Page 6 - at-winter-microscopy-pdf

Staurastrum is a genus of unicellular Fig. 8. Staurastrum

algae where each cell is divided into
two semi-cells each of which bears
arms in three or more planes. In the
specimen shown the semi-cells have
radiating arms in several planes which
are smooth-sided and terminate in
spiny tips (Fig. 8). I cannot imagine the
function of such a structure, would
appear very susceptible to damage.

All of the previous species of algae are
mainly sedentary and found on surfaces.
They can move slowly, not sure how! In
contrast,

Euglena spp. are active swimmers

using a long whip-like flagellum
emerging from the front of the organism.
When swimming the alga rotates along
its longitudinal axis and moves along a
spiral path. Structurally, Euglena species
are complex. The outer body wall is a
pellicle of microtubes (Fig. 9 pell) and a
body filled with green photosynthetic
chloroplasts (ch) which can synthesize a
form of starch that is stored as
paramylum bodies (pb). There is a
central nucleus (nu) and several
contractile vacuoles (cv) that discharge
excess water. At the anterior end is a
gullet (gu) with which the alga can ingest
tiny food particles. Adjacent to the gullet
is a red eyespot (ey) which is sensitive
to light .