ALGAE General Characters
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1. Algae are simple, autotrophic plants that lack differentiation into tissues. They can be unicellular or multicellular and are found in aquatic, terrestrial, and unusual habitats. 2. Algae thalli are either unicellular or form colonies, filaments, or pseudoparenchymatous structures. Unicellular algae can be flagellated, amoeboid, or non-motile coccoidal forms. Multicellular thalli include colonies, branched and unbranched filaments, and pseudoparenchymatous forms. 3. Algae differ from plants, fungi, bacteria, and other organisms in their habitat, autotrophic
ALGAE General Characters
- 1. ALGAE GENERAL CHARACTERS, HABITAT, THALLUS ORGANIZATION, REPRODUCTION,
- 2. ALGAE Algae are small autotrophic plants that fail to show any cellular differentiation. In simple we can call it chlorophyllous thallophytes. ALGAE IN LATIN MEANS SEA WEEDS The Algae word first used by Carolus Linnaeus 1753 (For a group of Bryophytes) The actual delimitation of a group plants from their macroscopical features naming as Algae was done by Antoine Laurent De Jussieu 1789 arvind wasnik
- 3. arvind wasnik The branch of botany under which we study about Algae is known as ALGOLOGY/PHYCOLOGY The father of Algology is Felix Eugen Fritsch The father of Modern Algology is William Henry Harvey The Indian father of Algology is M.O.P. Iyengar The book wrote by F.E. Fritsch was “The Structure and Reproduction of Algae” Vol. I & II 1935 The two main phycologist of india work on algae are: R. N. Singh- N2 fixing with the help of Blue Green Algae P. K. Dey- Pioneer of N2 fixation
- 4. GENERAL CHARACTERS Algae are simple, thalloid, autotrophic, non vascular having unicell sex organs (exception multicellular sex organ in Chara) and no embryo formation (embryo 1st forms in Bryophyta) In algae embryo did not formed because of zygotic meiosis. Due to zygotic meiosis haploid nuclei are formed which further grow in to the new plants. Algae generally are Haploid in nature and for very little duration diploid stage comes in the form of zygote. (If mitosis occurs in zygote results in the formation of Embryo) Unicellular Prokaryotes Monera Ex: BGA ALGAE Unicellular Eukaryotes Protista Ex: Euglena Multicellular Eukaryotes Plantae Ex: Spirogyra arvind wasnik
- 5. Algae differ from Bacteria in being eukaryotic in nature (except BGA) Algae differ from Fungi in being autotrophic in nature Algae differ from Bryophytes in not having a jacket of sterile cells around their reproductive structures (except Chara, Bryophytes has multicelled sex organ covered by sterile cell jacket while Algae has single cell sex organ and are exposed) BGA differ from bacteria in having oxygenic photosynthesis, it takes water as electron donor and release O2 while Bacteria take electron from hydrogen sulphide In Algae oxygenic photosynthesis occurs due to Chl. a arvind wasnik
- 6. GENERAL CHARACTERS I. Habit: Algae are Unicellular = Single Multicellular = Colony/Filamentous arvind wasnik
- 7. GENERAL CHARACTERS II. Habitat: Algae may be 1. Aquatic Algae 2. Terrestrial Algae 3. Aerial Algae 4. Algae of Unusual Habitats arvind wasnik
- 8. GENERAL CHARACTERS 1. Aquatic Algae may be Fresh Water OR Marine A. Fresh Water Still Water ( EX. Chara, Oedogonium, Zygnima) Running Water ( Has Holdfast for attachment, EX. Vaucheria, Ulothrix, Cosmopogan) B. Marine Algae = Members of Phaeophyceae and Rhodophyceae like Ectocarpus, Polysiphonia, Sargassum, Ulva. arvind wasnik
- 9. GENERAL CHARACTERS Terminologies used for Aquatic Algae: Habit Habitat Example 1. Benthophytes Algae remains attached to any substratum ( growing on mud and other bottom ) The Benthic Algae may be Epipelic Epipsammic Grows on Sediments Located on Sand Ex. Oedogonium Annual Perennial Ex. Porphyra Ex. Sargassum Fresh Water are Chara, Nitella Marine are members of Phaeophyceae and Rhodophyceae 2. Epactiphytes Growing along shores of lakes or ponds. Ex. Spirogyra, Chaetophora. 3. Neustonic They grow on water surface Ex. Hydrodictyon arvind wasnik
