On 22 July my other half and I found these interesting creatures in the sand pools of low tide at Bulverhythe, Hastings UK. There were loads of them but these two show the structure best. I didn't notice until going through these to post onto my Ipernity that one of them also has tenticles, loads of them (second photo).
We have looked at all of our resources but nothing shows the two openings, the smooth one was spitting out sand the other seemed to be ready to feed? They were in sand submerged under about 1-3 inches of water.
Thank you for your consideration and help!!
I think it may be a bivalve, one of the types that buries itself in the sediment, leaving just the inhalant and exhalant siphons visible at the sediment surface.
Here's a video of a cockle, for instance
And this page includes a nice diagram showing the cockle and its siphons
Let us know what you think...
Thank you for the quick reply! I'm sorry its taken a few days to answer. We decided that although your explanation does make sense (and of course we have no idea what they are) but the fact that we can find no similar photos of animals on any of the marine sites, and the tentacles had us set to go back out and find one.
Plan was simple, find one, dig it out (carefully with kitchen straining spoon and a tub to place it in while we see it) and get an answer finally...best laid plans.
We did eventually find some, in sandstone! No digging them out, we also found loads of another worm Lanice conchilega, these seemed to be in large numbers in the same area we found our mystery beasts.
So my question, because we did see many without any tentacles protruding from the sand, so could this other worm have those? And the fact that the Intake is sucking them down into that tubual making me think our beast has tentacles?
We did find one in the sand, but when I scooped up the contents of the area we had one winkle, and about 10 of those other Sand Mason worm cases (no worms).
Thanks for helping me with this.
The only other vague candidate that comes to mind is a sea squirt, but think they live on (not within) the sediment/substrate.
I do hope you manage to dig one out.
Just while the thought's in my head...
If it is a bivalve, and if you are seeing the same one in the rock that you saw in the sand, I think I'd go for a piddock (Pholadidae; lots of species)
If the one in the sand is different, it could be something like Abra alba
Ok, now that is looking good! Managed to find some photos of the feeding end of the piddocks, not the same as what we saw but as you say, lots of species. The sand ones we saw were different in they were lighter colored, and the spikey tentacles that were actually in the Intake siphon are ...more spikey
I've attached a new photo, this is the one we tried to capture, without success..haha. Read, these could be 30cm deep? Wow, no wonder my little kitchen spoon was no match. We do see shells of both of the above described on the beach here.
I'd still love to know what those red tentacles are from, but they do seem to me more associated with the other worm structures than the bivalves. One thing that is for certain, its got me slightly hooked on photographing the little worlds in the rock pools, it was windy when we went down and I'm dreaming up all sorts of ways to get better photos through the water.
Blue circles the red tentacles, the yellow circles the Sand Mason worm structures.
Thank you for all your help on this!! : )
Oh - those tentacles!
That makes me wonder what a young sea fir looks like...
Also have a look at sea beard (Nemertesia antennina)
...or for that matter a young wireweed (Sargassum)
Photos looking good Crystal!
You obviously know about polarizing filters re water reflections.
Passing thought: how about a front-silvered mirror at 45degrees on the bottom - to get sideways(-to-upwards) shots with the camera pointing downwards as normal. Large FSMs could be expensive, but you might be able to use a chrome/nickel-sheet mirror instead, though optically poorer (they used to be included in a gentleman's shaving kit).
On the shell, the habitat rules out Piddock (only in rock or clay), & fused siphons Abra alba which has long separate siphons; & given none of your pictures show any shell & you couldn't catch any rules out short-siphoned species like cockles or razor shells, so I'd say species with long siphons most likely, like Sand Gaper or Blunt Gaper (Mya arenaria/truncata) or Common Otter Shell, (Lutraria lutraria) or L. angustior/oblonga....Having said which it looks like the Lutraria lutraria in http://nature22.com/estran22/mollusques/lamellibranches/bivalves5.php could be the very thing, or very near (doesnt have the fine 'acorn-leaflike' shapes of your fine pictures though).
The red thread are of worms, of the Cirratulidae of which the Collins seashore guide '96 says "those with a large number of fine gills & tentacles have the collective popular name "red threads" as these are normally all that can be seen above the sediment surface. Eg see http://www.ispot.org.uk/node/307654 .Also http://www.ispot.org.uk/node/307654 which looks to show 1 of the worm species. The handbook of the marine fauna of NW Europe '95 (correcns2012) says 15 sp's but describes 6, & gives only 2 a 'sandyish' habitat,Cirratulus cirratus "mud or muddy sand" (gill threads red or yellow[Collins]), & Cirriformia tenticulata rich mud, muddy sand etc (threads red)'
see http://www.sealordphotography.net/Nature/Guernsey-marine-life-by-major/Guernsey-marine-worms/2074700_6H3w3Z/107822732_pVMwqfW#!i=107822732&k=pVMwqfW&lb=1&s=XL & see species.org, http://species-identification.org/species.php?species_group=macrobenthos_polychaeta&menuentry=soorten&id=495&tab=beschrijving
So I'd say Cirratulus cirratus, or maybe Cirriformia tenticulata.