( ( benthos ( ( The aggregate ) ( of ( organisms ( living ( ( ( on or ) at ) ( ( the bottom ) ( of ( ( a body ) ( of water ) ) ) ) ) ) ) ) ) ) . )
(ROOT (S (VP (VBZ benthos) (NP (NP (DT The) (NN aggregate)) (PP (IN of) (NP (NP (NNS organisms)) (VP (VBG living) (PP (IN on) (CC or) (IN at) (NP (NP (DT the) (NN bottom)) (PP (IN of) (NP (NP (DT a) (NN body)) (PP (IN of) (NP (NN water)))))))))))) (. .)))
benthos The aggregate of organisms living on or at the bottom of a body of water.
(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.