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.
There 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):
I 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.
The 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!