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!
OK, as I mentioned in the last post, I had been on three dives before my exceptional viz snorkel session but did not have the opportunity to post pictures. So here goes for the first dive at Swanpool with Thomas Daguerre. Swanpool is a nice little beach but I was sceptical about it, as it is mainly, well, beach. Thomas wanted to try to find some sand-dwelling creatures though and I was up for trying something new so in we went. See him at work below in some seriously murky water! Again, spider crabs were common, sitting still but running away when getting closer, stirring up the sand. There is some sparse seagrass, arranged in thickets parallel to the strandline, some Sand mason worms Lanice conchilega can be seen in the foreground. A Spiny starfish Marthasterias glacialis was eating up a Pod razor shell Ensis siliqua. A little swimming crab hid in the sand, not sure which species.Also, jelly season has started, I saw several Northern Comb Jellies Beroe cucumis. They are exquisitely beautiful and very hard to focus on, which makes for a photographers nightmare. Apart from a Compass jellyfish, I noticed a Blue jellyfish Cyanea lamarcki. It appears to have two parasites, which could be the amphipod Hyperia galba. All in all not a bad dive. Also, I found a frisbee and a decent pair of sunglasses!
Last Wednesday I went for a sneaky worktime dive across the Fal estuary on the Maerl beds between St Just in Roseland and St Mawes. Maerl is a slow growing, calcified type of seaweed (looks more like coral) which forms a unique and quite rare habitat, see these older posts. The water was 17°C so nice and comfortable and it was probably the shallowest dive I’ve ever done, no deeper than 3 meters. I took my new Canon G16 in a Fantasea housing and went all semi-pro by adjusting the white balance first (not that I had a go at any other settings…). I was really pleased with the results, a world of difference to the Canon D30. The beds are an expanse of maerl nodules with very little to break it up, no rocks, no sand, just the occasional old bottle and so it is hard to get any exciting angles. Still there is always something to see. In order: a baby Smallspotted catshark Scyliorhinus canicula, a Spiny starfish Marthasterias glacialis, a (breadcrumb?) sponge, a closed-up Snakelocks anemone Anemonia viridis (a rare sight), a Parasitic anemone Calliactis parasitica, a Fan worm Myxicola infundibulum, a Harbour crab Liocarcinus depurator, a Velvet swimming crab Necora puber and a very well-camouflaged Spider crab Maja squinado.
This friday, I tried my hand at some more underwater rock pool photography with my point-and-shoot Canon Powershot (see also here and here). This is both rewarding as the colours of seaweeds are so vivid and the textures so varied, and frustrating, as I cannot use the viewfinder and even if I could, lots of shots would be much better using a wider-angle lens. Also, I am often kicking up silt with my wellies and the nicest shots often are just out of reach. So next time, I should really photograph whilst snorkelling. (It would be great to use an SLR in an underwaterhousing. I bought a much cheaper and much more cumbersome ‘underwater-camera bag‘ without remembering that my old, not-so-frequently-used-anymore Canon EOS 400D does not have a viewfinder. I am afraid this will make the experience less, not more, fun…) Anyway, the trick for now is to take many pics and hope some turn out all right. I like the ones with a water surface reflection best. The nicest one was a snakelocks anemone among corraline algae. Next, what is may or may not be Sea flax weed Stypocaulon scoparium. After that, the brown Divided net weed Dictyota dichotoma growing inbetween Discoid fork weed Polyides rotundus, a Bull huss/Nursehound/Large-spotted dogfish Scyliorhinus stellaris mermaid’s purse and a Spiny starfish Marthasterias glacialis. Probably more photos soon as the pools look by far the best in early spring.
