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Algae Classification.pptx

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Thippeswamy M

The document discusses various systems of classifying algae proposed by different scientists over time. It describes how classification has been based on characteristics like pigmentation, flagellation, cell structure, chloroplast features, and phylogenetic relationships. Several major classification schemes are outlined that divide algae into kingdoms, divisions, classes, and phyla based on these distinguishing traits. There is no universal agreement on a single classification system.

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Algae: Classification Dr. M. Thippeswamy Davangere University Davanagere, India
Algae are simple autotrophic plants that generally lack root, stem, leaves, conducting vessels and complex sex organs. It refers to a heteromorphic group of organisms which can photosynthesize as they contain chlorophyll pigment and they lack a sterile covering around their reproductive cells. They are apparently simple group of organisms but possesses diverse nature in both morphological and physio-chemical characteristics.
It is often a hard task for phycologists to define the term algae. It is so diverse that putting all the common characters to define algae in a single sentence is almost an impossible task. To support such claim, we can recall two world famous phycologists’ statement: “Sometimes even the professional botanists and biologists find algae embarrassingly elusive of definition” (Bold and Wynne).
The primitive existence of algae is supported by the Precambrian fossil record which dates back to about 3 billion years ago. According to Guiry (2012) the number of living algae are estimated to range from 30,000 to more than one million species. M.D. Guiry (born 1949), According to Lee, “The algae are thallophytes (plants lacking roots, stems, and leaves) that have chlorophyll a as their primary photosynthetic pigment and lack a sterile covering of cells around the reproductive cells” (Lee, 1989).
Nomenclature of Algae The Greek word for algae is ”phykos” and according to International Code of Botanical Nomenclature (ICBN), a group of algae should necessarily be incorporated by the word ”phykos”. Because of such incorporation, the words such as Chlorophyceae, Phaeophyceae and Rhodophyceae indicate an idea of their relationship with algae. So, as the words like Chlorophyta, Phaeophyta and Rhodophyta end with ”phyta”, they are equivalent to the status of a division; words like Chlorophyceae, Phaeophyceae and Rhodophyceae end with ”phyceae” and are therefore equivalent to the status of a class and so on.
BASIS OF CLASSIFICATION Rarely one, and generally a combination of a few or more of the following characters are considered by the algal taxonomists while classifying algae: In normal microscope- Types of pigments, Types of reserve food materials Number and position of flagella Cell structure Under electron microscope- Flagella and types Eyespot Chloroplast Endoplasmic Reticulum (CER) Thylakoid grouping Phycobilisomes (out of 450-760 mm range) External scales Pit connection Silification vesicles Theca or scales Projectiles – To hold something/prey/to move. Nuclear structure and division Through biochemical analysis- Presence and structure of algal pigments Storage products Cell wall constituents
Algae Classification.pptx
Schools of thought Regarding the algal classification, there are different schools of thought: First school of thought • This school of thought is supported by Papenfuss, 1946; Bold and Wynne. • The algae should be divided first into several divisions (i.e. phyta such as Chlorophyta, Phaeophyta etc.) and then in each division, there should be different classes (i.e. phyceae such as Chlorophyceae, Phaeophyceae etc.). Why separate divisions? Supporters of the first view classified algae into divisions as they considered: Pigments differ in different phytas (=divisions). Product of photosynthesis is different in different divisions. Base of classification • Pigmentation • Storage product • Cellular organisation • Cell wall chemistry • Flagellation
Second school of thought • This school of thought is supported by Fritsch, 1935, 1945 and his followers. • Algae is itself equivalent to a division, and therefore it can only be further divided into classes (i.e. phyceae) and not into divisions (i.e. phyta). So in this school of thought there is no word as ”phyta”. Base of classification As the following characters are common in all algae, Fritsch and his followers opined not to form any divisions rather considered Algae itself as a division. Chlorophyll-a is ubiquitous to all algae, and so there is definitely a common origin from a common source. Therefore they all belong to the same group. • Internal structure of flagella is similar in all. • Product of assimilation may be different but the process of assimilation is same in all. • Methods of reproduction are almost common in all.
Third school of thought (supported by Lee, 1999) The above two classifications were proposed based on some physical and chemical characteristics of algae. There is a third classification as proposed by Robert Edward Lee based on the evolutionary features. This is the most modern classification scheme of algae. The basis of classification also includes- • Thyllakoid band • CER membrane • Phycobilins • Chlorophyll • Carotenoid pigment
The foundation of classification of algae was laid down by Linnaeus and De Jussieu. Linnaeus De Jussieu
Fritsch (1935) in his masterpiece on the ‘Structure and reproduction of algae’, gave a classification of algae into eleven classes based on His classification was based on… pigmentation, types of flagella, assimilatory products, thallus structure and methods of reproduction. Professor Felix Eugen Fritsch 1879 - 1954 Fritsch system of classification(1935, 48)
F.E. Fritsch (1935, 1948) divided algae into 11 classes
Smith (1955) classified algae into seven divisions and each division into several classes. The divisions are Chlorophyta, Euglenophyta, Pyrrhophyta, Chrysophyta, Phaeophyta, Cyanophyta and Rhodophyta. Gilbert Morgan Smith (1885–1959) Smith system of classification (1933,51,55)
Papenfuss (1955) classified algae into eight divisions such as Chrysophycophyta, Phaeophycophyta, Pyrrhophycophyta, Euglenophycophyta, Chlorophycophyta, Charophycophyta, Rhodophycophyta and Schizophycophyta. He included blue-green algae along with bacteria.
