Another Silver Steps shore dive with @shannonmoranphoto and her fellow student Chris on Friday. The conditions were not as good as last time: low viz and a bit of a swell. I had set my camera to a longer focal range to try to take pics of cuttles or larger fish but that did not work out (with better conditions it still might not work out!). I could still shoot macro so that is what I did. Above to Devonshire cup corals Caryophyllia smithii. Pretty decent, but I know I can get a better close-up; I will try again Monday! I will have another go at the one resident Cray (or Craw) fish, which lives very shallow. I will also try the Twin fan worm Bispira volutacornis again, as I think a shot filled with just the fans (and not assorted bits of seaweeds etc) could be really nice. I might try free-swimming fish if they come close, as did this Poor cod Trisopterus minutus. Below some before- and after postprocessing. Just the jpegs in Windows Photos, nothing fancy. A bit of cropping, increasing clarity and contrast works wonders. Only when I have a really good photo I will invest time processing raw files in Photoshop. First the best photo of the dive: a Black-faced blenny Tripterygion delaisi (a female or possibly a non-breeding male). Next, a common Edible crab Cancer pagurus and finally a Twospotted goby Gobiusculus flavescens.
Tag Archives: Edible crab
more macro rockpooling
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!
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!
This weekend I stopped by Castle Beach in Falmouth to release some of my Snakelocks anemones (more about the aquarium in a next post…). Although the weather was bad, of course that did not prevent me from turning over some rocks. My curiosity was rewarded with another new find: a Hairy crab Pilumnus hirtellus. A beautiful little crab which is not uncommon but here it definitely is not as ubiquitous as the Furrowed and Edible crabs:
I also found a Furrowed crab Xantho incisus with unusual coloration (perhaps because it had moulted but I did not check):
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:
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:
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:
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:
Welcome to this most obscure of blogs, my dear reader. The aquarium is a bit of a mess at the moment for a variety of reasons. First of all there are a lot of algae growing; I have a bag with Rowaphos hanging in the back compartment to remove phosphates but this does not seem to help much (I have had good experiences with before though). Second, one of my pumps broke and so filtration runs at half capacity. Third, the mixed success of planting many different seaweeds has left loads of detritus in the tank. I have made large water changes which helped a bit. An additional tank for experimenting would be nice to have… Fourth, I have been unlucky with some of the seaweeds: the Wireweed grew really well, but the large size meant it caught a lot of the current and was easily dislodged. The Dudresnay’s whorled weed Dudresnaya verticullosa was growing really well (see here) but broke off from the rocks and could not be replanted:
I could not attach the fine red seaweed (see last post) either and did not want to have it floating around so I have removed it. My nice red seaweed streaming from the pump outlet, most probably Devil’s tongue weed Grateloupia turutu (as the name indicates, another invader from the Pacific), broke of. A crap picture of both weeds:
I changed the white gravel with finer, beige Maerl gravel (Cornwall’s equivalent of coral sand, see previous post) here placed in a bowl for contrast:
I released my Shanny as well as the largest of the two Rock gobies. The former attacked to many of the snails (it was getting a bit of a mollusc graveyard) and the latter was just too voracious in general. The final straw was seeing it swimming around with half a Worm pipefish sticking out of its mouth (I still have a bunch of those). The Shore rockling did not survive, but I caught a glimpse of the Shore clingfish when I removed some of the rocks from the aquarium. The juvenile albino Edible crab (if that’s what it is) and the European sting winkle Ocenebra erinaceus I recently caught both still do well, as is a juvenile Shore crab Carcinus maenas:
The Netted dog whelk Hinia reticulata is not one of the most impressive looking snails, but they do very well in the aquarium, burrowing and moving around:
I am not sure whether replacing one of the actinic lamps with the daylight lamp was such a great idea, the tank looks too yellowish now, especially with the Maerl sand…However, I will stick with it and see whether it helps future attempts to successfully keep Bushy rainbow wrack Cystoseira tamariscifolia (i.e. to retain it’s iridescence). If not, I’ll go back to the original lighting. I will not do too much with the aquarium in the near future as I want to get rid of the algae first. There are not many critters in the tank, which should help (I have only introduced a nice big Snakelocks anemone Anemonia viridis recently). I will do some more water changes and order a new pump. Only then will I slowly start experimenting with seaweeds again.
I am still unsure about the chiller, but with the weather getting warmer it might be more than just a luxury to have one. Apart from the price, it standing on the floor next to the aquarium with tubes sticking out is what I don’t like about the idea though. It will also not be silent, but perhaps I could get away with disabling the noisy hood fans, resulting in an overall quieter aquarium. The stripped-down tank (note that the red encrusting algae/seaweeds at the top of the tank have died (turned white) as they were exposed for a couple of hours when changing water):
quick rockpooling session
Went to Castle Beach in Falmouth after work this week for a bit of rock pooling. I saw a beautiful grey-red Sea scorpion Taurulus bubalis; I could not tell the difference) or but it was gone before I could even attempt to catch it. Below the
much easier to spot Shanny Lipophrys pholis Giant goby Gobius cobitis (after lifting up a rock):
I spotted a small Eel Anguilla anguilla for the first time on the beach; it was quick but I could scoop it up from a very shallow sandy pool. Nice, but not of interest for the aquarium!
Also spotted for the first time: a European sting winkle Ocenebra erinacea. This I took home for the aquarium:
A tiny white Edible crab Cancer pagurus. I do not know if it is an albino or whether juveniles are generally white. I had a bigger one in the aquarium (carapace width 6 cm or so), but every night the light went out it came out of its burrow and started to rearranging the tank, knocking big rocks against the glass. This one is only one cm so I hope it will be better behaved: