10
Algae
the lifespan period of the individual colony, the colony is termed coenobium. Volvox (Chlorophyta)
(Figure 1.7) with its spherical colonies composed of up to 50,000 flagellated cells interconnected
by cytoplasmic bridges is an example of a motile coenobium, as well as Eudorina (Chlorophyta)
(Figure 1.8). Hydrodictyon (Chlorophyta) with its flat plat-like networks of several thousand cells
and Pediastrum (Chlorophyta) (Figure 1.9) with its flat colonies of cells characterized by spiny
protuberances are examples of nonmotile coenobia.
FilamenToUs Type
Filaments result from cell division in the plane perpendicular to the axis of the filament and
have cell chains consisting of daughter cells connected to each other by their end wall. Filaments
can be simple as in Oscillatoria (Cyanobacteria) (Figure 1.10), Spirogyra (Chlorophyta)
(Figure 1.11), or Ulothrix (Chlorophyta) (Figure 1.12), have false branching as in Tolypothrix
(Cyanobacteria) (Figure 1.13) or Scytonema (Cyanobacteria) (Figure 1.14), or true branching as
in Cladophora (Chlorophyta) (Figure 1.15). Filaments of Stigonema ocellatum (Cyanobacteria)
FIGURE 1.7 Motile coenobium of Volvox aureus.
FIGURE 1.8 Motile coenobium of Eudorina sp. Scale bar: 10 μm.