On the basis of the pigments in the plastid, morphological characters and biochemical differences. Chapman (1962) divided algae into four divisions, which were further subdivided into several classes. The divisions are Euphycophyta, Myxophycophyta, Chrysophycophyta and Pyrrhophycophyta
Papenfuss system of classification (1955) On the basis of Phylogeny recognized 8 phyla and 12 classes in algae Sl No Phyla Classes 1 Chlorophycophyta Chlorophyceae 2 Charophycophyta Charophyceae 3 Euglenophycophyta Euglenophyceae 4 Chrysophycophyta Chrysophyceae Xanthophyceae Bacillariophyceae 5 Pyrrophycophyta Cryptophyceae Chloromonadophycae Dinophyceae 6 Phaeophycophyta Phaeophyceae 7 Rhodophycophyta Rhodophyceae 8 Schizophycophyta Schizophyceae
Chapman and Chapman system of classification (1973)
Prescott (1969) emphasized the presence or absence of true nucleus in the algal cells for their classification along with other characters like pigmentation, biochemical nature of cell wall and reserve food material, and divided into nine divisions and fourteen classes. The divisions are Chlorophyta, Euglenophyta, Chrysophyta, Pyrrophyta, Phaeophyta, Rhodophyta, Cyanophyta, Cryptophyta and Chloromonadophyta. . G.W. Prescott
Round (1973) also recognized the importance of presence or absence of well organised nucleus in algal cells along with their phylogenetic relationships and other characteristics. He divided algae into two major groups and further divided into several divisions. Group 1 Prokaryota includes only one division Cyanophyta. Group 2 Eukaryota includes the following divisions such as Euglenophyta, Chlorophyta, Chrysophyta, Phaeophyta, Rhodophyta, Cryptophyta & Pyrrophyta Round system of classification (1973) Algae Procaryota Eucaryota Cynophyta Chlorophyta Euglenophyta Charophyta Parsinophyta Xanthophyta Haptophyta Dinophyta Bacillariophyta Chrysophyta Phaeophyta Rodhophyta Cryptophyta
Bold and Wynne (1978) classified algae into nine divisions such as Cyanochloronta, Chlorophycophyta, Charophyta, Euglenophycophyta, Phaeophycophyta, Chrysophycophyta, Pyrrophycophyta, Cryptophycophyta and Rhodophycophyta. Michael J. Wynne
Vanden Hoek et al., (1995) classified algae based on morphology, ultrastructure of cell, reproductive events, algal evolution, phylogeny, rRNA sequence data etc...
Algae, an Introduction to Phycology. C. van den Hoek , D. G. Mann , H. M. Jahns
Algae Classification.pptx
Lee (1989) classified algae into four groups and several Phyla. • Group 1 Prokaryotic algae includes phylum Cyanophyta and Prochlorophyta. • Group 2 Eukaryotic algae with chloroplasts surrounded only by the two membranes of the chloroplast envelope. It includes phylum Glaucophyta, Rhodophyta and Chlorophyta. • Group 3 Eukaryotic algae with chloroplasts surrounded by one membrane of chloroplast endoplasmic reticulum. It includes phylum Euglenophyta and Dinophyta. • Group 4 Eukaryotic algae with chloroplasts surrounded by two membranes of chloroplast endoplasmic reticulum. It includes phylum Cryptophyta, Chrysophyta, Prymnesiophyta, Bacillariophyta, Xanthophyta, Eustigmatophyta, Raphidophyta and Phaeophyta.
Guiry and Guiry (2011) classified algae into two Empires- Prokaryota and Eukaryota. Empire Prokaryota includes only one kingdom i.e., Bacteria comprising the phylum Cyanobacteria. Empire Eukaryota includes three algal kingdoms such as Chromista, Plantae and Protozoa.
Barsanti and Gualtieri (2014) grouped algae in four kingdoms of Bacteria, Plantae, Chromista and Protozoa. The prokaryotic kingdom bacteria includes phylum Cyanobacteria with a single class Cyanophyceae. Kingdom plantae includes four phyla i.e., Glaucophyta, Rhodophyta, Chlorophyta and Charophyta. Kingdom Chromista includes phylum Haplophyta, Cryptophyta, Ochrophyta and Cercozoa. Kingdom Protozoa includes phylum Myzozoa and Euglenozoa.
Algae Classification.pptx
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There are four distinct groups within the algae: 1. Prokaryotes: The cyanobacteria are the only prokaryotic algae. 2. Eukaryotic algae with chloroplasts surrounded by the two membranes of the chloroplast envelope. 3. Eukaryotic algae with the chloroplast surrounded by one membrane of chloroplast endoplasmic reticulum. 4. Eukaryotic algae with the chloroplast surrounded by two membranes of chloroplast endoplasmic reticulum. The standard botanical classification system is used in the systematics of the algae: Phylum – phyta Class – phyceae Order – ales Family – aceae Genus Species
Group 1 Prokaryotic algae Cyanophyta (cyanobacteria): • The cyanobacteria or blue-green algae form a natural group by virtue of being the only prokaryotic algae. • Prokaryotic algae have an outer plasma membrane enclosing protoplasm containing photosynthetic thylakoids, 70S ribosomes, and DNA fibrils not enclosed within a separate membrane. • Chlorophyll a is the main photosynthetic pigment, and oxygen is evolved during photosynthesis. • Phycobiliproteins are present which contains the pigments phycocyanin and phycoerythrin. • Examples include: Nostoc, Anabaena, Spirulina, Oscillatoria.
Group 2 Eukaryotic algae with chloroplasts surrounded only by the two membranes of the chloroplast envelope. Glaucophyta: • The Glaucophyta include those algae that have endosymbiotic cyanobacteria in the cytoplasm instead of chloroplasts. • Because of the nature of their symbiotic association, they are thought to represent intermediates in the evolution of the chloroplast. • Photosynthesis is carried out by modified endosymbiotic cyanobacteria; • The pigments of the Glaucophyta are similar to those of the Cyanophyceae: both chlorophyll a and the phycobiliproteins are present. • Examples include: Cyanophora paradoxa, Glaucocystis
Rhodophyta (red algae): • The Rhodophyceae lack flagellated cells, have chlorophyll a, phycobiliproteins, floridean starch as a storage product, and thylakoids occurring singly in the chloroplast. • The major features of a red algal cell are a chloroplast with one thylakoid per band and no chloroplast E.R. • The two most important polysaccharides derived from the Rhodophyceae are agar and carrageenan. • Agar is obtained commercially from species of Gelidium and Pterocladia as well as from various other algae, such as Acanthopeltis, Ahnfeltia, and Gracilaria Chlorophyta (green algae): • The Chlorophyta, or green algae, have chlorophylls a and b, and form starch within the chloroplast, usually in association with a pyrenoid. • The Chlorophyta thus differ from the rest of the eukaryotic algae in forming the storage product in the chloroplast instead of in the cytoplasm. • No chloroplast endoplasmic reticulum occurs around the chloroplasts. • Examples include: Chlamydomonas and Spirogyra.
Group 3 Eukaryotic algae with chloroplasts surrounded by one membrane of chloroplast endo-plasmic reticulum. Euglenophyta (euglenoids): • Euglenoids are characterized by chlorophylls a and b, one membrane of chloroplast endoplasmic reticulum, a mesokaryotic nucleus, one flagella with fibrillar hairs in one row, no sexual reproduction, and paramylon or chrysolaminarin as the storage product in the cytoplasm. • proteinaceous pellicle in strips under the plasma membrane; • Typical example includes Euglena. Dinophyta (dinoflagellates): mesokaryotic nucleus; chlorophylls a and c1; cell commonly divided into an epicone and a hypocone by a girdle; helical transverse flagellum; thecal plates in vesicles under the plasma membrane. Apicomplexa: heterotrophic flagellates with colorless plastids. Katablepharis ovalis
Group 4 Eukaryotic algae with chloroplasts surrounded by two membranes of chloroplast endoplasmic reticulum. Cryptophyta (cryptophytes): • Nucleomorph present between inner and outer membrane of chloroplast endoplasmic reticulum; • Starch formed as grains between inner membrane of chloroplast endoplasmic reticulum and chloroplast envelope; • chlorophyll a and c2; phycobiliproteins occur inside the thylakoids of the chloroplast; periplast inside plasma membrane. • The cell body is asymmetric with a clearly defined dorsi-ventral/ right-left sides. • The asymmetric cell shape results in a peculiar swaying motion during swimming. • Most cryptophytes have a single lobed chloroplast with a central pyrenoid. • Typical example includes Cryptomonas.
