I don't really understand the concept of jellyfish. They're photogenic little beasts, but aside from that I'm stumped.
These are from Toronto's newish aquarium, which I visited for the first time this weekend. The spotted jellies in the first two photos are quite small, so they were photographed with my Sigma DP3M, while the larger animals in the last three photos were recored with the DP2M. The Merrill's were very lucky to find blue light, which their black and white mode responds well to, but it was a tough place to shoot for colour.
This is with the Ricoh GR, which does better in colour in low light than the Sigma cameras do, but not as well for black and white under these conditions. Both styles of camera had a hard time with focusing speed and light levels, so it was just as well that this wasn't really a photographic visit; next time I'd probably carry the same cameras, but take a lot more care with each shot.