1. Phytoplankton

2. The phytoplankton - principal source of primary nutrition
Produces organic matter through photosynthesis
Contribute to about 95% of primary production in the oceans and supports the secondary production (zooplankton) and tertiary production (fish, shellfish, mammals, etc.)
About 5,000 phytoplankton have been identified in aquatic ecosystem

3. Diatoms 
Common forms of centric diatoms are Coscinodiscus, Chaetoceros, Biddulphia, Skeletonemia, Thallassionema, and Bacteriastrum, Thalassiosira, Navicula, Triceratium
Some common pennate diatoms are Pleurosigma, Gyrosigma, Rhizosolenia, Thalassiothrix, Thalassionema and Nitzschia

4. Dinoflagellates
Are next to diatoms
Abundant in trophical water producing red tides
The genera of Peridinium and Ceratium are most commen in the plankton
Common unarmored (“naked”) representatives of dinoflagellates are Gymnodinium, Cystidinium, and Glenodinium

5. Common armored dinoflagellate species are Peridinium, Ceratium, Dinophysis, and Goniaulax etc.
Non-photosynthetic species - Noctiluca. Sp.
Certain species produce a poison – PSP
Red tide is by Goniaulax sp. and Gymnodinium brevis. Noctiluca scintillans exhibit bioluminescence

6. Coccolithophores
Are one-celled marine plants that live in large numbers in the upper layers of the ocean
Abundant in the sub-trophical areas and also live in most subpolar regions.
Importatent forms - Dicrateria, Phaeocystis, Coccolithus, Prymnesium etc.

7. Silicoflagallates
Phytoflagellates are algae
Abundant in phytoplankton
Important forms are Dictyoche, Distephanus, Chromulina etc.

8. Blue-green algae
Are the hard, simple algae
Chief primary producers of organic matter
Trichodesmium sp species are tropical, dominant in warm seas and forms blooms
Green algae
The green algae are unicellular and colonial flagellates, often colonial, commonly found in fresh water.
Trichodesmium sp

9. ZOOPLANKTON
Are heterotrophic plankton except bacteria and viruses
Size range from 2 µm (flagellates) to several meters (jellyfish)
Adaptation to a pelagic mode of existence – holoplankton
Larval forms present temporarily in the plankton are called meroplankton

10. The holoplankton includes – foraminiferans, radiolarians, siphonophores, ctenophores, pelagic polychaetes, copepods, cladocerans euphausids, chaetognaths, pteropods, salps etc.
Whereas meropkankton - the drifting larval stages of numerous littoral and benthic species such as polychaetes, barnacles, decapods crustaceans, echinoderms, molluscs etc.
Fish eggs and fish larvae - ichthyoplankton