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A great find. I've seen many in the Mediterranean ands elsewhere, but have never come across a sec cucumber in the UK. How did you find it? Was is still buried in mud/sand with the tentacles showing, or was it washed up after a storm?
Nick Upton, naturalist and photographer.
I'd be interested to know if yours were offshore & in situ.This (my 2nd) was just floating.My 1st was 6th dec on Rhossili beach, http://www.ispot.org.uk/node/289641 ,(same time as the beached clms) & gives my ID sources (incl. Haywards's monmtl 2Vol in Swansea uni libr). My last 7dec'07 Rhossili beach; there w. lots of tiny ones (maybe down to size of a grape or less (wish I'd photo'd), but did snap one w. a white stalk & tiny tentacles. I've also found more than 1 (photo'd at least 1) of the small white kind stuck to rocks with the other epiphytes, which I took for Pawsonia saxicola, but could h.b. Ocni sp's (but no tentacles shown).. And fr. Musselwick nr Dale (Pembs) have I believe a fine photo of Pawsonia s., tentacles & all & originally stuck to rock, but the tentacles are yellow, but in text descriptions always black.
The species I see most often in the Med where I've done a lot of snorkelling, mostly around Greek islands, is probably Holothuria tubulosa http://en.wikipedia.org/wiki/Holothuria_tubulosa
These can be really common - from around 3 metres depth and deeper, simply lying around on sandy sea bottoms, often in Posidonia sea grass areas. They feed at night so I never see them with their tentacles out and are very inert and can be picked up easily without reacting. I once found a pale brown one with white spots (off the south coast of Crete) a long time ago, which did the classic Holothurian thing of spewing out masses of sticky white threads in defence (hence the cotton spinner name), but I've never worked out what species that was. Thyone is supposed to live under the surface of muddy sand, with just the tentacles out, so I can't explain your floating ones. Maybe a storm dug them up? unless they can disperse by floating.. P. saxicola sounds more of a rocky shore species (between/under boulders) as no doubt you've read.
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