Mystery cirrate octo

Discussion in 'Stauroteuthidae' started by Clem, May 9, 2011.

  1. Clem

    Clem Architeuthis Supporter Registered

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    Via the NZ antarctic fisheries observer known as hud2, he of the previously unknown M. Hamiltoni specimen, come these shots of a striking cirrate octopus.

    (Above images courtesy of and wholly owned by hud2)

    According to hud2, this gelatinous octopus was recovered from the stomach of a Patagonian toothfish, which makes the preservation of the specimen all the more remarkable, and suggests that toothfish might not be biters so much as gulpers. I can't think of any other explanation for the excellent condition of the thing. I talked about this one with OB, and we thought we were looking at a decapod, but what we took for an extra pair of arms was the animals umbrella-like webbing. The skin has separated from the mantle, which is nearly as transparent as the arms, and one fin can be seen. The measuring marks must be centimeters, and they are clearly visible through the arms...amazing transparency. The eyes are very well-defined, dark and barrel-shaped, and the arms present both cirri and small suckers not on stalks.

    This and other specimens were sent to Te Papa museum in NZ, so it's possible that Bald Tank Man himself has already ID'd it, but I'm going to throw out Stauroteuthis gilchristi as a possibility. It's a good-looking match, anyhow, the morphology being very similar, and S. gilchristi is known from South Georgian and sub-South African locales. On the other hand, the gut of the mystery cirrate appears to show a large caecum which I don't see on the S. gilchristi drawing, and the mystery cirrate's suckers appear to be smaller.

    A beautiful thing, whatever it is. Many thanks to hud2 for his generosity, and for allowing me to post these.

    Clem
     

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  2. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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    Very cool (what a great contact, hope he sends more your/our way). What excited me about it though was the skin "separation" from the mantle. I have seen this and wondered about it in O.briareus (at death).
     
  3. Clem

    Clem Architeuthis Supporter Registered

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    What's your take on the skin separation, D? I doubt it's the result of early-stage digestive processes in the toothfish, so perhaps it's the result of something mechanical, i.e. uniform pressure applied by the esophagus to the mantle as the octo went "down the hatch," or the toothfish generated sufficient suction to pull the skin away before the octo was swallowed. Where have you seen this?

    Clem
     
  4. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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    I wonder if the coldwater animal was a newly spent postbrood female. Biology is not my strong suit but my impression was that perhaps the skin is not connected to the mantle. Kooah suffered no death trama other than egg bearing/brooding (do you know if this one is male or female?) so I wondered if it was just more apparent in post brood females. However, KaySoh did not show this separation. She did not have hatchlings but her mantle was hugely extended and we believe she laid (and did sequester herself expectantly) infertile eggs (I did not see them though). SueNami (male - no final photo taken), did not show this separation, or I did not notice it. You can see the separation fairly clearly in Kaysoh's photo link. It was quite pronounced and difficult to set up the picture because of the sliding.
     
  5. Tintenfisch

    Tintenfisch Architeuthis Staff Member Moderator

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    Wow, that specimen is in AMAZING condition, all the more so for its origin! I will poke Steve with a sharp stick and see whether I can get him to respond. We have a bunch of photos (and specimens) of Antarctic cephs that we are working through, and this looks familiar.
    Clem, are you sure the skin is actually separated from the mantle? Some species have a really thick, gelatinous layer around the outside that looks very similar to this when they are lying on a flat surface. Sometimes this is only true at small stages (Cycloteuthis sirventyi is one that springs to mind - you can kind of see what I mean in the bottom illustration; gelatinous bolitaenid octos also have it). This really threw me off the first time I encountered it.
     
  6. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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    Kat,
    Blow up Kooah's final photo. This is a Common Caribbean octopus (O. briareus and not gelatinous). The separation was very noticable and the outer skin definitely slipped around separately from the mantle (making positioning it hard for photographing).
     
  7. Tintenfisch

    Tintenfisch Architeuthis Staff Member Moderator

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    D, sorry, was just trying to clarify what we're looking at here. I interpreted 'separated' as 'torn away from' (like over the arms, where you can see red skin peeled back to reveal white muscle underneath), whereas the gelatinous skin/tissue over the mantle in these photos looks loose enough to move independently of the much smaller, visible cone of muscle underneath, without actually being detached from it.

    Off to bother Steve now.
     
  8. Clem

    Clem Architeuthis Supporter Registered

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    T,

    I actually hadn't given that much thought to using the word "separated," but I was interpreting the photo as showing integument that had been pulled away from the muscle post-mortem, and not as a separate gelatinous envelope. I thought that the presence of chromatophores indicated skin, and I don't know what the other side looked like or how much arranging of the thing took place before being photographed. The whiteness of the two arms on top was one of the things that made me think we were looking at a decapod: I thought they were tentacles, more muscular and therefore more opaque.

    You could poke Steve with a sharp stick, or dangle a bottle of Just For Men hair-coloring in front of him. Whichever works best for you.

