Help me ID this octo

Discussion in 'Diving & Ceph Encounters' started by Jared, Aug 30, 2005.

  1. Jared

    Jared Cuttlefish Registered

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    Hey there everyone,

    I found this little octopus in Monterey bay last week. I tend to see octopus this size that are very clearly octopus rubescens. They're generally redish and look a lot like the O. rubescens photos in my invert ID book. This one didn't look exactly the same and his behavior was different than any of the others I've seen.

    It seems like bimac (bimaculatus or bimaculoides) would be the only other logical option but I couldn't find any false eye spot on this guy. My questions:

    - Is the eyespot always visible on a bimac or can it be covered over with chromatophores? The eyespot is always visible in the photos I've seen but none of my ID guides say explicitly whether it's always visible or not.

    - Are there any sure fire ways to tell which Monterey area octopus you're looking at? It seems that the suckers are pretty distinctive on the giant pacific octo but all the others are so variable that they leave me a bit confused.

    Thanks!
    -Jared
     

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  2. Cephkid

    Cephkid Sepia elegans Supporter

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    Bumping this thread, would like to know too!
     
  3. Neogonodactylus

    Neogonodactylus Haliphron Atlanticus Staff Member Moderator

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    It looks a bit too big to be Ocotpus micropyrsus and it is also too far north, but lots of "southern Californian marine animals have been showing up in Monterey this year. If it isn't O. rubescens, that would be my guess.

    Roy
     
  4. Jared

    Jared Cuttlefish Registered

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    It's been a while but I thought I'd let you know that the octo in the picture is indeed Octopus rubescens. It seems that the three papillae under the eye are dignostic for these critters. A friend of mine was kind enough to point me to this web page that describes the key differences between the red octopus and the giant pacific octopus.

    While I'm fairly sure that I've gotten this guy sorted out, I'm still a little confused about the bimacs. I searched the "web of science" and came up with some interesting papers about bimacs but none of them give a range. I've seen some sources (like Gotshall's Guide to Marine Invertebrates) that say they're only found south of point conception and other sources that claim they make it up to central california. I'm still looking for a fool proof way to distinguish a bimac from a similarly sized GPO. I know the bimac has the false eye spot but sometimes when I see an octopus, all I can see is an eye ball and a couple of arms squished into a crack in the rocks. I'm also not sure if the eye spot can be obscured by the chromatophores or if it's always visible.

    -Jared
     
  5. Lis

    Lis Larval Mass Registered

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  6. OB

    OB Colossal Squid Staff Member Moderator

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    Dosidicus gigas? By coincidence, also my avatar... :smile:
     
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  7. Jared

    Jared Cuttlefish Registered

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    According to the best source I've seen*, Dosidicus gigas is confined to the west coast of north and south america. It does look a lot like Dosidicus though. I'd guess that it's a member of the same family; Ommastrephidae. Perhaps it's one of the Sthenoteuthis species. They look a lot like Dosidicus and share the arm keel that's visible in the video.



    * Nigmatullin CM, Nesis KN, Arkhipkin AI
    A review of the biology of the jumbo squid Dosidicus gigas (Cephalopoda: Ommastrephidae)
    FISHERIES RESEARCH 54 (1): 9-19 DEC 2001
     
  8. OB

    OB Colossal Squid Staff Member Moderator

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    Sthenoteuthis oualaniensis perhaps? Otherwise, might Ommastrephes bartramii be considered? It's a bit hard to judge size from the video, but the animal appears to be of at least 45 cm ML.

    Lis, would you happen to know what the diameter of the (drilling?) pipe in the video is?

    I don't think the ventral dark patch is an unique identifier, either...

    Or it could still be that D. gigas has started to move out of its Humboldt current confinement, the dawn of our Squid Overlords is nigh! :grin:
     
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  9. main_board

    main_board Vampyroteuthis Supporter

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    I love these sort of "quests to ID this ceph" kind of posts. However, I'm having difficulty. Armed with my Nesis and a loose idea about what's what, heres what I found:

    Sthenotuethis is supposed to have a photophore on the ventral side of the eyeball. You'd think after watching the first video with the big red squid where the camera is really zoomed into the head you'd see this photophore. Maybe you did and I just didn't see it. Maybe it wasn't "turned on" at the time :grin: . Whatever. But at the same time, watching that video you can kind of see an eyelid sinus, which they are also supposed have (see: http://tolweb.org/accessory/Cephalopod_Eyelid_Sinus?acc_id=1994 for picies of a Sthenoteuthis). So now what?
    Other indicators: Nesis describes an absence of a silvery stripe on ventral side of the mantle on Sthenoteuthis. However there is no mention of the apparent dark red band on ventral side of mantle as shown in the second and third video. Can they change the colour of these bands? Oh, the mantle is supposed to be cylindrical, and in the video I didn't think it quite matched this description. Geographically it's questionable too, though if it did belong to this genus then it'd have to be S. oualaniensis as S. pteropus is strictly an Atlantic species.
    Moving on...

    Ommastrephes bartrami would be my bet. Still has the eye sinus, again check out the tolweb link above, but no eye photophore. The end of the fin is slight attenuated posteriorly which you can see in the video. The mantle is not supposed to be exactly cylindrical which I think better describes the video. This species is supposed to have a wide silvery stripe on the ventral side of the mantle, though in the video it appears red. Again, colour change? There appear to be a few undescribed "subspecies" floating around, with one living in Aussie waters, and generally epipelagic to mesopelagic. Mantle sizes matches round aboutly too. But most importantly....the picture looks right! LOL:lol:


    But really, the above means little. If was a lot of fun though, and got to learn more about squid and my Nesis! Smart man, that un! Oh, the other squid species is called "unidentified", as in you don't know what it is or it hasn't been described in science?

    Cheers!

    EDIT: Oh I forgot to mention: In the second video with the squid is coming through the cloud of whatever it appears to be in the classical histioteuthid position, mantle up and arms bent at right angle (sometimes head is bent too). If you really look, after it swims away from the camera and cloud it takes up this positioning again. (for some reason you have to watch the video through two cycles and on the second turn the video is longer and shows you the squid leaving the ROV to the upper right corner of the field of view.) Have any other species been documented doing this other than the histioteuthids? Any thoughts?
     
  10. main_board

    main_board Vampyroteuthis Supporter

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    I decided against editing again.
    I went to the home page of the SERPENT site and found more links to videos in other areas of the world. Wouldn't you know, in the Gulf of Mexico section they have more videos of that bizarre ?Magnipinnidae squid. I can't believe that no one has a specimen of it yet and can do some work on it. Its probably one of the best document "I don't have a clue what it is" species out there! I think that its just such a cool, majestic squid that I either want someone to figure it out already to quetch my curiousity or I want no one to figure it out so that I can do it! (though I think the former will happen long before the latter is possible).
    A really cool site with a neat job/mission and a ton of great videos and pictures. Definitely worth a look!

    Cheers!
     
  11. Lis

    Lis Larval Mass Registered

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    Thanks for all the input guys! :grin:

    Our contact at the Smithsonian also reckons the squid in the series of three videos is Ommastrephes bartramii. He has identified the other Australian squid to be Asperoteuthis acantoderma.

    I'm hoping we'll be sent more fab footage soon!
     
  12. Cameo

    Cameo Pygmy Octopus Registered

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    Incredible Creature

    Tell me what did it feel like when he wrapped his suckers around you or did he?
    What did he feel like?
    Very interested to know.:smile:
     

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