Plankton

“To Drift”

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Classification of Marine Organisms

• Plankton (floaters)• Nekton (swimmers)• Benthos (bottom

dwellers)

PlanktonNet

SizeDistribution

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Types of Plankton

• Most biomass on Earth consists of plankton.

• Phytoplankton– Autotrophic

• Zooplankton – Heterotrophic

• PHYTOPLANKTON“plant plankton”

Photosynthetic The very base of the food chain…

Fnft: A micrograph of pelagic diatoms

Diatom

(chain) diatom

Figure 3.11: Cells in a chain of Stephanopyxis

Courtesy of Kohki Itoh

Dinoflagellates

• Ceratium• A Dinoflaggelate• “Phytoplankton”

Fnft: SEM of Gonyaulax polygramma

Fnft: SEM of Ceratochoris horrida

© CSIRO Marine Research

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Types of Plankton

• Most biomass on Earth consists of plankton.

• Phytoplankton– Autotrophic

• Zooplankton – Heterotrophic

• ZOOPLANKTON“animal plankton”

NOT Photosynthetic – but “herbivores” and “carnivores” instead

They FEED ON the very base of the food chain (phytoplankton)…but how?

copepod

(crustacean)

Meroplankton

salp

Inhabitants of the Pelagic Division

• Some large gelatinous zooplankton: (b) A ctenophore, Bolinopsis, swimming with eight rows

of ciliated combs.

Courtesy of OAR/National Undersea Research Program/NOAA

They aren’t always “small!”

Some large gelatinous zooplankton: (c) A colony of salps (Pegea) cloned from a single parent.

© Eric Prine/age fotostock

The cycle from a larva stage to the upcoming of adult hood.

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Avoiding Sinking

• Ability to float– Zooplankton – some produce fats or oils to stay

afloat– Phytoplankton-different “shapes” of their tests

• This is what the LAB is about…

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Floating Zooplankton

• Microscopic zooplankton have shells or tests.–Radiolarians–Foraminifers–Copepods

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Copepods

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Macroscopic Zooplankton

• Krill– Resemble mini shrimp or

large copepods– Abundant near

Antarctica– Critical in Antarctic food

chains

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Adaptations of Marine Organisms

• Physical support– Buoyancy– How to resist sinking– Different support

structures in cold (fewer) rather than warm (more appendages) seawater

– Smaller size

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Adaptations of Marine Organisms

• High surface area to volume ratio– Unusual appendages to

increase surface area

• Oil in micro-organisms to increase buoyancy

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Viscosity and Streamlining Adaptations

• Streamlining important for larger organisms

• Less resistance to fluid flow

• Flattened body• Tapering back end