Why Do Certain Animals Glow?

 

By the time it gets dark, or say, deep under the ocean where there is no sunlight, certain animals glow naturally.

This ability to naturally glow in the dark is defined as bioluminescence. This happens when a creature capable of producing and emitting light as a result of a chemical reaction converts chemical energy to light energy. 

Bioluminescence can occur in two ways:

•  when a creature has a light-emitting organ called “photophore,” which can be simple or complex, capable of producing light after the digestion of a prey (example: cephalopods like the Sparkling Enope Squid)
• as a product of symbiosis with bacteria after it enters the animal’s body. These bacteria will reside and multiply, which will later result in a collection of very bright lights.

Normal luminescent reaction involves the oxidation of a pigment called “luciferin” to produce light:

luciferin + O₂ → oxyluciferin + light

Now, this process is extremely slow, until an enzyme called “luciferase” acts as a catalyst to the reaction, presenting cofactors such as ATP or calcium ions. Thus giving this much faster process reaction:

luciferin + ATP → luciferyl adenylate + PP_i

luciferyl adenylate + O₂ → oxyluciferin + AMP + light

Examples of bioluminescent creatures:

Angler Fish

Angler fishes are bony fishes that have at least one long fleshy filament growing from the middle of its head, used for predation. Most anglerfishes live in the deepest, darkest part of the ocean. The filament in the middle of its head is bioluminescent, and acts as a lure. When it glows, smaller fishes and other deep-sea creatures get attracted to the light. As soon as they swim towards it, the angler fish will strike and eat them up.

philpage3d.com

Flashlight Fish

The flashlight fish has a large bioluminescent organ beneath its eyes containing bright red bacteria. This fish uses its light to attract prey, find food, and communicate with other flashlight fishes. (image from philpage3d.com, visit the site for more interesting stuff)

Firefly

Fireflies belong in the beetle family of insects in the order Coleoptera. They are sometimes called lightning bugs because they produce light from the lower abdomen, varying from yellow, red, and green, with no ultraviolet or infrared frequencies.

Their bioluminescence is for attracting mate at night. Currently, there are 2,000 known species of fireflies living in the tropical environment. Their larvae also glow and are often called “glow worms.”

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