Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

What is this marine critter?

  1. Sep 8, 2015 #1

    DaveC426913

    User Avatar
    Gold Member

    Just came back from diving in Cuba.

    These are some sort of jellyfish or other invertebrate but I haven't found any reference to it.
    They have no tentacles, just a round body like a kiwi fruit. Extremely transparent and incredibly fragile.

    IMG_8801.jpg

    Video:
    http://www.davesbrain.ca/adventures/15solpalmeras/pic.html?pic=21
     
  2. jcsd
  3. Sep 8, 2015 #2

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    They look to me like scuba divers!
     
  4. Sep 8, 2015 #3

    DaveC426913

    User Avatar
    Gold Member

    Ba-ZINGA!
     
  5. Sep 8, 2015 #4

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    Seriously! I had to stare at that picture for several minutes before i saw the very hazy blobs in front of the swimmers that I presume are being referred to.
     
  6. Sep 8, 2015 #5
    Looks like what I swam through while swimming with dolphins in NZ
     
  7. Sep 8, 2015 #6

    DaveC426913

    User Avatar
    Gold Member

    True, true.

    It is more apparent in the video:
     
    Last edited: Sep 8, 2015
  8. Sep 8, 2015 #7

    jim mcnamara

    User Avatar

    Staff: Mentor

    FWIW: http://www.livescience.com/25889-jellyfish-bloom-cycles.html

    There are apparently long term cycles in jellyfish populations. We are in a boom period now. Without finding a direct citation, it seems human predation (fishing) may be altering those cycles -

    A partial explanation: ocean warming trends plus removal of predators for jellyfish larvae. Removal == overfishing smaller schooling fish species. The only stuff I can find is behind a paywall. Ugh. Can anyone do better than this?
     
  9. Sep 8, 2015 #8

    DaveC426913

    User Avatar
    Gold Member

    But do you recognize them (even if by description)? Are they merely generic jellyfish? Generic jellyfish larvae?

    It seems they're too generic to even find on the webernets.
     
  10. Sep 8, 2015 #9

    DaveC426913

    User Avatar
    Gold Member

    Ah! Got it!
    Comb jellies.
    comb-jellies_18687_21333213096753.jpg

    It is too ephemeral to catch on video, but those inner teeth light up like strings of running Christmas lights.

    Some articles say they're poisonous. These ones must have been sleeping.

    The above pic is highly optimal. These things are so transparent, it is difficult to see if you are holding one in your hand.
     
  11. Sep 8, 2015 #10

    jim mcnamara

    User Avatar

    Staff: Mentor

    The adult form of true jellies are called "medusa". They generally have at least some semblance of shape. Other blob-beasts that people confuse with jellies are Cnidarians and Ctenophores. Together some scientists call them gelatnious zookplankton.

    I cannot tell much from the video. What I see looks like round very transparent blobs.
     
  12. Sep 8, 2015 #11

    jim mcnamara

    User Avatar

    Staff: Mentor

    You got em. Ctenophores.
     
  13. Sep 8, 2015 #12

    Andy Resnick

    User Avatar
    Science Advisor
    Education Advisor
    2016 Award

  14. Sep 9, 2015 #13

    Chronos

    User Avatar
    Science Advisor
    Gold Member

    They will remind you when you tread barefoot on their tentacles.
     
  15. Sep 9, 2015 #14
    I remember several "run-ins" with aquatic invertebrates of this type and others as a high-schooler in Hawaii. Once we took a weekend vacation at a locale which I think was close to the famed "black sands" beach on the east coast of Oahu. If I remember correctly, it may even have been Labor day! :woot: 1984, though ?:). In any case, I think I was smoking "pakalolo" on the beach at the time when a surfer buddy of mine came running up with his face turned white and his ankle swollen up like a red tree log telling me that he got attacked by these things called Portuguese "man-o-wars." Their bodies were really small, about the size of an orange, but they had this one long tentacle that extended out what seemed to be about 10 meters or so. And they had these really creepy blue stingers in them. It was nasty. There were thousands of them everywhere. Bummed my trip that weekend.

    There was this other time, probably a couple years earlier, like 1982, when I first moved to Hawaii, when I was surfing on the tourist beach of Waikiki. These things called "reefs" were everywhere, basically coral growths in the surf break sands. Nobody paid much attention to them, you just had to put up with them. I think this was before that company put out those "reefwalker booties." In any case, I remember one day walking on one of the reefs after being caught inside after catching a wave. I felt this sharp pain scream up my left foot and leg. What happened is that I stepped on a sea urchin and it injected these poisonous spines in my foot. I remember hobbling, after great effort, down the beach to one of the lifeguard towers and informing them that I was going to die before I lost my virginity, hoping that might get me medical attention more quickly.

    The lifeguard just kind of laughed and said I stepped on what they called, then, a "vana." for lack of a better cladistic definition. What he recommended to me was the same thing he recommended to all the the tourists that met that same fate; walk into one of the public restrooms on the beach and urinate on your foot. So that's what I did. I remember standing at one of the urinals with my foot in the urinal and urinating on it while some fat old tourist guy from Nebraska in a g-string took the urinal next to me and watched me with mild dis-interest. People urinating on their foot in Waikiki in 1982 was not an uncommon or particularly shocking sight in public restrooms at that time.
     
  16. Sep 9, 2015 #15

    Pythagorean

    User Avatar
    Gold Member

    When I fished commercially out of Alaska, we would pull all manner of creature occasionally over time. When you set on a group of jellies, and they start flying over the block (powered wheel that pulls net back on board) you can often get them in your face. The eyes, the nose, the mouth... all burn. The red ones are "hotter" than the white ones. Sometimes I'll eat their fleshy bodies. I've never had an urchin attack me. I'd like to see them actually use their harpoon. The octopi were my favorite though. I loved Watching a decently sized octopus melt through the skupper holes to get back to the sea.

    I'm kind of thinking we should sing a sea shanty now.
     
  17. Sep 14, 2015 #16
    Let's do it!

     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: What is this marine critter?
Loading...