Heterokontophyta (heterokonts) : • The algae in the Heterokontophyta usually have cells with an anterior tinsel and posterior whiplash flagellum. • The plastids contain chlorophylls a and c along with fucoxanthin. • The storage product is usually chrysolaminarin in cytoplasmic vesicles. Chrysophyceae (golden-brown algae): • The Chrysophyceae are distinguished chemically by having chlorophylls a, c1, and c2 and structurally by two flagella inserted into the cell perpendicular to each other, • One photoreceptor on the short flagellum that is usually shaded by an eyespot in the anterior portion of the chloroplast, • Contractile vacuoles in the anterior portion of the cell, chloroplast endoplasmic reticulum, and radially or biradially symmetrical silica scales (if they are present). • The storage product is chrysolaminarin. • Many members of the class produce statospores enclosed in a silicified wall with a terminal pore. • Example includes Ochromonas, Dinobryon
Synurophyceae: • The Synurophyceae have chlorophylls a and c1, the flagella are inserted into the cell approximately parallel to one another, • There is a photoreceptor near the base of each flagellum, there is no eyespot, and the contractile vacuole is in the posterior portion of the cell. • Chloroplast endoplasmic reticulum is present in a few species, but absent in most. • The cells usually are covered by bilaterally symmetrical scales. • Example includes Mallomonas Eustigmatophyceae: • Characteristics of the class include a basal swelling of the tinsel flagellum adjacent to the eyespot, only chlorophyll a, chloroplasts without girdle lamellae and no peripheral ring of DNA, and chloroplast endoplasmic reticulum not connected to the nuclear envelope; an eyespot outside the chloroplast. • Examples include Pleurochloris magna, Polyedriella helvetica,
Pinguiophyceae: • An anterior tinsel flagellum with tripartite hairs and a posterior smooth whiplash flagellum. • The chloroplasts have two membranes of chloroplast endoplasmic reticulum, the outer membrane continuous with the nuclear envelope. • A girdle band of thylakoids occurs under the chloroplast envelope. • Pyrenoids occur in the chloroplast and the mitochondria have tubular cristae. • Chlorophyll a and chlorophyll c-related pigments as well as fucoxanthin, violaxanthin, zeaxanthin, and carotene are present. • The class is characterized by unusually high concentrations of polyunsaturated acids, especially 20:5 (n-3) (EPAeicosapentaenoic acid) in the cells. • Example is Phaeomonas parva Dictyochophyceae (silicoflagellates): • These golden-brown algae are characterized by tentacles or rhizopodia on basically amoeboid vegetative cells. • Chrysoamoeba is an example.
Pelagophyceae: Pelagomonas calceolata is a very small ultraplanktonic marine alga with a single tinsel flagellum and basal body, and a single chloroplast and mitochondrion. Bolidophyceae: The cells contain chlorophylls a, c1,c2,c3, Beta carotene, diatoxanthin, and fucoxanthin, as do the diatoms; Bolidomonas is an example. Bacillariophyceae (diatoms): The cells are surrounded by a rigid two-part box-like cell wall composed of silica, called the frustule. The chloroplasts contain chlorophylls a, c1, and c2 with the major carotenoid being the golden-brown fucoxanthin, which gives the cells their characteristic color. Navicula, Achnanthes longipes Raphidophyceae (chloromonads): The Raphidophyceae, or chloromonads, have chlorophylls a and c, and two membranes of chloroplast endoplasmic reticulum. The anterior flagellum is commonly tinsel, whereas the posterior flagellum is naked. Chattonella, Fibrocapsa, and Heterosigma
Xanthophyceae (yellow-green algae): • The class is characterized by motile cells with a forwardly directed tinsel flagellum and a posteriorly directed whiplash flagellum. • The chloroplasts contain chlorophylls a and c, lack fucoxanthin, and are colored yellowish- green. The eyespot in motile cells is always in the chloroplast, and the chloroplasts are surrounded by two membranes of chloroplast endoplasmic reticulum. The outer membrane of the chloroplast E.R. is usually continuous with the outer membrane of the nucleus. • In most non-motile cells the wall is composed of two overlapping halves. • Botrydium and Vaucheria Phaeothamniophyceae: The cells have two membranes of chloroplast endoplasmic reticulum with the outer membrane of chloroplast E.R. continuous with the outer membrane of the nuclear envelope. The chloroplasts have a ring-shaped genophore and girdle lamellae. The flagella are inserted laterally into the motile cells. Tetrasporopsis Phaeophyceae (brown algae): The Phaeophyceae, derive their characteristic color from the large amounts of the carotenoid fucoxanthin in their chloroplasts as well as from any phaeophycean tannins that might be present. The chloroplasts also have chlorophylls a, c1, andc2. There are two membranes of chloroplast E.R., which are usually continuous with the outer membrane of the nuclear envelope. The storage product is laminarin. Prymnesiophyta (haptophytes): two whiplash flagella; haptonema present; chlorophyll a and c; fucoxanthin; scales common outside cell; storage product chrysolaminarin occurring in vesicles.
