( ( As ( a group ) ) ( , ( ( Pfiesteria ( - ( like ( dinoflagellates ( ( ( are ( non-photosynthetic ( -LRB- ( heterotrophic -RRB- ) ) ) ) and ) require ) ) ) ) ) ( ( suspended ( ( microalgae ( -LRB- ( phytoplankton -RRB- ) ) ) ( prey ( as ( a ( primary ( food source ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN As) (NP (DT a) (NN group))) (, ,) (NP (NP (NNP Pfiesteria)) (PRN (: -) (SBAR (IN like) (S (NP (NNS dinoflagellates)) (VP (VP (VBP are) (ADJP (ADJP (JJ non-photosynthetic)) (PRN (-LRB- -LRB-) (ADJP (JJ heterotrophic)) (-RRB- -RRB-)))) (CC and) (VP (VBP require))))))) (VP (VBD suspended) (SBAR (S (NP (NP (NN microalgae)) (PRN (-LRB- -LRB-) (NP (NN phytoplankton)) (-RRB- -RRB-))) (VP (VBP prey) (PP (IN as) (NP (DT a) (JJ primary) (NN food) (NN source))))))) (. .)))
As a group, Pfiesteria -like dinoflagellates are non-photosynthetic (heterotrophic) and require suspended microalgae (phytoplankton) prey as a primary food source.
(ROOT (S (SBAR (IN Because) (S (NP (DT all) (NNS animals)) (VP (VBP require) (NP (NP (DT an) (JJ external) (NN source)) (PP (IN of) (NP (NN food))))))) (, ,) (NP (PRP they)) (VP (VBP are) (VP (VBN called) (S (ADJP (JJ heterotrophic))))) (. .)))