When going out rock pooling, I always take my iPhone and Canon Powershot (for underwater use) and take at least a couple of photos. Because of a lack of time, or because a single good photo is not enough for a new post, not everything ends up on the blog. Now I have some free time, I picked a couple of unused photos made this year that seem blog-worthy. First up, In realized only what I had found on the beach at St. Ives when leafing through the The Essential Guide to Beachcombing and the Strandline: a Seabeard! This hydroid, Nemertesia antennina, grows as stiff colonies protruding from a matted base and occasionally washes up on shore. It looks a bit plant-like; at the time I did not have the opportunity to have a closer look and just snapped a quick photo. Next a Lesser sandeel Ammodytes tobianus found at Gylly beach. I always see them when snorkeling or diving (see here) but this was a good opportunity to see one up close (I get excited when I spot a dead fish on the beach (see also here) and I am not afraid to admit it!). Following are two colour varieties of the Spiny starfish Marthasterias glacialis, a Common brittlestar Ophiothrix fragilis and a shot of an Aequorea forskalea (or maybe A. vitrina) jellyfish. Next the gastropod mollusc Chinaman’s hat Calyptraea chinensis. I went back to Mylor marina for some pontooning recently but not much was growing; the only thing that stood out was the luxuriant sponge growth (I am not sure of the species, perhaps Halichondria).And of course some seaweed pictures. By iPhone: Under tongue weed Hypoglossum hypoglossoides in Flushing, Black scour weed Ahnfeltia plicata in St. Agnes and a photo showing a variety of wracks all colonizing the same patch (Flushing): Serrated wrack Fucus serratus, Spiraled wrack Fucus spiralis, Bladderwrack Fucus vesiculosis and Egg wrack Ascophylum nodosum. Next some Canon Powershot underwater pics (see also this post and this one): a random rock pool picture of mostly decaying seaweed, a closeup of my favourite the Bushy rainbow wrack Cystoseira tamariscifolia and a shot of Wireweed Sargassum muticum that has completely taken over a pool. Finally an SLR photo of a rock pool at Gylly beach with large Cystoseira baccata plants (middle, Wireweed on the left).
Low tides over the weekend, see the previous post for the trip on Saturday in Flushing. On Sunday the wind resulted in the water being swept up quite high on the shore unfortunately (the next very good tide I will make sure to check the wind a bit better, probably would have been a good idea to have gone to the north coast). Also the rain made swiping my iPhone very difficult and I was absolutely drenched. Luckily I had already taken a long lunch break on Friday when it was sunny! As I found a good number of species I will divide them up over two short posts instead of a very long one. In this post some species that have featured before, but that I now have taken better pictures of: a Shore clingfish (or Cornish sucker) Lepadogaster lepadogaster, a particularly purple Spiny starfish Marthasterias glacialis, a particularly orange Painted topshell Calliostoma zizyphinum as well as a close-up of the ‘normal’ colour variety, Blue-rayed limpets Helcion pellucidum, Seven-armed starfish Luidia ciliaris and a Bull huss (Nursehound shark) Scyliorhinus stellaris mermaids purse. Nice colours all around:
A couple of weeks back I went for a boat trip and snorkel over Maerl beds with friends on the other side of the Fal Estuary, just north of St. Mawes. I did not post about it at the time, as my photographs were quite crap and I reckoned I could go back to try and come home with something better. However, there hasn’t been any time for that, nor will there be in the near future, and as it was such a cool experience I reckoned it would be nice to write a little post about it for now anyway. The beach was fringed with sea grass, but the Maerl beds started very near the coast, at around two meters depth at low tide. Maerl is something special; it must have taken early biologists a while to figure out whether it was mineral, animal or plant. It is actually a calcareous alga that (very slowly) grows in fist-sized nodules or thalli. The Fal and Helford estuaries are one of the few places in the country where it occurs, and the Maerl beds here are under threat of dredging. Although Falmouth has the third deepest natural harbour in the world, big cruise ships cannot land close to the town centre which makes it unattractive for ships to stop. Falmouth would be a very pretty last port of call sailing west and cruise ships are of course good for business, hence the dredging plans. I will save the debate on economy versus conservation for a future post, as it will require a lot more text. I was able to take some pictures of the Maerl with my old Canon Powershot in plastic housing before the new batteries decided to quit on me prematurely:As you can see the Maerl really looks more like a coral than a seaweed (and dead pieces of Maerl form a type of coral sand, see here and here). It provides an ideal structured habitat for all kinds of organisms to live in and on (for instance fine seaweeds and snakelocks anemones). Besides various fish, crabs and sponges and small things darting to safety in general, we saw a big hermit crab in a Buccinum undatum shell with the large anemone Calliactis parasitica on top. Very cool, and apparently not very commonly encountered (this was of course after my batteries had run out). What was striking as well, were the very large (one of them measured half a meter across), very fat and very pale Spiny starfish Marthasterias glacialis:Maerl with a sponge growing through it (or possibly the other way around):Maerl is protected, so not an option for the aquarium, although I am sure it would make for a fantastic looking display (moreover potentially a very stable display as Maerl is not seasonal but grows for centuries). Hopefully more and better pictures later this year!
