1 ZOOPLANKTON Zooplankton are the primary consumers, called heterotrophic herbivores, in food webs....
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1 ZOOPLANKTON Zooplankton are the primary consumers, called heterotrophic herbivores, in food webs. They are the smallest and most numerous marine animals. Their population density depends on the availability of phytoplankton upon which they graze. USGS
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Transcript of 1 ZOOPLANKTON Zooplankton are the primary consumers, called heterotrophic herbivores, in food webs....
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ZOOPLANKTON
Zooplankton are the primary consumers, called heterotrophic herbivores, in food webs.
They are the smallest and most numerous marine animals. Their population density depends on the availability of phytoplankton upon which they graze.
USGS
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There are two groups of zooplankton:
Crab Zoe
1. Meroplankton - planktonic larvae who will become adult forms of fish, worms, Mollusks, and Crustaceans
The advantage of meroplanktonic lifestyle is reduced competition from adults for the same basic needs.
However, predation is extremely high because of their size and lack of adaptability.
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2. Holoplankton - will remain plankton throughout life. They remain visible, but tiny.
Adult Daphnia
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VERTICAL MIGRATION (or IT’S A PHYLUM EAT PHYLUM WORLD)
Copepods (Phylum: Arthropoda) are 95% of all zooplankton. Others are krill, foraminifera and members of Kingdom Protista, Phylum Protozoa.
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Zooplankton are grouped by the way they move - either by pseudopods like the amoeba (1), flagella like euglena (2) or by cilia as in paramecium (3).
1. 2. 3.
Amoeba in motion Euglena in motion Paramecium in motion
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Vertical migration is a daily pattern of phytoplankton and zooplankton changing positions like a day and night shift.
During the day phytoplankton produce lipids by photosynthesis.
Because oils are less dense than water, the products of photosynthesis increase their buoyancy.
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As the sun goes down, the phytoplankton use lipids for energy which causes them to sink in the water column.
In response to the “rain” of phytoplankton descending, the zooplankton move up in the water column to graze on them.
As the sun comes up, photosynthesis again causes more production than the organisms need at that time, the phytoplankton become lighter and begin to float upward.
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The zooplankton begin their downward response to graze again and to take advantage of reduced visibility and less heat than at the surface.
These two periods of grazing protect both populations, reduces predation and distributes stress in the ecosystem.
