Algae are a diverse group of primitive, mostly aquatic photosynthetic organisms that are found in a wide range of habitats around the world. They can be unicellular or multicellular and exhibit significant variation in their morphology, pigmentation, and life cycles. Algae are divided into aquatic, terrestrial, and special habitat types depending on where they grow. Aquatic algae include phytoplankton that float in water and benthic algae that attach to surfaces at the bottom of water bodies. Terrestrial algae grow in moist soil or on the surface of soil and rocks. Special habitat algae are found in extreme environments like hot springs, polar regions, inside or on the surfaces of other organisms. Al

1. ALGAE
General Characters
Kamaljit Sidhu
Associate professor
Department of Botany
KCW , Civil lines Ludhiana

2. General Characters
• Phycology-The branch of science which deals with the
study of algae
• The word Phycology is derived from two words Phykos-
Sea weeds and logos-discourse
• Phycologist- A Scientist who studies different aspects of
algae
• Algae-It is a group of most primitive organisms with
simple thalloid plant body.
• They are autotrophic,o2 evolving green plants
• 90% of the oxygen comes from these simple plants
• They can be unicellular or multicellular
• They show wide variation in their morphology , pigments
and other metabolic products
• They bear unicellular or multicellular sex organs
• They differ in their life histories as well

3. Distribution and Habitat
• Includes 30,000 species distributed world-wide
• They are found growing in a wide variety of habitats
• They are ubiquitous and cosmopolitan
• Predominantly aquatic , could be terrestrial
• Depending upon habitat divided into 3 categories
• Aquatic habitat
• Terrestrial habitat
• Special habitat

4. Habitat

5. Habitat
• Aquatic habitat-They occur in fresh water aquatic habitats and in
marine habitat they are grouped as
• Phyto planktons-Plants growing and covering the surface of water
body , move on the mercy of the water currents , color of the water
changes due to the colour of the of water blooms example Chlorella,
volvox, Chlamydomonas
• Benthos-All the bottom dwelling organisms both the plants and
animals , Algae growing attached to the bottom of the water reservoir
are called benthophytes , forms growing at the bottom of the soil-
epipellic, those which are attached to the rocks and stones- epilithic

6. Aquatic Algae
Phytoplankton-Volvox Benthophytes-Chara

7. Terrestrial Algae
• Algae grow in the moist and well aerated soil-Edaphophytes
• They grow on the surface of the soil-Saprophytes-Vaucheria
• Some can grow below the surface of the soil-Cryptophytes-Oscillatoria
Vaucheria Oscillatoria

8. Special Habitats
• Thermal Algae-They grow in hot water springs with a temperature ranging
from70-85°C,Example-Phormidium
• Cryophytes-Algae growing in the polar regions on ice and Snow-Chlamydomonas
• Epiphytes-Algae growing on the surface of other plant parts Oedogonium
• Surface of the Angiosperms leaves-Epiphyllophytes
• On the barks of Angiosperms-Epiphloeophytes
• Endophytes-Algae grow within the tissues of the other plants-Anabaena growing
inside Azolla
• Epizoophytes-Algae growing on the body of other animals-Cladophora on the
snails
• Endozoophytes-Algae growing inside the body of the animals-Chlorella within the
tissues of Hydra

9. Special Habitats
Thermal Algae-
Phormidium
Cryophytes-Chlamydomonas Epiphytes-Oedogonium
Endophytes-Nostoc in Anthoceros

10. Special Habitats
Epizoophytic Algae Endozoophytic Algae

11. Special Habitats
• Symbiotic Algae- Algae growing in association with the plants in which both are
benefitted from each other like Nostoc , Anabaena, Lichens
• Parasitic Algae-Algae growing as parasites on other plants- Cephaleuros
Symbiotic Algae-Lichens
Parasitic Algae-Cephaleuros

12. Range of Thallus Structure

13. Range of Thallus Structure
• Unicellular thallus- Single celled organism-Chlamydomonas
• Multicellular thallus- Organisms made of large no of cells-Volvox
• Palmelloid form- Palm shaped thallus-Tetraspora
• Coenobial form- A colony having fixed no of cells-Volvox
• Dendroid form- A tree shaped thallus-Ecballocystis
• Siphonaceous form- Siphon shaped thallusVaucheria
• Filamentous form- Cylindrical , elongated thallus- Oedogonium
• Foliaceous form-leaf shaped thallus - Sargassum

14. Structure of A Typical Eukaryotic Cell
Typical Algal Cell

15. Structure Of Flagella

16. Pigments in Algae

17. Pigments in Algae
• Types of pigments in algae-3 types
• Chlorophylls
• Carotenoids
• Phycobilins
• Chlorophylls-5 types-chla chlb chlc chld chle -chla widely distributed in all the algae
• Carotenoids-2 types-carotenes and xanthophylls
• Phycobilins-Acessory pigments-3 types-phycocyanin , phycoethyrin and
allophycocyanin

18. Pigments in Algae

19. Reproduction in Algae

20. Types of Vegetative
Reproduction

21. Asexual Reproduction
• Asexual reproduction takes by formation of spores which are haploid and formed
in special cells-sporangium
• Different types of spores formed are-
• Autospore
• Hypnospore
• Endospore
• Exospore
• Nannocytes
• Monospore
• Akinete

22. Types of Asexual reproduction In
Algae

23. Sexual Reproduction
• Sexual Reproduction in Algae- The sexual reproduction
takes place by formation of gametes
• The gametes are of (+) and(-) strain
• The sexual reproduction is of three types
• Isogamy
• Anisogamy
• Oogamy
• Isogamy-When the fusing gametes are of the same shape
size and morphology
• Anisogamy-When the fusing gametes are of different
shape size and morphology
• Oogamy-When the male gamete is motile and the female
gamete is non motile ,male gamete swims and reaches
the female gamete