Nick Upton's picture

Sea Lemon eggs?

Observed: 21st August 2012 By: Nick UptonNick Upton’s reputation in InvertebratesNick Upton’s reputation in InvertebratesNick Upton’s reputation in InvertebratesNick Upton’s reputation in Invertebrates
Eggs of Sea Lemon (Archidoris pseudoargus).
Egg ribbon,
Description:

Spiral ribbon of eggs found under boulder in a rockpool low on the shore alongsie sponges and sea squirts. From a sea slug I'm pretty sure and they seem to match the quite common Sea Lemon (a sponge predator) well in form.

Identifications
Species interactions

No interactions present.

Comments

ChrisMcA's picture

Haminoea navicula?

These look different from the many images in google images,which are white or the same yellow but never see-through. But have found a match in the photobook living shells (bandford press transl. by Picton, 1979) P.64 virtually same, of Haminoea navicula spawn (size 35mm) but doesn't have whole shape (P.68 has sea lemon laying it's eggs). This was in zostera grass (lays in late spring & summer). H.nav is an ophistobranch with a fab shell "found in muddy estuaries & inlets".
google images "Haminoea" showed more eggs H.vesicula a bit different & nr bottom H.japonica more like.

Nick Upton's picture

Bubble shell

Hi Chris: many thanks for this good research. This could well be it! I have found a pic that matches well and some eggs of another in the genus which are a close match. The habitat is right - a slightly muddy part of the Helford river estuary and NBN records it for that area.

Nick Upton, naturalist and photographer.

dejayM's picture

Hard

Much harder than any I've looked at over my very short 'studenthood'.
We can infer the ring (more a pretzel) size by the Botryllus zooids, as being about 25-30mm (Nick?). I don't think it's a ribbon in the sense of, say, my >>Picture 3<< but more dense like (if not identical to) these http://www.ispotnature.org/node/439445 which have yet to be identified.
Chasing Chris's ID is difficult as even the mollusc itself is not well illustrated (only its shield). In his favour I'd say a shelled mollusc is more likely because I have noticed that nude nudibranchs generally, generally mind you, produce eggs or their ribbons in spiralled form and 'snails' in more robust clumps or strings or small tight rings (Chris?).
Note that there are other (attachment?) strands in the picture
So, just now I can't get nearer but you'll know I'll keep trying

Nick Upton's picture

Eggs

I should have posted the link to the pic I said I'd found of Haminoea navicula eggs at the time, but can't find it now, but here is one of another in the genus, which has the right kind of short ribbon shaped ring form http://mollus.oxfordjournals.org/content/72/1/89/F2.expansion. Yes, the egg mass would have been around 3cm across. I still think Chris's ID is likely. The 439445 node image seems to have less structure, a bit more like a smaller version of the Actaeon tornatilis egg strings I found at RhossilIi: http://www.ispotnature.org/node/285862

Nick Upton, naturalist and photographer.

ChrisMcA's picture

I found the link to rather

I found the link to rather similar eggs of Haminoea virens, http://www.seaslugforum.net/showall/hamivire (but the eggs in lines); but also the very striking http://www.opistobranquis.org/_cache/4059_1000x1000_0_0.jpg presumably showing it laying eggs, but the 1979 book illn was a better match (translated & edited by Bernard Picton). (the bk was full of colour closeups of seaslugs & living molluscs & their eggs). However the identification of eggs is pretty debatable.

dejayM's picture

prtetzel

I am completely unconvinced by the Oxfordjournals link Nick. Those eggs are highly arranged in lines and the ribbon is a ribbon, your photo shows none of that, even allowing for collapse. 300mm is probably large for a intertidal molluscan egg mass but certainly points to a nudibranch.
The other link (node/285862 which I have agreed to) is much more like an organised mass - there are distinct lines of eggs but again it's not like this one here.
Chris, the first link is broke as they say and I've tried as much fixing as I can - always arriving at this http://www.seaslugforum.net/find/haminavi, which is unsatisfactory (no eggs). The other opistobranquis link shows an egg pattern that we do not see in this post. I have implied, in my largely undeveloped wisdom, that nudibranch egg masses are organised and often in spirals and or ribbons - this post does not show those features.
Chris's final sentence is slightly damning of his Likely ID, despite your (Nick) support.
I still see this as a fairly disorganised mass in a pretzel shape, typical of the type I have posted a few times and which are probably worms. And note this pretzel http://www.ispotnature.org/node/327982 and here http://www.aphotomarine.com/sea_slug_ancula_gibbosa.html (Dave Fenwick again!), lastly http://www.seaslugforum.net/find/21784 - which I am beginning to favour.
None of us will give up - it's not in our nature, so we'll strive on.