The above discussion certifies well that the science of classification is a complicated one and in case of algae it has reached its highest point. This article will be incomplete without the words of Prescott (1969) about the complexity of classification schemes: …..ideas concerning classification systems continually vary as more and more facts are disclosed which require modifications of the previous concepts. Further, we may come to realize that as long as there are three men on the earth, there will be at least two different interpretations of the facts, possibly three, and we may find that none of them is correct…
DIVISION CHLOROPHYTA (green algae) Chlorophylls a and b; starch stored inside chloroplast; mitochondria with flattened cristae; flagella, when present, lack tubular hairs (mastigonemes); unmineralized scales on cells or flagella of flagellates and zoospores; conservatively, between 9,000 and 12,000 species. Class Chlorophyceae Primarily freshwater; includes Chlamydomonas, Chlorella, Dunaliella, Oedogonium, and Volvox. Class Charophyceae Includes the macroscopic stonewort Chara, filamentous Spirogyra, and desmids. Class Pleurastrophyceae Freshwater and marine; includes marine flagellate Tetraselmis. Class Prasinophyceae (Micromonadophyceae) Paraphyletic, primarily marine; includes Micromonas (sometimes placed in Mamiellophyceae), Ostreococcus, and Pyramimonas. Class Ulvophyceae Primarily marine; includes Acetabularia, Caulerpa, Monostroma, and sea lettuce (Ulva). Chlamydomonas
DIVISION CHROMOPHYTA Most with chlorophyll a; one or two with chlorophyllide c; carotenoids present; storage product beta-1,3-linked polysaccharide outside chloroplast; mitochondria with tubular cristae; biflagellate cells and zoospores usually with tubular hairs on one flagellum; mucous organelles common. Class Bacillariophyceae (diatoms) Silica cell walls, or frustules; centric diatoms commonly planktonic and valves radially symmetrical; pennate diatoms, usually attached or gliding over solid substrates, with valves bilaterally symmetrical; primarily in freshwater, marine, and soil environments; at least 12,000 to 15,000 living species; tens of thousands more species described from fossil diatomite deposits; includes Cyclotella and Thalassiosira (centrics) and Bacillaria, Navicula and Nitzschia (pennates). Class Bicosoecaceae May be included in the Chrysophyceae or in the protozoan group Zoomastigophora; colourless flagellate cells in vase-shaped loricas (wall-like coverings); cell attached to lorica using flagellum as a stalk; lorica attaches to plants, algae, animals, or water surface; freshwater and marine; fewer than 50 species described; includes Bicosoeca and Cafeteria. Class Chrysophyceae(golden algae) Many unicellular or colonial flagellates; also capsoid, coccoid, amoeboid, filamentous, parenchymatous, or plasmodial; many produce silica cysts (statospores); predominantly freshwater; approximately 1,200 species; includes Chrysamoeba, Chrysocapsa, Lagynion, and Ochromonas. diatoms
Class Dictyochophyceae Predominantly marine flagellates, including silicoflagellates that form skeletons common in diatomite deposits; fewer than 25 described species. Order Pedinellales When pigmented, has 6 chloroplasts in a radial arrangement; flagella bases attached almost directly to nucleus; includes Apedinella, Actinomonas, Mesopedinella, Parapedinella, and Pteridomonas. Order Dictyochales (silicoflagellates) Typically with siliceous skeletons like spiny baskets enclosing the cells; flagella bases attach almost directly to nucleus; silicoflagellate skeletons common in diatomite deposits; includes Dictyocha, Pedinella, and Pseudopedinella. Class Eustigmatophyceae Mostly small, pale green, and spherical; fewer than 15 species; Eustigmatos and Nannochloropsis. Class Phaeophyceae(brown algae or brown seaweeds) Range from microscopic forms to large kelps more than 20 metres long; at least 1,500 species, almost all marine; includes Ascophyllum, Ectocarpus, Fucus, Laminaria, Macrocystis, Nereocystis, Pelago phycus, Pelvetia, Postelsia, and Sargassum. seaweeds
Class Prymnesiophyceae (Haptophyceae) Many with haptonema, a hairlike appendage between two flagella; no tubular hairs; many with organic scales; some deposit calcium carbonate on scales to form coccoliths; coccolithophorids may play a role in global warming because they can remove large amounts of carbon from the ocean water; predominantly marine and planktonic; approximately 300 species; more fossil coccolithophores known; includes Chrysochromulina, Emiliania, Phaeocystis, and Prymnesium. Class Raphidophyceae (Chloromonadophyceae) Flagellates with mucocysts (mucilage-releasing bodies) occasionally found in freshwater or marine environments; fewer than 50 species; includes Chattonella, Gonyostomum, Heterosigma, Psammamonas, and Vacuolaria. Class Synurophyceae Previously placed in Chrysophyceae; silica-scaled; unicellular or colonial flagellates sometimes alternating with capsoid benthic stage; cells covered with elaborately structured silica scales; approximately 250 species; Mallomonas and Synura. Class Xanthophyceae(yellow-green algae) Primarily coccoid, capsoid, or filamentous; mostly in freshwater environments; about 600 species; includes Botrydium, Bumilleriopsis, Tribonema, and Vaucheria Vaucheria
DIVISION CRYPTOPHYTA Unicellular flagellates. Class Cryptophyceae Chlorophyll a, chlorophyllide c2, and phycobiliproteins; starch stored outside of chloroplast; mitochondria with flattened cristae; tubular hairs on one or both flagella; special ejectosomes in a furrow or gullet near base of flagella; cell covered with periplast, often elaborately decorated sheet or scale covering; nucleomorph may represent reduced nucleus of symbiotic organism; approximately 200 described species; includes Chilomonas, Cryptomonas, Falcomonas, Plagioselmis, Rhinomonas, and Teleaulax. Cryptomonas
DIVISION RHODOPHYTA(red algae) Predominantly filamentous; mostly photosynthetic, a few parasitic; photosynthetic species with chlorophyll a; chlorophyll d present in some species; phycobiliproteins (phycocyanin and phycoerythrin) in discrete structures (phycobilisomes); starch stored outside chloroplast; mitochondria with flattened cristae; flagella completely absent; coralline red algae contribute to coral reefs and coral sands; predominantly marine; approximately 6,000 described species; includes Bangia, Chondrus, Corallina, Gelidium, Gracilaria, Kappaphycus, Palmaria, Polysiphonia, Porphyra, and Rhodymenia. Porphyra Polysiphonia
DIVISION DINOFLAGELLATA (PYRROPHYTA) Taxonomy is contentious. Predominantly unicellular flagellates; approximately half of the species are heterotrophic rather than photosynthetic; photosynthetic forms with chlorophyll a, one or more chlorophyllide c types, and peridinin or fucoxanthin; mitochondria with tubular cristae and flagella without tubular hairs; ejectile trichocysts below surface in many members; many with cellulosic plates that form a so-called armour around cell; some bioluminescent, some containing symbionts; resting (interphase) nucleus contains permanently condensed chromosomes; several produce toxins that either kill fish or accumulate in shellfish and cause sickness or death in humans when ingested; more than 1,500 species described, most in the class Dinophyceae; includes Alexandrium, Ceratium, Dinophysis, Gonyaulax, Gymnodinium, Noctiluca, Pe ridinium, and Polykrikos. Gonyaulax
DIVISION EUGLENOPHYTA Taxonomy is contentious. Primarily unicellular flagellates; both photosynthetic and heterotrophic. Class Euglenophyceae Chlorophylls a and b; paramylon stored outside chloroplasts; mitochondria with paddle- shaped cristae; flagella lack tubular hairs, but some with hairlike scales; pellicle covering of sliding sheets allows cells to change shape; approximately 1,000 described species; includes Colacium, Euglena, Eutreptiella, and Phacus.

