Consumers make up the
next trophic level; and must
eat other organisms to obtain
their energy. Consumers, in
turn, occupy different trophic
levels. Trophic levels of
common aquatic organisms
are shown in table 1.
Primary consumers are
herbivores, they eat plants.
In our aquatic ecosystem
example, zooplankton feeding
on phytoplankton occupy the
primary consumer trophic
level. Cattle are primary
consumers in terrestrial
ecosystems.
Secondary consumers,
represented by certain aquatic
insects are carnivores and
feed upon primary consumers,
the zooplankton.
Our example also includes
a tertiary consumer, the
largemouth bass that feeds
upon other carnivores.