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Plankton
What is Plankton?
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Animals and plants that either float
passively in the water, or possess
such limited powers of swimming that
they are carried from place to place
by the currents.
Where does the word
“plankton” come from?
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The word plankton comes from the
Greek word planktos, which means
‘wandering’ or ‘drifting’.
Where are plankton found?
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Plankton dominates the well-lit
surface layers of the world's oceans.
Types of Plankton
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Phytoplankton- microscopic plants and
bacteria.
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Zooplankton- microscopic animals
Phytoplankton
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Carry out photosynthesis.
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Produce 80% of the Earth’s oxygen and 7580% of the organic matter.
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Why must they live in the photic zone?
Can undergo rapid population growth
or “algae blooms” when water
temperatures rise in the presence of
excess nutrients.
 During a bloom most phytoplankton
dies, sinks to bottom and decomposes.
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This depletes the bottom waters of
dissolved oxygen which is necessary
for the survival of other organisms.
Plankton Bloom
Picture taken by
astronauts from the
International Space
Station.
Location: the
Capricorn Channel
off the Queensland
coast of Australia.
Trichodesmium -photosynthetic
cyanobacteria, also
called "sea saw
dust"
Phytoplankton
Impact of Ozone on
Phytoplankton
Produce more oxygen than all plant life on
earth and are vital in maintaining the
earth’s atmosphere.
 They are also the organisms most likely to
be affected by global warming and climate
change.
 Scientists around the world are concerned
that harmful rays from the sun could pass
through the hole in the ozone layer and kill
phytoplankton, which live mostly in the
upper layers of the ocean.
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Diatoms
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Single-celled yellow green algae.
Have a cell wall.
Cell wall contains silica, a glass-like
substance.
Come in lots of shapes and sizes
Intricate lines and etchings

Word “diatom” means cut in two
because its cell wall is made of 2
parts one fitting over the other.
Kind of like a
petri dish!!!
Diatoms
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Probably the single most important
food source in the ocean!!!!
YUMMMY!!!
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Eaten by small plankton and by larger
oysters and clams.
Dinoflagellates
Propel themselves using 2 flagella
 Can swim like simple animals
 Photosynthesize like plants
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2 Species: Gonyaulax &
Gymnodinium responsible for
Red tides
What is a Red Tide?
Plankton-rich water.
 Responsible for fish mortality and
paralytic shellfish poisoning.
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Zooplankton
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Floating or weakly swimming animals
that rely on water currents to move
any great distance.
– Microzooplankton (< 200 microns) in size
– Mesozooplankton (200 microns- 2 mm)
– Macrozooplankton (> 2 mm)
Classified according to size
Smallest  Largest
Nannoplankton (Ex. Protozoans)
 Microplankton (Ex. Primarily eggs and larvae,
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usually of invertebrates).
Macroplankton (Ex. Copepods)
 Megaplankton (Ex. Portuguese Man of War)
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Camouflage
Zooplankton are the favorite food of a
great many marine animals so camouflaging
themselves is a very important survival
strategy.
 Developing effective camouflage when you
live in clear, blue water is no easy matter.
 The best solution and the one most often
used by members of the zooplankton is to
be as transparent as possible or, in the
case of many surface floating jellyfishes,
blue.
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There are two major types
of zooplankton:
1) Those that spend their entire lives
as part of the plankton (called
HOLOPLANKTON)
2)Those that only spend a larval or
reproductive stage as part of the
plankton (called MEROPLANKTON).
Holoplankton
Blue Sea Slug
 Adapted for life floating upside
down in the sea and is often found
with the beautiful blue jellyfish
Porpita.
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Blue Sea Slugs feed almost exclusively on
the tentacles of 'Bluebottles'.
 Interestingly, the nematocysts (stinging
cells) on these tentacles pass through the
Blue Sea Slug intact. The slug can then use
these stinging cells in its own defense.
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Holoplankton
Heteropod Atlanta
peronii
A snail with a thin fragile shell containing only a
heart and gills. It swims upside down. Can eat prey
as large as itself with its toothy tongue (radula).
Polychaete Worm or bristle
worm.
