A nice low tide at Falmouth’s Castle Beach today. The weather was not great but at least it was not raining (I still managed to get quite soaked, including my wallet…). Quite a lot of brittlestars, urchins, worm pipefish and porcelain crabs around. I did some collecting for the aquarium: beadlet and strawberry anemones, snails and urchins. Otherwise I focused on the smaller stuff and took pictures with the olloclip macrolens on my iPhone. First two tiny crustaceans that I have not attempted to identify and what I think is a tiny Edible crab Cancer pagurus. The nicest find was a white colonial tunicate that at very first sight looked like an eggmass. I could not readily identify it using the usual websites, so hope that the NE Atlantic Tunicates facebook page members can help me out (Note: they did, it could be a ‘regressed’ Diplosoma spongiforme). On Sunday I had a quick look in Flushing and for the first time found some juvenile Candy-striped flatworms Prostheceraeus vittatus (see here for adults), very pretty!
Category Archives: worms
Black-faced blenny Tripterygion delaisi
Went on a good dive at Silver Steps in Falmouth yesterday.The visibility wasn’t that great, but for the most part we were rummaging under overhangs in gulleys just off the coast. Sweeping aside the kelp reveals many fine red seaweeds, sponges, bryozoans and small Devonshire cupcorals. We saw the ubiquitous Tompot blenny Parablennius gattorugine as well as a Bib (or Pout) Trisopterus luscus. Overhead there were many Sandeels as well as some relatively large Pollock Pollachius pollachius hunting them:
However, there was a much more remarkable fish we spotted, namely the Black-faced blenny Tripterygion delaisi. We first saw a male, bright yellow with a black head and beautifully skyblue-lined fins. Only after a while we noticed the inconspicuously coloured female. The male is coured this way only in the breeding season. (We later saw another larger male, no female, although that was probably closeby.) My fish guides tell me that this Mediterranean species was first spotted in the UK in the 70s and that it is currently present in only two or three locations on the South West coast. Some browsing on the web has told me that in recent years they have been recorded in more locations but they still must be relatively rare (and I therefore won’t be attempting to catch them). Global warming will likely extend the range of this species more firmly northwards; one of the very few positive effects of our addicition to carbon… Lastly, I now managed to get a shot of the Candy striped flatworm Prostheceraeus vittatus:
A superlow tide at St. Michael’s Mount
The lowest tide of the century so far, on a Saturday, with beautiful weather and on a stunning location: what could go wrong? Very little! St. Michael’s Mount, Marazion, Mount’s Bay is one of the most beautiful spots in Cornwall and an excellent site for rock pooling with a mixture of eelgrass beds, rocks and sandy expanses. I felt like a kid in a candy shop: wanting to turn every stone, photograph every seaweed and inspect every gully before the tide would come back in. I needed to collect some more Clawed fork weed Furcellaria lumbricalis for a cool student project. That was abundant so easy to sort. Chock full of Pheasant shells Tricolia pullus. One other amazing thing was that the place was littered with Bull huss Scyliorhinus stellaris (a.k.a. Nursehound, a.k.a. Large-spotted dogfish) mermaids purses. Mount’s bay is an important breeding ground for these sharks. The yolk was easy to spot, but the embryo’s still to small to be seen. There were loads of pretty seaweeds gently waving among the eelgrass in the crystal clear water. I saw a bright green Chameleon prawn swimming about, but the picture I took was a bit underwhelming. 
I had met up with David Fenwick, so could get all species identified on the spot. Very striking was a great amount of small, fuzzy pink seaweed balls: Falkenbergia, the tetrasporophyte stage of the Harpoon weed Asparagopsis armata (it looks so different from the gametophyte stage, see some old posts, that it was long considered a separate species). Also, a picture of Bushy rainbow wrack Cystoseira tamariscifolia, simply because one cannot post too many pictures of Bushy rainbow wrack….
Some invertebrates: the large scale worm Alentia gelatinosa, a Strawberry worm Eupolymnia nebulosa larger still, a tiny hermit crab Anapagurus hyndmanni and the Arctic cowrie Trivia arctica:
The find of the day (the month probably) was a Little cuttlefish Sepiola atlantica. This picture is crap, but David has made some stunning photos back in his lab and they will appear sometime soon on his aphotomarine site I am sure.
