1. Heterotrophic – they require organic substrates (as opposed to inorganic ones)
Herbivores – which consume plants;
Carnivores – which are capable of eating only other animals;
Detritivores – which consume dead organic material.
Omnivores – with mixed diets of plant and animal material.
Holoplankton – (or permanent plankton) spend their entire life cycles in the water
column.
Meroplankton – are temporary residents of the plankton community.
Protists – the smallest of the zooplankton are certain unicellular.
Dinoflagellates – that are partly wholly heterotrophic.
Zooflagellates – includes all those species that are colourless strictly heterotrophic
Foraminifera – which are characterized by having a calcareous perforated shell, or
test, that is usually composed a series of chambers.
Foraminiferan ooze – the shells of these protozoans sink and accumulate in large
quantities on the seafloor, forming a sediment.
Radiolaria – are spherical, amoeboid protozoans with a central, perforated capsule
composed of silica.
Radiolarian ooze - a sediment composed of the siliceous remains of these protozoans
Ciliates – are present in all marine regions and are often extremely abundant.
Tintinnids – make up one large subgroup (>1000 species) of marine ciliates.
Medusae – are conspicuous and common inhabitants of both the open sea and coastal
waters.
Siphonophores – in which many individuals with specialized functions are united to
form the whole organism.
Ctenophores – are closely related to jellyfish, but their structure is sufficiently different
to warrant their placed in a separated phylum.
Chaetognaths – are one of the best known and most abundant carnivorous planktonic
groups.

2. Polychaete – (Phylum Annelida) genus Tomopteris with about 40 species distributed
throughout the world ocean.
Heteropods – are a small group of molluscs that are closely related to snails, but these
pelagic forms swim by undulating motions of a single fin developed from the creeping
foot of their benthic ancestors.
Pteropods or Thecosomes – (are also Holoplankton snails) most of them have a thin,
external, calcareous shell measuring from a few to about 30 mm in largest dimension.
Pteropod ooze – is a carbonate shells of dead animals eventually sink and accumulate
in certain areas to form a type of sediment.
Gymnosome – these animals lack shells as adults, but they too swim by means of
paired wings.
Copepods – are the predominant forms.
Calanoida – which comprises about 1850 species, free living calanoid copepods are
present in all marine regions and usually make up 70% or more of all net-collected
plankton.
Nauplius – the first six stages (plural, nauplii) larvae;
Copepodite – the last six stages (CI to CVI) with CVI being the sexually mature adult.
Cyclopoida – differs in that members have relatively shortened antennae and more
segments in the posteriot third of the body.
Harpacticoida – are coastal or live in association with the sea bottom.
Euphausiids – from another important group of marine Crustacea with 86 species.
Krill – where this abundant species is a major component of the diet of many larger
animals and is itself harvested commercially.
Amphipods – are distinguished from other Crustacea by having laterally compressed
bodies.
Ostracods – are usually minors components of the zooplankton community.
Cladocera – (including Daphnia, the common water flea), there are only about eight
marine species.
Parthenogenesis – (i.e. reproduction without males and without fertilization)
Mysids – they seldom are important components of the plankton community.

3. Decapods – a group that encompasses shrimp, lobsters, and crabs.
Appendicularians / Larvaceans – are closely related to benthic tunicates or sea
squirts.
Marine snow – a term applied to macroscopic aggregates of amorphous particulate
material derived from living organisms.
Salps – constitute another class of chordates, but these animals are commonly found
only in warm surface or near-surface waters. (Solitary and aggregate)
Veliger – is a larva that has a distinctive ciliated membrane (called a velum) that is used
for locomotion as well as food collection.
Cypris – this attaches to a substrate and metamorphoses to the adult.
Trochophore – larva, with several bands of cilia, that eventually develops a segmented
body and appendages before settlement.
Megalopa – that resembles a miniature adult.
Ichthyoplankton – is an important part of the meroplankton.
Pleuston – are sometimes considered to form a special category because they are
passively transported by wind instead of by currents.
Neuston – includes those species that inhabit the uppermost few to tens of millimeters
of the surface water.
Counter-shading – that is, those body surfaces that are directed downward in the
water are lighter in colour that areas close to the surface, and this too may be a
predator defence.
Endemic – (that is, those restricted to this particular habitat) including some of the
crabs, and fish, have developed special camouflage protection by coming to resemble
Sargassum weed both in shape and colour.
Epipelagic zone – extending to 200 or 300m
Mesopelagic zone – lies between the bottom of the epipelagic region and a depth of
approximately 1000 m, and the animals that live here in the daytime.
Oxygen minimum layers – where oxygen concentrations may fall from the normal
range.