The Hair Curler Seaslug (Spurilla neapolitana) is a southern species that was first discovered in Cornwall by @charlotte.cumming last year. It has quickly established itself as one of the most common species found here in Falmouth. As always I was a little bit late to the party spotting this nudibranch but lately they have become hard to miss! This species feeds on anemones using their radular teeth and can easily be found at the base of Snakelocks anemones. The stinging cells of their prey are neatly incorporated into their own curly cerata. I found baby slugs as well and this species is clearly here to stay. What will this explosion of new predators mean for the anemones? Will Snakelocks populations collapse before antipredation mutations appear? Or perhaps it is not such a problem for them, we will find out!
The weather is slowly taking a turn for the worse now, so if there is a window to get in the water I am ready for it (I am absolutely dreading the coming half year of wind, rain, darkness and no snorkelling or diving!). Last weekend I took a look underwater in my local seagrass patch in Flushing. The viz was not great at all (as anticipated), so I was looking to do some macrophotography. I clocked plenty of egg masses and indeed some Polycera quadrilineata, which is one of the more common species here in Cornwall but up there with the prettiest! Individuals of this species are often white with yellow stripes and dots, but they can have black lines as well. After taking ages reviewing shots full of backscatter and re-positioning my strobe, the photos started to work out. I noticed one blade of seagrass with two individuals side by side. I suspected they were mating but as they are quite small and my eyesight is getting worse, the anatomical action that was going one only became apparent reviewing the photos back on land. Nudibranchs are simultaneous hermaphrodites and when they mate act both in the female and male role. In the pics below you can see the sexual organs protruding from their right flank. Interesting!
I was on a roll and I pretty much stayed the entire dive on the same square meter, taking photo after photo of the slugs around me. I follow the ‘spray and pray’ routine of photography to make sure at least some of the pics are in perfect focus and without overblown highlights, although the downside of this method is that you have to wade through 200+ pics afterwards. Using the nauticam cmc-1 wetlens I managed to get ‘supermacro’ and was rewarded with some really nice head shots, showing oral flaps, foraging on bryozoans on the seagrass and the slugs generally being very pretty! I am getting more and more into nudibranchs now and hope to find some other species before the sea turns too choppy!
P.S. The previous post was all about low depth of field images; for the photos in this post I took the opposite approach and used the smallest aperture available.
Apologies for the title, but this is what this post is about: snorkelling in one meter of water taking soft focus images. Low depth of field (DoF) results from a large (or wide) aperture (somewhat confusingly, to make the aperture larger you need to select a lower f-number on your camera). A wider aperture results in more light hitting the sensor, so it is something you’d do when taking photos under low light, but it can also be used for creative effects, as it results in only a thin slice of the image being in focus. This leaves cluttered backgrounds and foregrounds blurred out which makes for a more pleasing aesthetic effect. I used this technique for the photos above and below of a European Cowrie (Trivia monacha) (M43: f4, 1/160s, ISO100). Of course there is a trade-off: most of the subject is out of focus, so it is not a setting you would use for an ID shot that needs as much detail as possible. The golden rule is to keep the eye(s) in focus – something that worked slightly better in the second pic. Strangely, this snail has two pupils in its right eye! I have indicated the slice that is in focus in the second photo with a red line; the shell is 10-15mm in length.
While I was taking photo after photo of this snail, I was approached by several small Tompot Blennies. This species (as well as Common Blennies, but not so much Montagu’s Blennies) is very curious which is great for a photographer (although sometimes they come too close and you have to keep moving back). I used the same settings as above for the smallest individual (not longer than 4 cm). I noticed for the first time the blue spots on the dorsal fin (see first pic). I did not get THE photo but it was good practice. Finally, a close-up of a baby Topknot; although the aperture was smaller this time, the mouth is still not in focus. Sorry for all the photography talk if you are not into that, but at least I hope you enjoyed the pictures!
Has ‘an bollenessor’ turned into a macro photography-only blog? It seems so, I have not posted about my aquarium in ages. I still end up doing macrophotography when I go rockpooling. I tried wide-angle photography last week in the rockpools and failed miserably (so no photos for the blog). I hope to mix it up later in the year but for the moment here are some more macro photos. Above a picture I am quite pleased with: a solar-powered seaslug Elysia viridis on its favourite food the green seaweed Codium with some nice orange seaweed as a background. The pictures below show the snail Raphitoma purpurea (a first for me in Cornwall), the nudibranch Okenia nodosa (a lifer for me), a European Cowrie Trivia monacha and a patch of goby eggs (sans goby-egg eating seaslugs unfortunately).
