Sagartia anemones at Ste Anne la Palud Brittany France

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

2 thoughts on “From Cornwall to Cornouailles – a dabble in the Breton rock pools”

    1. Thanks Mark. Lots of people do go rock pooling in Brittany, especially children, but among adults ‘Peche a Pied’ is the usual term (Fishing on foot) and it generally means collecting and eating things! Our lovely host showed me a book she has which sets out beautiful photos of rockpool creatures… and how to cook them! :O Lots of great places and species to explore though.

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