( ( Secondary consumers ) ( ( eat ( ( ( ( meat , ) ( although ( they ( sometimes ( eat plants ) ) ) ) ) , ) ( ( fluctuating ( their ( trophic levels ) ) ) ( within ( the ( food chain ) ) ) ) ) ) . ) )
(ROOT (S (NP (JJ Secondary) (NNS consumers)) (VP (VBP eat) (S (NP (NP (NN meat)) (, ,) (SBAR (IN although) (S (NP (PRP they)) (ADVP (RB sometimes)) (VP (VBP eat) (NP (NNS plants))))) (, ,)) (VP (VBG fluctuating) (NP (PRP$ their) (JJ trophic) (NNS levels)) (PP (IN within) (NP (DT the) (NN food) (NN chain)))))) (. .)))
Secondary consumers eat meat, although they sometimes eat plants, fluctuating their trophic levels within the food chain.
(ROOT (S (NP (NP (JJ Secondary) (NNS consumers)) (PRN (-LRB- -LRB-) (SBAR (WHNP (WDT which)) (S (VP (VBP eat) (NP (JJ primary) (NNS consumers))))) (-RRB- -RRB-))) (VP (VBP are) (VP (VBN considered) (S (VP (TO to) (VP (VB be) (ADJP (JJ trophic) (NP (NN level) (CD 3)))))))) (. .)))