The Amazing Phenomenon of Bioluminescence

The 'Milky Seas' phenomenon has been noted by many sailors, but was thought to be a legend brought on by hallucinations. It was also noted in in Jules Verne's 'A Thousand Leagues Under the Sea'.
For those who have heard of the well-known Pixar motion picture 'Finding Nemo', there is a scene in which the main characters are attracted, even mesmerized, with a glowing appendange. As the appendage glows, and Dory and Marlin very nearly become snacks for the predator. The predator is an anglerfish, which exists in real life. The orb attached to its body glows because of the phenomenon known as bioluminescence. Anglerfish use bioluminescence primarily to help them catch food, but it is used for many other functions by various creatures.
Bioluminescence is a reaction between two chemical compounds within the creatures body. So really its a form of chemiluminescence.
Don't confuse it with radiation, incandescence, fluorescence, and phosphorescence. Incandescence is when light is created due to heat, for example, within incandescent light bulbs. The filament in the light bulb heats up and glows in the bulb, getting very hot. Fluorescence is when light is first absorbed and then its released at the same time. Flouresence requires an original light source and cannot take place in totally dark places. Phosphorescsence is a subset of fluorescence, however, the absorbed light is released fro a protracted time, so it can be apparent at night. This phenomenon is shown by marine creatures and is very easily mixed up with bioluminescence.

Bioluminescence properties
Bioluminescence doesn't need a heat source or light source. It can take place in total darkness. It does not create heat nor increase the temperature of its host while producing light.
The phenomenon is generally accomplished by blending two chemical substances, specifically luciferin and luciferase. Luciferin is oxidized to give off light. While Luciferase is a or catalyst that speeds up the effect. Although these are the main chemicals used to create the light, there are various other substances secreted also.
Basically, a test tube of luciferin and oxygen would have a faint glow. Adding some luciferase would give the glow a boost. Adding more increases the the brightness because the chemical reaction speeds up. This also means that the light will glow for a shorter time.
In an organism such as the firefly, the two chemical compounds occur normally in their bodies. When a firefly wants to glow, it will allow in a flush of luciferase, and it starts to glow. We see lights blinking from their bodies because the firefly is managing its bursts of luciferase.
The phenomenon of bioluminescence is a result of evolutionary advancement. It is present more in deep sea creatures than in land-based ones. In the deep sea, the light decreases the deeper we go. After a certain point, it is very dark, even during the brightest daylight. Even without light, there is a thriving ecosystem in the deep oceans.
For many creatures, bioluminescence is a a characteristic for sustenance and survival. It is used for evasion, for luring prey, and for navigation. For these good reasons, bioluminescence has developed.
Anglerfish are particularly efficient predators in the deep sea. Anglerfish have a fishing-rod-like aperture on the top of their body. The tip of this aperture is a bulbous swell that glows and attracts the attention of smaller fish. The luminous bulb is to the front of the the anglerfish's mouth, making for simple and effective ambush.
Research has been performed on this fish and it was uncovered that on its own, it cannot produce all the the chemical substances necessary for luminesence. A special class of bacteria has a symbiotic relationship with the anglerfish and lives inside the bulb to create the enzyme for luminescence.
Most people know about the ink that an octopus sprays to confuse its predator and escape. This is similar to the vampire squid, that spews bioluminescent mucus for up to 10 full minutes. The main advantage of this type of evasions technique is that the spew is brighter than its surroundings so that the vampire squid can escape into the darkness.
The strain of bacteria known as Vibrio fischeri,shows microbial bioluminescence. This is the bacteria contained within the bulb of the anglerfish and some other bioluminescent creature
This bacteria is plentiful in the ocean but is really scattered. There has been occasions where a good span of the ocean was covered by these bacteria and then they give off a radiance. The glow has been sufficient at times to be picked up by a satellite.