About 10 individuals of this unusal species were found in a benthic sample of the Great Belt area (Baltic Sea) with water depth around 40 m and a salinity around 25 psu. Unfortunately I have no idea what taxonomical group it could be. Our first idea was, it is a part of a medusae, however, all individuals have the same shape and seem to be complete. For a priapulid it is quite unusal "open".
Actually I don't know, but if I would make a guess I would guess a Platyhelminthes.
Hi
I think it resembles a Nudibranch with the tentacles/ rhinophores retracted. Is there another little openening on the dorsal side, for retracted gills?
Regards, Halldis Ringvold
no, both Plathyhelminthes and nudibranch gastropod I can very probably exclude from the candidates.
Another option is perhaps a detached pharynx from a polychaete, perhaps Phyllodocidae. This happened to me a couple of years ago with an unknown animal (see:https://www.researchgate.net/post/Would_this_be_Nematostella_vectensis) which appeared to be the Pharynx of Eumida. It took me several years to find out what this might be untill I had found an Eumida with the Pharynx still attached. In some samples we found several of these pharynxs and they all look the same with no apparent damages.
I would say no. The size is about 1 cm in length, very robust, not damaged, and the most important thing is, that I found 10 specimens, one looks like each other. No other species in the sample where it could belongs to.
Probably it is not a benthic species, my first thought was pelagic medusae or salps, but again I don't konow.
I goit right now a tip from my colleague Carmen Pia Günther, it ist the pharynx of Echiurus echiurus! E. echiurus was also in the sample, very large individuals. Ton, your pharynx idea is not as far as I thought.
Thank you very much for your comments
Michael
I am assuming the first photo is dorsal and the second ventral. Is this a good guess? Also, is any of the internal anatomy visible? Last, were all 10 individuals found in the same benthic sample? As you have said Michael, this organism would not fit the typical priapulid body plan and I agree.
Its is actually resembles a holothurian, some of the species may have less or more developed sole.
Thank you to all of you. It is solved surely. It is the pharynx (appendix) of Echiurus echiurus, very common at this site.
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