worldbio

Life styles of organism found in the pelagic zone in the ocean

3 major life styles of organism found in the pelagic zone in the ocean.

1. pleuston

2. plankton

3. nekton

1.Pleuston

The animals feed on neuston are pleuston . part of their bodies projected into air .and not capable of directional locomotion.sails possessed by them enable the movement with the direction of wind.

All are carnivores belongs to hydrozoan  Cnidaria : Vellella & Physalis

Neuston

These are found on surface and are highly productive part of the ocean & supports biomass of life.

They are bluish in colour. : Zooplankton, decapods crustacean, floating fish eggs.

2.Plankton

They are weakly swimming organisms so they mostly depend on water currents for locomotion.

According to the size they are classified into:

Ultra nanoplankton , nanoplankton, microplankton , megaplankton.

Phytoplankton

They capture the sun’s energy to marine environment is important.

Among those diatoms are most important.

Dinoflagellates also common neritic & mid latitude waters. Their blooms form red tides. They release toxins to surrounding waters & kill many aquatic organisms.

Zooplankton

They are also small ,capable of limited movement  feed on phytoplanktons.

They are : micro planktons ,macro  planktons,  mero planktons 

 

Micro planktons : protozoans such as foraminiferans ,radiolarians & tintinnids.

Foraminiferans are primarily benthic although some planktonic forms are common

They have Calcium carbonate shells  ,shells sink & become part of the sediments.

Sediment is also called “ globigerinous ooze “ .

Radiolarians have silica skeleton of intricate lattice work extending from the body as spines.

Sediments of their skeleton are called radiolarian ooze.

Tintinnids are small ciliated protozoa  with shells called lorica . shell is made up of chitinous material secreted by  protozoan & it may adorned with particles o sand / coccoliths.

Macro planktons

These are Ctenophora & chaetognatha .

Ctenophora shows rotational movements using their Ctenes.

And scyphozoan medusa & siphonophora are 2 groups of Cnidaria are colonial forms.

Few annalids ,snails  & tunicates also included.

Meroplankton

They are species that spend part of their life cycle in plankton. most of them are larval forms. Such as mysids in shallow water spend day time in benthos & night among plankton. Often have a sessile stage in their life cycle.scyphozoan medusa.

3.Nekton

These animals can swim well &can  move against the water current. Fishes, squids,marine mammals ,marine reptiles are included.

 

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