File:Underside of expanded bluefire jellyfish in Brofjorden at Sandvik 57.jpg

English: Underside of an expanded bluefire jellyfish (Cyanea lamarckii) in Brofjorden at Sandvik, Lysekil Municipality, Sweden. The jellies at this photo shoot were about 6–12 cm (2.4–4.7 in) in diameter. The blue jellies are streamlined when contracted, and the rim of their top is very lobed so when they expand to get ready for a "swim stroke", they get little resistance from the water until they are fully expanded and ready to contract again. That makes them more agile, quicker and faster swimmers than Cyanea capillata and Aurelia aurita. Their darting movements in the water are more resembling that of dragonflies than other jellies. Most of the little dots in the photo are out-of-focus daphnias. A sharper one can be seen almost at the center bottom of the tentacles.