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Return to the Planet of the Nudibranchs!
Posted by Graeme Lyons , Friday, 3 October 2025 10:29
Firstly, if you didn't read the last two I did about Menai Bridge, have a look here before reading on. OK, so how on Earth did I add eight more nudibranchs to my list over two days recently? The answer: some incredibly talented Gen Z naturalists who were the real stars of the show. But before we get to them, here's some nudibranchs (I'll come back to the showy Trinchesia cuanensis later).
The first rock I turned had several Coryphella gracilis under it (yet this wasn't entirely down to chance, I was guided to this particular small area of rocks). This species I found on my own there back in July, love that orange.
Seconds later, Cameron Wilkins (who has especially sharp eyes and a great deal of patience) found a Coryphella lineata, lifer no. 1 of the trip! I soon found my own. I think this was my favourite species. A shade redder than gracilis but there is not much in it and they do vary. Those white lines though!
Now Yolanda Evans is an absolute wonder. She has amassed an incredible amount of knowledge on nudibranchs and many other marine groups...all by the age of 20. Her passion for all living things, especially those in the sea, is a joy to witness and is close to my own heart. Sadly for us, her partner Nathan (who I was in regular contact planning this weekend) was abroad for all the low tides featured here but we did get to meet briefly in the dunes at Rhosneigr. Anyways, back to the nudibranchs.
Yolanda found this little coconut-toastie-of-a-sea-slug, it's Onchidoris bilamellata. Quite a common species over the winter apparently but a new one for me. Lifer no. 2!
And then something I was super pleased to see, as it's a big genus that I have not met yet. Doto coronata. What a superb thing! Those cerata are mental. Lifer no. 3, thus concluding the first evening's antics.
The next morning we headed back down and had a look for some fish on the water's edge but we didn't see anything like what they saw 24 hours earlier. My mate Simon came along too, the pair of us representing and book-ending the Gen X brigade. The photos of Humans (Homo sapiens) were taken by our resident Boomer, Mark Colvin. Ultimately it was Mark that got me onto the site, so a big thanks to him for starting all this. Well, to be fair showing Mark his first nudi at Ovingdean earlier this year also helped. One thing is for sure, lots of different people sharing their passion and knowledge for natural history both online and in the field is what is so vitally important at allowing us to connect. And a great deal of fun too. These are all my kind of people, my tribe!
Shortly after this I found my 4th nudi lifer of the trip. Aeolidiella glauca. Very close to Aeolidiella alderi which I see commonly away from Sussex (we had one on the first night even). The white collar is much less distinct than it is on alderi, the rhinophores and tentacles lack any hint of yellow pigment and the clincher - gold flecks on the back of the animal in the bare area between cerata. Having seen dozens of alderi in the last two years, I did think this was glauca straight away. The black box by the way is a great idea, I have even edited my book to reflect just a little of what I learned on the trip!
Here's me and Yolanda searching the rocks. Both Yolanda and Cameron, as well as having incredible eyesight and patience, have this uncanny ability to fold almost in half. Even at 18 I had back issues and couldn't do that, I can just about get to 90 degrees look. The only way I am getting that close to the rocks is if they rolled me out on a skate board! Being that close to the rocks clearly really helps though!
Yolanda showed us this parasitic crustacean on Edible Crab. Always wanted to see one of these, I didn't realise they were host specific but it's kind of obvious when you think about it. They have a really strange life cycle. This one is Sacculina inflata. "Where is it in relation to that sponge-like thing?" I hear you say? "It IS that sponge-like thing", I say! Yep, that is a crustacean.
That evening, we were again accompanied by Cameron who was finding nudis faster than I could photograph them. First up one Ancula gibbosa. One of the white ones with yellow flecks but much smaller and differently-proportioned than Polycera. It liked hunching up in 'blob form', so again I have some not very good photos of it in a white tray but you can at least see the detail of the rhinophores here. New nudibranch no. 6!
Then, the awesome Tricnhesia cuanensis. Cameron spotted three! Love those 'fishing float' cerata. New nudi no. 7! I mean, just look at it!!!
I feel utterly spoilt. I am now on 30 species of nudibranch, all 30 of which I have seen in 2025. It doesn't end there though. We did a fair bit of terrestrial stuff too, where I got to show everyone some spiders, we found some really nice stuff and I was amazed at how good Nathan, Cameron and Saffron (Cameron's partner who joined us later in the weekend) were on terrestrial stuff too. I am glad that they're all on PSL now, even if it means me being pushed down to third place for nudibranchs. Saffron got me on to my first Risso's Dolphin near South Stack!
The last night we did a bit of wading in the straits at low tide, by torch. Here's Mark and I not in any way posing for the camera.
Yolanda caught this crustacean, which I think was Processa edulis, yet another new species for me.
I found these strange colonial tunicates growing on some as yet unidentified jelly like stuff, hanging down under an overhanging rock. I believe the tunicates are the invasive Perophora japonica.
And finally I found this Rayed Artemis (Dosinia exoleta). Yet another new mollusc for me, helping me to claw back my title of top mollusc lister on PSL. I doubt I will hold it for long though!
What an amazing three days! A huge thank you to everyone involved but especially to Yolanda, Cameron, Nathan and Saffron. It gives me great hope for the future that such passionate and talented young naturalists are doing all this work in their own time and reaping the benefits already. I have no doubt they will all go on to great things soon and the world of PSL is richer for their involvement too.
I miss the sea already :(
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