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[ben-thos] /ˈbɛn θɒs/
the biogeographic region that includes the bottom of a lake, sea, or ocean, and the littoral and supralittoral zones of the shore.
Also called benthic division, benthonic zone.
1890-95; < Greek bénthos depth (of the sea); akin to bathos, bathy- Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for benthos
  • The animals that live on the bottom or in the sediments are called benthos.
  • Some zooplankton live their whole life as plankton, while others change to become nekton and benthos.
  • The animals and plants that live on or in the bottom are known as the benthos.
British Dictionary definitions for benthos


the animals and plants living at the bottom of a sea or lake
the bottom of a sea or lake
Derived Forms
benthic, benthal, benthonic, adjective
Word Origin
C19: from Greek: depth; related to bathus deep
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
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Word Origin and History for benthos

"life forms of the deep ocean and sea floor," 1891, coined by Haeckel from Greek benthos "depth of the sea," related to bathos "depth," bathys "deep," of unknown origin. Adjective benthic is attested from 1902.

Online Etymology Dictionary, © 2010 Douglas Harper
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benthos in Science
  1. The bottom of a sea or lake.

  2. The organisms living on sea or lake bottoms. The benthos are divided into sessile organisms (those that are attached to the bottom or to objects on or near the bottom) and vagrant organisms (those that crawl or swim along the bottom). Compare nekton, plankton. See more at epifauna, infauna.

The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Encyclopedia Article for benthos

the assemblage of organisms inhabiting the seafloor. Benthic epifauna live upon the seafloor or upon bottom objects; the so-called infauna live within the sediments of the seafloor. By far the best-studied benthos are the macrobenthos, those forms larger than 1 mm (0.04 inch), which are dominated by polychaete worms, pelecypods, anthozoans, echinoderms, sponges, ascidians, and crustaceans. Meiobenthos, those organisms between 0.1 and 1 mm in size, include polychaetes, pelecypods, copepods, ostracodes, cumaceans, nematodes, turbellarians, and foraminiferans. The microbenthos, smaller than 0.1 mm, include bacteria, diatoms, ciliates, amoeba, and flagellates.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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