picture: http://www.guardian.co.uk/

The deep-sea schyphozoan jellyfish, Atolla wyvillei, as seen from the Johnson-Sea-Link submersible with the lights on and then in the laboratory, after capture, with the lights off, exhibiting a burglar alarm display. Video courtesy of Operation Deep Scope 2005 Exploration, Edith A. Widder, NOAA-OE.

Please visit source: http://oceanexplorer.noaa.gov/explorations/05deepscope/background/eyeinsea/media/movies/video2_video.html