2. They are Thallophytes which have chlorophyll
as their primary photosynthetic pigment and
lack a sterile covering of cells around the
reproductive cells.
3. Habit and Habitat
They may be free floating , free swimming or
attached to the bottom in the shallow water.
According to habitat, algaes can be classified as
follows:
Aquatic algae: Example:- Chlamydomonas.
Terrestrial algae : Example:- Fritschiella.
Aerophytes : Example:- Scytonema.
Cryophytes : Example:- Scotiella.
Thermophytes : Example:- Oscillatoria brevis.
Algae of unusual habit : Example:- Dunaliella.
18. Epiphytic Algae
• The algaes grow on other plants.
Ceplaleuros algae on Chrysophyllun
leaf
19. Epizoic Algae
These algaes are found on shells of
molluscans, turtles and fins of fishes.
Example: Acrosiphonia.
20. These are found inside the body of aquatic
animals.
• Example: Zoochlorella found
inside the Hydra Viridis
21. Eg: Cephaleuros virescens causes ‘ Red rust
of tea’,by which a severe damage is caused.
22. Many Cyanophycean members grow in
symbiotic association with other plants.
Association of
Nostoc within thalli
of Anthoceros.
23. Their sizes varies from 0.5microns to 700 feet(
giant kelps) in length.
24. Thallus Organization
Algae exhibit great diversity in organization of
plant body.
Unicellular Motile
Non-motile
Colonial
Coenobial
Filamentous Simple
Branched
Dendroid
25. They are single celled algae.
They may be motile flagellated.
example: Chlamydomonas.
They may be non-motile coccoid.
example: Chlorella
26. The cells are grouped in aggregations called
Colonies.
27. It is a colony with fixed number of cells.
Example:16 cells in Pandorina, 32 cells in
Eudorina.
28. Filamentous
Filamentous types are multicellular.
They may be simple or
unbranched.
Example: ulothrix, spirogyra.
They may be branched.
Branching is of 2 types:
True branching. Ex: Sytonema.
False branching. Ex:Cladophora.
29. Dendroid means tree like. These appear like
microscopic trees .example: Prasinocladus.
30. Structure of the algal cell
Prokaryotic cell
They are found in the members of
Cyanophyta.
Cell wall contains mucopeptide.
DNA materials are concentrated in the
centre and nuclear membrane is
absent.
Chloroplast, Mitochondria, Golgi
bodies, Plastids and Endoplasmic
reticulum is absent.
Ribosomes are present.
Nuclear division doesnt take place by
mitosis.
31. Eukaryotic cell
Eukaryotic cell has the
structure as in typical cell
of higher plants.
Nucleus separated from
Cytoplasm by distinct
nuclear membrane.
It divides by mitosis.
Cytoplasm contains
chloroplasts,
mitochondria, golgi bodies
and endoplasmic
reticulum.
32. Algal Pigments
Colour of algaes varies due to
presence of definite chemical
compounds called as pigments.
Photosynthetic pigments in algae are
of 3kinds,
Chlorophyll
Carotenoids
Phycobilins or biliproteins.
33. CHLOROPHYLL
Algal chlorophylls is
represented by
greencolour.
They are fat soluble
compounds.
Chlorophyll a is
comman in all group
of algaes.
Chlorophyll b, c, d
and e have restricted
distribution.
34. Carotenoids
These are fat soluble
yellow coloured
pigments.
They are sub divided
into carotenes and
xanthophylls.
There may be 20
xanthophylls so far
known.
Carotenes are of 5types.
α, β, γ, lycopene and ε
carotene.
35. Phycobilins
Phycobilins include red
coloured
Phycoerythrins and
blue coloured
phycocyanins.
They are present in
members of
Cyanophyceae and
Rhodophyceae.
36. Algal Flagella
Flagella are extremely fine and
hyaline emergence of the
cytoplasm.
Single anterior flagellum
In pairs
Many in number
Isokont( equal in length)
Heterokont(unequal in length)
37. Nutrition
Algaes are Autotrophic.
All or most of the cells of thallus normally
contain chlorophyll.
The cells can manufacture their own
carbohydrate food from carbon dioxide and
water through the agency of sunlight.
38. FOOD RESERVES
Food accumulates in the form of
polysaccharides.
Those are cyanophycean starch and
floridean starch(rhodophyta).
Three important reserve food are laminarin,
paramylin and leucosin.
Mannitol is also another reserve food in red
algae.
41. Sexual Reproduction
By fusion of two
specialised cell
known as sex cells
or gametes.
Isogamous- two
identical gametes
fuse to form
zygotes.
Heterogamous-
dissimilar gametes
fuse
46. Beneficial Aspects of Algae
Food for humans
Food for invertebrates and fishes in mariculture
Animal feed
Soil fertilizers and conditioners in agriculture
Treatment of waste water
Diatomaceous earth (= diatoms)
Phycocolloids (agar, carrageenan from red algae;
alginates from brown algae)
Drugs
Model system for research
47. Blooms of freshwater algae
Red tides and marine blooms
Toxins accumulated in food chains
Damage to cave paintings, frescoes, and
other works of art
Fouling of ships and other submerged
surfaces
Fouling of the shells of commercially
important bivalves
48. No other forms of organisms are so
colourful as that of algae.
Various pigments can be found in the algae.
They are ubiquitous and the thallus
organisation contains diversity.
49. References
O.P.Sharma .1986. Textbook of Algae,
Tata Mcgraw-Hill Education:Pg.no.2-4.
A.V.S.S.Sambamurty.2005. A Textbook
of Algae, I.K.International
Pvt.Ltd:Pg.no.3-4.
http://www.algologists.yolasite.com