2. 18.3.3
These eukaryotic,photosynthetic protists are classified into smaller
groups according to the dominant pigments they produce.The algal
groups discussed in this section include the green,brown,and red algae
Diatoms and Dinoflagellates.
3. GREEN ALAGE
•Most green algae live in freshwater,only about
10%of them live in the sea a few species live
on land.Figure 18.11 shows some freshwater
green algae.Chlorella is a single-celled algae
while spirogyrais said to be filamentous
because its cells are arrange one after
another,forming a thread like body or
filament.on the other hand,figure 18.12 show
some of green algae that live in the sea .They
are each made up of colony of many cells.in
4.
5. • Green algae contain chlorophyll a and b these are the same type of chlorophyll
found in higher plants.besides chlorophyll,green algae also contain small amounts
of yellow and brown pigments known as xanthophylls and focuxanthin.
• Brown algae
The multicellular brown algae are all marine.the largest alga,the kelps,and
sargassum(figure 18.13) belong to this group.brown algae contain chlorophyll a and
c.however,the green color is masked by the brown pigment focuxanthin.
6.
7. • Red algae
As to there habitat,the red algae are mostly marine;some are freshwater.the
marine alga porphyra(figure 18.14)is similar in structure to ulva but it is deep
red.red algae contain chlorophyll a and d.however,the green color is masked
bye the red pigment phycoerythin
8. • Diatoms,thegolden algae
Refer to figure 18.15.it shows microscopic single-celled algae,which have
different shapes and designs.they are known as diatoms.they are generally
found among other algae such as the green and the blue-green algae.they
contain chlorophyll a and c.However,the green color is masked by the yellow
pigments xanthophyll or the orange pigment carotene.presence of these
pigments account for their popular name,
‘golden algae’.
9. • Dinoflagellates
These unicellular algae are provided with two flagella.one is free and the other
one is wrapped about a transverse groove around the cell.this is the reason
why their cells spin like a top.they contain green pigments chlorophyll a and
c,and a brown pigment focuxanthin.A dinoflagellate,gonyaulax,is shown in
figure 18.15
