These organs also allow them to smell, taste, and to balance. Special sacs around the rim of the bell help them keep balanced. If the jellyfish shifts too far to one side, the sacs stimulate the nerve endings to contract the muscles that will re-orient it in the right direction. Not only does this re-orient them, it also lets them know if they are moving up or down. From depths below 200 meters, the water is darks and cold but there are quite often shapes of creatures glowing all around.
Jellyfish often glow blue and green.
GFP only needs blue light and a little oxygen to glow. Scientists have found this jellyfish trait very interesting and are trying to use it to be able to physically see chemical reactions, such as how much chlorine it takes to kill bacteria in drinking water. They are also trying to inject this protein into crops so that the crops will glow blue if they are stressed. This will allow farmers to be able to see in advance if something needs to be done to help the crops. It is believed that jellyfish use their florescent lighting to see, communicate, find a mate, or to attract a meal.