- 10. Habit Habitat Example 4.Thermophytes Growing in thermal water can tolerate very high temperature Based on temp. Hypothermae ( Below 18 ‘C) Hliarothermae (18- 30 ‘C) Euthermae (30 -50 ‘C) Aerothermae (50 -70 ‘C) Hyperthermae ( Above 70’C) Majority of thermal algae belongs to Myxophyceae group Ex. Synechococus elongatus, Mastigocladus laminosus 5. Planktophytes Floating Algae. Are of two types: 1.Euplanktophytes: True floating Algae ex. Volvox, Hydrodictyon 2.Tychoplanktophytes: Becomes floating accidentally ex. Oedogonium, Nostoc Ex. Spirulina, Volvox, Euglena, Chlorella, Chlamydomonas etc arvind wasnik
- 11. ALGAL BLOOM Abundant growth of planktonic algae begin to impart colour to the water, such phenomenon is called Water Bloom as caused due to algae so called as Algal Water Bloom. Formation of blooms depends on temp. increase and nutrient availability. Water Bloom may be Temporary/Permanent Mixed/Pure 1. Temporary & Mixed type are produced by Chlamydomonas, Scendesmus, Chlorella, Ankistrodesmus, Pediastrum etc. 2. Temporary & Pure contains only one species Volvox globator or Chlamydomonas sp. 3. Permanent & Mixed are made up of Anabaena, Anabaenopsis, Microcystis etc. 4. Permanent & Pure a. Trichodesmium sp forms a permanent red water bloom in red sea. b. Microcystis aeruginosa forms permanent blue green water bloom in temple ponds. arvind wasnik
- 12. Habit Habitat Example 6. Halophytes Growing in saline habitat In salt lakes ex. Chlamydomonas ehrenberghii In salt springs ex. Enteromorpha sp. Dunaliella etc 7. Epiphytes Growing attached on other plants or algae. Epiphytic algae on submerged hydrophytes known as Periphyton Choleocheate in association with Chara & Nitella Cladophora on leaves of Vallisneria & Nelumbo Oedogonium on Hydrilla 8. Epizoophytes Grows on aquatic organisms Cladophora crispata on Snail Shell Characium on Mosquito Larva Protoderma on Turtle Shell arvind wasnik
- 13. GENERAL CHARACTERS 2. TERRESTRIAL ALGAE Algae that grows on or in soil called as Edaphophytes a. Sapophytes- Algae grows on the soil surface ex. Vaucheria b.Cryptophytes- Algae grows in the soil, fix nitrogen for the soil fertility ex. Nostoc, Anabeana arvind wasnik
- 14. GENERAL CHARACTERS 3. AERIAL ALGAE Habitat is aerial and are called as Aerophytes Habit Habitat Example 1. Epiphyllophytes Grows on the leaves of terrestrial plants Trentopholia sp on the leaves of Butea monosperma 2. Epiphloephytes or Corticolous Growing on the Mosses, Liverworts and on the Barks Ex. Pleurococus, Microcolous. 3. Epizoophytes They grow on the body of terrestrial animals Ex. Cyanoderma on the hairs of Sloth Bear 4. Lithophytes Growing attached to stones and rocky surface a.Epilithic- On rock surface ex. Calothrix b.Endolithic- Inside the rock or inside the skeleton of corals ex. Dalmatella c.Chasmolithic- Grows in rock fissures ex. Gleocapsa arvind wasnik
- 15. GENERAL CHARACTERS 4. Algae of Unusual Habitat A. Cryophytes: Algae grow on Ice or Snow Only on snow- Raphidonema Only on ice- Ancyclonema On both ice & snow- Trachiscia Not true cryophytes-Phormidium In Europe some mountain become green colour due to Raphidonema Yellowishgreen due to Chlamydomonas yellowstonensis Red colour due to Chlamydomonas nivalis (Arctic & Alpine Region) Brown colour due to Ancyclonema nordenskioldii Yellow colour due to Protoderma Green colour due to Scotiella arvind wasnik
- 16. GENERAL CHARACTERS B. Symbionts Some Algae live in association with certain Plants and Animals 1. Endophytic Algae: With Plants Nostoc in Anthoceros Anabeana cycadeae in the corolloid root of Cycas BGA Cyanailae in Protozoa 2. Endozoic Algae: With Animals Zoochlorella in Hydra viridis Trochisia sp. In Rana agilis Oedogonium undulatum in Insect Larva Oscillospira sp. In Guinea Pig arvind wasnik
- 17. GENERAL CHARACTERS C. Parasitic Algae Some BGA like Simonosiella sp. are found as parasite in the Human Intestine Cephaleuros virescens grows on the leaf of Thea sinensis (Tea Plant) and cause the disease known as Red Rust arvind wasnik
