Sexing an Octopus - Photos of Hectocotylized Arm

Discussion in 'Physiology and Biology' started by DWhatley, Aug 14, 2009.

  1. DWhatley

    DWhatley Cthulhu Staff Member Moderator

    Joined:
    Sep 4, 2006
    Messages:
    19,079
    Likes Received:
    1,126
    Location:
    Gainesville, GA USA
    One of the first questions a new octopus keeper asks is for help identifying the sex of their new ward. Usually the easiest way to sex an octopus is by observing the third arm to the right (clockwise) on a sexually mature animal. This arm (hectocotylus) has a suckerless tip (ligula) and a channel for delivering spermataphores. The ligula is very difficult to identify while looking at a live animal but can be just be seen in the second (hummelincki) photograph. The channel is easier to see in photographs than trying to view it on a moving animal and is seen as a white line in the third (briareus) photograph. The easiest way to identifiy it is to see if the octopus keeps it rolled up protectively (all photos). SueNami (the briareus in photos 1 and 3) came with this arm removed up to the webbing. The assumption was that a male would be less likely to loose the arm and we assumed female. As the arm regrew we discovered that we have a boy named Sue and that the hectocotylized arm appears to grow back normally (functionality can only be assumed).
     

    Attached Files:

  2. haggs

    haggs Vampyroteuthis Supporter

    Joined:
    Oct 4, 2008
    Messages:
    384
    Likes Received:
    64
    Location:
    Coffs Harbour N.S.W.Australia
    D, thank you for those images, it clearly shows what too look for.
     
  3. #30Girl

    #30Girl Wonderpus Registered

    Joined:
    Nov 28, 2008
    Messages:
    182
    Likes Received:
    0
    I thought Octpuses arms didn't grow back...
     
  4. DWhatley

    DWhatley Cthulhu Staff Member Moderator

    Joined:
    Sep 4, 2006
    Messages:
    19,079
    Likes Received:
    1,126
    Location:
    Gainesville, GA USA
    More male octos More photos
     

    Attached Files:

  5. AshixLove

    AshixLove Larval Mass Registered

    Joined:
    Apr 18, 2010
    Messages:
    4
    Likes Received:
    0
    So the male octopus always has that leg curled up?
     
  6. DWhatley

    DWhatley Cthulhu Staff Member Moderator

    Joined:
    Sep 4, 2006
    Messages:
    19,079
    Likes Received:
    1,126
    Location:
    Gainesville, GA USA
    The specialized arm is common to most male octopuses (I recently read a paper that said one species drops a normal arm and grows out hectocotylized arm when it is sexually mature) but not every species roles up the arm. The arm is used (by some more than others) as an arm too but you will usually see it curled when not in direct use. My unknown species Macropus male only curls the tip (and then it is more just at right angles to the arm rather than curled) and it took me three month to see the specialized end (the ligula will not have suckers). Puddles moves his arms around a lot and is nocturnal so the limited lighting has made him difficult to sex.
     
  7. AshixLove

    AshixLove Larval Mass Registered

    Joined:
    Apr 18, 2010
    Messages:
    4
    Likes Received:
    0
    Ohhh alright, thanks!
     
  8. neurobadger

    neurobadger Vampyroteuthis Registered

    Joined:
    Apr 19, 2010
    Messages:
    475
    Likes Received:
    22
    Good crud, octopuses get erections too? (That appears to be what the latter article says.)
     
  9. DWhatley

    DWhatley Cthulhu Staff Member Moderator

    Joined:
    Sep 4, 2006
    Messages:
    19,079
    Likes Received:
    1,126
    Location:
    Gainesville, GA USA
    :smile:Certainly biologically interesting. It is not seen by the observer as it appears to happen only when they are depositing the spermataphores while the ligula is inside the mantle. The scientist first noticed the physical change during a failed mating attempt.
     
  10. mucktopus

    mucktopus Haliphron Atlanticus Staff Member Moderator

    Joined:
    Dec 31, 2003
    Messages:
    523
    Likes Received:
    51
    We have evidence for this in the wild too (Amphioctopus marginatus)- we hope the short little note, with frames of video, will be out this summer.
     
  11. DWhatley

    DWhatley Cthulhu Staff Member Moderator

    Joined:
    Sep 4, 2006
    Messages:
    19,079
    Likes Received:
    1,126
    Location:
    Gainesville, GA USA
    I thought about asking you if you had seen this (I just ran across the paper while looking for an external reference for ligula) since you have seen more in situ matings than the rest of us combined (including Roy or we have almost no numbers at all :sagrin:) .
     
  12. Steve O'Shea

    Steve O'Shea Colossal Squid Supporter

    Joined:
    Nov 19, 2002
    Messages:
    4,668
    Likes Received:
    17
    I am afraid to comment ....
     
  13. DWhatley

    DWhatley Cthulhu Staff Member Moderator

    Joined:
    Sep 4, 2006
    Messages:
    19,079
    Likes Received:
    1,126
    Location:
    Gainesville, GA USA
    You are lucky I could not find the video of your backyard squid anatomy class :gigas:
     
  14. esquid

    esquid Haliphron Atlanticus Supporter

    Joined:
    Dec 22, 2007
    Messages:
    526
    Likes Received:
    0
    I misread the this thread as "Sexting an octopus"

    I need more coffee...
     
  15. DWhatley

    DWhatley Cthulhu Staff Member Moderator

    Joined:
    Sep 4, 2006
    Messages:
    19,079
    Likes Received:
    1,126
    Location:
    Gainesville, GA USA
    so would that be pornographic texting?
     
  16. CaptFish

    CaptFish Colossal Squid Staff Member Moderator

    Joined:
    Jul 9, 2009
    Messages:
    2,832
    Likes Received:
    96
    Location:
    South Florida
    Bump...[​IMG]

    On the third arm, hectocotylus, how much of the tip will be suckerless, ligula, say on a Hummelincki or Vulgaris?

    At what age does an octopus become sexually mature? is it the same age for male and female?
     
  17. DWhatley

    DWhatley Cthulhu Staff Member Moderator

    Joined:
    Sep 4, 2006
    Messages:
    19,079
    Likes Received:
    1,126
    Location:
    Gainesville, GA USA
    I put a list of papers I found on hummelicki in the Cephalopod Species (by family)->Octopodidae forum. The first paper has this to say about ligula length:
    . It is my guess that the calamus spout would be the part of the ligula that would be suckerless :bonk:

    With the eye spots, Penney will not be vulgaris but someone else may know of a reference with similar info on vulgaris.
     
  18. CaptFish

    CaptFish Colossal Squid Staff Member Moderator

    Joined:
    Jul 9, 2009
    Messages:
    2,832
    Likes Received:
    96
    Location:
    South Florida
    Hmmm I thought the whole suckerless part was ligula and the calamus spout is where spermataphores come from...[​IMG]

    She's a Vulgarlicki! Too big to hummelincki, and possible eye spot equals not Vulgaris. I wish someone knew!
     
  19. Steve O'Shea

    Steve O'Shea Colossal Squid Supporter

    Joined:
    Nov 19, 2002
    Messages:
    4,668
    Likes Received:
    17
    I've never heard of a 'calamus spout' - the calamus and ligula are quite different structures, neither with suckers. I think someone has been making up words. Bizarre.
     
  20. DWhatley

    DWhatley Cthulhu Staff Member Moderator

    Joined:
    Sep 4, 2006
    Messages:
    19,079
    Likes Received:
    1,126
    Location:
    Gainesville, GA USA
    Steve, can you give us a diagram?
     

Share This Page