Plankton classification based on size
Picoplankton – any planktonic organism between 0.2 and 2µm in length. Picoplankton can be
either prokaryotic or eukaryotic, including the cyanobacterium Synechococcus and the flagellated
heterokonts Triparma and Florenciella.
Nanoplankton – autotrophic, heterotrophic and mixotrophic microbes between 2 and 20µm in
length. This group includes the majority of flagellated protists, and some smaller diatoms and
ciliates. Examples include the flagellates Gymnodinium and Thalassomonas, and the diatom
Chaetoceros.
Microplankton – any planktonic organisms between 20 and 200µm, these can be phytoplankton,
microzooplankton or mixotrophic organisms, and include diatoms, other green algae, some
invertebrate larvae and protozoa. Example species include the diatom Pseudo-Nitzchia, the
dinoflagellate Dinophysis, and the ciliates Strobilidium and Didinium
Mesoplankton – all plankton between 200µm and 2mm in length. This group contains many
metazoan zooplankton, such as ostracods, copepods, tunicates and medusae. Example genera
include Diaptomus, Tomopteris, Oikopleura and Centropages
Macroplankton – any plankton between 2mm and 200mm in size. This grouping contains larger
zooplankton, including jellyfish and planktonic crustaceans. Example species include Oxygiris,
Euphausia superba and Bolinopsis vitrea
Megaplankton – all plankton over 20cm in size. This group incorporates all larger forms, such as
larger medusae, ctenophores and macroalgae. Examples include Cyanea capillata, Mnemiopsis,
Macrocystis pyrifera and Phacellophora camtschatica
Picoplankton – any planktonic organism between 0.2 and 2µm in length. Picoplankton can be
either prokaryotic or eukaryotic, including the cyanobacterium Synechococcus and the flagellated
heterokonts Triparma and Florenciella.
Nanoplankton – autotrophic, heterotrophic and mixotrophic microbes between 2 and 20µm in
length. This group includes the majority of flagellated protists, and some smaller diatoms and
ciliates. Examples include the flagellates Gymnodinium and Thalassomonas, and the diatom
Chaetoceros.
Microplankton – any planktonic organisms between 20 and 200µm, these can be phytoplankton,
microzooplankton or mixotrophic organisms, and include diatoms, other green algae, some
invertebrate larvae and protozoa. Example species include the diatom Pseudo-Nitzchia, the
dinoflagellate Dinophysis, and the ciliates Strobilidium and Didinium
Mesoplankton – all plankton between 200µm and 2mm in length. This group contains many
metazoan zooplankton, such as ostracods, copepods, tunicates and medusae. Example genera
include Diaptomus, Tomopteris, Oikopleura and Centropages
Macroplankton – any plankton between 2mm and 200mm in size. This grouping contains larger
zooplankton, including jellyfish and planktonic crustaceans. Example species include Oxygiris,
Euphausia superba and Bolinopsis vitrea
Megaplankton – all plankton over 20cm in size. This group incorporates all larger forms, such as
larger medusae, ctenophores and macroalgae. Examples include Cyanea capillata, Mnemiopsis,
Macrocystis pyrifera and Phacellophora camtschatica
