new camera: Olympus OM-D E-M5 Mark II + M.ZUIKO 60mm f/2.8 Macro Lens

Santa Claus was very generous last year and I am now the proud owner of an Olympus OM-D E-M5 Mark II mirrorless camera! A big step up from my Canon Powershot G16 compact camera (which I still find a great little camera btw). Apart from a better sensor, greater dynamic range, more pixels etc, the main reason for going for a so-called micro four thirds camera was that I can use separate lenses. By that I mean lenses that actually go on the camera rather than wetlenses that are attached to the camera housing. The wetlens approach has the problem that air bubbles can form on three surfaces rather than one, and also, water seeps out from between the lens and housing every time you lift it out of the water (which I tend to do a lot in rockpools less than a meter deep). I first thought of going for an SLR, but these are much more expensive (the housings at least), require looking through a viewfinder which seems annoying to me and also they are considerably bigger, which is also not handy in rock pools. Luckily I learned that mirrorless cameras also existed! I bought an M.ZUIKO 60mm f/2.8 Macro Lens as well. I have not been in the water yet, as the weather has been grim, but took the camera out for some above-water rock pooling last weekend. The first day I did not take the separate flash, which demonstrates my ignorance (to maximize the depth of field, a small aperture is needed which lets in little light, resulting in long shutter times and high ISO). The photos were not great, but the next day with flash it went a lot better. Above a Broad-clawed porcelain crab Porcellana platycheles and a Long-clawed porcelain crab Pisidia longicornis. Next time I will bring a ruler to show exactly how tiny these crabs can be (these are juveniles).

Above a flat worm (check the eyespots!) and a Thick top shell Phorcus lineatus. A main problem is that all subjects are covered with a film of water, resulting in glistening highlights when using the flash. Another issue is the shallow depth of field. The next time I might try to do some photo bracketing/stacking, merging images of a different focal depth (I need a tripod for this). The great thing is that there is no shortage of subjects: turning over a single rock can reveal multiple species each of echinoderms, molluscs, crustaceans, bryozoans, worms, flat worms etc. Below a selection of chitons, I have not had time to check out which species; there are not that many here but they are tricky to identify from photographs. I will check Ian Smiths fantastic photo resources on flickr to do so.

 

animals that did not do that well in my aquarium…

A while back I wrote two posts on my personal top ten animals for the (unchilled) aquarium (here and here). Of course, there were also organisms that were not such a success. Animals can be unsuited for the aquarium for many reasons, and of course this depends on the size of aquarium, the combination of animals and what you define by ‘unsuited’; so please keep in mind that the following is a personal account!

Aggressive species: Another reasons that makes animals unsuitable for a community tank is that they are bullish. (Animals becoming too big is not a real problem for the native aquarium as you can release them again and replace with smaller individuals.) Crabs often get rowdy for instance. I kept a small (5 cm carapace width) Edible crab Cancer pagurus for a little while (his name was Barry). It would bury (Barry!) itself during the day, but as soon as the lights turned off it would go about and rearrange the tank. Rocks weighing over a kilo were knocked against the glass and I found a Cushion star cut in two. It was quite an operation to remove it from the tank using a net (but during all that rummaging I interestingly saw bioluminescence in the tank which was very cool). Shannies like to feed on snails and hermit crabs and so in a relatively small aquarium at least, so sometimes you have to choose between one or the other:

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Truly littoral species: I had a couple of limpets Patella vulgata in the aquarium that just sat in the same place on the glass for months. At this time, algal growth was a problem, so I should have known if they had moved during the day or night by the tracks they would have made but they did not move a millimeter. The animals seemed a bit thinner in their shell, but seemingly they can survive for very long periods without food. Not being able to emerge from the water as they do normally seems to be a big problem for these animals.

Secretive species: Other animals simply are too shy or live underneath rocks; no point really in putting them in the aquarium if you cannot see them. This happened with Broad-clawed porcelain crabs, a Shore rockling and also a Shore clingfish (although hidden, all of these animals did survive for a long time). I have seen Brittle stars in a Mediterranean aquarium but the ones found in the intertidal here tend to live under rocks and I never saw one back in the aquarium. A Sand star Astropecten irregularis quickly buried itself in the gravel:

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Filter feeders: I quickly realized that filter feeders, mussels or tunicates for example, were very difficult. There simply were not enough algae growing in the water to feed them (unfortunately, at times there were plenty of algae growing on the rocks and on the glass). One way to keep filter feeders is to separately cultivate algae for food. A really nice blog describing such a project can be found here. Another solution might be to feed these animals with artificial plankton, which is available commercially. This requires very good skimming to get rid of excess nutrients though. Both options I find too cumbersome at the moment. Having said all this, one filter feeder managed to survive for many months in my aquarium: the variegated scallop.

Other fussy eaters: Worm pipefish did OK in the aquarium, but that was probably because I regularly brought in new seaweeds housing fresh zooplankton. Unlike Mullet, Gobies or Blennies, I have never seen them take frozen food and therefore I will not keep them again until I can provide them regularly with live brineshrimp or similar. Snakelocks anemones always did well in the aquarium, but Beadlet and Strawberry anemones didn’t (they actually did not die but seem to shrink rather than grow over time). The former are able to grow because of their symbiosis with photosynthesizing algae and so do not rely as much on food. I must say that the latter two  species are probably relatively easy to keep when you make the effort to regularly dunk a piece of dead prawn on them. The European cowrie Trivia monacha feeds on tunicates which I had trouble keeping alive and so they are unfortunately not an option yet:

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Unknown reasons: On a few occasions a species just died and I had no idea why. The only thing this taught me was to not try that species again. This happened to a Common starfish Asterias rubens:

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Three crabs

The diversity of crabs here in Cornwall is quite high: it is easy to spot more than five species in just a minute of rock pooling. The Furrowed crab Xantho incisus (or X. hydrophilus) has relatively large claws and can do a lot of posturing when disturbed but it is actually quite docile and never pinches hard:

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I have only once encountered the small crab Pirimela denticulata (but I must say I have not been looking particularly hard):

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The Broad-clawed porcelain crab Porcellana platycheles is extremely common under rocks. I have added a couple to my aquarium when I started but as they just hide under rocks that wasn’t a very smart idea. Months later when re-arranging a rock I found them again so at least they seem to do well in the aquarium:

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