Most are mesoplanktonic.
Portuguese Man of War
Also called bluebottle.
They are a colony of polyps.
They feed using their long
tentacles on surface plankton.
Meroplankton
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Meroplankton spend only the larval or
early stages of their life as part of
the plankton and spend their adult
lives on the reef.
Meroplankton
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Many meroplankton bear little
resemblance to the adults that they
will become.
Meroplankton
 While
living in the plankton,
meroplankton either feed on
other members of the plankton,
or they live off the yolk they
have retained from the egg they
hatched from.
Meroplankton
Larvae spend varying amounts of time
in the plankton, from minutes to over
a year.
 However, just how long these tiny
animals can be considered truly
planktonic is under some debate.
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Meroplankton- Examples
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sea urchins
Starfish
sea squirts
most of the sea snails and slugs
crabs
Lobsters
Octopus
marine worms
most reef fishes.
Meroplankton
Lobster Larvae
Lobster Larvae
Anemone Larva & Adult
Sea Cucumber Larva & Adult
Brittle Star Larvae & Adult
Cone Shell Larvae & Adult
Octopus Larvae & Adult
Starfish Larvae & Adult
Meroplankton
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Meroplankton that sinks to the
bottom of the ocean and lives there is
called BENTHOS.
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Nearly 16% of all animal species are
benthic.
There are 3 types:
INFAUNA- animals that live in the
bottom like clams and worms
 EPIFAUNA- animals on the bottom
surface like crabs, coral and starfish
 EPIFLORA- plants that live on the
bottom.
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Epidermis ( epi- means on the
surface)
Nekton
Not plankton
 Swim
 Ex. Invertebrates & vertebrates
(Squid)
(Whales)
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How long are they larvae?
Larvae spend varying amounts of time in
the plankton, from minutes to over a year.
 However, just how long these tiny animals
can be considered truly planktonic is under
some debate.
 Scientists in recent years have discovered
that many of these tiny animals in the
plankton quickly become very good
swimmers capable of incredible speed and
endurance.
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Marine Protozoa
Protozoan = one celled organism.
 Usually microscopic
 Most live in water
 Some are plankton, others benthic
 Three groups: Sarcodinians, ciliates,
flagellates.
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Sarcodina
Word “sarcodina” means creeping
flesh.
 Describes how they move.
 Contract and expand projections of
their bodies called pseudopodia or
“false feet.”
 2 groups: forams & radiolarians
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Facts about Forams
Shell made of Calcium carbonate.
 Pseudopodia project out through
holes in shell.
 Feed on diatoms & other protozoans.
 Secrete digestive juices onto their
food to dissolve it!!!
 Waste expelled through body
surface.
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Globigerina
Planktonic
 Large amount of
these shells have
been deposited
in sediment.
 Studied to reveal information about
climate in past geological eras.
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Archaias angulatus
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Turtle grass foram
Archaias compressus
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Button foram
Radiolarians
Mostly planktonic
 Perforated outer skeleton of silica.
 Pseudopodia extend through holes as
long, sticky filaments.
 Skeleton does NOT dissolve at great
depths like the Forams.
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Radiolarians
Studied by micro
paleontologists
Radiolarian Art
Artist: Barbara West
Canada
Artist: Eva Bjerke
(Sweden)
Ciliates
Covered with hair like cilia
 Cilia used in eating, locomotion,
respiration.
 Most are solitary and free swimming.
 Some are attached and colonial.
 Common among sand grains (eat plant
cells and bacteria!)
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Ciliates
Tintinnids
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Bell animals
Planktonic ciliates
Common in open ocean
Ring of cilia surround mouth (locomotion &
catching food).
Hard shell of protein.
Phylum Mastigophora
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Flagellates
Propelled by a flagella
Whip like
Colonial, live attached to
bottom. Collar filters particles
from the water.
Choanoflagellates
The most abundant members of the
zooplankton, both in species and total
numbers are the crustaceans.
 Crustaceans include lobsters, crabs,
prawns, pill bugs, krill, barnacles,
water fleas, brine shrimp (sea
monkeys) and copepods.
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