Animals show a great diversity in their structure and functions (working of their lining machinery),
Some living animals have a surprising and unique quality which is the luminescence (the production of light). This property is present among almost all the groups of animals starting from the bacteria and unicellular animals to the highest multi cellular organisms the chordates.
Quality of light production is present in marine, land and fresh water animals.
Some of these animals are continuously illuminated and others produce light at any stimulus.
Luminescence Production
Energy can be transformed from one form to another, as a rule. The animals transform the chemical energy of their body into light energy.
The conversion is done by some granules in the unicellular animals and bacteria or by cells which form the organs in the higher animals.
These granules, cells and organs contain two substances,
1- Luciferin (A heat stable substance)
2- Luciferase (enzyme)
These two substances can be extracted from these organs by water. These can be mixed to produce light but these are group specific i-e the both chemicals should be from same group of animals, otherwise, these cannot produce light.
Two ways of luminescence
1- These chemicals are released in water or outside the body which mix to produce light.
2- The light reaction occurs inside the body and body looks like illuminated.
Reasons of luminescence
This is an adaptations of animals for their survival in the environment. It serves for three main purposes,
1- Sexual Attraction
Animals use this light for sexual attraction, just like the voice of male frogs that that act as signal for the females.
2- Protection
Light is used fro the protection by either blinding the prey or by escaping the site of predator.
3- Attraction of Prey
It is also used to attract the prey. Prey is attracted towards the light.
Groups of animals which show luminescence
Luminescence is present in many groups of animals, which are as follows,
Protozoa
Among protozoa, marine radiolarians and dinoflagellates show luminescence.
Coelentrate
This group show a lot of luminescent animals like jelly fish, sea pens etc.
Annelida
In this group some marine forms (polychaeta and oligochaeta show luminescence
Arthopoda
In this group, many animals produce light, shrimps, beetles bugs and flies produce luminescence
Mollusca
In mollusca, squids, calms show luminescence. Squids show too much development of luminescence.
Echinodermata
In this group, only ophiuroids (brittle stars) show luminescence.
Chordata
Among chordates, the most lowest group, the protochordates and some fishes show luminescence.
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