Protozoa -
They
are
a
group
of
single
celled
organisms,
simple
in
structure,
though
functionally
complex.
More
than
30,000
species
have
been
reported
which
exist
mostly
in
aquatic
habitats.
They
are
often
included
in
zoology
textbooks.
They
are
considered in microbiology
due
to
their
unicellular
structure,
microscopic
size
and
as
agents
of
human
diseases.
