No, no polarizer. I did shoot it through a glass wall, and I used Lightroom's Dehaze filter to help clean it up. I then enhanced the body structure a bit with Topaz Restyle before I converted it to B&W.
I love watching them swim. Was glad to be on a ship when I saw a swarm of very large jellyfish in Alaska. I never knew they thrived in such cold water.
I find jellies painfully fascinating. Never been stung but I've seen others get nailed. It looks very unpleasant. Vinegar if I remember right stops the stinging. Love to see the color version in pending. Paul.