Pontooning
Unfortunately, the weather turned before I had another opportunity to go diving (or snorkeling). The wind and rain have reduced visibility too much and so I’ll have to wait half a year or so before conditions improve….too bad! I missed the low tides recently as well. However, today there was time for a bit of ‘pontooning’, i.e. lying flat on a pontoon and staring at the creatures attached to it. It is quite convenient as it is not dependent on tides and the communities are very different from that of rock pools. There is a very large marina at nearby Mylor Bridge that I had visited before in summer. There was a bit more life then (schools of mysid shrimp, more seaweeds, more tunicates) but it is still looking nice now. I used my iPhone to take pictures before, but holding it above the water was tricky and did not produce good results so I brought my new Canon Powershot instead (still not easy to take pictures as at the same time I had to prevent my two-year old son falling in the water). The bulk of the biomass hanging from the pontoons consists of tunicates (mainly Ciona intestinalis). Small Plumose anemones Metridium senile are common (more about those in the next aquarium update), as well as the sponge Sycon ciliatum. I even found a small Elegant anemone Sagartia elegans (var. venusta). The invasive Bryozoan Bugula neritina is very common; it looks a bit like seaweed even though it is an animal (see here for a description). Finally, the Peacock worm Sabella pavonina is common (and very striking). Just two pictures below as the rest was subpar; I have to go back on my own sometime soon maybe.
diving in the Helford Passage
A new location for the second dive: Helford Passage between Falmouth and the Lizard Peninsula. This is a shallow, sheltered creek with a sandy bottom and eelgrass beds and can only be dived (well) at high tide. A good site to spot Thornback rays Raja clavata we heard and we were indeed lucky to find several of them. We entered the water at Grebe Beach next to Durgan:
Again, we spotted some cuttlefish, which are not very shy at all. What was very cool were Great scallops Pecten maximus lying around and swimming away for a bit by opening and closing the shell, I will try to film that next time. Many Turban top shells and some large heremit crabs with one or more Parasitic anemones Calliactic parasitica on top. The shells of smaller hermit crabs were covered in the hydroid Hydractinia echinata:
We got to about nine meters depth (near the buoy) and found a large concrete block. Scattered among it lay the remains of crabs and in a hole dug underneath the snout of a Conger eel poked out. As I had to get close for a better look, I stirred up too much sediment and so I do not have a good picture but I will definitely like to go back and have a better look! Interesting was an old crab pot covered in sea squirts (mainly Morchellium) which was swarming with Leach’s spider crabs Inachus phalangium. Normally they sit under a Snakelocks anemone but there were none attached to the pot, strange. Very common were large Peacock Worms Sabella pavonina and Fan worms Myxicola infundibulum:
diving at Silver Steps
I am really getting back into this diving thing! Last week, I made another trip to Seaways Dive Centre in Penryn to rent some gear (£25 for 24 hrs) and go out with dive buddy Chris. First a dive at the end of the day at low tide at Silver Steps in Falmouth. A great encounter a minute after we got in with a cuttlefish:
We then set out over the gravel beds towards the open sea. A pretty barren affair, with lots of decaying seaweed. Mainly Spiny and Common starfish and Pulled carpet shell Tapes corrugata, Warty venus Venus verrucosa and Rayed Artemis Dosinia exolata. A picture of the latter being eaten by a common starfish:
Turban top shells Gibbula magus were on my list to get for the aquarium and I noticed that this species is extremely common (several per square meter) so I took a bunch home. The shells look pretty beaten up with lots of stuff growing on ’em but I think they are pretty cool; truly subtidal so no risk of them creeping out of the tank:
We then made it back to the rocky coast and found a nice gully with overhanging rocks with lots of interesting critters. One little cove was home to ten or so shy Leopard-spotted gobies (I plan to go back with my GoPro and leave it there filming for half an hour to pick it up later). We found a big lobster Homarus vulgaris, a beautiful Bispira volutacornis worm (I have already posted pics of these species recently and I will try to show more self-restrainst from now on and not keep posting similar photos). Also for the first time some large Edible sea urchins Echinus esculentus. Probably a really common species when you dive a little deeper but the very first time I saw it. Have to practice a bit more with the new Canon Powershot D30 as I am not completely convinced about its qualities yet (I did not bother to post-process any of the pics btw). 
