Category Archives: anemones

a weird mollusc in Mylor Marina

Posted on by under anemones, bryozoans, Canon Powershot D30, invasive species, molluscs, pontooning, tunicates

In the series ‘pontooning‘, I returned to Mylor a week ago Friday to have a quick look around in the marina. The water was choppy, but visibility on the sheltered side of the pontoons was OK. I noticed a brown slug-like thing flapping about next to a boat. My first thought was a sea hare (I have seen plenty but have not yet seen them swimming). Upon closer inspection, I saw that it was something else, it had a shell like Haminoea or Akera, species I had never seen, especially not swimming. It turns out that it was Akera bullata, an Ophistobranch mollusc that is rarely seen in Cornwall and generally is observed crawling on the mud, not swimming. Why they swim is not well understood, but they usually swarm in numbers and so there must be some general response to the environment or mating behaviour going on. I saw four other individuals nearby so that fits. I made a couple of movies but as I could not look through the viewfinder the footage is not great (I went back Saturday and Sunday to try and find them back but was not able to). The shell can be clearly seen hanging down (Akera is related to the Sea hare but has retained its external shell). When lifted out of the water, the animal folds its mantle around its shell.

IMG_9973There were some other interesting things to see. The dominant organism on the pontoons is the tunicate Cione intestinalis (I see there are some other tunicate species hiding in these pictures; I will have to take a closer look next time). Amongst it grows the purple invasive Bryozoan Bugula neritina. Next, a colonial tunicate thta could be Botrylloides violaceus, Trididemnum cereum or Didemnun maculosum (or something else again). After that, the beautiful Lightbulb sea squirt Clavelina lepadiformis.IMG_1849IMG_1656IMG_1677IMG_1704Plumose anemones Metridium senile are always common here. I for the first time noticed another species Diadumene cincta, very pretty! IMG_1867IMG_1859 IMG_1754 IMG_1745

aquarium update 12

Posted on by under anemones, aquarium update, echinoderms, fish, planted aquarium

It has been a while since I last posted an aquarium update; I have been a bit busy and have not done much with the tank recently. I have not done any water changes, never use the skimmer but have had zero algae because I have kept the light level low. I have experimented a bit with various seaweeds but nothing thrived. The Chrysemenia was doing well growing on the Tunze pump but disappeared overnight. Kelp always does well when attached to the pump. The tank is still a bit bare so no ‘full tank shot’ but some inhabitants below. I collected some Parasitic anemones Calliactis parasitica attached to an empty shell figuring that a not so pretty species might be actually quite hardy. Turns out they just stayed a bit limp and I therefore returned them to the sea.IMG_9139The Tompot blenny is a real character, very alert and always hungry. If you stick your finger in the water he immediately comes and nips it. The small scallop remarkably survived over the summer (remarkably because there is almost nothing to filter from the water) but the hungry Tompot ate it in the end (like most other snails). As the snails were not going to last long anyway, I introduced two small Common starfish Asterias rubens and two small Spiny starfish Marthasterias glacialis. They are usually hidden but that makes it extra fun when you spot one. The Cushion star Asterina gibbosa of course remain unperturbed and are always on the prowl. I noticed a tiny offspring (<2 mm).IMG_9759IMG_9391IMG_9752

Diving the Helford

Posted on by under anemones, Canon Powershot D30, crustaceans, ctenophores, eelgrass, eggs, Helford, molluscs, nudibranchs

IMG_8454After 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.)IMG_1081IMG_1014This 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.IMG_1012IMG_1065IMG_1058No 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.IMG_1083IMG_1085IMG_1032IMG_1031IMG_1039One 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.IMG_1041IMG_1035IMG_1019IMG_1026IMG_1072IMG_1048IMG_1090

snorkelling in the Helford

Posted on by under anemones, Canon Powershot D30, eelgrass, Helford, molluscs

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:

IMG_0923 IMG_0925Another 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:IMG_0905

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aquarium update 11

Posted on by under anemones, aquarium update, eelgrass, eggs, fish, invasive species, planted aquarium, seaweeds, tunicates

