Light bulb sea squirts – and some mystery orange eggs

For the love of sea slugs…

I love sea slugs a bit more than is probably usual. My other half even made sure I have the t-shirt, which I wear with pride in the Cornish rock pools despite the odd looks it gets me.

Trend setting in my waterlogged wellies and 'I love sea slugs' t-shirt.
Trend setting in my waterlogged wellies and ‘I love sea slugs’ t-shirt. Hannafore beach, Looe.

If you don’t already have your own t-shirt, it might be that you haven’t yet met these amazing little creatures. Unlike land slugs, sea slugs come in a mind-boggling variety of colours and shapes and have cool super-powers.

So, this week I’ve been braving the traditional British summer-holiday weather to find top slugs to convert you to the cause. My lucky t-shirt worked its wonders… Continue reading For the love of sea slugs…

Cross-Border Rockpooling with the Porcupine Marine Natural History Society

It sometimes feels like I don’t get out much – either socially or out of the county (Not that it’s a hardship to be in Cornwall!). So, I could barely contain my excitement at having the opportunity to attend the Porcupine Marine Natural History Society Conference in Plymouth. I packed my passport and set forth across the Tamar.

Not only did I mingle with the most amazing bunch of fellow marine wildlife obsessives and hear their latest findings, but the third day of the conference was spent rockpooling at Wembury in South Devon.

 

A prickle of Porcupines at work
A prickle of Porcupines at work at Wembury, Devon

While the environment at Wembury is similar to my home patch in South East Cornwall, a major difference is that Wembury has a marine centre, staffed by lovely people from the Devon Wildlife Trust. The centre promotes marine conservation and runs all sorts of public and educational events. It also provided a handy indoor base to set up some microscopes and a refreshment station. Luxury after my recent all-weather forays! Continue reading Cross-Border Rockpooling with the Porcupine Marine Natural History Society

Looking Rock Pools in the Eyes

Is there anywhere better in the UK to get up close to an array of wild animals than the rock pools? When the tides and weather come together, as they did this weekend, the rockpool creatures are hard to miss. There are eyes staring back at you from every shimmering pool.

This clump of fish eggs was dangling among some red Lomentaria seaweed. Through my camera lens the dark, metallic specks in the eggs were magnified and I could see hundreds of fish eyes staring out at me.

Fish eggs, each one a nearly-developed animal with colourful eyes.
Fish eggs, each one a nearly-developed animal with colourful eyes.

As Cornish Rock Pools junior and I moved a rock, he shrieked with excitement. He knows better than to get close to a ‘devil’ crab –  velvet swimming crab – but we watched it sculling through the shallow water. It buried itself there with just its eyes showing.

The unmistakeable red eyes of the velvet swimming crab.
The unmistakeable red eyes of the velvet swimming crab.
This shot of the velvet swimming crab's back leg shows why it's such a great swimmer. The flat paddle and side hairs propel it through the water at great speed.
This shot of the velvet swimming crab’s back leg shows why it’s such a great swimmer. The flat paddle and side hairs propel it through the water at great speed.

It was hard to see the eyes on the next creature we found – or even to tell if it was anything at all. Still, if a shell or some seaweed starts running off, it’s a good sign there’s an animal in it. This wriggling piece of seaweed turned out to be a small species of spider crab – a decorator crab. This one was beautifully adorned with seaweed it had collected. The left claw is clearly visible in this photo and the eyestalks are just behind it (honest!).

OLYMPUS DIGITAL CAMERA
A decorator spider crab (macropodia sp.) well-covered in seaweed.

A highlight of this weekend’s rockpooling was the range of sea slugs. Some species were so small they looked like nothing more than a spot of jelly on a rock. Out of the water they lose all of their structure so we always put them in a shallow tray of water to watch them fluff up into their true selves.

An Aeolidiella alderi sea slug. This slug has a distinctive white ruff of short cerrata (tentacles) behind its head.
An Aeolidiella alderi sea slug. This slug has a distinctive white ruff of short cerrata (tentacles) behind its head.
Limacia clavigera sea slug. This slug has striking orange-tipped clubs all around its body, with matching feathery gills on its back and ridged rhinophores (like antennae).
Limacia clavigera sea slug. This slug has striking orange-tipped clubs all around its semi-transparent body, with matching feathery gills on its back and ridged rhinophores (like antennae).
This plump sheep slug (Aeolidia papillosa) was so fluffy and soft that one of Cornish Rock Pools junior's friends fell in love with it.
This plump sheep slug (Aeolidia papillosa) was so fluffy and soft that one of Cornish Rock Pools junior’s friends fell in love with it.
Out of the water, sea slugs appear to be blobs of jelly. In the water they are transformed.
Out of the water, sea slugs appear to be blobs of jelly. In the water they are transformed.

The rockpools were so full of life in the spring sunshine that we could hardly move for crabs running around our feet and anemones nestling in the sand.

An especially red dahlia anemone buried in the sand.
An especially red dahlia anemone buried in the sand.

Right at the end of our rockpooling session I pulled back some seaweed and moved in close to the rock, looking for tiny sea slugs. It took me several seconds to realise how close my nose was to this hefty crab (at which point I gave an unprofessional shriek and nearly fell over backwards).

A large edible crab in a crevice.
A large edible crab in a crevice.

Fortunately it was just an edible crab. This species is generally placid and has calm green eyes, unlike the red-eyed devil crab which would probably have taken my nose and run off with it!

There were more eyes looking at us out of the pools than I can write about here, from huge spider crabs to the tiny sea spiders – as well as some creatures that had no visible eyes at all. This is a wonderful time of year in the rock pools and we’re already looking forward to the next spring tides so we can see who we meet next.

Cornish rock pools junior found this lively ragworm that swam so vigorously it almost jumped out of the pot.
Cornish rock pools junior found this lively ragworm that swam so vigorously it almost jumped out of the pot.