- 18. GENERAL CHARACTERS III. THALLUS ORGANIZATION Vegetative body of Algae is called as thallus It is not differentiated in to Root, Stem and Leaf, so algae are simple plants arvind wasnik
- 19. GENERAL CHARACTERS A. Unicellular- All vital function of life performed by a single cell, these are of 1. Flagellated/Motile 2. Amoeboid/Rhizopodial 3. Non-Motile/Coccoidal 1. Flagellated/Motile Form: Have flagella One Flagella ex. Trachelomonas, Chromulina Two Flagella- When both flagella are equal in size is called Isokont ex. Chlamydomonas, Haematococcus When both flagella are unequal in size called Hetrokont ex. Gonyostomum arvind wasnik
- 20. GENERAL CHARACTERS 2. Amoeboid/Rhizopodial Form Having protoplasmic projection called pseudopodia ex. Chrysamoeba 3. Non Motile/Coccoidal Form Lack cell wall and no locomotary organ ex, Diatoms, Chlorella arvind wasnik
- 21. GENERAL CHARACTERS B. MULTICELLULAR THALLUS: Multicelled Thallus 1. Colony: It is formed by the aggregation of individual cells a. Coenobium- A colony with definite numbers of cells and having a constant shape and size Non Motile : Aggregations of non-motile cells in the form of a colony (non-motile) are common only in Chlorophyceae. Here the cells are, more or less, fused together (e.g., Hydrodictyon) or connected by mucilaginous threads (e.g., Dictyosphaerium) and the colony may be of various shapes. It may be plate like e.g.. Scenedesmus or net-like as in Hydrodictyon. arvind wasnik
- 22. Motile Motile flagellated cells aggregate together to form motile colonies. Colonies vary in shape and size and in the number of cells. The colonies are either “plate-like” (e.g., Gonium) or spherical (e.g., Volvox). arvind wasnik
- 23. arvind wasnik Pamelloid In a large number of genera this habit is a permanent one e.g., Tetraspora (Chlorophyceae), Phaeocystis (Chrysophyceae) or is a temporary phase, in the life- cycle e.g., Chlamydomonas (Chlorophyceae) Chromulina, (Chrysophyceae). The habit is named after the genus Palmella (Palmeflaceae, Chlorophyceae) Here the individual lion-flagellated cells have mucilaginous sheaths around them and are enveloped in a common gelatinous matrix of indefinite shape which may be microscopic or macroscopic in size.
- 24. arvind wasnik Dendroid A variation of the palmelloid condition is seen in dendroid colonies. Here the mucilage is produced locally, generally at the base of the cell. Dendroid forms are seen e.g. Prasinocladus (Chlorophyceae), Mischococcus (Xanthophyccae) and in Chrysophyceae and Euglenineae
- 25. 2. Filamentous Forms: the division of the single cell into many daughter cells with septa between the divided cells a filamentous type of construction would be formed. (i) Un-branched Filaments: Simple un-branched filaments are found in many forms. They are either free-living e.g., Spirogyra or attached, at least initially e.g., Oedogonium, or aggregated in colonies e.g., Nostoc arvind wasnik
- 26. (ii) Branched Filaments: (i) Simple (ii) Heterotrichous (iii) Pseudoparenchymatous (i) Simple A simple branched filament with dichotomous branching pattern and a basal attaching cell, holdfast or hapteron is common with many types e.g., Cladophora. A peculiar form of branching, known as ‘false’-branching is observed in Cyanophyceae e.g., Scytonema arvind wasnik
- 27. arvind wasnik (ii) Heterotrichous This most highly evolved type of plant-body, showing a good amount of division of labour. The plant-body consists of two distinct parts: (1) A basal or prostrate creeping system, and (2) An erect or upright system. The prostrate system is attached to some substratum, grows apically and gives rise to numerous photosynthetic and rhizoidal filaments. Rhizoidal filaments sometimes penetrate the substratum . The erect system develops from the prostrate system and is composed of one or more and usually branched photosynthetic filaments. In Stigeoclonium and Trentepohlia these two systems are equally developed and easily distinguished.