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Algae Classification.pptx

  • 1. Algae: Classification Dr. M. Thippeswamy Davangere University Davanagere, India
  • 2. Algae are simple autotrophic plants that generally lack root, stem, leaves, conducting vessels and complex sex organs. It refers to a heteromorphic group of organisms which can photosynthesize as they contain chlorophyll pigment and they lack a sterile covering around their reproductive cells. They are apparently simple group of organisms but possesses diverse nature in both morphological and physio-chemical characteristics.
  • 3. It is often a hard task for phycologists to define the term algae. It is so diverse that putting all the common characters to define algae in a single sentence is almost an impossible task. To support such claim, we can recall two world famous phycologists’ statement: “Sometimes even the professional botanists and biologists find algae embarrassingly elusive of definition” (Bold and Wynne).
  • 4. The primitive existence of algae is supported by the Precambrian fossil record which dates back to about 3 billion years ago. According to Guiry (2012) the number of living algae are estimated to range from 30,000 to more than one million species. M.D. Guiry (born 1949), According to Lee, “The algae are thallophytes (plants lacking roots, stems, and leaves) that have chlorophyll a as their primary photosynthetic pigment and lack a sterile covering of cells around the reproductive cells” (Lee, 1989).
  • 5. Nomenclature of Algae The Greek word for algae is ”phykos” and according to International Code of Botanical Nomenclature (ICBN), a group of algae should necessarily be incorporated by the word ”phykos”. Because of such incorporation, the words such as Chlorophyceae, Phaeophyceae and Rhodophyceae indicate an idea of their relationship with algae. So, as the words like Chlorophyta, Phaeophyta and Rhodophyta end with ”phyta”, they are equivalent to the status of a division; words like Chlorophyceae, Phaeophyceae and Rhodophyceae end with ”phyceae” and are therefore equivalent to the status of a class and so on.
  • 6. BASIS OF CLASSIFICATION Rarely one, and generally a combination of a few or more of the following characters are considered by the algal taxonomists while classifying algae: In normal microscope- Types of pigments, Types of reserve food materials Number and position of flagella Cell structure Under electron microscope- Flagella and types Eyespot Chloroplast Endoplasmic Reticulum (CER) Thylakoid grouping Phycobilisomes (out of 450-760 mm range) External scales Pit connection Silification vesicles Theca or scales Projectiles – To hold something/prey/to move. Nuclear structure and division Through biochemical analysis- Presence and structure of algal pigments Storage products Cell wall constituents
  • 8. Schools of thought Regarding the algal classification, there are different schools of thought: First school of thought • This school of thought is supported by Papenfuss, 1946; Bold and Wynne. • The algae should be divided first into several divisions (i.e. phyta such as Chlorophyta, Phaeophyta etc.) and then in each division, there should be different classes (i.e. phyceae such as Chlorophyceae, Phaeophyceae etc.). Why separate divisions? Supporters of the first view classified algae into divisions as they considered: Pigments differ in different phytas (=divisions). Product of photosynthesis is different in different divisions. Base of classification • Pigmentation • Storage product • Cellular organisation • Cell wall chemistry • Flagellation
  • 9. Second school of thought • This school of thought is supported by Fritsch, 1935, 1945 and his followers. • Algae is itself equivalent to a division, and therefore it can only be further divided into classes (i.e. phyceae) and not into divisions (i.e. phyta). So in this school of thought there is no word as ”phyta”. Base of classification As the following characters are common in all algae, Fritsch and his followers opined not to form any divisions rather considered Algae itself as a division. Chlorophyll-a is ubiquitous to all algae, and so there is definitely a common origin from a common source. Therefore they all belong to the same group. • Internal structure of flagella is similar in all. • Product of assimilation may be different but the process of assimilation is same in all. • Methods of reproduction are almost common in all.
  • 10. Third school of thought (supported by Lee, 1999) The above two classifications were proposed based on some physical and chemical characteristics of algae. There is a third classification as proposed by Robert Edward Lee based on the evolutionary features. This is the most modern classification scheme of algae. The basis of classification also includes- • Thyllakoid band • CER membrane • Phycobilins • Chlorophyll • Carotenoid pigment
  • 11. The foundation of classification of algae was laid down by Linnaeus and De Jussieu. Linnaeus De Jussieu
  • 12. Fritsch (1935) in his masterpiece on the ‘Structure and reproduction of algae’, gave a classification of algae into eleven classes based on His classification was based on… pigmentation, types of flagella, assimilatory products, thallus structure and methods of reproduction. Professor Felix Eugen Fritsch 1879 - 1954 Fritsch system of classification(1935, 48)
  • 13. F.E. Fritsch (1935, 1948) divided algae into 11 classes
  • 14. Smith (1955) classified algae into seven divisions and each division into several classes. The divisions are Chlorophyta, Euglenophyta, Pyrrhophyta, Chrysophyta, Phaeophyta, Cyanophyta and Rhodophyta. Gilbert Morgan Smith (1885–1959) Smith system of classification (1933,51,55)
  • 15. Papenfuss (1955) classified algae into eight divisions such as Chrysophycophyta, Phaeophycophyta, Pyrrhophycophyta, Euglenophycophyta, Chlorophycophyta, Charophycophyta, Rhodophycophyta and Schizophycophyta. He included blue-green algae along with bacteria.
  • 16. On the basis of the pigments in the plastid, morphological characters and biochemical differences. Chapman (1962) divided algae into four divisions, which were further subdivided into several classes. The divisions are Euphycophyta, Myxophycophyta, Chrysophycophyta and Pyrrhophycophyta
  • 17. Papenfuss system of classification (1955) On the basis of Phylogeny recognized 8 phyla and 12 classes in algae Sl No Phyla Classes 1 Chlorophycophyta Chlorophyceae 2 Charophycophyta Charophyceae 3 Euglenophycophyta Euglenophyceae 4 Chrysophycophyta Chrysophyceae Xanthophyceae Bacillariophyceae 5 Pyrrophycophyta Cryptophyceae Chloromonadophycae Dinophyceae 6 Phaeophycophyta Phaeophyceae 7 Rhodophycophyta Rhodophyceae 8 Schizophycophyta Schizophyceae
  • 18. Chapman and Chapman system of classification (1973)
  • 19. Prescott (1969) emphasized the presence or absence of true nucleus in the algal cells for their classification along with other characters like pigmentation, biochemical nature of cell wall and reserve food material, and divided into nine divisions and fourteen classes. The divisions are Chlorophyta, Euglenophyta, Chrysophyta, Pyrrophyta, Phaeophyta, Rhodophyta, Cyanophyta, Cryptophyta and Chloromonadophyta. . G.W. Prescott
  • 20. Round (1973) also recognized the importance of presence or absence of well organised nucleus in algal cells along with their phylogenetic relationships and other characteristics. He divided algae into two major groups and further divided into several divisions. Group 1 Prokaryota includes only one division Cyanophyta. Group 2 Eukaryota includes the following divisions such as Euglenophyta, Chlorophyta, Chrysophyta, Phaeophyta, Rhodophyta, Cryptophyta & Pyrrophyta Round system of classification (1973) Algae Procaryota Eucaryota Cynophyta Chlorophyta Euglenophyta Charophyta Parsinophyta Xanthophyta Haptophyta Dinophyta Bacillariophyta Chrysophyta Phaeophyta Rodhophyta Cryptophyta
  • 21. Bold and Wynne (1978) classified algae into nine divisions such as Cyanochloronta, Chlorophycophyta, Charophyta, Euglenophycophyta, Phaeophycophyta, Chrysophycophyta, Pyrrophycophyta, Cryptophycophyta and Rhodophycophyta. Michael J. Wynne
  • 22. Vanden Hoek et al., (1995) classified algae based on morphology, ultrastructure of cell, reproductive events, algal evolution, phylogeny, rRNA sequence data etc...