It has been a while since I last posted about the aquarium, mainly because I had a problem with algae and did not like the look of the tank in general. Combined with being away for two weeks over the holiday season, I decided to remove the rocks and most animals from the tank. Only left are some snails, Cushion stars and a Spiny starfish (who seems to do fine except for being less brightly coloured than when I caught it). The snails made a good start and cleaned up a lot of algae but it was too little too late. Also, (non Spiny starfish-related) mortality was quite high. Of all snails, the periwinkles fared least well (as I had noticed on earlier occasions); the Grey top shells seemed to do best. A main problem is that the snails move out of the water and often die there. Grey top shells can be found in the intertidal but are also common in the subtidal and so might be more suitable for the aquarium.
Anyway, time for a fresh start in the new year. I have decided to buy a chiller (and pump), mainly so I can switch off the noisy hood fans, but also because a more natural temperature regime might help keeping some of the more difficult species (see eg here and here). I have trawled the internet to find recommendations for the least noisy chiller but to no avail. I will stick with a more expensive brand and hope for the best. I will also invest in LED lighting. LED lights give a nice shimmer effect, generate less heat, use less electricity, need less replacement and are more easily dimmable. I’ve found this interesting Red Sea Max 130D retrofit kit:I will need to buy a separate dimmer and probably will have to ask my local sparky for help fitting it in the hood but it seems like a good investment. I’d like to supplement white LEDs appropiate for shallow water with some blue ones so I’ll be able to get a deeper water feel as well. This week I saw an inspirational aquarium back in Blijdorp Zoo in Rotterdam: a deep water reef with gorgonians, many brittle stars, Boar fish (or Zulu fish) Capros aper, Snipe fish Macrorhamphosus scolopax and John Dory Zeus faber. A crap photo:
However, I will go for a more brightly lit seaweed aquarium first. I will switch to finer gravel and reduce the amount of rocks to improve water flow. This time I will also focus more on fish. Marius has a great picture of a Two-spotted goby Gobiusculus flavescens in his Irish rock pool aquarium here and I definitely want to have a couple of these (I had a tiny one recently but it was eaten by one of the Snakelocks…). The other fish I definitely want to have is a bright green juvenile Ballan wrasse Labrus bergylta (although the other species are pretty too):
Small wrasse can be caught using a hand net but I reckoned it would be easier using a cast net. After my first trial run with such a net in the Helford river a while back I am not so sure though: loads of leaves and twigs but no fish. Youtube has hundreds and hundreds of ‘how to throw a cast net’ videos but these all use slightly different techniques which sometimes involve a throw whilst holding the led line between the teeth… Anyway, I’ll have to practice!
Another ‘lifer’ yesterday: a Sea gherkin Pawsonia saxicola, at Castle Beach in Falmouth. It is a small sea cucumber (a relative of the Cushion star next to it); a very cool find indeed!
The main aim though was to collect more snails to help out in the grazing project. This was pretty easy of course. I collected a couple more Painted top shells Calliostoma zizyphinum and many, mainly juvenile, Grey top shells Gibbula umbilicalis. I also picked up a beautiful small Spiny starfish Marthasterias glacialis; this fellow will go after the snails but as long as the predation is not too severe that will be OK, let’s see. Finally, using my little aquarium net, I went after some fish high up the shore and caught a tiny Two-spotted goby Gobiusculus flavescens. I need to catch a bunch more of those, hope to post about that soon
The sun was shining this weekend and the sea water is currently at its warmest so we went out for a bit of snorkeling off Pendennis Point in Falmouth. My experience with the iPhone waterproof case was not that good, so I took my Panasonic Lumix (DMC-FT10) along (which is not too great either!). The seaweeds are dying off mostly; the kelp is covered by bryozoans and hydroids to the point that they are completely fuzzy:
I mentioned in the previous post that the Spiny starfish Marthasterias glacialis was common in rock pools; bigger ones can be found when snorkeling:
Big Snakelocks anemones Anemonia viridis were everywhere and perhaps half of them had a little Leach’s spider crab Inachus phalangium associated with them. Wikipedia tells me that these crabs eat the anemones’ leftover food and also their mucus:
This hour of snorkeling gave me some inspiration for a new aquarium set-up: less seaweeds (specifically less dying seaweeds clogging up the filter and releasing nutrients) and more rocks. On top of these a couple of big snakelocks with spider crabs and some Two-spotted gobies Gobiusculus flavescens. The latter are very common and pretty. I will have to catch them underwater with a net though, which will probably be difficult…