dejayM's picture

Opaque Sea Squirt

Observed: 20th June 2013 By: dejayM
Biological Recording In ScotlandHighland Biological Recording GroupOrkney Biodiversity Records Centre
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Description:

A battle to ID this one; an absolute waterline plague among serrated wrack. Found alongside A.mentula; the latter very few in number.
See http://www.ispot.org.uk/node/341136
Possibly Corella parallelogramma (much less likely because of size and jizz)
But see http://www.ispot.org.uk/node/333588
EDIT
Added the word jizz!

Identifications
Species interactions

No interactions present.

Comments

JoC's picture

Ascidians

dj, I have been reading (H&R) and looking at websites of ascidians, and I have 2 questions on this post.
No 4 photo clearly shows the siphon placement and side attachment. Were there any other features that helped you decide on A. conchilega?

Why 'a plague'? These animals live here... What's not to celebrate finding them? (I know, that's now 3 questions.)
Jo

Jo

dejayM's picture

backwater

Well plague because that's what it seemed (though I don't mean it in the offensive or Biblical way). This is a tidal stagnation zone - an area where the tide goes up and down with little or no lateral movement, caused by the local topography. Where I found these was a 'stagnant mass' of dead and dying ones and I picked out a few more savoury ones to photograph.
The attachments, where seen, seemed to be towards their base but at the side - some were joined together.
Picture four is taken where the serrated wrack was more vibrant and, note importantly, in water. I'm certain they are vents, not attachments, we see. Present on the others but not seen and, it's worth noting, handled, which makes then a bit stiff (a kind of reaction to having been squeezed a little).
>>MarLIN<< described them well - though not perfectly.
I came close to >>virginea<< but erred away because of the word 'rectangular' in the description.
I discarded >>aspersa<< because of the absence of the large oral tentacles.
And on it went, 'round and 'round. But I'm happy with my overall conclusion - despite there being no agreers.
Incidently cycling through the pictures >>Here<< is a feast (sort of opposite to plague).
And note my possible (wishful!) Corella parallelogramma here http://www.ispotnature.org/node/333588

JoC's picture

Ascidians

dj, I follow your argument; ascidians are a bit difficult, n'est-ce pas?

The advice in H&R is that "their identification depends upon features of their internal anatomy", which is bad news for the tunicate as well as for us.
So maybe external features are of no help, but what else have we got but the H&R key and descriptions, and images on websites.
Your Marlin link says. "...two inconspicuous siphons; a terminal inhalant oral siphon and a longer, exhalant atrial siphon that is positioned approximately two-thirds of the body length from the oral siphon.", which the photo they use does not show.
The photos on habitas  are not much help, but the Marine Portal diagram and text suggest you are right and I am agreeing.
Jo

Jo

dejayM's picture

Education in a nutshell

Well, I am amazed really - all that snow and you can still do this!
Nevertheless, you are quite right and I concur. I am always grateful for the challenges and agreements.
That iSpot has few active experts in this field is a bit dismaying, though I know that some do lurk in the peripheral corridors and find this very door occasionally.
But the issue is, really, that we cannot be certain of anything anymore. The more we enquire, the more we need to enquire - I love it! Education in a nutshell?
ð

dejayM's picture

Returning

I have returned to this, after a summer's study.
Sea squirts are not easy, the grey ones the hardest, few conforming precisely to textbook descriptions.
This I feel might be A.aspersa. Text and Fig on P438/9 of Fish&Fish** rather confirms it

I fear now that the (missing) oral tentacles in picture 4 are collapsed -whilst they are submerged, I fear I had disturbed them.
The test is brownish, stiff and lumpy, possibly warted, certainly rough and not smooth "Stiff and rough to touch".
The inhalant siphon is seen in P1 and is about one third down the body - we may be able to argue that the submerged example does not fit, so it may (only may) be A.scabra.
A.conhilega "Inhalant siphon at free end, with 8 red spots"! "exhalent siphon about 2/3rds of way along body with 6 red spots"! Does not fit.
I returned to the location today after a storm to find a huge number of washed up ones (another plague then) I will make another post quite soon.

**A student's guide to the seashore - http://www.amazon.co.uk/Students-Guide-Seashore-J-Fish/dp/0521720591