  • 23. Algae, an Introduction to Phycology. C. van den Hoek , D. G. Mann , H. M. Jahns
  • 25. Lee (1989) classified algae into four groups and several Phyla. • Group 1 Prokaryotic algae includes phylum Cyanophyta and Prochlorophyta. • Group 2 Eukaryotic algae with chloroplasts surrounded only by the two membranes of the chloroplast envelope. It includes phylum Glaucophyta, Rhodophyta and Chlorophyta. • Group 3 Eukaryotic algae with chloroplasts surrounded by one membrane of chloroplast endoplasmic reticulum. It includes phylum Euglenophyta and Dinophyta. • Group 4 Eukaryotic algae with chloroplasts surrounded by two membranes of chloroplast endoplasmic reticulum. It includes phylum Cryptophyta, Chrysophyta, Prymnesiophyta, Bacillariophyta, Xanthophyta, Eustigmatophyta, Raphidophyta and Phaeophyta.
  • 26. Guiry and Guiry (2011) classified algae into two Empires- Prokaryota and Eukaryota. Empire Prokaryota includes only one kingdom i.e., Bacteria comprising the phylum Cyanobacteria. Empire Eukaryota includes three algal kingdoms such as Chromista, Plantae and Protozoa.
  • 27. Barsanti and Gualtieri (2014) grouped algae in four kingdoms of Bacteria, Plantae, Chromista and Protozoa. The prokaryotic kingdom bacteria includes phylum Cyanobacteria with a single class Cyanophyceae. Kingdom plantae includes four phyla i.e., Glaucophyta, Rhodophyta, Chlorophyta and Charophyta. Kingdom Chromista includes phylum Haplophyta, Cryptophyta, Ochrophyta and Cercozoa. Kingdom Protozoa includes phylum Myzozoa and Euglenozoa.
  • 30. There are four distinct groups within the algae: 1. Prokaryotes: The cyanobacteria are the only prokaryotic algae. 2. Eukaryotic algae with chloroplasts surrounded by the two membranes of the chloroplast envelope. 3. Eukaryotic algae with the chloroplast surrounded by one membrane of chloroplast endoplasmic reticulum. 4. Eukaryotic algae with the chloroplast surrounded by two membranes of chloroplast endoplasmic reticulum. The standard botanical classification system is used in the systematics of the algae: Phylum – phyta Class – phyceae Order – ales Family – aceae Genus Species
  • 31. Group 1 Prokaryotic algae Cyanophyta (cyanobacteria): • The cyanobacteria or blue-green algae form a natural group by virtue of being the only prokaryotic algae. • Prokaryotic algae have an outer plasma membrane enclosing protoplasm containing photosynthetic thylakoids, 70S ribosomes, and DNA fibrils not enclosed within a separate membrane. • Chlorophyll a is the main photosynthetic pigment, and oxygen is evolved during photosynthesis. • Phycobiliproteins are present which contains the pigments phycocyanin and phycoerythrin. • Examples include: Nostoc, Anabaena, Spirulina, Oscillatoria.
  • 32. Group 2 Eukaryotic algae with chloroplasts surrounded only by the two membranes of the chloroplast envelope. Glaucophyta: • The Glaucophyta include those algae that have endosymbiotic cyanobacteria in the cytoplasm instead of chloroplasts. • Because of the nature of their symbiotic association, they are thought to represent intermediates in the evolution of the chloroplast. • Photosynthesis is carried out by modified endosymbiotic cyanobacteria; • The pigments of the Glaucophyta are similar to those of the Cyanophyceae: both chlorophyll a and the phycobiliproteins are present. • Examples include: Cyanophora paradoxa, Glaucocystis
  • 33. Rhodophyta (red algae): • The Rhodophyceae lack flagellated cells, have chlorophyll a, phycobiliproteins, floridean starch as a storage product, and thylakoids occurring singly in the chloroplast. • The major features of a red algal cell are a chloroplast with one thylakoid per band and no chloroplast E.R. • The two most important polysaccharides derived from the Rhodophyceae are agar and carrageenan. • Agar is obtained commercially from species of Gelidium and Pterocladia as well as from various other algae, such as Acanthopeltis, Ahnfeltia, and Gracilaria Chlorophyta (green algae): • The Chlorophyta, or green algae, have chlorophylls a and b, and form starch within the chloroplast, usually in association with a pyrenoid. • The Chlorophyta thus differ from the rest of the eukaryotic algae in forming the storage product in the chloroplast instead of in the cytoplasm. • No chloroplast endoplasmic reticulum occurs around the chloroplasts. • Examples include: Chlamydomonas and Spirogyra.
  • 34. Group 3 Eukaryotic algae with chloroplasts surrounded by one membrane of chloroplast endo-plasmic reticulum. Euglenophyta (euglenoids): • Euglenoids are characterized by chlorophylls a and b, one membrane of chloroplast endoplasmic reticulum, a mesokaryotic nucleus, one flagella with fibrillar hairs in one row, no sexual reproduction, and paramylon or chrysolaminarin as the storage product in the cytoplasm. • proteinaceous pellicle in strips under the plasma membrane; • Typical example includes Euglena. Dinophyta (dinoflagellates): mesokaryotic nucleus; chlorophylls a and c1; cell commonly divided into an epicone and a hypocone by a girdle; helical transverse flagellum; thecal plates in vesicles under the plasma membrane. Apicomplexa: heterotrophic flagellates with colorless plastids. Katablepharis ovalis
  • 35. Group 4 Eukaryotic algae with chloroplasts surrounded by two membranes of chloroplast endoplasmic reticulum. Cryptophyta (cryptophytes): • Nucleomorph present between inner and outer membrane of chloroplast endoplasmic reticulum; • Starch formed as grains between inner membrane of chloroplast endoplasmic reticulum and chloroplast envelope; • chlorophyll a and c2; phycobiliproteins occur inside the thylakoids of the chloroplast; periplast inside plasma membrane. • The cell body is asymmetric with a clearly defined dorsi-ventral/ right-left sides. • The asymmetric cell shape results in a peculiar swaying motion during swimming. • Most cryptophytes have a single lobed chloroplast with a central pyrenoid. • Typical example includes Cryptomonas.
