Simple Marine Organisms – PLANKTON
Plankton Basics
 What is plankton?
Any organism that floats/drifts with ocean
currents. Being plankton is a behavior, not a size-based or feeding
classification.
 What is nekton?
Organisms that can swim against currents and
control their position in the water- the opposite of plankton.
 Most plankton are

Plankton
tiny , but some- like jellyfish can be large.
comes from a Greek term meaning “drifter”.
 How do plankton remain floating for days or years?
cilia or
flagella (used by the smallest plankton), tentacles (jellyfish), oil
(being lighter than water), and long spikes to distribute their body
weight.
Phytoplankton

Phytoplankton are
primary producers
that use the
sun’s energy to convert CO2 and
H2O into sugars.
 In doing so, they form the base of the ocean’s food chain , and
provide more than 50% of our world’s O2.
 Because of these two roles, phytoplankton are arguably
important organisms on Earth!
the most
 The growth of
phytoplankton depends on temperature ,
light , and
nutrient availability. Because of their light
requirements, the growth of phytoplankton is limited to the photic
zone
 Examples of
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Zooplankton
phytoplankton
include:
diatoms : unicellular algae with skeletons of silica
dinoflagellates : unicellular algae with flagella
cyanobacteria : called blue-green algae- actually bacteria
green algae : unicellular green protists
coccolithophores : unicellular algae with CaCO3 plates
 Zooplankton
are passively drifting animals. Can range from micro
to macro in size.
 Example of
zooplankton
include:
radiolarians
: unicellular protozoans with silica tests
foraminifera
: unicellular protozoans with CaCO3 tests
larvae
: newly hatched young of fish/invertebrates
crustaceans : including tiny copepods, cladocerans and
ostracods, and larval krill and shrimp
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jellies : multicellular stinging organisms including true
jellyfish, comb jellies, and their relatives
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Planktonic organisms can be either:

Meroplankton
: organisms that spend
only part of their
lives
as plankton (for example: fish and invertebrate larvae)
 Holoplankton
: organisms that spend
their entire
lives
as plankton (for example:
diatoms, jellyfish, copepods)