What friends predicted happened last Sunday morning: someone scrambled down the rocks to check if this figure lying motionless in a shallow pool was dead or alive. Luckily, I was feeling very alive indeed, watching a sizable Spiny starfish Marthasterias glacialis moving over the rocks using its hydraulic tube feet. A beautiful blue-grey colour, the surface of these animals are very richly textured. I am not sure exactly what is going on at the tips of the arms: the very end shows a red organ, potentially light sensing. It is surrounded by nodules, which might be the precursors of the centres of new plates covering its body, or something else. The tube feet at the tips are smaller and orange-tinged and I am again not sure whether they are just newly developing or having special sensory functions. I noticed the madreporite at the top of the animal: this sieve plate is involved in pumping the water in the body for hydraulic locomotion. It resembles a stony coral ‘madrepore’ colony, hence its name. In general, the seastar surface resembles a coral I think. The photos are nice, but I know I could do a lot better: next time!
I recently posted my first photos taken with the nauticam CMC macro wetlens using stalked jellyfish as a subject. I since lost my lens, which I in large part blame on the bad fit of the adapter with which it is attached to the housing. The best thing in these cases is not to agonize over it too much, order a new one straight away and keep going, so that is what I did (also I am now a bit more careful of course). Here some more photos of macro subjects. Above a very easy subject as it is very common this time of year and also it does not move….Paddle worm egg capsules (probably Eulalia viridis). The individual eggs can be just made out in the gelatinous blob. Below, one of the more common nudibranch species Polycera quadrilineata. Nudibranchs come in all kinds of stunning colour variations and are very species rich and so are a favourite of macro photographers (see this old post hunting for them with David Fenwick in Newlyn, and check out the NE Atlantic Nudibranch facebook page for lots of eye candy). Tricky with the narrow depth of field to get the whole animal in focus. Mysid shrimp are quite common and beautiful little animals hovering about in small groups. They need dissection to determine which species it is, but this might be Leptomysis lingvura (around 10 mm). Finally, the colonial star Ascidian Botryllus schlosseri; these form colonies (‘systems’) where zooids have individual inhalant openings and a shared exhalant opening. They are common, sessile, flat, and come in a range of colours so they make ideal subjects for a beginning macro photographer. Not only that, apart from fish they are our closest relatives in rock pools, which is most obvious in the tadpole-like larvae which have a dorsal notochord (a cartilage rod functioning as a backbone). I hope to devote a post to them later in the year.
More photography practice lately. I have started to use Photoshop to post-process images, which is hard. I have sat with Thomas Daguerre for a session which was very helpful. For some images, the twiddling is of not much use; the image above of a Bull huss egg case for instance I am pretty happy with as is. Below I have pasted some before and after-Photoshop photo’s. Mostly adjusting highlights and contrast, cropping and playing around with sharpness (in the RAW files), most images tend to be a bit reddish. I have not bothered to tackle the ‘marine snow’ with the Spot Healing brush tool. First, Snakelocks anemones, next, Cocks’ comb Plocamium, then Harpoonweed Asparagopsis armata and an old kelp holdfast covered in feeding Grey topshells Gibbula cineraria. On and under the seaweeds I encounter many interesting tiny animals, but it is hard to take good photo’s without a macrolens. I have pasted a couple photo’s below (none have been edited in any way): the Stalked jellyfish Haliclystus octoradiatus (these can also be reddish or brownish, and can be found on a wide variety of seaweeds), a sponge, a juvenile Snakelocks anemone Anemonia viridis (next to a Flat top shell Gibbula umbilicalis) and the Star ascidian Botryllus schlosseri where I later noticed the fecal pellets underneath. Pooping tunicates, that is what we need more pictures of!Finally, some more before- and after- Photoshop images. The first is the nudibranch Rostanga rubra (‘Red doris’) which was only 5mm or so (see also the tiny Daisy anemone in the background). I shot it today, very cold: 4 degrees, and the water might have been only 8 degrees, brrrr! Next, a closeup of the seaweed Osmundea (see the first photo of this post) which shows its interesting pigmentation. The photo’s are nothing special yet, but I notice I am making progress. Excitingly, I just have ordered a macro wetlens and so hope to get some proper macro photography going soon!
