Which is exactly what happened to me! Our divemaster had warned us that the suction was so strong that if we accidentally got our fingers sucked into the mouth, that we wouldn't be able to get them out! He then explained that if this should happen, you should just relax and that after a few seconds, the stingray would realize our fingers were non-edible and would stop the suction and then you can get your fingers out.
This is exactly what happened to me! Except that when my finger got sucked in, I felt his grindplates grind on my finger, thought "HOLY FUCK! This one's got TEETH!" and then panicked and ripped my hand out of it's mouth as hard as I could! The cut you see on my hand is from where the suction pulled the skin right off my finger! Crazy, right?
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