- 28. Whereas in Coleochaete (Chlorophyceae) and Ascocyclus (Phaeophyceae) the prostrate system is highly elaborated and the erect system is reduced. This gives the body a discoid type of appearance. On the other hand, in many species of Ectocarpus, the prostrate system is reduced, and the erect system is well developed. This gives the body a crust or cushion type of appearance. In many cases the reduction of one system has gone to the limit of practical elimination. Thus in an endophytic species, Endoderia and in Chaetopeltis (Chlorophyceae) only the prostrate system is developed. Complete absence of prostrate system is noticed in Microthamnion. arvind wasnik
- 29. (iii) Pseudoparenchymatous forms: As indicated by the term ‘pseudo’ = false, the plant body gives the appearance of parenchymatous construction. The pseudoparenchymatous structure is a secondary development, close association of cells is a result of interweaving of filaments. Intercellular connections may be densely packed and firmly coherent (e.g., Dumontia, Rhodophyceae) or, the association may be loose and can easily be separated by pressure (e.g., Castanea, Phaeophyceae). Two types are: (1) uniaxial construction = a single colourless central axial filament e.g., Batrachospermum (2) multi-axial = many filaments e.g., Polysiphonia arvind wasnik
- 30. 5. Siphonaceous Forms: In a number of algae, belonging to Siphonales e.g., in Vaucheria, Botrydium, the growth of the plant body takes place without the usual cross-wall formation except during formation of reproductive organs. Thus a ‘tube’- like multinucleate structure, or a coenocyte, is produced. arvind wasnik
- 31. 6. Parenchymatous Forms: Parenchymatous thallus organization also is a modification of the filamentous habit, with cell division in more than one plane. The parenchymatous thalli may be ‘leaf-like’ or foliose, tubular or highly developed structure. Foliose or Tubular thalli are formed by the division of the cells two or three planes. Common examples of foliose structures in Viva (Chlorophyceae), Porphyra (Rhodophyceae). The example of tubular structure is Enteromorpha (Chlorophyceae). arvind wasnik
- 32. Reproduction Found in Algae There are three common methods of reproduction found in algae – (i) vegetative, (ii) asexual, and (iii) sexual. 1. Vegetative reproduction: This may be of several types. (i) By cell division: The mother cells divide and the daughter cells are produced, which become new plants. This is exclusive type of reproduction in Pleurococcus, some desmids, diatoms, Euglena, etc. (ii) Fragmentation: The plant body breaks into several parts or fragments and each such fragment develops into an individual. This type of vegetative reproduction is commonly met within filamentous forms, e.g., Ulothrix, Spirogyra, etc. The fragmentation of colonies also takes place in several blue green algae, e.g., Aphanocapsa, Aphanothece, Nostoc, etc. arvind wasnik
- 33. arvind wasnik (iii) Hormogone formation: When the trichomes break in small pieces of two or more cells, such pieces are called ‘hormogones’. Each hormogone develops into a new plant, e.g., Oscillatoria, Nostoc, etc. (iv) Hormospores or hormocysts: They are thick-walled hormogones, and produced in somewhat drier conditions. (v) By adventitious thalli: Certain special structures of thalli are formed which help in vegetative reproduction. The well known propagula of Bryopsis, Sphacelaria and Nereocystis are good examples. (vi) By primary secondary protonema: Such thread-like vegetative bodies develop in the case of Chara, which help in reproduction. (vii) Tubers: Usually these bodies are rounded and filled up with abundance of starch. Each body may give rise to a new plant, e.g., Chara. (viii) Starch or amylum stars: Such special star-shaped, starch filled bodies give rise to new plants frequently reported from Chara.
