Inachus

Posted on March 9, 2024 by An Bollenessor under anemones, cnidarians, crustaceans, diving, Macro, Silver Steps

This seems like a familiar way to start a blog post but here I go again: ‘the weather has been terrible lately and I have not been in the water!’. March used to be my favourite time for snorkeling because the seaweeds look at their best, but the last three years it has been windy and wet, surely because of climate change…

To keep the blog going (a bit), I have dug out some images from a few dives last year featuring Inachus spider crabs. There are three species, I. phalangium, I. dorsettensis and I. leptochirus, which can be told apart by the arrangement of tubercules on their carapace, but these are often obscured by epiphyte growth, and so I am keeping it to Inachus sp. All species are associated with Snakelocks Anemone (Anemonia viridis) hosts. The photo above is taken using a weird ‘wide angle macro’ wetlens (INON UFL-M150 ZM80). This perspective always fascinated me but it is difficult to achieve. This lens does the job, although it is incredibly ‘soft’, especially around the edges. The close focusing also makes it difficult to direct the strobe light on the subject. So there is a tradeoff between getting the surroundings in view and sharpness. Below first some sharper shots using my 60mm macrolens, followed by some macro wide angle shots (they happen to be each of the different Anemonia colour morph):

I will leave you with the following interesting bit on the biology of these crabs by Diesel (Ethology, 1986):

I. phalangium females are site-constant, and live in the protection of one anemone or group. Males travel frequently between anemones harbouring females due to spawn; they copulate and guard the females until spawning, after which the male leaves again. A male operates in a patrol area containing 3-8 anemone groups and up to 8 females, visiting each female in turn repeatedly just before it is due to spawn. Patrol areas of different males may overlap, with resulting competition to fertilize a female’s next brood. Large males have higher reproductive success than small ones. Females live up to 8 months after the moult of puberty and hatch up to six broods, and males live up to 7 months as adults. A male could fertilize a calculated 26,000 eggs, whilst a female’s reproductive potential is ca. 4,200 eggs. Mortality risks are higher for males than for females, probably because of increased predation while leaving the protection of anemones in order to visit females. Males learn the positions of anemones harbouring females in their patrol areas, and when these are due to spawn. This allows a male to travel with a target and arrive punctually to fertilize the next brood due in his circuit. I. phalangium is the first marine invertebrate reported to use a “schedule” of localities and times for visiting prespawning females. In this way males minimize searching time and mortality risk, and maximize the number of broods fertilized.

Sennen Cove

Posted on September 4, 2023 by An Bollenessor under anemones, rock pooling, snorkeling

Last Friday I had a really enjoyable rockpool/snorkeling trip with my rockpool buddy David Fenwick (see his website aphotomarine for all your marine ID questions). Dave suggested we go far west, down to Sennen Cove where he knew about some interesting mini sea caves with jewel anemones and other things to explore. That is what we did, see the photo below!

Jewel anemones were indeed found in this spot….the water was too shallow to take a good photo though. I therefore jumped in the water where at first I got a bit seasick of all the waving Furbelows kelp. The water was noticeably colder than on the South Coast too. I discovered a nice deep gully with a whole variety of sea anemones growing on the vertical rock face. Orange, purple and green Jewel Anemones (Corynactis viridis) were common from 6 meters deep (at low tide). Very tricky for this middle-aged man to take good photos on one breath though! I was stumped by one white anemone but as Dave pointed out it looked like a Dahlia Anemone (Urticina felina) (and multiple ‘normally’ coloured individuals lived nearby so that makes sense). Finally a Sandalled Anemone (Actinothoe sphyrodeta) (my photos of the White-striped Anemone Anthothoe albocincta were unfortunately out of focus).

We had a blast and David found a Nemertean worm which might be new to the UK, or even new to science! It will find its way to aphotomarine eventually I am sure (check for ribbon worms here). I certainly like to go back snorkeling here some (windstill, swell-less) time.

Tiny critters under rocks

Posted on July 1, 2023 by An Bollenessor under anemones, bryozoans, chitons, cnidarians, crustaceans, echinoderms, fish, Macro, molluscs, mzuiko60mm, rock pooling, snorkeling

When the viz is bad, I take my macrolens (sometimes with the Nauticam CMC-1 wetlens for a bit of extra magnification) out to the pools. Sometimes I stick to the surface of rocks and seaweeds (to look for stalked jellyfish for instance), but other times I turn over rocks under water to see what hides beneath. Quite a lot! There are larger animals, such as Topknots and different types of crabs (and Worm pipefish as pictured here) but mainly they are quite small (around a centimetre or even less). See the selection below (Tricolia, Bittium and Limacia were not from under rocks but I had to make the grid fit!).

