Tag Archives: Littorina littorea

Periwinkles

Posted on by under Macro, molluscs

Long time no post – the idea was to spend time taking photos during spring and summer and enjoy the underwater world vicariously by blogging in autumn and winter. However, something terrible happened on my only dive of 2025: my underwater housing sprung a leak! The housing was not flooded to an extent that it damaged my camera but it needed to be repaired before I could get back underwater. Unfortunately there is only one place that can do that, backscatter all the way in California, and even more unfortunately, U.S. customs decided to keep my package on a shelf for over a month. I have never seen an octopus in my decade of diving but of course people reported eight or so per dive last month so I was feeling very sorry for myself!* Anyway, I have been confined to the shoreline so far. To cope with that, I bought a weird chinese macro-wide angle lens to play with which I will post about later. I also used my ‘normal’ 60mm macro lens (sometimes with a Raynox lens attached to the front for extra magnification) and took some time to focus on periwinkles.

At the top and below a Flat Periwinkle (Littorina obtusata or maybe L. fabialis – distinguishing is very hard as it requires investigating differences in penis shape!). As you can see the locations are not always glamorous, but if you zoom in you can still find beauty!

Flat periwinkles tend to be most active above-water, followed by the smaller Rough Periwinkle (Littorina saxatilis – below) with the Common Periwinkle (Littorina littorea – below that) only occasionally moving about.

Finally, a tiny species the Small Periwinkle (Littorina Melharaphe neritoides). Probably overlooked by most, as it is tiny (up to 8mm, usually smaller) and hidden between barnacles (or even nestled in empty barnacle cases) high on the shore.

* and no, I could not bring myself to go diving without a camera…

more macro rockpooling

Posted on by under molluscs, Olympus OM-D E-M5 Mark II, rock pooling

Another quick, brisk trip to the rocky shore in my village of Flushing today to practice my macro photography with the 60mm lens. I used the highest F-stop, varied the output of the flash and let the camera decide the shutterspeed and ISO. I did not find anything too special, but the very common organisms are just as pretty as the rarer species. Above and below juveniles of the Flat topshell Gibbula umbilicalis and the Grey topshell Gibbula cineraria on pink encrusting algae. Still not quite used to not having optical zoom as with my old Canon Powershot but quite happy with the shots, especially as all were hand-held. As I am lazy, these are JPEGs with some  tweaking using Windows photoviewer.

Below a Black-footed limpet Patella depressa, a more ‘atmospheric’ shot of a periwinkle, might be the ‘normal’ Littorina littorea but not 100% sure, and a baby Edible crab Cancer pagurus. Really looking forward to go into the water again, but not only is it still cold and grey, it is very windy and choppy so bad viz. Probably another rockpooling post next weekend!

aquarium update: snails

Posted on by under algae, anemones, aquarium update, crustaceans, molluscs

Time for an update. The five Snakelocks anemones have settled and are doing very well (I have fed them some defrosted shrimps which they quickly devour). The Leach’s spider crab was sitting happily under one of the anemones until it decided to move behind a piece of slate and now does not show itself much anymore. Perhaps this has to do with a prawn I introduced, although I have not seen any scuffles. I have to see what I’ll do about this. If it is really shy then I perhaps have to choose between keeping it or introducing fish. In any case I have seen it munching on some algae and a dead Cushion star and it seems to do OK.

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The main problem I have is the dreaded return of algae…There is quite a diversity of them: fuzzy green ones, darker green blotches, slimy purple ones, brown diatoms and more. All interesting organisms surely but I do not want them to take over the tank! I have used food sparingly and used the skimmer most nights, but now have also removed my daylight lamp, to leave a single actinic lamp (see this post about lighting). I still have to get used to this new look, but less light must surely help. Most interestingly, I have enlisted the help of 80 or so grazing snails. Mainly the Common periwinkle Littorina littorea and the Flat top shell Gibbula umbilicalis but also some other species, including two very small Painted top shells Calliostoma zizyphimum. I never had many snails in my aquarium, as they were always eaten by Shannies, but hopefully they will survive this time. I will dunk in a lot more snails, and keep an eye out which species does best. A Flat top shell (picture taken using my olloclip macrolens for the iPhone):

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One returning encrusting red algae is actually a seaweed, with new ‘leaves’ growing from the round crusts. I suspect it is Devil’s tongue weed Grateloupia turuturu. I have been scraping it off the glass, except from the corners where the scraper is of no use, but will let the rest sit and see how it grows:

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I also noticed that Sea lettuce Ulva has started to grow from the slate. The aquarium does not look that nice yet, but with the new animals there is plenty to watch in any case!