( ( The benthos ) ( ( ( is simply ) ( ( a term ) ( describing ( ( all ( the organisms ) ) ( living ( ( ( on or ) in ) ( the ( ocean bottom ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NNS benthos)) (VP (VBZ is) (ADVP (RB simply)) (NP (NP (DT a) (NN term)) (VP (VBG describing) (NP (NP (PDT all) (DT the) (NNS organisms)) (VP (VBG living) (PP (IN on) (CC or) (IN in) (NP (DT the) (NN ocean) (NN bottom)))))))) (. .)))
The benthos is simply a term describing all the organisms living on or in the ocean bottom.
(ROOT (S (NP (NP (VBG Living) (NNS things)) (PP (IN on) (NP (DT the) (NN ocean) (NN floor)))) (VP (VBP are) (VP (VBN known) (PP (IN as) (NP (NNS benthos))))) (. .)))
Living things on the ocean floor are known as benthos.