  • 36. Heterokontophyta (heterokonts) : • The algae in the Heterokontophyta usually have cells with an anterior tinsel and posterior whiplash flagellum. • The plastids contain chlorophylls a and c along with fucoxanthin. • The storage product is usually chrysolaminarin in cytoplasmic vesicles. Chrysophyceae (golden-brown algae): • The Chrysophyceae are distinguished chemically by having chlorophylls a, c1, and c2 and structurally by two flagella inserted into the cell perpendicular to each other, • One photoreceptor on the short flagellum that is usually shaded by an eyespot in the anterior portion of the chloroplast, • Contractile vacuoles in the anterior portion of the cell, chloroplast endoplasmic reticulum, and radially or biradially symmetrical silica scales (if they are present). • The storage product is chrysolaminarin. • Many members of the class produce statospores enclosed in a silicified wall with a terminal pore. • Example includes Ochromonas, Dinobryon
  • 37. Synurophyceae: • The Synurophyceae have chlorophylls a and c1, the flagella are inserted into the cell approximately parallel to one another, • There is a photoreceptor near the base of each flagellum, there is no eyespot, and the contractile vacuole is in the posterior portion of the cell. • Chloroplast endoplasmic reticulum is present in a few species, but absent in most. • The cells usually are covered by bilaterally symmetrical scales. • Example includes Mallomonas Eustigmatophyceae: • Characteristics of the class include a basal swelling of the tinsel flagellum adjacent to the eyespot, only chlorophyll a, chloroplasts without girdle lamellae and no peripheral ring of DNA, and chloroplast endoplasmic reticulum not connected to the nuclear envelope; an eyespot outside the chloroplast. • Examples include Pleurochloris magna, Polyedriella helvetica,
  • 38. Pinguiophyceae: • An anterior tinsel flagellum with tripartite hairs and a posterior smooth whiplash flagellum. • The chloroplasts have two membranes of chloroplast endoplasmic reticulum, the outer membrane continuous with the nuclear envelope. • A girdle band of thylakoids occurs under the chloroplast envelope. • Pyrenoids occur in the chloroplast and the mitochondria have tubular cristae. • Chlorophyll a and chlorophyll c-related pigments as well as fucoxanthin, violaxanthin, zeaxanthin, and carotene are present. • The class is characterized by unusually high concentrations of polyunsaturated acids, especially 20:5 (n-3) (EPAeicosapentaenoic acid) in the cells. • Example is Phaeomonas parva Dictyochophyceae (silicoflagellates): • These golden-brown algae are characterized by tentacles or rhizopodia on basically amoeboid vegetative cells. • Chrysoamoeba is an example.
  • 39. Pelagophyceae: Pelagomonas calceolata is a very small ultraplanktonic marine alga with a single tinsel flagellum and basal body, and a single chloroplast and mitochondrion. Bolidophyceae: The cells contain chlorophylls a, c1,c2,c3, Beta carotene, diatoxanthin, and fucoxanthin, as do the diatoms; Bolidomonas is an example. Bacillariophyceae (diatoms): The cells are surrounded by a rigid two-part box-like cell wall composed of silica, called the frustule. The chloroplasts contain chlorophylls a, c1, and c2 with the major carotenoid being the golden-brown fucoxanthin, which gives the cells their characteristic color. Navicula, Achnanthes longipes Raphidophyceae (chloromonads): The Raphidophyceae, or chloromonads, have chlorophylls a and c, and two membranes of chloroplast endoplasmic reticulum. The anterior flagellum is commonly tinsel, whereas the posterior flagellum is naked. Chattonella, Fibrocapsa, and Heterosigma
  • 40. Xanthophyceae (yellow-green algae): • The class is characterized by motile cells with a forwardly directed tinsel flagellum and a posteriorly directed whiplash flagellum. • The chloroplasts contain chlorophylls a and c, lack fucoxanthin, and are colored yellowish- green. The eyespot in motile cells is always in the chloroplast, and the chloroplasts are surrounded by two membranes of chloroplast endoplasmic reticulum. The outer membrane of the chloroplast E.R. is usually continuous with the outer membrane of the nucleus. • In most non-motile cells the wall is composed of two overlapping halves. • Botrydium and Vaucheria Phaeothamniophyceae: The cells have two membranes of chloroplast endoplasmic reticulum with the outer membrane of chloroplast E.R. continuous with the outer membrane of the nuclear envelope. The chloroplasts have a ring-shaped genophore and girdle lamellae. The flagella are inserted laterally into the motile cells. Tetrasporopsis Phaeophyceae (brown algae): The Phaeophyceae, derive their characteristic color from the large amounts of the carotenoid fucoxanthin in their chloroplasts as well as from any phaeophycean tannins that might be present. The chloroplasts also have chlorophylls a, c1, andc2. There are two membranes of chloroplast E.R., which are usually continuous with the outer membrane of the nuclear envelope. The storage product is laminarin. Prymnesiophyta (haptophytes): two whiplash flagella; haptonema present; chlorophyll a and c; fucoxanthin; scales common outside cell; storage product chrysolaminarin occurring in vesicles.