I am a bit stuck in a limbo where on one hand I want to see interesting, new species and take good ID pictures (for recording on iNaturalist and sharing on facebook groups), but on the other hand I have gone a bit above my station and developed an interest in taking more ‘arty’ photos such as the solar-powered seaslug one at the top of this post. Sometimes the two aims converge, sometimes not. As an illustration of that, below a few shots of the nudibranch Polycera quadrilineata that ended up quite differently: a ‘good for ID’ photo but with an ugly cluttered background, a more arty photo (although the bokeh effect is due to backscatter and it is actually not that great), an overall ‘nice’ photo (posted before), a ‘shore studio’ shot of a slug (more about that in a next post) and an artsy fartsy version of a studio shot where the highlight have been so blown out that the slug basically is shown as a set of yellow stripes. I must say I can have ideas about how to take a certain shot, but my general approach is still ‘spray and pray’!
High time for a quick update. Spring has not started in earnest yet and so the number of days in the water have been limited. As is usual, I have practiced taking pics of Flat Periwinkles (Littorina obtusata or L. fabialis) on a bank of the Penryn River. Below that another set of pics taken in Flushing and Falmouth when it was too windy and choppy to get in the water. These were all taken with my cygnustech diffuser which give the pictures a quite distinctive, slightly subdued look.
I did go in the water a few days in a row when the weather and tides allowed it, which was great. I think one time I stayed in for three hours – my core temperature took some time to recover! No special finds and only a few good pics as my strobe placement had become quite rusty but here are the best and/or the most interesting ones. (Species names in the photo captions.) Bring on proper spring weather and flat seas!
A nudibranch, a snail and a seaslug crawl into a bar…no seriously, what actually is the difference between these three types of molluscs? According to Kerney and Cameron (1979), those animals that cannot fit into their shell are called slugs, and those that can are called snails (definition brought under my attention by Ian Smith, see his amazing species accounts of British molluscs on flickr: Morddyn). Seaslugs either have an outer shell in which they cannot retract, an internal shell or no shell at all. The Solar-powered seaslug (Elysia viridis) pictured above is a species without a shell that is an example of a seaslug. Nudibranchs are a type of seaslug with ‘naked’ (nudi) gills (branchs) on their back. Nudibranchs never have a shell (although many have one when they are a larva). Books on nudibranchs often include seaslugs and sometimes they even feature snails! This happens when these species are related to seaslugs (the ‘lathe acteon’ or ‘beer barrel’ Acteon tornatilis is an example of that – a goal of this year is to take a good photo of that species). I have posted a range of photos on here as an illustrations of seaslugs (or not!); read the captions for species info.
I realised I had not posted (much) about this year’s rockpool snorkels so I am taking the opportunity to post a ‘picdump’ with a whole array of tiny species. These photos were taken with a macrolens, and for most a wetlens was used for even greater magnification. Above the White Tortoiseshell Limpet Tectura virginea, a tiny species living on calcified red seaweed. I have added species names to the photos below.
I really like macrophotography and I really like wide angle photography, but what I REALLY like is macro-wide angle photography! Examples of that underwater can be seen in previous posts (e.g. here and here) but this year I also bought a normal ‘topside’ lens for this purpose: the kuangren k42. It is a difficult lens to use: it is manual focus and it is very (VERY) dark. The first few times trying it out I was almost ready to give it up – that is how hard it was to get a usable photo out of it. With a lot of perseverance I narrowed down the combination of camera and lens settings but there is a lot of practice to be done next year. (Ideally I’d also have two flashes on bendy arms instead one mounted on top of the camera to properly light the subject.) Anyway, above a White Italian Snail which has a bunch of other common names so the Latin one is always best: Theba pisana. It is not all in focus (the eyestalks are not a friend of DoF) but the perspective does manage to show both the (small) animal and its habitat which is otherwise impossible to do. I have also tried the lens a bit closer to the water, some examples below. I have since purchased another kuangren lens and hope to also experiment with – and blog about – that next year!
I had a couple of good snorkels at the end of summer in the seagrass beds off my local beach in Flushing. The water at the end of summer is warm enough to go without wetsuit – I just had a weightbelt to let me sink down on the sand at low tide, no fins needed. I managed to do what I normally find very difficult: spot nudibranchs! Mainly one of the more common species, Polycera quadrilineata, but that was fine by me, as they are very beautiful, especially the black colour morph pictured above. I spotted one other species, the egg-eating Favorinus branchialis (with its own eggs also visible). Not great photos, but in my defense they are very small!
Shelled molluscs are easier to find. Below 1) the ubiquitous Grey Topshell Steromphala cinerarea, 2) the Grooved Topshell Jujubinus striatus and 3) the tiny Rissoa membranacea (faecal pellets on show, even within the shell). The latter two species are strongly associated with seagrass.
Some assorted macro photos below and at the end a view at a very low tide of the Flushing seagrass site this October.
A quick post with some finds from a recent walk on the shores of Flushing, specifically above-water (‘topside’) macro shots with a diffuser. This always leads to my subjects turning out with subdued grey and brown tones, but that is OK. A velvet crab, the amphipod Cymodoce truncata (looks a bit like a trilobite!), a worm pipefish covered in a film of water with some more shots (with descriptions) at the end.
