I was lucky to go diving twice this weekend, first at Grebe beach next to Durgan in the Helford Passage. As the photo above shows, this is as pretty as Cornwall gets, and the water looked crystal clear at high tide as well. It was a pain to get all picknick stuff and diving gear down (no parking nearby) but it was worth it. Unfortunately I left my fins in my car, so it was a very slow swim out. I emptied my stab jacket and tried walking over the seabed which half-worked (let’s say it was an interesting way of diving). Unfortunately the viz was not as great as expected. I spotted a small squid but it took off before I could take a snap. Other than that no special sightings. Below two images of the eelgrass, two frisky Sea hares Aplysia punctata and a macro photo of a Necklace shell Euspira catena. 
I had the rented tank refilled at Seaways in Penryn in case there was an opportunity to go out Sunday. The opportunity turned out to be limited to the village where I live, Flushing (opposite the harbour of Falmouth). I had never seen divers in Flushing or heard of anyone diving there, and judging from the siltier conditions and presence of boats that seemed to make sense. However, I always was a bit curious how this bit looked underwater, especially I wanted to check out the extent of the eelgrass emerging at very low tides (see this old rock pooling post). The visibility was not very good and near the shore there was only decaying seaweed. After a while though, lots of eelgras appeared. I was unsure whether this spot is known for eelgrass so I recorded my findings on the seagrass spotter site. This was the first time I brought my new strobe to have a play with, I need lots of practice for sure. Below a Thornback ray Raja clavata photographed with and without flash (no postprocessing used). 
The eelgrass looked very tall and healthy and many plants were flowering (middle of the photo). Towards the channel the eelgrass thinned out which allowed to observe little mud dwelling creatures. Sea lemons Doris pseudoargus Pleurobranchus membranaceus are not that little actually (egg masses present). Finally, a lucky shot. Looking through the eelgrass, a curious school of Seabass Dicentrarchus labrax circled around me quite closeby. (After I left the water I heard a seal was near too but it would have had to be right in front of me for me to see it.) All in all it was a very interesting shallow dive close to home and I will definitely try to return soon.
Tag Archives: Sea hare
A Seagrass dive with the Canon G16
It was a glorious bank holiday morning today and high time for another dive before the season is over. This was a dive just by myself; I had never done that before and I kept it very easy with a maximum depth of 5 meters so could surface with two kicks if needed (it was low tide so I needed to go less deep to begin with). I chose the eelgrass beds of the Helford river to play around with my new camera, a very different habitat than last weeks Maerl dive In the Fal estuary. Unfortunately no catsharks or thornback rays this time, but there were some nice invertebrates to practice on (I did not bother with the fish, way too difficult). Although I still have a long way to go to get anywhere near the quality of some of the photo’s I see on various facebook groups and blogs, it is definitely a lot easier to take good pictures with my new camera. Compare for instance the photo of a Necklace shell Euspira catena below with that of a pic taken with my old camera. Next, two very different molluscs: the Hard-shell clam Mercenaria mercenaria (introduced from North America, there called ‘Quahog’) and the Sea hare Aplysia punctata. The latter can be abundant but it is rare at the moment. The one I saw was not the usual brown but very pale, I have no idea how uncommon this colouration is.
Hermit crabs are always common here however. Some of these belong to the species Pagurus prideaux, as the shell they inhabit is covered in the Cloak anemone Adamsia palliata (creamy with purple spots on the left of the shell, need to take some close-ups of that one next time). One crab was covered in the thin, white acontia threads of its anemone, which it might have induced from its partner for defence. The last photo is of the Football jersey worm Tubulanus annulatus, a very distinctive nemertean worm that I could easily identify through the excellent aphotomarine website. Now I need to get serious about the camera settings and practice, practice, practice…
Diving the Helford
After the success of last weeks snorkelling session, it was high time for a proper dive! Again the Helford did not disappoint. In the end, my Sea hare stroking proved a bit inconclusive; also, my estimate of 30 cm long individuals might have been a slight exaggeration, 20-25 cm is more likely for the larger individuals. My guess is that it might be Aplysia punctata after all, and perhaps this is just a very good year where they reach their maximum size. (Note that three individuals can be seen in the first photo and two in the second photo.)