The aquarium was in desperate need of a make-over (again…). I hauled a ton of rocks over from the beach and stacked them up. (I thought at first that I would need something to stick the rocks together (epoxy, superglue or waterfall foam) but that wasn’t really necessary). I also removed most of the gravel and replaced it with sand. So quite a big change but it really looks a lot better. However, my nice burrowing Red-speckled anemones suffered a bit when putting the sand in, and even after siphoning it off again I could not really find them anymore….hopefully they turn up again!IMG_7849 The aquarium is still a bit bare and I have to go out and collect things that will live on the rocks, such as anemones and seaweeds. However, there is some progress on the seaweed front. There is a bit of Irish moss Chondrus crispus growing spontaneosly from the back wall. There are also some patches of pink corraline algae; which must be Coral weed Corralina officinalis judging from one outgrowing patch. Having this species grow would be great, but they do not seem like fast growers. Chrysymenia wrighti is still thriving on the circulation pump; I remove a bit every now and then, so it acts as an ‘algae scrubber’, removing nutrients from the water. I have placed a couple of other seaweeds in the aquarium, a bit risky as they can die off and start trouble, but I can’t help it. The red Soliera chordalis below has done well before but unfortunately has started to die off a little already (first pic). I have a big piece of a flat red species that has started to grow from nowhere as well (second pic).IMG_7908IMG_7652One day, the aquarium was full of strings of Painted topshell eggs. I noticed when feeding a day later that the water was not very cold: I had forgotten to switch the pump/chiller back on two days previously! So the trick to breed this species is to increase the temperature, although I am not expecting much to happen with the eggs. Either the Thick-lipped or Netted dogwhelks are also occasionally sticking their egg masses to the glass. I placed a chunk of orange Estuarine sponge in the aquarium; this was devoured by Painted topshells and Cushion stars, so it is a good bit of live food to add. I had planted a little washed-up eelgrass plant to see if it would survive and indeed it has grown more roots. (If you want to try this yourself, please always use washed up plants and don’t dig out any, as eelgrass beds are vulnerable habitats.) It would be great to have a second tank dedicated to eelgrass….The little scallop is still happy (see close-up). I have added another filter feeder: a Leathery sea squirt Styela clavata. Butt-ugly, but that is actually fun too. I am trying it out as they are an invasive species and so probably pretty hardy. A Sting winkle seems to like it (but not eat it). I have never seen my two Sting winkles eat anything actually. They move about very slowly, but they have grown.IMG_7651IMG_7914Now the snakelocks anemones are gone, I have added some more fish. I have caught some juvenile Pollack Pollachius pollachius with my net. At first I caught ones that were less than an inch, but they did not survive. Of the six two-inch or so ones I caught, three dissappeared after one day, but the remaining three are going strong. Very nice looking fish! I also caught a little Tompot blenny Parablennius gattorugine (by hand at low tide). It is quite shy, but is increasingly showing itself. A beautiful little fish! I have one remaining Two-spotted goby. The Common goby is doing very well and eats from my hand. I think I’ll go for another little tompot, more Pollack and Two-spotted gobies. Ideally I would catch some Leopard-spotted gobies with a trap when diving, let’s see….The other fish I would like to have again is the Goldsinny wrasse: very pretty and not as nervous as Corkwing wrasse. IMG_7887

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a superlow tide at Flushing

Posted on by under anemones, eelgrass, eggs, fish, seaweeds, sponges

IMG_6840The tide this Sunday in Flushing was as low as it was the day before in Mount’s Bay and the weather was just as great too. We could walk among the Eelgrass and Golden kelp Laminaria ochroleuca. There were lots of Snakelocks anemones Anemonia viridis around; especially striking were patches of what must be clones. The tentacles are much shorter than the ones in my aquarium or those found deeper on kelp, must be due to being less exposed to the waves. Loads of fish as is usual here, a single overturned rock yielded five species alone! Again pictures of the Connemara clingfish Lepadogaster candollei, a Butterfish Pholis gunnellus (very wriggly, hard to get a good shot) and Tompot blenny Parablennius gattorugine eggs:IMG_6880

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IMG_6865This site is sheltered and silty and some species are more characteristic for this habitat and much less common in Castle Beach in Falmouth. Examples include the Keyhole limpet Diodora graeca, the Elephant hide sponge Pachymatisma johnstonia and the Yellow-plumed seaslug Berthella plumula:IMG_6869

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IMG_6885The diversity of seaweeds was very high and I think the pictures below give a good impression of that. Very low on the shore Bushy noduled wrack Cystoseira nodicaulis can be found; in this case almost as iridescent as is Bushy rainbow wrack Cystoseira tamariscifolia. We found some Beautiful kidney weed Kallymenia reniformis, here David Fenwick is taking a photo of it on his first visit to my local haunt. All in all one of the best rock pooling weekends so far!

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Aquarium Update 8

Posted on by under anemones, aquarium update, echinoderms, fish, molluscs, seaweeds

Another long time without a post. A lot has happened to the aquarium and some of what I post here is already outdated, but here goes. My Daisy anemone has buried itself and has not resurfaced but the Red-speckled anemone is growing well. I found the Dahlia anemone I was looking for, but lately it has been pestered by a Purple top shell, which has left a scar on its column, I hope it survives. The most dramatic event was that the Snakelocks anemone managed to kill my Sea scorpion (but not eat it, it was too large). This must have happened when I  removed some of the rocks, startling it and make it swim in the wrong direction:IMG_4963Poor thing (although it had eaten 22 of my mullet so it works both ways I guess…). The good thing was that I could try keeping some other fish again. Using my net, I caught some Two-spotted gobies as well as a Common goby Pomatoschistus microps (I think, there are some very similar species) and a Goldsinny wrasse Ctenolabrus rupestris. The total tally from netting off the Flushing quay is now eleven fish species, not bad. The Goldsinny swims around the tank a lot and does some digging; it seems to be a more interesting fish to watch than the Corkwing:

The Plumose anemones Metridium senile are strange, they can be all shrivelled up for days, be short and squat or all extended. Here three pics of the same individual:Presentation1The Turban top shells Gibbula magus are very nice to watch (the Grey topshell Gibbula cinerarea gives a sense of scale). I found a Sea urchin Psammechinus miliaris and decided to try it out. It spends half its time under the gravel and pops up here and there with shells and pebbles attached to it. Let’s see what it does! Lastly a picture of the tank. I had attached a young Sugar kelp Saccharina latissima to the tunze pump with an elastic band and now it has attached itself to the plastic.IMG_5091

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Aquarium Update 7

Posted on by under algae, anemones, aquarium update, cnidarians, fish, molluscs, not suitable for the aquarium, seaweeds

Long time no post, just been too busy! The aquarium is doing reasonably well at the moment, especially considering the fact that I have not done any water changes since the last update and I have added a bunch of new organisms. I have added two Beadlet anemones Actinia equina. They are a dullish brown (except for a nice blue band around the base); I have not found the bright red or green individuals yet. Very similar but more striking are Strawberry anemones Actinia fragacea of which I have collected three. They are voracious, I could easily feed them a shrimp a day. The same goes for the Sea scorpion. I am afraid of sticking my hand in now as it comes after me! Time to let this buddy go. This will also give me the opportunity to add some other things such as squat lobsters.IMG_4825I have taken a break from experimenting with seaweeds and am focusing on anemones instead. I have added a bunch of small Plumose anemones Metridium senile that I scraped of the side of a pontoon. Weird fellas, they can fill up with water to be quite large, or just reduce to a crumpled little pancake. I have four white ones; I could only find very small ones of the orange variety and these were all devoured by Cushion stars (interesting). I’d like to have a large orange one as well, but I have to wait half a year until I can go diving again (they are very common in deeper water).

IMG_4812On the sheltered, silty shore of Flushing I found two small anemones attached to rock and half buried in the maerl sand. My excellent Seasearch Sea Anemones and Corals guide told me they were a Daisy anemone Cereus pedunculatus (uniform greay with many very short tentacles) and a Red speckled anemone Anthopleura balli (purplish and speckled, for a better picture of a different colour variant see this old post). Both quickly half buried/half nestled themselves under a rock so only the tentacles and the mouth are visible. They take pieces of shrimp and so hopefully they’ll be able to grow; these species should reach a decent size: IMG_4721

IMG_4729My friend marine biologist Chris gave me a snakelocks anemone that he had cured from its symbiotic algae. A very cool, bright white individual but it has returned to its original purplish colour so it must have taken up symbionts again. The snakelocks I already had, grew big, split into two and grew some more. Interestingly, one of the individuals seems to be turning from the green- to the purple colour variety:IMG_4828So six anemone species in all. I would really like to have some Dahlia anemones, they are very colourful, large, and not uncommon (old pic here). I need to go anemone hunting at a good low tide soon (I have not been out in ages).

I had the Chryseminia seaweed growing attached to the Tunze for a while and it worked OK, but it looks a bit messy and so I will remove it. However, I see that little Chryseminia plants have started to grow from the rock in many places (see top picture). I have to give the glass a weekly clean (with a tooth brush) and the rocks have turned a bit too greenish recently. I have noticed however that near the Snakelocks anemones, tufts of filamentous algae have appeared, as the grazers do not want to come too close to their tentacles (this reminds me of a work by an ecologist friend of mine who studies how seedlings can be protected from grazers when growing close to thorny shrubs, I’ll have to tell him of this observation!).

There has been some snail mortality. I mainly have Grey top shells but there are less than half of them left. I do not know why, part might be predation (which is not all bad as at least they serve as food for other inhabitants). I need to collects some more in any case. The Netted dog whelks are doing well. They are usually hidden below the sand, but as soon as they smell a defrosted shrimp, they come up like a Shai-Hulud. Their plowing through the sand is definitely good in preventing mats of diatoms to appear. Their little cousins the Thicklipped dog whelks are also doing fine. They tend to creep up the Daisy anemone to steal its food. I still have a Sting winkle Ocenebra erinacea which moves slowly but is very pretty. There are a variety of other species such as Blacklined- and Rough periwinkles. The best species however are the truly sublittoral large Turban top shells Gibbula magus (some of which have died as well, one of the shells has been taken over by a hermit crab, wich are also doing fine):

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Pontooning

Posted on by under anemones, bryozoans, Canon Powershot D30, cnidarians, invasive species, pontooning, sponges, worms

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.IMG_0402IMG_0405

Snorkelling at Silver Steps Part I

Posted on by under anemones, cnidarians, crustaceans, fish, snorkeling, worms

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:P1040041

P1040031We 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.

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