  • 41. The above discussion certifies well that the science of classification is a complicated one and in case of algae it has reached its highest point. This article will be incomplete without the words of Prescott (1969) about the complexity of classification schemes: …..ideas concerning classification systems continually vary as more and more facts are disclosed which require modifications of the previous concepts. Further, we may come to realize that as long as there are three men on the earth, there will be at least two different interpretations of the facts, possibly three, and we may find that none of them is correct…
  • 42. DIVISION CHLOROPHYTA (green algae) Chlorophylls a and b; starch stored inside chloroplast; mitochondria with flattened cristae; flagella, when present, lack tubular hairs (mastigonemes); unmineralized scales on cells or flagella of flagellates and zoospores; conservatively, between 9,000 and 12,000 species. Class Chlorophyceae Primarily freshwater; includes Chlamydomonas, Chlorella, Dunaliella, Oedogonium, and Volvox. Class Charophyceae Includes the macroscopic stonewort Chara, filamentous Spirogyra, and desmids. Class Pleurastrophyceae Freshwater and marine; includes marine flagellate Tetraselmis. Class Prasinophyceae (Micromonadophyceae) Paraphyletic, primarily marine; includes Micromonas (sometimes placed in Mamiellophyceae), Ostreococcus, and Pyramimonas. Class Ulvophyceae Primarily marine; includes Acetabularia, Caulerpa, Monostroma, and sea lettuce (Ulva). Chlamydomonas
  • 43. DIVISION CHROMOPHYTA Most with chlorophyll a; one or two with chlorophyllide c; carotenoids present; storage product beta-1,3-linked polysaccharide outside chloroplast; mitochondria with tubular cristae; biflagellate cells and zoospores usually with tubular hairs on one flagellum; mucous organelles common. Class Bacillariophyceae (diatoms) Silica cell walls, or frustules; centric diatoms commonly planktonic and valves radially symmetrical; pennate diatoms, usually attached or gliding over solid substrates, with valves bilaterally symmetrical; primarily in freshwater, marine, and soil environments; at least 12,000 to 15,000 living species; tens of thousands more species described from fossil diatomite deposits; includes Cyclotella and Thalassiosira (centrics) and Bacillaria, Navicula and Nitzschia (pennates). Class Bicosoecaceae May be included in the Chrysophyceae or in the protozoan group Zoomastigophora; colourless flagellate cells in vase-shaped loricas (wall-like coverings); cell attached to lorica using flagellum as a stalk; lorica attaches to plants, algae, animals, or water surface; freshwater and marine; fewer than 50 species described; includes Bicosoeca and Cafeteria. Class Chrysophyceae(golden algae) Many unicellular or colonial flagellates; also capsoid, coccoid, amoeboid, filamentous, parenchymatous, or plasmodial; many produce silica cysts (statospores); predominantly freshwater; approximately 1,200 species; includes Chrysamoeba, Chrysocapsa, Lagynion, and Ochromonas. diatoms
  • 44. Class Dictyochophyceae Predominantly marine flagellates, including silicoflagellates that form skeletons common in diatomite deposits; fewer than 25 described species. Order Pedinellales When pigmented, has 6 chloroplasts in a radial arrangement; flagella bases attached almost directly to nucleus; includes Apedinella, Actinomonas, Mesopedinella, Parapedinella, and Pteridomonas. Order Dictyochales (silicoflagellates) Typically with siliceous skeletons like spiny baskets enclosing the cells; flagella bases attach almost directly to nucleus; silicoflagellate skeletons common in diatomite deposits; includes Dictyocha, Pedinella, and Pseudopedinella. Class Eustigmatophyceae Mostly small, pale green, and spherical; fewer than 15 species; Eustigmatos and Nannochloropsis. Class Phaeophyceae(brown algae or brown seaweeds) Range from microscopic forms to large kelps more than 20 metres long; at least 1,500 species, almost all marine; includes Ascophyllum, Ectocarpus, Fucus, Laminaria, Macrocystis, Nereocystis, Pelago phycus, Pelvetia, Postelsia, and Sargassum. seaweeds
  • 45. Class Prymnesiophyceae (Haptophyceae) Many with haptonema, a hairlike appendage between two flagella; no tubular hairs; many with organic scales; some deposit calcium carbonate on scales to form coccoliths; coccolithophorids may play a role in global warming because they can remove large amounts of carbon from the ocean water; predominantly marine and planktonic; approximately 300 species; more fossil coccolithophores known; includes Chrysochromulina, Emiliania, Phaeocystis, and Prymnesium. Class Raphidophyceae (Chloromonadophyceae) Flagellates with mucocysts (mucilage-releasing bodies) occasionally found in freshwater or marine environments; fewer than 50 species; includes Chattonella, Gonyostomum, Heterosigma, Psammamonas, and Vacuolaria. Class Synurophyceae Previously placed in Chrysophyceae; silica-scaled; unicellular or colonial flagellates sometimes alternating with capsoid benthic stage; cells covered with elaborately structured silica scales; approximately 250 species; Mallomonas and Synura. Class Xanthophyceae(yellow-green algae) Primarily coccoid, capsoid, or filamentous; mostly in freshwater environments; about 600 species; includes Botrydium, Bumilleriopsis, Tribonema, and Vaucheria Vaucheria
  • 46. DIVISION CRYPTOPHYTA Unicellular flagellates. Class Cryptophyceae Chlorophyll a, chlorophyllide c2, and phycobiliproteins; starch stored outside of chloroplast; mitochondria with flattened cristae; tubular hairs on one or both flagella; special ejectosomes in a furrow or gullet near base of flagella; cell covered with periplast, often elaborately decorated sheet or scale covering; nucleomorph may represent reduced nucleus of symbiotic organism; approximately 200 described species; includes Chilomonas, Cryptomonas, Falcomonas, Plagioselmis, Rhinomonas, and Teleaulax. Cryptomonas
  • 47. DIVISION RHODOPHYTA(red algae) Predominantly filamentous; mostly photosynthetic, a few parasitic; photosynthetic species with chlorophyll a; chlorophyll d present in some species; phycobiliproteins (phycocyanin and phycoerythrin) in discrete structures (phycobilisomes); starch stored outside chloroplast; mitochondria with flattened cristae; flagella completely absent; coralline red algae contribute to coral reefs and coral sands; predominantly marine; approximately 6,000 described species; includes Bangia, Chondrus, Corallina, Gelidium, Gracilaria, Kappaphycus, Palmaria, Polysiphonia, Porphyra, and Rhodymenia. Porphyra Polysiphonia
  • 48. DIVISION DINOFLAGELLATA (PYRROPHYTA) Taxonomy is contentious. Predominantly unicellular flagellates; approximately half of the species are heterotrophic rather than photosynthetic; photosynthetic forms with chlorophyll a, one or more chlorophyllide c types, and peridinin or fucoxanthin; mitochondria with tubular cristae and flagella without tubular hairs; ejectile trichocysts below surface in many members; many with cellulosic plates that form a so-called armour around cell; some bioluminescent, some containing symbionts; resting (interphase) nucleus contains permanently condensed chromosomes; several produce toxins that either kill fish or accumulate in shellfish and cause sickness or death in humans when ingested; more than 1,500 species described, most in the class Dinophyceae; includes Alexandrium, Ceratium, Dinophysis, Gonyaulax, Gymnodinium, Noctiluca, Pe ridinium, and Polykrikos. Gonyaulax
  • 49. DIVISION EUGLENOPHYTA Taxonomy is contentious. Primarily unicellular flagellates; both photosynthetic and heterotrophic. Class Euglenophyceae Chlorophylls a and b; paramylon stored outside chloroplasts; mitochondria with paddle- shaped cristae; flagella lack tubular hairs, but some with hairlike scales; pellicle covering of sliding sheets allows cells to change shape; approximately 1,000 described species; includes Colacium, Euglena, Eutreptiella, and Phacus.