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Article: Life in Water
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- Water:Science and Issues
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CopyrightCOPYRIGHT 2003 The Gale Group Inc. This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
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Life in Water
Life is thought to have originated in an aquatic environment
—
the oceans. Living organisms have since adapted to numerous aquatic
habitats
, both
marine and fresh-water. They occupy environments as diverse as lakes, rivers, and oceans.
Marine Environment
About 17 percent of known biological species live in oceans. Marine species are described as either pelagic or benthic. Pelagic organisms live in the water column itself. Benthic species live on the ocean bottom.
Pelagic.
Pelagic organisms include plankton, which float along with currents, and nekton, which are active swimmers. Plankton are divided into phytoplankton, which include photosynthesizing species such ...