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Plankton
Picoplankton: Viruses, archaea, bacteria
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Fluorescent image of openocean
• water sample showing
marine viruses (small dots)
and either bacteria or
archaea (large dots).
Most viruses are <0.2 µm.
Picoplankton (which include
cyanobacteria) may
contribute up to 70% of
photosynthetic activity in
some ocean regions.
So small that they were not
even recognized by
oceanographers until mid
1970’s.
(Text Fig. 14-25, p. 422)
The three main phytoplankton groups
1) Diatoms (silica skeletons, non-swimming)
2) Dinoflagellates
(cellulose skeletons,
swim with flagella)
3) Coccoliths (calcareous skeletons,
non-swimming)
(Text Fig. 14-10, p. 405)
Diversity of protist phytoplankton
Dinoflagellates (naked or cellulose skeletons)
Ceratium
Noctiluca: luminescent
Diatoms (silica skeletons)
Deadly phytoplankton: Red-tide dinoflagellates
Gonyaulax: Produces “Red-tides”
concentrated
dinoflagellates in
digestive gland
A “blood-oyster” following a
red-tide in Cortes Island, BC
(photos by Christian Gronau)
“Red-tide” Cortes Island, BC
Diversity of protist zooplankton
Foraminifera: chambered, mostly calcareous skeleton
foram
Radiolaria: radial, mostly silica skeleton
Ostracod!
spine-like axoopods
Heliozoa
Mostly from: Image Quest 3-D (http://imagequest3d.com)
Mesozooplankton: Copepods- the most numerous animals on earth
Animations:
male
female
mating pair
swimming & attack behavior
female with eggs
Copepods may be grazers
(primary consumers) or
predators (secondary
consumers)
prey capture
(Text Fig. 15-5, p. 429)
Gelationous mesoplankton & macroplankton
Ctenophore: Pleurobrachia
Colonial salps (Urochordata): Salpa
(Text Fig. 15-8, p. 431)
Macrozooplankton: Ctenophora (sea gooseberries)
comb rows
The
voracious
predator, Beroe;
swallows other
ctenophores whole
(Roger Steene,
“Coral Seas”, 1998)
Sea-butterfly, Ocyropsis
(Roger Steene, “Coral Seas”, 1998)
Mnemiopsis
Pleurobranchia
Cestus
(note 2 long,
branched tentacles)
Unnamed
deep-sea
species
Other mesoplankton & macroplankton: Chaetognaths
Chaetognaths are
major predators on
small zooplankton.
(Text Fig. 15-9,
p. 432)
Chaetognatha: arrow worm
Macrozooplankton: Krill (Crustacea)
Krill (euphausiid shrimp) are major primary consumers in the
world’s Southern Oceans. They, in turn, are important prey
for baleen whales because they may form swarms that are
kilometers across . . . visible from an airplane!
Adaptations to reduce sinking
Characteristic forms of warm-water (left)
and cold-water (right) copepods
A warm-water diatom that has
a prominent marginal ring to
increase its surface area and
reduce its rate of sinking
(Text Fig. 13-9, p. 381)
(Text Fig. 13-7, p. 380)
end