Marine Lifestyles
Populations of organisms in Ocean (groups) are divided by means of locomotion
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II. Benthos
(Greek for “deep sea”)
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Live on or in ocean bottom
-Epifaunal- above ocean floor (filter feeders)
-Infaunal- below ocean floor (burrowers)
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Most are sessile or burrowers; a few are active foragers
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Most benthic organisms have planktonic immatures or larval forms
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These organisms often become fossilized; important for geological indicators
Ex: Barnacles, coral, sponges, some algae, clams, worms, starfish
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III. Nekton (means swimming)
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Includes all marine animals capable of swimming freely, independent of currents
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Includes many large forms
Ex: Chondrichthyes- Sharks and rays
Ostiechthyes- fish
Cetaceans- Whales
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Have ability to actively search for food and avoid predators, some have migration routes
Commercially important to man!
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IV. Plankton (Floater)
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Usually small forms or unicellular
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Includes many algal and larval (immature) stages of various marine animals
- Meroplankton- temporary plankton. Spends part of its life as plankton, floats as juveniles then
becomes Benthic or Neritic as adults.
- Holoplankton- permanent plankton. Float entire life, Copepods
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Due to size and weak locomotion, they move by the ocean currents
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Larger plankters: Jellyfish and sargassum
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V. Phytoplankton
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Contain most of the “producers” (autotrophs) and start ecological basis for food chain in ocean.
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Phytoplankton use chlorophyll to photosynthesize and produce food for themselves and
produce free O2 as a biproduct “Grasses of the Sea”
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VI. Zooplankton
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Unicellular and multicellular heterotrophs. 1st order consumers in food chain.
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Almost every group of marine animal is represented during earliest life stages.
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Often called “grazers”; 2nd level in food chain.
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Marine Lifestyles