I usually head down straight to the lowest reaches of the shore when rock pooling, but when there is a neap tide and a lot of inshore wind as there was this weekend, you have to make do with turning rocks higher up the shore. Although biodiversity is lower, there are some species that are only found there (see for instance this recent post) and so it is actually nice to have a look there for a change. The very first rock turned over actually had a couple of interesting inhabitants underneath it. Another lifer, the tiny gastropod mollusc Onoba semicostata (surrounded by a couple of even tinier Rissoa parva), very quickly identified by members from the British Marine Mollusca facebook group:
The same rock had a number of the tiny (< 1 cm) Cushion star species Asterina phylactica on it as well. It is prettier than the common Cushion star Asterina gibbosa (one of my favourite aquarium species), but perhaps a bit too small to be an option for the tank.
One other beautiful species, the colonial tunicate Botryllus schlosseri, this is a nice blue/purple one:
After being abroad a couple of times this summer (Slovenia, France 1 2 3 and The Netherlands), I have started rock pooling in Falmouth and Flushing again. Things have noticeably changed since the spring, most prominent being the recent abundance of all kinds of sea squirts (tunicates). They are everywhere, and some of them I have not seen before. The solitary sea squirt Corella eumyota is very common, with smaller individuals a translucent white and larger individuals more orange:
My personal favourites the colonial Botryllus (in the above picture bottom left among the bryozoans) and Botrylloides are also very abundant at the moment. I should measure the width of a population on a recognizable, large rock and go back to check how fast they grow actually. Below a picture of both species growing side by side:
Some more Botryllus schlosseri pictures demonstrating the variability in colour (the Botrylloides leachi here look all the same):
A species that I had not noticed before and is growing in every rock pool in Flushing at the moment is the orange Morchellium argum, which grows as a colony as does Botryllus or Botrylloides but in a rather different way. A colony consists of a stalked club with individual zooids protruding from the ‘head’:
Hello! For the last half year or so, I have been messing with a marine aquarium housing sea weeds and critters collected from local rock pools here in Cornwall. I thought it would be fun to blog about my aquarium project, especially after I discovered that it is quite easy to take nice aquarium pictures using an iPhone (which I found nearly impossible using a standard digital camera). After doing some internet research, I settled on a Red Sea Max 130D ‘plug-and-play’ aquarium (I will post about the actual tank later). I could not find much information on the web on temperate marine tanks, especially ones without a chiller or a sump. and few of those seem to focus on seaweeds. So who knows I may have found a niche. Below I have posted some pictures from when I was setting it up last year:
Half a bucket of gravel collected from a nearby beach, RO water taken home from the lab where I work (carried back 2×10 L at the time, the tank is 130 L) mixed with a free bucket of sea salt that came with the tank. Few sea weeds and not too many rocks. I have since replaced the rocks with bigger ones; most critters are benthic and you do not want to have too much ‘open water’ around with nothing in it. Although too bare, I do like the purple look of this set-up, which has since disappeared because of inevitable algae taking over from the purple crustose seaweeds.
A shanny Lipophrys pholis, this is a very common fish around here that can easily be picked up when turning stones at low tide. The branched seaweed on the left is Solier’s red string weed Solieria chordalis; in the back on the right there is a little pluck of Berry wart cress Sphaerococcus coronopifolius.
A snakelocks anemone Anemonia viridis. Behind it some Slender-beaded coral weed Jania rubens. This weed died off quite quickly; first it turned a bright orange, then white.
The Star ascidian Botryllus schlosseri, a colony-forming tunicate. It did not survive for too long, but that might just have been because the particular broad-leaved red seaweed they grew on are very popular with prawns and hermit crabs. What animals and sea weeds do well has been trial and error. I might compile a list of ‘easy’ species and ones to avoid at some point.