Algae

Algae

1. ALGAE

2. Characteristics Range in size from microscopic like single celled organisms to large seaweeds Autotrophic Form the reproductive structures – gametangia or gamete chambers Aquatic and have flagella at some point in life Often contain pyrenoids , organelles that synthesis and store starch

3. Size of Algae Their sizes varies from 0.5microns to 700 feet( giant kelps) in length.

4. Algal construction types : Morphology 1. Unicellular algae 2. Colonies 3. Filaments 4. Multicellular

5. Algae - What are they? Primitive plants No true roots , only attachment structures ( Holdfasts ) Produce spores ( not seeds )– motile or non-motile Most have sexual and asexual reproduction Non-vascular , do not possess an internal transport system.

6. Algae vs . ‘REAL’ plants Similarities and differences: Both are photoautotrophic Similar metabolic functions to higher plants eg . photosynthesis different anatomical structures, reproductive structures. different reproduction. No true roots, stems leaves . Non-vascular, therefore nutrient uptake over surface . And wastes are washed away from surface by aquatic environment

7. Where do Algae live? Marine habitats : seaweeds, phytoplankton Freshwater habitats : streams, rivers, lakes and ponds Terrestrial habitats : stone walls, tree bark, leaves, in lichens, on snow

8. Algal Pigments Colour of algaes varies due to presence of definite chemical compounds called as pigments . Photosynthetic pigments in algae are of 3kinds, Chlorophyll - “a” is common, whereas b, c and d have restricted distribution. Carotenoids -These are fat soluble yellow coloured pigments. Phycobilins or biliproteins - include red coloured Phycoerythrins and blue coloured phycocyanins .

9. Reproduction Vegetative reproduction: Fragmentation Cell division Hormogone formation. Tubers Bulbils Akinetes

10. Asexual Reproduction By zoospores, aplanospores , autospores , endospore, auxospores and cyst formation. Palmella stage occurs in Chlamydomonas .

11. 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 Anisogamy Oogamy - Aplanogamy or conjugation Oogamy Anisogamy

12. CLASSIFICATION OF ALGAE PHYLUM ARE BASED ON Primary Photosynthetic Pigment Food-storage Substance Cell Wall Composition

13. Name Brown Algae Red Algae Green Algae Diatoms Dinoflagellates Water Molds Phylum Phaeophyta Rhodophyta Chlorophyta Diatoms Dinoflagellata Oomycota Colour Brownish Reddish Green Brownish Brownish Colourless, white Cell Wall Cellulose and alginic acid Cellulose Cellulose Pectin and silica Cellulose Cellulose Cell Arrangement Multicellular Most are Multicellular Unicellular and Multicellular Unicellular Unicellular Multicellular Photosynthetic Pigments Chlorophyll a and c, xanthophylls Chlorophyll a and d, carotenoids, phycobilins Chlorophyll a and b, carotenoids Chlorophyll a and c, carotene, xanthophylls Chlorophyll a and c, carotene, xanthins none Sexual reproduction Yes Yes Yes Yes In a few Yes Storage Material Carbohydrate Glucose polymer Glucose polymer Oil Starch none Flagella 2, unequal, lateral Absent Mostly 2 per cell Absent Mostly biflagellate Most produce zoospores with 2 flagella

14. Phylum Phaeophyta 1500 species of Brown algae All are multicellular and large (often reaching lengths of 147 feet) Individual alga may grow to a length of 100m with a holdfast, stipe and blade Used in cosmetics and most ice creams

15. Phylum Rhodophyta 4000 species of RED Algae Most are marine Smaller than brown algae and are often found at a depth of 200 meters. Contain chlorophyll a and c as well as phycobilins which are important in absorbing light that can penetrate deep into the water Have cells coated in carageenan which is used in cosmetics, gelatin capsules and some cheeses

16. Phylum Chlorophyta Green algae 7000 diverse species Biologist reason that green algae gave rise to land plants. Both green algae and land plants have chlorophyll a and b as well as carotenoids and store food as starch Both have walls made of cellulose

17. Diatoms Diatoms are a major group of algae, and are among the most common types of phytoplankton. Diatoms are unicellular, although they can form colonies in the shape of filaments or ribbons, fans, zigzags, or stars. Eukaryotic algae Common type of phytoplankton Primary producers in the food chain Found in freshwater and marine environments

18. Dinoflagellates The dinoflagellates are a large group of flagellated protists that constitute the phylum Dinoflagellata . Most are marine plankton, but they are common in fresh water habitats as well. Causes Red tide phenomenon in coastal waters.

19. Oomycota Oomycota or oomycetes form a distinct phylogenetic lineage of fungus-like eukaryotic microorganisms . They are filamentous, microscopic, absorptive organisms that reproduce both sexually and asexually.

20. How do algae function? Photoautotrophs: 6C0 2 + 6H 2  C 6 H 12 6 + O 2 use carbon, light, and water produce chemical energy (carbohydrates) and produce O 2 as a by-product. Basic storage products: carbohydrates as starch or converted to fats as oil Require nutrients: N, P and minerals.

21. Why are ALGAE important? Ecological importance of algae a) Production of Oxygen as ‘by-product’ of photosynthesis: All aerobic heterotrophic organisms require O 2 e.g. fungi and animals need O 2 , to run cellular respiration to stay alive b) Production of biomass : autotrophic organisms - represent the base of the food chain/web, particularly in aquatic environments.

22. Why are algae important? Primary producers, basis of food webs, “FORESTS/GRASSES OF THE SEA ” Pioneer Species: on rocky shores, mudflats, hot springs, lichen communities, 'snow algae' O 2 production and carbon fixation in aquatic habitats.

23. 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 Drugs Model system for research

24. 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 HARMFUL EFFECTS of Algae

25. Uses of Seaweeds Present Food Hydrocolloids and some chemical substances Fertilizers Potential Source of energy/compost by digestion Waste-water treatment

26. Algae as human food Annual value is about US$6 billion Main market and production area is Asia “Mariculture” has become very important Main high-value species are ‘Nori’, ‘Kombu’ and ‘Wakame’ ( Porphyra , Laminaria and Undaria ) Mainly used as a subsidiary food: adding relish, taste and 'feel' to food European and North American market presently very small but has potential