Snorkelling at Silver Steps Part I
High time for a snorkel, and few better places in the area than ‘Silver Steps’, between Castle Beach and Pendennis Point in Falmouth. I took my little Lumix camera (goes up to 10 meters deep, no optical zoom) with me to take some sub-standard pics (all other photos on the blog are taken with my iPhone). This site is a mix of rocks covered in kelp and gravel and even the remains of two U-Boats (they are no longer recognisable as such though, see here for more specifics on these and other wrecks off Falmouth). There is always something to see: schools of Smelt chased by Sand eels, hovering Two-spotted gobies, Corkwing and Ballan wrasse, Spiny starfish and loads of seaweeds. In fact, there was so much to see that I have divided the pictures over two posts. First a photo of the site and some of the U-Boat wreckage:
We were in for a nice surprise: a good-sized John Dory Zeus faber at around seven meters depth. I have posted a very nice picture from my first and only dive in Cornwall courtesy of Charlotte Sams, but here a short, jittery video as well:
Anyway, a perhaps even nicer find were Leopard-spotted gobies Thorogobius ephippiatus. Some sources make it seem like this is a rare species only ever encountered by divers, but it is actually not uncommon and we saw them at two meters down (the tide was low though). It is a shy species that lives under ledges, burying between the rock and the gravel. The picture is crap but also proof I am not lying. The next picture is of a Tompot blenny Parablennius gattorugine peeking from a crack in the rocks. Large snakelocks anemones are everywhere on the kelp, and although a month ago I saw none, many of them again housed commensal Leach’s spider crabs Inachus phalangium. (These anemones and crabs do well in the aquarium btw, see here.) It would be interesting to know if these crabs arrive from deeper waters or just grow up really fast.
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:
two tiny snail species
On my way back from rock pooling yesterday in Flushing I turned one last rock on the upper shore and found two species of tiny snails that I had not noticed before. First, a couple of Two-toothed white snails Leucophytia bidentata, one of the few terrestrial, airbreathing snails that have returned to a marine habitat:
More numerous was the smaller species Cingula trifasciata. Below a group next to a large wormshaped eggmass that my Seasearch Identifications friends quickly pointed out belonged to the Ribbon Worm Lineus ruber:
a very low tide at Castle beach
There were exceptionally low tides this weekend so I was quite stoked to get out and find some new species in what is normally the subtidal. It was raining and even hailing quite a bit but we were on a mission! Fortunately, the sun came out later and my jeans could dry up. Sea urchins are not common in the rock pools that are usually accessible at low tide, but they are quite common a little deeper. The same goes for Sea cucumbers. These are hardly ever pretty but the following species is ugly even in holothurian terms. According to David Fenwick it is a Pawsonia saxicola (I have seen a prettier incarnation before):
I noticed a little gastropod which looked vaguely familiar on a Pawsonia when checking my pictures. I could identify it as a Eulimida species in my old Poppe and Goto ‘European Seashells’ book, which also mentioned that many species in this family parasitize echinoderms so that fitted. David Fenwick’s excellent site Aphotomarine has great pictures of pretty much all species occurring here in the Southwest, including a much better one of this Vitreolina philippi Melanella sp (identified through David’s correspondence with Jakov Prkic). David has also just launched a website dedicated to Stalked jellyfish: stauromedusa which looks amazing.
At the end of the ‘session’ I glanced something red, white and blue; a colour combination that I had seen only on photographs before. It was a single, juvenile Spiny squat lobster Galathea strigosa:
A lot of usual suspects were found as well of course, here a Cornish sucker Lepadogaster lepadogaster and a Shore rockling Gaidropsarus mediterraneus:
The rockling has a groove in front of its dorsal fin filled with hairlike fin rays that are continuously beating. Finally, not a very good picture but I’ve posted it because this is the longest animal in Britain: the Bootlace worm Lineus longissimus can grow up to 10 meters!
