Plankton

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Plankton
http//www.dnr.sc.gov/marine/sertc/gallery.htm
http//www.coralreeffish.com/larvae.htm
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Ocean Zones

• Horizontal divisions
• Coastal (neritic) on/over shelf (shallow)
• Oceanic beyond continental shelf (deep)

• Vertical divisions
• Pelagic open water
• Benthic
• ocean bottom

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Ocean Zones
Holoplankton Meroplankton
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Plankton or Nekton?
How fast can you swim?

• Gulf Stream peak velocity
• 5 knots 2.5 m/sec
• Surface currents more typically
• lt0.5 knot 0.25 m/sec (0.56 mph)

http//oceancurrents.rsmas.miami.edu/atlantic/img_
mgsva/gulf-stream-YYY.gif
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Plankton or Nekton?
Swim faster than 25 cm/sec?

• Yes ? Nekton
• Dolphin 170 cm/sec (up to 40 mph!)
• Tuna 75 cm/sec (higher burst speeds)
• No ? Plankton
• Shrimp 5 cm/sec
• Bacteria 0.005 cm/sec

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Slow, but not necessarily small
Portuguese man-of-war float 12 inches
wide tentacles over 150 ft. long (ouch!)
http//www.dnr.sc.gov/marine/sertc/gallery.htm
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Net Plankton
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Phytoplankton

• Cyanobacteria
• Unicellular microalgae
• Diatoms
• Dinoflagellates
• Coccolithophorids

c2004 Pearson Education, Inc., publishing as
Benjamin Cummings
http//www.daviddarling.info/images/diatoms.jpg
http//www.microscopy-uk.org.uk/micropolitan/fresh
/protozoa/ceratiumdic2.jpg
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Zooplankton

• Divided by life history
• Holoplankton spend whole life (larval and
  adult stages) living as plankton
• Meroplankton spend only larval stage living as
  plankton, then grow up to be nekton or benthic as
  adults

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Zooplankton - Holoplankton

• Protozoans (unicellular)
• Foraminiferans
• Radiolarians
• Ciliates

http//server1.fandm.edu/Departments/Biology/Peopl
e/Shimeta/research/tin2.JPG
http//www.anu.edu.au/EMU/Images/radiol.jpg
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Zooplankton - Holoplankton

• Gelatinous
• Jellyfish (medusa)
• Siphonophores

NOAA
http//life.bio.sunysb.edu/marinebio/plankton.html
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Zooplankton - Holoplankton

• Gelatinous
• Comb jellies
• (ctenophores)

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Zooplankton - Holoplankton

• Gelatinous
• Salps
• Larvaceans (invertebrate chordates)

NOAA
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Zooplankton - Holoplankton

• Molluscs
• Pteropods (gastropods),
• with and without shell

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Zooplankton - Holoplankton

• Crustaceans
• Copepods
• Amphipods
• Ostracods
• Isopods
• Krill, shrimp

http//www.oceanexplorer.noaa.gov/gallery/livingoc
ean/livingocean.html
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Zooplankton - Holoplankton

• Arrow worms (Phylum Chaetognatha)

http//pharyngula.org/images/chaetognathhead.jpg
http//www.microscopy-uk.org.uk/mag/imgjan00/CHAET
2b.JPG
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Zooplankton - Meroplankton

• Mollusc larvae
• Trochophore
• Veliger

http//people.bu.edu/veliger/
http//oceanlink.island.net/abaloneproject/growtha
nddevelopment/growth20and20development.htm
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Zooplankton - Meroplankton

• Crustacean larvae
• Crab zoea
• Shrimp, barnacle nauplius
• Lobster phyllosoma

NOAA
http//www.dnr.sc.gov/marine/sertc/gallery.htm
http//www.science-in-salamanca.tas.csiro.au/theme
s/larval/phyllosoma-early.htm
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Zooplankton - Meroplankton

• Other larvae
• Starfish (bipinnaria)
• Brittle stars, urchins (pluteus)

http//raven.zoology.washington.edu/embryos/
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Zooplankton - Meroplankton

• More larvae
• Polychaete worms (trochophore)

http//www.microscopy-uk.org.uk/mag/imgmar99/poly3
.jpg
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Zooplankton - Meroplankton

• Fish larvae

http//www.coralreeffish.com/larvae.htm
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That Sinking Feeling

• Its a long way down average ocean depth
  around 4000 m
• Phytoplankton need to stay in the light
  surface layer (0-200 m)
• Zooplankton eat the phytoplankton and/or other
  zooplankton, so need to be where the food is

http//www.nerc.ac.uk/images/photos/lp-ocean-sunli
ght.jpg
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That Sinking Feeling

• Why am I sinking? Denser than water
• Densities (in g/cm3)
• Seawater 1.025
• Air 0.00125
• Lipids 0.9
• Proteins 1.3
• Carbohydrates 1.5
• Cellulose 1.5
• Silica shell 2.6
• Calcareous shell 2.8

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That Sinking Feeling

• How not to sink
• Float
• Lipids (less dense than water)
• Gas vacuoles, sacs, bubbles

http//www-cyanosite.bio.purdue.edu/images/images.
html
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That Sinking Feeling

• How not to sink
• Stay neutral
• High water content (gelatinous)
• Reduced or no shell

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That Sinking Feeling

• How not to sink
• Drag (high surface area)
• Small size
• Flat shape
• Spines, long structures

-------- Isopod
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That Sinking Feeling

• How not to sink
• Upwelling (also good for nutrients)

Southern Hemisphere Ekman transport to the left
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That Sinking Feeling

• How not to sink
• Actively swim cilia, flagella, muscles,
  appendages

http//www.coralreeffish.com/larvae.htm
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Nowhere to Hide

• Active predators cant eat what they cant see
  so be invisible

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Nowhere to Hide

• Active predators cant eat what they cant see
  so hide where it is dark

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Somewhere to Hide

• Floating mats of macroalgae and seagrasses form
  pelagic communities - camouflage

Sargassum
http//www.bigelow.org/bacteria/teach/images/open_
orgs/sargassum.jpg
http//www.naturalsciences.org/education/deepsea/i
mages/sargassum_fish.jpg
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Food Webs
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Food Webs