( ( ( ( ( Carnivores ( which ( eat mainly ) ) ) or ) only ) ( fish ( are called ) ) ) ( piscivores . ) )
(ROOT (S (NP (NP (NP (NNS Carnivores)) (SBAR (WHNP (WDT which)) (S (VP (VBP eat) (ADVP (RB mainly)))))) (CC or) (RB only) (NP (NP (NN fish)) (SBAR (S (VP (VBP are) (VP (VBN called))))))) (VP (VBZ piscivores)) (. .)))
Carnivores which eat mainly or only fish are called piscivores.
(ROOT (S (NP (NNS Carnivores)) (VP (VBZ is) (NP (NP (DT the) (NN term)) (PP (IN for) (NP (NP (NP (NNS heterotrophs)) (SBAR (WHNP (WDT that)) (S (VP (VBP eat) (ADVP (RB only)))))) (CC or) (NP (RB mainly) (NNS animals)))))) (. .)))