Although jellyfish often appear to glow in an aquarium, this is only because their translucent tissue disperses and colorizes light to make it look like they are glowing jellyfish.
Indeed, jellyfish look magnificent under the right lighting but they do not produce their own light.
The key to making jellyfish look their best is balancing strong spotlights with a soft back light.
Often the back of a jellyfish aquarium will be lit through a translucent blue background that fades to black at the bottom of the tank to give the illusion the jellyfish are floating in the open ocean.
Lighting is one of the most important factors in making an attractive jellyfish aquarium and it takes experience to get it right.
There is one species of jellyfish that can glow in the dark by producing its own light.
The crystal jellyfish (Aequorea sp.
) has two molecules, aequorin and green fluorescent protein, that enable it to emit flashes of green light.
Green fluorescent protein is used in cellular research to label and track biological processes that occur on a very small scale that would otherwise be difficult to quantify.
Drs.
Osamu Shimomura, Martin Chalfie and Roger Tsien were awarded the 2008 Nobel Prize in Chemistry for their work discovering and using green fluorescent protein.
Jellyfish will often take on the color of their prey, especially with white jellyfish like the Moon Jellyfish (Aurelia sp.
).
In California waters, moon jellies often have a purple tint because of the copepods they eat.
In captivity, jellyfish will take on an orange red color because of the brine shrimp and krill-like animals fed to them.
Some companies offer jellyfish food that appears to glow under blue light.
In rare cases, black lights will make jellyfish or their food appear to glow.
In the deep ocean, there is practically no light, so many species of jellyfish will produce their own light to attract prey, deter predators, or communicate.
In conclusion, most common jellyfish do not glow, although they appear to under certain lighting conditions.
If you have a jellyfish aquarium, you can set up the lighting so the jellyfish reflect the light and look very beautiful.