    Clem
     
  9. Tintenfisch

    Tintenfisch Architeuthis Staff Member Moderator

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    I am still hoping it evolves to bright blue... right now he looks kind of like Zuse from TRON: Legacy. With a beard. And not in a good way. :hmm:

    I think the width of the gelatinous, red-skin-covered layer is possibly just the 'slump' that comes from spreading a thick, cylindrical, neutrally buoyant object onto a flat surface out of water, as in the attached (extremely crude) diagram. But there may also be detachment; as you say, we can only see the 2D image and with no chance to manipulate, we do have to guess at some details. The impression is also maybe further distorted by the fact that we're looking at a right-lateral view of the animal, with the gelatinous layer spread out so far dorsally that it has sort of smeared the fins into a strange orientation. The overall coloration and tissue appearance does look like S. gilchristi to me, but then the gelatinous layer is WAY thicker than I've ever seen for that species.
     

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  10. tonmo

    tonmo Titanites Staff Member Webmaster Moderator

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  11. main_board

    main_board Vampyroteuthis Supporter

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    Hi everyone,

    Very interesting thread. Noticed the 90, 100, and 140 increments on the fish board (agree with you Clem, with fisheries observers guaranteed to be cm's) and extrapolated some measurements. See attached.



    Depending on what you take to be the posterior tip (I'd opted for green) there's some variation in ML but arm length and total length should be reasonable. I took the yellow line to be the end of the mantle, which is about the 101 mark. Appears a more exact limit in the other image posted.

    I like Stauroteuthis gilchristi as an ID, but there are some real issues with proportions. Mainly, the head is way too big. For S. gilchristi mean ML/TL*100 = 15.94 +/- 2.09 (N = 8; fixed specimens; Collins and Henriques 2000). From the image, it's more like 28, 32, or 34 depending on your marks. While the its possible the arms could be made to lie straighter, which might increase the TL relative to the ML, I don't think it could make up for the difference. Can't comment on the different between fixed and fresh specimens.

    Also, as T pointed out, there's all that gelatinous tissue. It looks like some is to be expected (also in Collins and Henriques 2000) but not to that degree. What I find interesting is that both of these are posterior oriented features, which to me supports the distortion by suction feeding of the toothfish. I mean, a fish that can engulf a critter this big without raking it with its teeth likely has a large mouth capable of generating plenty of suction.

    Plusses: a TL of 50 cm fits expected size range, and the crazy cool colour is, apparently, appropriate. I've never handled this species, but I've worked with its Altantic cousin syrtensis a bit and I think this specimen certainly fits stauro morphology better than the other cirrate options.

    Great photos! Hope there's more to come.
    Cheers

    Collins, M. A. and C. Henriques. 2000. A revision of the family Stauroteuthidae (Octopoda: Cirrata) with redescriptions of Stauroteuthis syrtensis and S. gilchristi. J. Mar. Biol. Ass. U.K., 80: 685-697.
     

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  12. Clem

    Clem Architeuthis Supporter Registered

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    Main_board, great job on the measurements. I didn't zero in on S. gilchristi until I'd received the second photo, which gives a better idea of the proportions of the armature relative to the body. The second photo seems to show roughly one third of the arms length, suggesting proportions appropriate for S. gilchristi, that is, if I'm correcting for angle of view and optical distortion as well as I hope I am.

    Am I correct in thinking that this animal's chromatophores are on/in the superficial gelatinous layer? Could someone give me an idea of what the cross-section of the mantle tissue layers looks like?

    I've been thinking about how this specimen was recovered. The preservation is so good that it can't have been in the toothfish's stomach for very long at all, which means that it had to have been gulped shortly before the toothfish took the baited hook. I'd ask hud2 about this, but does anyone here know what the hooks would be baited with? Perhaps the octopus was investigating or snacking on the bait when the fish snuck-up on it. Would've made for a major "D'oh!" moment for the toothfish.

    Clem
     
  13. main_board

    main_board Vampyroteuthis Supporter

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    Yeah, Clem, that the photographs are all angled initially drove me to measure out the specimen. To give a less biased impression of proportions.

    From Collins and Henriques (2000), again, body gelatinous. Can't give more details as per a cross-section, but as far as colour goes, here's what they say: the area around the mouth is supposed to be darkly pigmented, pink or purple, which extends roughly 2/3 down the oral surface of the arms before lightening. Aborally, arms are transparent. The viscera are contained in a semi-enclosed pigmented membrane. The species has both a primary and secondary web, from which I believe most of the red colour is coming from on/around the arms (Google image 'Stauroteuthis'; in situ they're quite red). They later note that fresh specimens are quite different in appearance than fixed ones, and that when fresh much of the tissue is transparent and the eyes and viscera clearly visible. So, helpful? Haha.
     
  14. Clem

    Clem Architeuthis Supporter Registered

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    If the area around the buccal is darkly pigmented, then I wonder if the females show the sort of bright rings associated with your avatar. No need to deprecate with a "Haha." Always bear in mind that I don't really know what I'm doing.

    Clem
     
  15. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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    If we knew exactly what we were doing there would be no reason do do it :grin:
     
  16. Clem

    Clem Architeuthis Supporter Registered

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    Depends on the salary.

    Clem
     
  17. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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    POINT!
     

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