a very low tide at Castle beach

IMG_7884There were exceptionally low tides this weekend so I was quite stoked to get out and find some new species in what is normally the subtidal. It was raining and even hailing quite a bit but we were on a mission! Fortunately, the sun came out later and my jeans could dry up. Sea urchins are not common in the rock pools that are usually accessible at low tide, but they are quite common a little deeper. The same goes for Sea cucumbers. These are hardly ever pretty but the following species is ugly even in holothurian terms. According to David Fenwick it is a Pawsonia saxicola (I have seen a prettier incarnation before):

IMG_7900I noticed a little gastropod which looked vaguely familiar on a Pawsonia when checking my pictures. I could identify it as a Eulimida species in my old Poppe and Goto ‘European Seashells’ book, which also mentioned that many species in this family parasitize echinoderms so that fitted. David Fenwick’s excellent site Aphotomarine has great pictures of pretty much all species occurring here in the Southwest, including a much better one of this Vitreolina philippi Melanella sp (identified through David’s correspondence with Jakov Prkic). David has also just launched a website dedicated to Stalked jellyfish: stauromedusa which looks amazing.

IMG_7891 - CopyAt the end of the ‘session’ I glanced something red, white and blue; a colour combination that I had seen only on photographs before. It was a single, juvenile Spiny squat lobster Galathea strigosa:


IMG_8010A lot of usual suspects were found as well of course, here a Cornish sucker Lepadogaster lepadogaster and a Shore rockling Gaidropsarus mediterraneus:

IMG_7925The rockling has a groove in front of its dorsal fin filled with hairlike fin rays that are continuously beating. Finally, not a very good picture but I’ve posted it because this is the longest animal in Britain: the Bootlace worm Lineus longissimus can grow up to 10 meters!


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:



When looking for pictures of the squat lobster, I realized I have quite some neat old pictures to post. I should have started the blog when starting up the aquarium to keep things chronological, I will use the next couple of posts to get rid of this back log. First the fish. I have two Rock gobies Gobius paganellus in my tank. The big one is voracious and after a feeding session has a visibly distended belly. It is a curious fish that often comes to check me out when I am taking a picture. It is beautiful too:




However, I will attempt to catch it and release it, as I suspect it to be a bit too large (three inches) and rash. My worm pipefish Nerophis lumbriciformis are very shy and they might be bullied by large gobies and blennies. I actually suspect the big rock goby to have eaten my recently disappeared beautiful little Montagu’s blenny Coryphoblennius galerita, a species I have only found one time:



A worm pipefish Nerophis lumbriciformis. To replace the rock goby, I will try to catch some Two-spotted gobies Gobiusculus flavescens later. This species is also beautiful, but smaller and it spends more time in the water column which is nice. It is not a rock pool inhabitant though; it lives among seagrass. I have seen many last year when snorkelling. I need to look into a good net to catch them! I had two  large Shannies Lipophrys pholis as well that I released again, I still have a small one left:


I also had three thick-lipped mullet Chelon labrosus in the tank. These fish are quite ugly as adults, but juveniles are nice, restless silver fish. All  fish mentioned above are benthic (hang around the rocks rather than in the water column), whereas this species mostly swims at the surface and so really adds to the aquarium. I released these three when changing up the tank once and I now regret that. They are fast swimmers so quite difficult to catch (at least with the small aquarium net I use). Since they are so restless I did not manage to take a decent photograph. I have also added a Shore rockling Gaidropsarus mediterraneus and the cling fish the Cornish sucker Lepadogaster purpurea at one point. I should have known that these were mistakes as these are fish that mainly hide under rocks and I have not seen them since adding them to the aquarium. I will post some pictures of these fish in their natural habitat later.