Bioluminescence

Remember the Episode of Little mermaid, where Ariel befriends a huge purple sea monster called Simon? I guess it was called "Message in Bottle". Let me recap it a bit, Simon sends a message in a bottle, with a map on back, and Ariel and her gang follows the map to a dark cave where they bump into a jolly old "Lantern Fish" with a lit-bulb hanging out of his head? Remember him? If you don't just follow this link.. Tadaaa

Unfortunately I have never got the chance to see a real lantern fish, or any other fish that lit up deep in the ocean yet. Hope to see one soon though. Ever wondered how they are able to light up themselves like that?

This phenomena is referred to as "Bioluminescence", in which a compound called "LUCIFERIN" is oxidised with the help of Luciferase enzyme that results in a molecule which emits light. The type of Luciferin and Luciferase may differ from species to species, but the reaction is similar.

Those underwater organisms that exhibit this feat, have a special organ in them called the photophores to emit light. The complexity of this organ varies from species to species; it could be just a a bunch of glandular-like light emitting cells packed together, a simple glandular cup that holds bacterial culture (mostly vibrio or photobacterium cultures) that produces light, or the photophore may also have lenses to focus the light, a color filter, or an adjustable diagphragm of pigment cells.

There are several hypotheses formulated as to why these fishes emit light; most believe the light is used to capture food, or as a defence mechanism against predators. Zzzzzz