- 34. arvind wasnik (ix) Bulbils: Small bud-like structures. Usually develop on the rhizoids of Chara are called bulbils. Each such bulbil may develop into a new plant. (x) Akinetes: In most of the Chlorophyceae members, the Akinetes are developed. Usually the protoplast of each cell converts in a single akinete. Sometimes they are formed in chains. Each akinete may develop into a new plant, e.g., Oedogonium, Ulothrix, etc. 2. Asexual reproduction: Usually the protoplast of a cell divides into several protoplasts and thereafter they escape from the mother and develop into new plants. (i) By zoospores: The zoospores are formed from certain older cells of the filaments. The cytoplasm divides to form zoospores which are escaped from the mother cell. They are always formed in favourable conditions. The zoospores are always motile. They may be (i) biflagellate, (ii) tetraflagellate, (iii) stephanokontean type of zoospores, e.g., Oedogoniales and (iv) compound zoospores, e.g., Vaucheriaceae
- 35. arvind wasnik (ii) By aplanospores: When motile phase of zoospores is eliminated, the bodies are called aplanospores. The aplanospores develop in unfavourable conditions. Each such spore is surrounded by a wall. (iii) By hypnospores: Actually they are very thick-walled aplanospores and develop only in adverse conditions, e.g., Pediastrum, Vaucheria. (iv) Palmella stage: Here the successive generations of divided cells are gelatinized and a thick mucilaginous envelope develops, e.g., Chlamydomonas, Ulothrix, etc. (v) Autospores: They are just like aplanospores except that they are smaller in size. They resemble in shape to mother cell except in size. Each autospore gives rise to a new plant. Such autospores are reported from many Chlorococcales. (vi) Endospores: In many blue green algae and Bacillariophyceae, the endospores are formed within the cells. On the approach of favourable conditions, each endospore develops in a new individual. (vii) Exospores:
- 36. arvind wasnik (viii) Carpospores: They are found in the carposporophytes of red algae (Rhodophyceae). Each such spore develops in a new individual. (ix) Tetra spores: (x) Monospores: These spores develop within monosporangia. Each spore gives rise to a new plant, e.g., many members of Rhodophyceae (Bangia, Porphyra, Porphyridium, etc). (xi) Paraspores: Such spores are reported from many members of Rhodophyceae. Each spore develops into a new plant. (xii) Statospores: They are found in Xanthophyceae and Bacillariophyceae where they act as perennating bodies. (xiii) Daughter colonies: In many Volvocales and Chlorococcales, the daughter colonies are developed asexually, e.g., Volvox, Hydrodictyon, Pediastrum, etc. (xiv) Gongrosira stage of Vaucheria: In the aseptate filaments of Vaucheria, the protoplast divides into several parts, several hypnospores or cysts are produced and the whole filament looks like an algal form ‘Gongrosira’. (xv) Microspores: They are produced in many Bacillariophyceae.
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- 38. arvind wasnik It is greatly advanced method of reproduction and not known in Myxophyceae (blue green algae). There are two main types, i.e., (i) isogamy and (ii) heterogamy. (i) Isogamy: The fusion of similar motile gametes is found in many species. Usually the gametes taking part in fusion come from two different individuals or filaments, sometimes these gametes come from two different cells of the same filament. Thousands of gametes come and aggregate in clumps. (See Fig. 3.8). (ii) Heterogamy: The fusion of dissimilar gametes is called heterogamy. There are variations of it. (a) Anisogamy: The motile gametes taking part in fusion may either differ in size (morphological anisogamy) or physiological behaviour (physiological anisogamy). (b) Oogamy: In this case, the male antherozoid fuses with the female egg. This fusion may be of primitive type as found in Cylindrocapsa, or advanced type as in Oedogonium, Vaucheria, Chara, Polysiphonia, etc.
- 39. arvind wasnik (iii) Aplanogamy or conjugation: It implies the fusion of two non-flagellate amoeboid gametes (aplanogametes). They are morphologically similar but physiologically dissimilar, e.g., order Conjugales. In fresh water algae, the sexual reproduction is best means of perennation because it is followed by the formation of thick-walled zygote or oospore. Parthenogenesis: The female gametes convert into zygotes without fusion. The resultants are called azygospores or parthenospores and the phenomenon ‘parthenogenesis’, e.g., Spirogyra, Oedogonium and many others. Autogamy: In this phenomenon, the fusion of the daughter protoplasts or of the divided nuclei of a cell without liberation takes place. This process is known in many diatoms and colour-less dinoflagellates.
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