Snorkel Adventures

Posted on June 4, 2022 by An Bollenessor under anemones, cnidarians, eelgrass, jellies, seaweeds, snorkeling, wide angle

The sun is shining (most days) and the water has warmed up, so ideal conditions for a bit of snorkeling. I have been out at my usual spot in Falmouth (rockpools and kelp forest) and my local beach in Flushing (seagrass) (and yes, I really count myself lucky every time that l live here!). The last couple of times I have brought my son along, as he is now old enough (nine). He is a nature freak just like his dad, actually probably more so! I need to get him fins and a weight belt soon, but he has been doing fine in the water already.

The photos above and below illustrate the state of the rock pools at the moment: quite brownish with the Sargassum and Himanthalia growing everywhere. The red, pink and purple species have largely disappeared (apart from Harpoon weed) and there is quite a bit of green Ulva growing. The water teems with juvenile pollack in the rock pools and schools of sand eels a bit further out. Diving over sandy patches, you can see the latter species shooting out of the sand en masse. It is crazy how such a silvery pelagic fish can also burrow in the sand. I guess it does take its toll, as there are quite some dead ones to be seen too.

The Flushing snorkel site is very different, no (deep) rockpools, only a little bit of kelp but with a very healthy patch of seagrass. No catsharks or thornback rays when we went in, just the odd small sea bass. There are many small Snakelocks anemones on the seagrass. I used to think that it was mostly the purple form that did this but I now noticed that most were the green variety, so the morphs do not seem to differ in this respect after all. One anemone had ‘caught’ a crystal jellyfish (an Aequorea medusa). Not sure if it was in the process of being digested or just ‘stuck’.

I have played around with my new INON strobe, which works a lot better than my old strobe. I have ordered a second one for Wide Angle photos too….(as you can see there is quite some backscatter in the pic of the Shore Crab above). I will need to get back to some shore diving to make optimal use of two strobes, as I am too lousy a freediver to get the lighting and exposure right in one breath!

Back in the Water

Posted on June 11, 2021 by An Bollenessor under anemones, snorkeling

I had not been in the water for many weeks due to bad weather, work and laziness, but as the sun was shining last Tuesday and there were indications from social media that the plankton bloom had gone, I went back in for a snorkel. The water has warmed up, although the viz was not as good as I had hoped. I swam a bit further than my usual shallow rockpools to explore the kelp forest. Pollack, wrasse, mullet and sandeels swam about. I noticed a line with crabpots starting very close to shore, something I had not seen before. Unlucky spider crabs and some lobsters could be seen in the pots. Below a Spider Crab that was still free….

After exploring the slightly deeper waters I went back into the pools where the viz actually cleared up a bit. Seaweed-wise, things have deteriorated a bit compared to early spring, but it was a very nice swim around all the same!

Rockpooling in Flushing

Posted on March 28, 2021 by An Bollenessor under anemones, echinoderms, eggs, iPhone, molluscs, rock pooling

The wind has picked up and will ruin any chances of getting good seaweed shots this week. Too bad, but what can you do? A bit of rockpooling I guess. I took my son out to our local beach in Flushing where the rocks gently slope into Penryn River. Although there are no ‘proper’ rockpools, low tide gives access to a mixture of maerl sand and rocks that can be turned over. It is silty and definitely not very pretty, but there is always something to find. It was an especially good weekend for finding fish, seeing Shannies, Tompot blennies, Rock gobies, Gunnels, Worm Pipefish, Shore Rocklings and a tiny Eel, as well as Sea Scorpion eggs. (One Shanny was quite big and proceeded to bite my son’s hand; he was very brave and we slowly put it back.)

Invertebrates were plentiful too. The main mollusc here is the Variegated Scallop Chlamys varia, which is attached underneath every single rock. We found our smallest Great Scallop Pecten maximus as well. We found some Sea lemons Archidoris pseudoargus and lots of Yellow-plumed Sea slugs Berthella plumula (which apparently can secrete sulphuric acid when disturbed…). A small selection of what we found below, all pics taken with an Iphone.

