Lovely shot! Congratulations on top 20 and you're right, that camera did a great job at a high iso, I don't think my E-300 could do it without a lot of noise.
Wow! This is spectacular..the color of this jellyfish, the soft look of the light and tentacles is just wonderful; it appears lit from within, I love this shot! 10 Back for another look: my top pick..eerie and wonderful image.
Nice Moon Jelly, and very well defined with the black all around. With a bit of a tilt or direction so as the eye would slip down the tenticles would make this very nice.
Gotta be one of the absolute best answers to the challenge topic; the image is ALL about lighting. Compositionally it's bone-simple, but this only serves to draw attention to the remarkable subtlety of surface rendition. Beautiful image, 10.