( However ( , ( ( ( some cases ) ( of ( ( ( ( functional and ) adaptive ) significance ) ( of ( biofluorescence ( in ( ( the ( aphotic zone ) ) ( of ( the ( deep ocean ) ) ) ) ) ) ) ) ) ) ( ( is ( ( an ( active area ) ) ( of research ) ) ) . ) ) ) )
(ROOT (S (ADVP (RB However)) (, ,) (NP (NP (DT some) (NNS cases)) (PP (IN of) (NP (NP (ADJP (JJ functional) (CC and) (JJ adaptive)) (NN significance)) (PP (IN of) (NP (NP (NN biofluorescence)) (PP (IN in) (NP (NP (DT the) (JJ aphotic) (NN zone)) (PP (IN of) (NP (DT the) (JJ deep) (NN ocean)))))))))) (VP (VBZ is) (NP (NP (DT an) (JJ active) (NN area)) (PP (IN of) (NP (NN research))))) (. .)))
However, some cases of functional and adaptive significance of biofluorescence in the aphotic zone of the deep ocean is an active area of research.
(ROOT (S (NP (PRP You)) (VP (VBP call) (NP (NP (DT the) (JJ lightless) (NN part)) (PP (IN of) (NP (DT the) (NN ocean) (JJ aphotic) (NN zone))))) (. .)))