PLANKTON

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PLANKTON

• planktos - Greek for drifter or wanderer
• Organisms that are passively carried along with
  the flow of the water - they are at the mercy of
  currents and winds
• 2 types of plankton
• Phytoplankton
• Zooplankton

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Phytoplankton

• Photosynthetic plankton (plants)
• Need to live near the surface
• e.g. diatoms

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More phytoplankton

• e.g. cyanobacteria, green algae
• e.g. dinoflagellates

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Zooplankton

• animal plankton

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2 groups of zooplankton

• Holoplankton and meroplankton
• Holoplankton - spend their whole life as plankton
  e.g. comb jellies, copepods
• Meroplankton - only part of their life cycle is
  spent in the plankton before they metamorphose
  and live benthically e.g. crab larvae,
  sea star larvae, barnacle larvae

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More zooplankton
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Plankton videos and images

• http//www.racerocks.com/racerock/archiveinvertebr
  ates.htm
• http//jellieszone.com/pacificjellies.htm

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Physical adaptations of planktonic organisms

• Transparency e.g. chaetognaths
• Red or black in color e.g. deep-sea shrimp
• Gelatinous e.g. jellyfish, larvaceans, comb
  jellies
• Increase surface area
• with spines e.g. diatoms, crab larvae
• by flattening body e.g. amphipods
• Oil droplets for buoyancy e.g. diatoms
• Big eyes e.g. amphipods

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Behavioural adaptations of planktonic organisms

• Vertical migration e.g. krill, copepods
• Bioluminescence
• http//www.lifesci.ucsb.edu/biolum/organism/photo
  .html

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Importance of plankton

• Base of marine (and freshwater) food webs
• Copepods are the largest source of protein in the
  ocean
• Major role in material cycling (carbon fixation
  by phytoplankton nitrogen fixing bacteria)
• Responsible for at least 40 of total
  photosynthesis on earth
• Dispersal of organisms (meroplankton)
• Introduced species by ballast water
• Red tides

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For further information

• Marine Biology by J. Nybakken
• pp. 38 - 54