The Isles of Scilly: St. Martins

Posted on September 19, 2020 by An Bollenessor under anemones, eelgrass, fisheye, Olympus OM-D E-M5 Mark II, seaweeds, snorkeling

Two weeks ago we werelucky to spend a mid-week on St. Martins, one of the Scilly Islands. The Scillies are a group of tiny inhabited and uninhabited islands 28 miles off Lands’ End (before I moved to Cornwall eight years ago, I had never even heard of them…). The water over there is bluer, the sand is whiter and the viz much (much) better than in ‘mainland’ Cornwall, so a true paradise for snorkelling. I tried to get underwater as much as I could, in-between exploring the island (and going to the one pub). As we did not have much time, I mainly snorkelled in the seagrass just off Par Beach. It does not really look like England does it!? The seagrass was teeming with stalked jellyfish. However, because of the great viz I stuck with my fisheye lens, which meant it was tricky to photograph them. This species is Calvadosia campanulata, a protected and generally uncommon species, so worth recording (which I will get on when work is quieter and the weather is crappier). The ID was confirmed by expert David Fenwick, have a look at his excellent site on stalker jellies stauromedusae.co.uk (and his general site for marine species in the SW of the UK aphotomarine.com). Dave also pointed out some other organisms growing on the seagrass seen on these pics: the small red algae Rhodophysema georgei and the slime mold Labyrinthula zosterae (the black bits). As always, I learned something new talking to Dave. Snakelocks anemones were abundant on the seagrass, and the sand inbetween was full of Daisy anemones and Red-Speckled anemones Anthopleura balli (one of my favourites, they do well in my aquarium). As always, I bother crabs by sticking a lens in their face. Bigger Green Shore Crabs Carcinus maenas can get a bit feisty and attack the dome port (maybe because they see their own reflection). Finally a juvenile Straight-nosed Pipefish Nerophis ophidion (about 3 inches), a new one for me. I am always facinated by piepfish (and hope to one day see a seahorse). Unfortunately the shot is not in focus, I really needed a macrolens for this one. Still, you can marvel at the white sand and blue water! Some photos are allright, but I could do a lot better with a bit more time. Luckily we rebooked for a stay in spring already!

some good’uns

Posted on April 19, 2020 by An Bollenessor under anemones, echinoderms, photography, wide angle

l have not made much progress sorting through recent seaweed pics but it is easy to post two recent photos that came out well. Above the Spiny starfish Marthasterias glacialis. This seastar can grow up to 70 cm across, but on the shore you generally do not find them much larger than 20 cm. It occurs from Northern Norway down to West Africa. Below a patch of Snakelocks anemones Anemonia viridis, probably originating via binary fission. The most common anemone in the rockpools here, around half are this tan colour, the other half is green with purple tips. No one knows why. (And interestingly, it is not the only anemone species that shows two colour variants, beadlets are red or green, plumose anemones white or orange). Although the water was 9C, with the sun on the white sand it looks pretty tropical to me, a clownfish would not have been out of place! (I took a photo of this same patch in March but that one was not nearly as good.)

Macro Practice VI

Posted on December 8, 2019 by An Bollenessor under anemones, crustaceans, Macro, molluscs, mzuiko60mm, Olympus OM-D E-M5 Mark II, photography, snorkeling, worms

The tide was bad (i.e. low and too early to catch it on time), the water was cold and it was very windy but it was good to go for a dip this morning. I now have a different strobe arm which makes it easier to position my strobe, which has often been tricky. Time for some macro practice. The photos are not that special but I hope interesting enough for you blog readers! Above a Peacock worm Sabella pavonina sticking out of an abandoned piddock hole. Below a common Hermit crab Pagurus bernhardus, a Grey chiton Lepidochitona cinerea, a very small Dahlia anemone Urticina felina (note the warty, adhesive column) and some Daisy anemones Cereus pedunculatus.

Macro Practice V

Posted on November 24, 2019 by An Bollenessor under anemones, crustaceans, molluscs, mzuiko60mm, Olympus OM-D E-M5 Mark II, rock pooling, snorkeling

It has been a while since exploring the rockpools, as the weather has been pretty horrific. However, I had a good go last week and this weekend. Although quite bleak, there was no wind and no rain. The water is getting down to 11 degrees probably (I have not measured it), so pretty chilly. There are quite some solarpowered seaslugs Elysia viridis on the Codium seaweed but I did not manage to get any good photos. In fact, I am still struggling a lot just getting the strobe to properly light up what I am aiming to photograph. A bit frustrating but that is why I keep practicing. Above a pill isopod, probably Cymodoce truncata (with the fringing hair on the rear uropods indicating it is a male). Below, a tiny Gem anemone Aulactinia verrucosa. There are a lot of small Daisy anemones Cereus pedunculatus amidst the Coral weed, they look brownish but when you zoom in there is some blue as well. Finally, a Netted dogwhelk Tritia reticulata, which are very common and active in the rockpools. Cold but always nice to be in the water. Luckily I emerged right on time when I saw my Sainsbury’s bag with glasses, car keys and phone drifting away due to the incoming tide!