Adaptations of pelagic organism to Over come predation


Lack of colour is an adaptation of life in photic zone :planktons and transparancy of zooplanktons reduce their visibility in pelagic zone thus reduce the chance of being discoversd by predators.;

Blue colour of neuston to reduce the predation from sea birds.

Some zooplanktons are red & silver colour ;silver colour produces mirror like reflection.

Red colour is strong absorber to blue green light thus make diffult for predator to form a sharp immage in bioluminescent light.

Many fishes use counter shading colour pattern in which the upper part of the body is dark makes difficult see them from above & lower part of the body is lighter so that predators look up towards the brightly lit surface can’t see them.

Locomotory powers

Many adapted to swim fast some meso plankton have cilia ;

Fishes having streamline body surface secretes slime & special ribbing of skin to reduce the drag.

Tuna like fishes have lunate tail & retractable finlets to increase the swimming speed & ther mussels are well developed for it.


Vertical migration of  zooplankton diurnally during the day they move down wards to avoid predation by pelagic fish & at night they move to surface .


Bacteria , phytoplankton ,zooplankton, benthic invertebrates   & fish .

Generally blue /greenish  ;

Dinoflagelate ,  ctenophora, copepods , medusa may produce light but some bacteria luminesce constantly.

Function is startle or blind predators .predators man scared / confused by flash of light.

Other defensive adaptations

Small size & transparency of planktons is most common to avoid detection by predators.

Schooling is a common adaptation of fishes (makeral) & zooplanktons this behavior of forming large schools may confuse predators.

Largebody size : some can contain large amount of water in their tissues :puffer fish.

Grow spines : Foraminiference &Radiolariana.

Some use toxins :skin of the parrot fish has toxins.

Squids use several ways:

Ink ejection : they eject cloud of ink and become hidden while escape.

Jet propelsion: propel spray of water on predator to escape.

Colour change .








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