heterotrophic producers present in the water column are the
the protista and the zooplankton. The latter group can be
sub-divided on the basis of size into micro- (35-200 Ám), meso-
(200-2000 Ám) and macro- (> 2000 Ám) zooplankton.
heterotrophic producers present in the benthos can be sub-divided
into meiofauna (metazoans ranging between 100 and 2000 Ám in
size) and macrofauna (metazoans measuring more than 2 mm). These
organisms live either within the sediments (in the case of the
meiofauna and some of the macrofauna), on top of the sedimentary
layer or on the coral pinnacles.