Meeting up and staying apart in the rock pools

When I’m sitting here writing my blog in the evening, with the cat snoring gently beside me, I find it hard to imagine that people anywhere in the world might be reading about my finds the next day. So, it’s always lovely to receive messages from people who follow the blog and share my passion for our rock pool wildlife. It’s especially surprising to me that these include many people I’ve never met and that some of my readers even live beyond the Tamar!

With the days beginning to draw in and with all normal group activities off due to Covid, making connections with others is more important than ever. When I heard from a couple of keen naturalists and Shoresearchers planning a trip to Cornwall, I thought it could be fun to head out on the shore together with my family. I couldn’t have been more right!

You know someone is a good person when they like finding slugs. Within minutes of meeting our new friends on Millendreath beach near Looe, we had established that slugs were top of their wishlist of things to find. I led the way to “slug alley”, a deep gully between the rocks where I often find sea slugs feeding on the sponges, squirts, bryozoans and hydroids that line the dripping overhangs.

We advance in our family groups, keeping several metres apart, pointing at interesting creatures, giving directions then backing away. By this stage in the pandemic, we’re all confident in these new dance steps.

Botryllus leachii colonial sea squirts

Large patches of colonial sea squirts smooth over the rocky surfaces, providing not just striking colours and patterns but food for many animals that predate them. We find both the European three-spot cowrie and the Arctic cowrie happily gorging themselves on this beautiful feast.

A cowrie on the search for sea squirts to eat.

A brown spot among the squirts and barnacles catches my eye. Although the colours blend in perfectly, it looks different from its surrounds. I gently touch it and it comes away. In a seawater-filled petri dish it rapidly transforms itself, puffing up, elongating and sprouting feathery gills and tall rhinophores. There’s no doubt about it, we have our first slug. My excitement is as great as that of our new friends – this is a species I have never seen before.

Goniodoris castanea exploring the petri dish.

We take turns to examine the slug and take photos. As soon as it is under my camera, which shows far more detail than I can make out with the naked eye, I recognise it from my books (yes, I browse slug books for fun). It’s my first Goniodoris castanea. Castanea means chestnut and the slug’s autumnal mottling of red, brown and white hues make seems a perfect fit with the oncoming season.

Goniodoris castanea showing off its beautiful autumnal colours.
Goniodoris castanea

While our friends marvel at the slug, Junior makes another exciting find. He knows what it is just by the purplish tips of the arms protruding from under the rock. “Spiny starfish!” he calls. We carefully move it out to take a look and it’s a monster. Our starfish has clearly found plenty to eat in this area. Although we regularly see them on the shore here, spiny starfish aren’t found in rockpools in some other parts of the country and this is another new species for our visitors.

I forgot to take photos of the spiny starfish due to my excitement over the slugs – but here’s a pic of one we found on an earlier expedition to Millendreath.

We edge ever outwards with the tide. Although we can hear the shouts of holidaymakers playing in the waves on the beach beyond the rocks, no one else ventures into our magical gully where startled sand eels zip across the surface of the water like skimming stones and velvet swimming crabs scuttle across the seabed then bury themselves in the sand, leaving only their red eyes visible.

A lurking velvet swimming crab.

Some of the rocks are fringed with a dense covering of brown seaweeds. Toothed wrack and kelp compete for space here and clinging to this forest, mossy bryozoans and delicate hydroids thrive, creating a perfect habitat for isopods and slugs. Some of the seaweeds have crescents of white jelly scattered among their fronds. These are sea slug eggs but it takes me some time to find the slug itself, which is smaller than its spawn and decorated with bright yellow and black which somehow make it hard to see.

Sea slug spawn…. now to find the slugs.

These pretty little slugs were, until very recently, known as Polycera quadrilineata. Scientists have now discovered that there are two separate species and the ones we see here, which sometimes have black lines and spots, are now called Polycera norvegica.

Polycera norvegica feeding on bryozoans.

In the moving seaweed, it’s hard to take clear photos and the tide is, of course, coming in just as I’m trying to position the camera in water that’s already waist deep, but we are all content just to be here, together but apart, sharing this experience of encountering incredible creatures.

Polycera norvegica.
Pair of Polycera norvegica sea slugs with the edge of a fingernail in shot showing just how tiny these stunning little creatures are!

These are strange times for everyone, but finding ways to come together and enjoy nature is what makes the world go round (for me at least). Thanks to our new friends for making it a fabulous day. Happy rock pooling!

This time of year, the kelp is studded with blue-rayed limpets – always a joy to see.
Brown sea cucumber – Aslia lefevrei.

14 thoughts on “Meeting up and staying apart in the rock pools”

  1. As ever a lovely blog. In normal times I visit my sister near Liskeard quite often. When I next visit I’ll have to seek out this beach and slug gulley.


      1. Sounds great. In normal times the Cornwall Wildlife Trust beach ranger project organises some brilliant events for teenagers – snorkelling, coasteering, that sort of thing. Maybe they’d go for night rockpooling? If not, leave them somewhere comfortable to play on their phones!

        Liked by 1 person

  2. Hello Heather-i just wondered, have you ever caught/seen European conger eels before? i went to Cornwall in the summer and left a lobster pot off a pier for about an hour and i had a large eel in it.


    1. Hello Leo, Sorry it’s taken me a while to spot this message and get back to you. Both common eels and conger eels are found around our shores. The common eel is more frequently found in the intertidal zone but I do sometimes see conger eels (which are more common further out to sea). They are quite similar looking so the main way to tell them apart is by looking at their mouth. On the conger the upper jaw sticks out whereas in the common eel, the lower jaw protrudes more. The conger also has bigger eyes and their dorsal fin starts closer to their head. As you may be aware, the common eel is a critically endangered species at risk of extinction and is a protected species in the UK. Both species only spawn once in their lives which can make them vulnerable. Hopefully your eel made a safe return to the sea! If you’re interested in seeing more wildlife, look out for rockpooling events next time you’re down – they’re a great way to see lots of species and learn more about conserving them. Obviously everything’s been on hold this year, but hopefully things will be back to normal before long. Best wishes, Heather


      1. oh thanks for replying, yes the eel was realized back into the sea and i saw another one the next day swimming around the pier. i think i will return (if covid allows) do you have any tips on finding lobsters(not for eating just looking)

        thanks again


      2. That’s great to hear, Leo. Eels often do spend a long time in one place but they aren’t always easy to see. Lobsters aren’t the easiest to see on the shore and I’m always careful about giving much away as unfortunately many people aren’t as kindly to them as you are. If you spend time rock pooling with experts – ideally on organised events – there’s always a chance you’ll get to see a lobster… and you’re guaranteed to see lots of other amazing species along the way. Some of our most incredible marine wildlife is also tiny! I’ve often found lobsters by accident when looking at much smaller things that share their habitat! Happy rock pooling! 🙂


    1. Absolutely Ross. We’ve made so many lovely friends through exploring nature together. We haven’t been able to see as many people as usual this year, but we’ve still had some moments to treasure. 🙂


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