Tag Archives: starfish

Octopus in Porthkerris

Posted on by under bryozoans, crustaceans, diving, echinoderms, fisheye, molluscs, photography, Porthkerris, wide angle

This is the second year of an ‘octopus boom’ here in Cornwall. One of our two native species (Octopus vulgaris) has become much more common, probably due to warming waters. They wreak havoc on the crab pots (it is a big local story), but have made many snorkellers and divers very happy! Although I have spotted them once or twice before, this week I headed down to Porthkerris to have a proper look. Porthkerris is one of the best known shore dive sites in the country, and the only shoredive site in Cornwall I know of that let’s you get a bit deeper than ten meters. Those extra few meters make the difference in spotting things like Cuckoo Wrasse and Sea Fans, and also make it more likely to spot octopus (although these also occur in shallow water; one was even found in a rockpool in Falmouth). Armed with my 8mm fisheye lens I drove down on a Tuesday for two (solo)dives. It wasn’t long before I spotted the first octopus, however it quickly jetted away from me – either they have different personalities or different moods (or both) but not every octopus reacts the same to a passing diver. I managed to get a bunch of shots of several cooperative individuals shown below. Some individuals looked a bit ropey as they were nearing the end of their life-span and I even spotted a dead individual.

I managed shots of some other animals as well, see the gallery below (click on pics for legends). I have done much more macro- than wide-angle photography lately, as it is quite hard in murky English waters. When using strobes it is easy to get backscatter, moving very close to the subject minimises that but makes it hard to get any light between the dome and the subject, often resulting in an unlit centre of the shot and/or blown out spots at the sides. Anyway. I went back on Friday for another two dives. Fewer octopuses (octopi is incorrect!) and worse viz but enjoyable all the same. A selection of critters below. I found a nudibranch new to me (Acanthodoris pilosa) that was so large I could take a halfdecent photo of it using the fisheye lens!

Rockpooling on St. Martins

Posted on by under crustaceans, echinoderms, fish, rock pooling

Although St. Martins does not seem to have any rockpools, the beach that was nearest to us (called ‘Lawrences’) has a stretch of rocks lying on the sand that can be turned over at low tide, and so we did! A nice find was a small Sevenarmed Starfish Luidia ciliaris (these can grow up to half a meter across, although you will not find them that size in rockpools). We also found a Bootlace Worm Lineus longissimus, which is (probably) the longest animal on the planet. These nermertean worms secrete a powerful toxin in their mucus, but luckily for us it affects arthropods and not mammals. They are not very rare btw, I see them here in Flushing and Falmouth too. It was about 5 meters long (without stretching it), but they can grow ten times the size of this! In the second photo you can see it in its natural habitat, under a rock, with some photobombing crabs and worm pipefish. Another cool find was a juvenile Conger Eel Conger conger. Otherwise we found the usual suspects, lots of crabs and a bunch of fish, see for a small selection below.

  • Edible crab Cancer pagurus
  • Furrowed crab Xantho hydrophilus
  • juvenile Squat lobster Galathea squamifera
  • Shore rockling Gaidropsarus mediterraneus
  • an unusual reddish Cushion star Asterina gibbosa

Macro Practice III

Posted on by under echinoderms, mzuiko60mm, Olympus OM-D E-M5 Mark II, tunicates

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!

Three echinoderms

Posted on by under echinoderms

I have been traveling quite a bit over summer but now I am back and hope to soon kick start my aquarium (it just has sand and some cushion stars in it at the moment). I have already gone out rock pooling again a couple of times. For the very first time I have found a sea urchin at Castle Beach in Falmouth, a little Psammechinus miliaris:

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I found the Common starfish Asterias rubens and especially the Spiny starfish Marthasterias glacialis to be very common this time of year:

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The abundant Cushion star Asterina gibbosa:

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I hope to soon post about the aquarium again!