The Short Answer
Jellyfish glow in a variety of colors including blue, green, yellow, orange, red, and purple. The specific color depends on the species of jellyfish and the bioluminescent proteins they contain. The most common glow color is green or blue.
An Overview of Jellyfish Bioluminescence
Many species of jellyfish are bioluminescent, meaning they produce their own light through a chemical reaction. They contain light-emitting photoprotein compounds in their umbrella-shaped bodies and tentacles. When these photoproteins react with calcium ions, they give off visible light in a process called chemiluminescence.
The bioluminescence serves several purposes for the jellyfish. It can be used to attract prey, deter predators, and communicate with other jellies. The glow color and patterns are often unique to the species, used to identify one another.
What Causes the Color Variation?
Jellyfish bioluminescence comes in such a wide array of colors because the light emission depends on the specific photoprotein found within each species. Some of the key light-emitting photoproteins are:
- Green fluorescent protein (GFP) – Produces bright green bioluminescence at 508 nm wavelength.
- Aequorin – Emits blue light at 469 nm wavelength.
- Obelin – Generates a vibrant blue glow.
- Mnemiopsin – Emits violet-blue light.
- Clytin – Produces green, yellow, or orange bioluminescence depending on conditions.
Slight molecular differences in these photoproteins cause the color variations we see. Some jellyfish even have more than one type of photoprotein, allowing them to produce multiple glow colors.
Common Jellyfish Glow Colors
Here are some of the most common bioluminescent jellyfish species and the colors they typically glow:
|Aequorea victoria||Green, blue|
|Mnemiopsis leidyi||Blue, violet|
|Pelagia noctiluca||Purple, red|
Some of the most brilliant bioluminescent displays come from massive jellyfish blooms where millions of individuals congregate. The Sea of Cortez in Mexico is famous for its bioluminescent jellyfish shows of stunning electric blues.
Green Fluorescent Protein (GFP)
One of the most studied and widely utilized jellyfish photoproteins is GFP from Aequorea victoria. This species of jellyfish off the west coast of North America glows green when stimulated. The GFP photoprotein emits an intense green light peak at 508 nm on the light spectrum when exposed to blue light.
GFP has become enormously important in biological research. It is used as a biological marker to tag and visualize specific proteins, cells, and tissues. GFP has even been inserted into the DNA of other organisms like fish, cats, pigs, and monkeys to make them glow green under certain lights!
While rare, some jellyfish species exhibit a red fluorescent glow. This includes the fire jelly Rhopilema esculentum and several Giant jellyfish like Nemopilema. These generate their glow from a different set of fluorescent proteins that emit light in the red wavelengths.
However, the red glow is weaker than other jellyfish colors. Most photos of glowing red jellies are enhanced or exposed longer by the camera to capture their dim bioluminescence. So while beautiful, the vibrant red may be exaggerated in imagery.
Glowing Jellyfish Distribution
Bioluminescent jellyfish have been observed in oceans around the world. Some regions with high densities include:
- West coast of North America – Common jellyfish like Aequorea proliferate here.
- East coast of Asia – Nomura’s jellyfish glows blue and can swarm massive blooms.
- Arabian Sea – The world’s largest jelly Atolla wyvillei emits blue light.
- Gulf of Mexico – Mass spawning creates stunning bioluminescent displays.
- Southern Ocean – Antarctic jellyfish glow blue and orange hues.
- Norwegian fjords – Dense populations of Periphylla jellyfish glow red here.
Bioluminescent Jellyfish Habitats
Glowing jellyfish can be found inhabiting coastal regions, open ocean, and deep sea environments. Some key bioluminescent jellyfish habitats include:
- Surface waters – Many jellyfish remain near the illuminated surface waters during the day or night. This includes most moon jellies.
- Deep sea – Some species migrate down to deeper, darker parts of the ocean during the daytime where bioluminescence is useful. These include the deep sea Atolla.
- Arctic waters – Bioluminescent jellies thrive in frigid, low light Arctic and Antarctic regions, emitting blue and green hues.
- Fjords – Jellies crowd into the confined bodies of water along fjord landscapes, creating glowing displays.
One key purpose of bioluminescence in jellyfish is to facilitate nocturnal hunting. Many jelly species use their glow to help capture prey in the dark of night. The light attracts small fish and crustaceans towards the jellies, which are then stung and consumed.
Some jellies like the spot-lit Periphylla even have glowing “fishing lines” that dangle down from their tentacles, luring in prey. The bioluminescence gives jellies a tactical hunting advantage in the darkness.
Defense Against Predators
The glow of jellyfish may also help deter potential predators. By illuminating their bodies, the jellies make themselves more visible and apparent in the dark waters to animals that may prey upon them.
Being boldly bioluminescent advertises the jelly’s stinging capabilities and unsavory taste. The light says “beware” and helps scare off would-be attackers. Some jellyfish can even rapidly flash their bioluminescence when threatened as a warning display.
Mating and Aggregation
In addition to hunting and defense, the bioluminescent displays of jellyfish play a role in mating and aggregation. The species-specific colors and patterns help jellies identify potential mates of their own kind. The glow also enables aggregations of jellyfish to form large blooms, synchronizing through their illuminating cues.
Threats to Bioluminescent Jellies
Although beautiful, the existence of glowing jellyfish is threatened by several factors:
- Climate change and warming oceans may impact food chains and conditions jellyfish depend on.
- Overfishing depletes prey fish that many jellies rely on.
- Plastic pollution and debris can choke and kill jellies.
- Coastal anthropogenic light pollution can outshine natural bioluminescent displays.
If these issues continue growing, loss of bioluminescent jellyfish would not just mean less glowing sea creatures. It would indicate collapsing marine ecosystems around the world. Their bioluminescence serves as sensitive indicators of ocean health.
The amazing bioluminescent displays of glowing jellyfish provide crucial ecological functions and insights into our oceans. Their glowing greens, blues, purples, and reds derive from specialized light-emitting photoprotein compounds in their cells. These marine creatures utilize bioluminescence for vital processes like hunting, defense, and mating in the darkness of night. With so much we have yet to learn about the deep seas, preserving these living light spectacles remains integral to understanding and maintaining our oceans.