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Crazy Nurse Shark

Discussion in 'Basic Scuba Discussions' started by wsr523, Oct 24, 2018.

  1. Rollin Bonz

    Rollin Bonz Solo Diver

    # of Dives: 200 - 499
    Location: Georgia, the state, not the country ;-)
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    Actually, I think @divad did LOL
     
    Seaweed Doc likes this.
  2. falcon125

    falcon125 Nassau Grouper

    # of Dives: 25 - 49
    Location: Colorado
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    It would appear the shark is swimming.
     
  3. wsr523

    wsr523 Angel Fish

    # of Dives: 100 - 199
    Location: Wylie, Texas
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    Swimming erratically maybe...haha
     
  4. Hank49

    Hank49 Solo Diver

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    Turning sharks onto their back makes them pass out?. Maybe this one was just getting high and rolling back over before he blacked out.
     
    chillyinCanada likes this.
  5. RyanT

    RyanT Solo Diver

    # of Dives: 500 - 999
    Location: Maryland
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    This is referred to as "tonic immobility." It occurs when sharks, that normally swim at midwater depths, are turned upside down. Virtually all vertebrate animals retain an orientation in the world based on the information their sensory systems give them. If you take a shark that normally swims in the water column, and uses the sun as one of it's sensory cues, and turn it upside down, then its sensory systems no longer provide the correct information to the animal. Gravity is pulling on the sensory organs in the opposite direction, the sun is in the wrong position, etc. So the animal becomes disoriented and goes limp. For a nurse shark, whose world exists on the bottom, the bottom provides a visual and tactile cue for orientation. So rolling upside down isn't a big deal because they are able to orient to the bottom and tonic immobility isn't such an issue.

    The nurse shark in the video was almost certainly scratching parasites.
     
    NYCNaiad, divad and chillyinCanada like this.
  6. Hank49

    Hank49 Solo Diver

    6,780
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    I was joking.
     
    ystrout and chillyinCanada like this.
  7. RyanT

    RyanT Solo Diver

    # of Dives: 500 - 999
    Location: Maryland
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    Doh! Apparently my humor filter was inadvertently turned up too high. :(
     
    Hank49 likes this.
  8. wsr523

    wsr523 Angel Fish

    # of Dives: 100 - 199
    Location: Wylie, Texas
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    When I was recording the nurse shark my first thoughts were hey, I thought sharks couldnt be on their backs like that. Thanks for the excellent explanation!
     
  9. CT-Rich

    CT-Rich Solo Diver

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    Yeah, this voting thing just seems to make the parasites worse....
     
    Kharon likes this.
  10. ystrout

    ystrout Nassau Grouper

    # of Dives: 25 - 49
    Location: San Diego
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    Scratching. Sometimes external parasites or their skin just itches for whatever reason. Every once in a while, I'll see one of my pet fish do it even though none of them have parasites or anything.

    You'll frequently see many fish do it on rocks, bouy lines, etc.
     

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