This was not the only Ophistobranch activity going on, as I spotted a small nudibranch sitting on the eelgrass. Probably Eubranchus farrani, although it could well be something that is deserving of a new name, there is a lot of (cryptic) species discovery and taxonomic revision ongoing in nudibranch biology. I also spotted several largish egg masses on the eelgrass that are likely to be from a larger, shelled Ophistobranch; I am waiting for suggestions from various facebook groups *could be Haminoea navicula*. I found a beautiful Wooden canoe bubble shell Scaphander lignarius, these animals live buried in the sand so are not commonly spotted. Next time I’ll bring a small garden rake to see what is hidden below the sand (I am serious!), lots of echinoderms and molluscs to be sure. Pelican’s foot shells Aporrhais pespelecani live in sand, but I found some on top of the sand too, so full of muck that they were barely recognizable. I have found empty shells of this species washed up on holidays before, but it was cool to see them alive for the first time.
No cuttlefish in sight this time, but loads of eggs so it is likely that this is an important breeding ground for this species. We encountered one Thornback ray Raya clavata, which, like cuttlefish, are not very shy. These species occur in very shallow waters (we probably did not dive deeper than 7 meter) and the influence of the surrounding woodland is clear, with decaying oak leaves and pine cones amidst the seaweeds and eelgrass.
One very well-camouflaged species is the Scorpion spider crab Inachus dorsettensis. Medium-sized Common hermit crabs Pagurus bernhardus are common, running around in Turban top shells covered with hydroids. Although present in the last post, another pic of a Mud sagartia Sagartia troglodytes anemone Red speckled anemone Anthopleuris ballii. Filterfeeding worms are abundant too, including the beautiful Fan worm Myxicola infundibulum as well as a large tube-dwelling worm and worms in white calcareous tubes with bright red bristles that I could not identify. As we got out of the water, we saw a Comb jelly Beroe cucumis, very pretty but hard to photograph. The next dive will have to wait two weeks or so, but then I hope to finally play around with my GoPro.
snorkelling in the Helford
A nice long snorkel in the Helford ‘River’ from Grebe Beach today. The weather was great and so was the water temperature. The timing was good too, close to low tide, so the Eelgrass beds started at only about one meter depth. There were a lot of cool new finds. What was most striking was the extremely large number of Sea hares Aplysia. There was almost one every other square meter, ranging from 5 to 30 cm, and from grey to light brown to very dark brown. The common species Aplysia punctata ususally reaches 7 cm (occasionally up to 20 cm), so the size and often reticulated veining probably make it A. depilans. From David Fenwicks aphotomarine site: “An easy way to distinguish this species from (a third species) Aplysia fasciata is to run a finger from front to back on the dorsal surface. If the finger cannot travel all along the animal from head to tail then it is A. depilans.” This I did not know so I need to go back and stroke some slugs! I see that these large (up to 40 cm!) beasts have been found here before. A not particularly large individual on my hand, as well as an orgy, with some orangy strings of eggs visible:
Another interesting mollusc to see was the predatory Necklace shell Euspira catena (not a very good shot, would be nice to go back diving soon so there is more time to take pictures). Other nice finds include a Mud sagartia Sagartia troglodytes anemone (I think!) and a small Sagartiogeton undatus anemone. Finally, at only 2 meters depth, we found a good-sized cuttlefish Sepia officinalis, lying still trusting its camouflage. In places, black Sepia eggs could be seen attached to the Eelgrass. Some of us also spotted a juvenile thornback ray in the shallows:
a most peculiar animal
The rock around Falmouth is very soft in places, and when turning over large stones, sometimes they break and reveal interesting things (I have posted previously about the high density of worms in rocks). I recently had another rock crumbling on Castle Beach and I noticed something unusual-looking slipping away in its burrow. A Sipuncula (‘peanut worms’) or Echiura (‘spoon worms’) I thought, something not featured in any old guide anyway, so I browsed David Fenwick’s aphotomarine site where I quickly found the suspect: the Spoon worm Thalassema neptuni. The Echiura are recognised as a separate Phylum in most books, but recent research has revealed that they are not as special as they look: they are actually ‘ordinary’ Annelid worms (see this Open Access paper):
The diversity of life within rocks is actually quite surprising. I have not taken a good look at all the types of worms yet, but this one stands out: a tiny Green leaf worm Eulalia viridis (looks like a sock puppet):
The boring bivalve Wrinkled rock borer Hiatella arctica (a juvenile):
And even a small Sea cucumber:
Perhaps I should make a list of all the species living in the rock. Finally, on the rock surface, I sighted a small Sea hare Aplysia punctata for the first time in Cornwall:
An Bollenessor 