ChrisMcA's picture

My link was only briefly

My link was only briefly broke & works now.The Picton book clearly show a clear, non-ribbon egg mass (your examples are almost,or completely opaque), & he says 35mm. (shape of a squat banana, but you can't see whether it's round or flat).Ii anyone knows what it is it's B.E. Picton, THE authority on UK seaslugs (see Habitas!). My seaslugforum link's the same species as Nick's; yes in lines but same colour eggs & same clear gel. Try to find some examples with yellow eggs in clear gel

Nick Upton's picture

I can assure you the eggs

I can assure you the eggs were in a ribbon shape, even if the 3D nature is not apparent to you in this photo. I may have some other angles of view on some very old photo files, but am not sure I'll have time to scour them on back up drives and discs..

Nick Upton, naturalist and photographer.

dejayM's picture

Still

Chris - yes, I could not make the link work, sorry, you're right, it does.
My egg masses in the examples are dense and immature. It was the shape of the mass that should interest us, as I believe that marine eggs yellow with age (that is as the yolk/embryo develops). I have posted examples of that, for instance see P4 in http://www.ispotnature.org/node/321807.
I am still unconvinced by the opistobranquis picture - it is a disc of fresh laid yellow eggs with a strikingly organised pattern. And, of course the Oxford link leads to the same species, same linear pattern, same colour.
I believe that Nicks picture here is of somewhat clouded jelly, whilst the disorganised eggs are ivory colour - in my MEAGRE experience many marine eggs are ivory coloured.
"Try to find some examples with yellow eggs in clear gel" (ChrisMcA)
Here are some yellow, well ivory coloured, eggs in clear jelly http://www.ispotnature.org/node/323003
I can feel your exasperation and Nick's assurances quite strongly!

Nick Upton's picture

Egg "ribbon"

I found I have no very different angles on this egg mass. It was taken through a rather hard-to-manoeuvre underwater housing (this is an underwater shot, so the look may be different to what you are used to seeing), but I have now attached a higher resolution version which may show you the "fat" ribbon shape more clearly which I definitely noticed at the time. The egg mass was maybe around 5 cms long and nearly 1 cm wide, and maybe 4 mm "thick", but then curled around into a 3cm diameter ring, attached by the 'ribbon" edge to the rock. The shape is very different to the 3 links of curled, more collapsed sausage shaped structures you posted in the last 3 links at 8.33pm on the 19th. As for how organised/disorganised the eggs look, I imagine the pattern changes as the eggs mature from smaller and more organised initially to larger and more diffuse, and the colour may well change also, but I haven't seen enough series of images of opisthobranch egg masses developing to know how much change to expect. From my own PhD studies way back of developing viviparous Gnathiidae crustacea, I know their initial mass of discrete eggs changes to a very diffuse mass of developing embryos/larvae over time. Squid eggs sacs which I've photographed http://www.ispotnature.org/node/278980 -Alloteuthis/Loligo subulata probably I now think - also show clearly defined eggs initially, then a more diffuse pattern as the embryos develop and the egs sac expands (my pic shows developing embryos, but there is a series of shots of Loligo eggs on p.47 of this link http://content.cdlib.org/view?docId=kt267n98pt&brand=c...here&doc.view=e... showing the pattern becoming more diffuse). I agree with Chris that egg masses are often hard to make definitive IDs on, but I felt his suggestion was a likely ID and don't see better one in the offing yet. Derek's concerns, if I've understood them right, seem to be based largely on a misinterpretation of the shape of the egg mass from a 2 dimensional photo, and an assumption that orderly pattern of freshly laid eggs will continue to be obvious as they mature, which may not be correct. Hope this helps, but I'm away for a while now, so can't react for a while.

Nick Upton, naturalist and photographer.

dejayM's picture

No nearer..

yet...as I wrote, I can feel your persuasions.
Interestingly I visited the (quite old) Australian site again to find additional pages http://www.seaslugforum.net/showall/hamihyda. The link appears to be the very same as Chris's yet reveals some more additional material (doesn't it?). This link shows Haminoea from Turkey, which I don't recall seeing before (am I going mad?)
It's the egg-mass that's interesting.
Then, even though I don't think it helps your cause much, I searched for Haminoea cornea (a synonym) to find this http://www.asnailsodyssey.com/LEARNABOUT/NUDIBRANCH/nudiHatc.php - there's a little bit of (a LOT for me) enlightenment under HAMINOEA.
I am warming but we few know how difficult it is to ID Marine mollusc eggs. I really know, having so few agreements and a meagre 3 Icon's worth of experience.
It is such a difficult quest because even if we see (photos of) the animal with some spawn, we have to assume that predation might be happening.