Protozoans For class_modified.ppt
- 2. Historical Background 2 Historically Protozoa included nearly every group known as ‘Protista”- fungus like, animal-like, plantlike, and other unicellular group. Protozoa means ‘first animals’, coined by Goldfuss (1820)
- 3. Historical Background 3 Early biologists considered this group as the ancestors of metazoans among the free-living protists Specialized in sub cellular/biochemical level Specialized in cellular level Specialized in tissue level
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- 8. It is now an established taxon including…. 8 Collared flagellates (Choanoflagellates), the sister taxon of metazoa and truly qualifies the ‘first animals’.
- 9. Taxonomic relationship 9 Remarkably Myxozoans exhibit similarities with cnidarians (anemones & jellyfish) Thus, protozoa is the name for grade within a scheme of organization, a loose confederation of eukaryotic taxa, rather than a monophylatic taxon
- 10. A descriptive account Nearly 215,000 species equal in no the vascular plants and 10 times more plentiful than bacterial & viral species combined. Protozoan parasites have enormous impact on humans, poultry, fish, wild animals. Mutualism: photosynthetic protozoa & corals – forming coral reef. Myriads- in soil & water – essential role in food chain. 10
- 12. Volvox : a very good missing link 12
- 13. Many are colonial…. 13 Body: A single cell Cell size: ranges form 10 μm, as in choanoflagellates, to several cm in some dinoflagellates, forams & amoeabe Vorticella colony
- 16. Therefore…. They are unicellular with some colonial and multicellular stages. Most are microscopic. All symmetries are present within members of the group. No germ layers No organs or tissues are formed, but specialized organelles serve many of these functions 16
- 17. Exo or endoskeleton 17 Protozoan skeleton, like metazoans, can be both endo & exo skeletons. It forms a complete covering, called as a test (or lorica/theca/shell) Star sands: Foraminiferans
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- 21. 21 This is how it moves
- 22. Thus….. They include free-living, mutualistic, commensal and parasitic forms… may be aquatic or terrestrial They move by pseudopodia, flagella, cilia and they can direct cell movements. Most are naked, but some have a simple endoskeleton or exoskeleton. All types of nutrition are present: autotrophic, heterotrophic and saprozoic. 22
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- 24. 24 Adaptability Protozoans are ecologically important primary producers, consumers and as vital links in the food chain Humans are greatly effected by parasitic protozoans either directly or indirectly – Effects range from irritating - fatal Malaria (Plasmodium spp.) worldwide epidemic
- 25. 25 Reproduction Asexual reproduction – Replication of chromosomes and the splitting of the parent into two or more parts – Binary fission – Multiple fission – Budding Protozoans are problematic in their associations as colonial forms
- 27. Multiple Fission in Amoeba 27
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- 30. Biological Contributions in Protozoa have intracellular specialization or organization of organelles in cells. Cells may have distinct functions; some colonial protozoa have separate somatic and reproductive zooids. Asexual reproduction occurs by mitotic division. Some have true sexual reproduction with zygote formation. 30
- 31. Biological Contributions in Responses to stimuli represent the simplest reflexes and inborn behaviors known. Shelled protozoa have the simplest exoskeletons Basic enzymes systems support all types of nutrition: autotrophic, saprozoic and holozoic. Many have developed means of locomotion 31
- 32. 32 Classification (Levine et al., 1980) Subkingdom Protozoa 1. Phylum Ciliophora (Ciliates) 2. Phylum Sarcomastigophora 3. Phylum Apicomplexa 4. Phylum Microspora 5. Phylum Labyrinthomorpha 6. Phylum Asecterospora 7. Phylum Myxozoa
- 33. 33 Phylum Ciliophora Defining characteristics – Body externally ciliated in at least some lifecycle stages Have the highest degree of subcellular specialization and are considered advanced protozoans Paramecium feces
- 34. Phylum Ciliophora Most of the species are free living; quite a number are commensal, some shortly parasitic and a large number symphorionts on variety of hosts Simple cilia or compound ciliary organelles are present at least one stage in life cycle 34
- 36. Phylum Ciliophora Nuclei are of two types Presence of contrctile vacuole(s) Kingdom Protozoa 36
- 37. Phylum Ciliophora Asexual reproduction by binary transverse fission, basically homothetogenic (Miotic fission across the rows of cilia of a protozoan) and generally parakinetal, but budding & multiple fission also occur 37
- 39. 39 Cilia Cilia – Hair-like structures by which the organism moves, collects food and senses their surroundings Fastest of all the protozoans Cilia structure
- 40. Ciliate Biology Oral groove Cytostome Cytoproct Contractile vacuole Parakinetal: anlage for the opisthe oral apparatus is derived directly from the first ordinary somatic ciliary row right of the glabrous stripe and has no connection with parental mouth structures. Paramecium
- 41. 41 Ciliate Lifestyles 65% of all ciliate species are free-living and mobile Some ciliates form colonial aggregations and have sessile habits Other ciliates have symbiotic relationships in invertebrates and vertebrates Vorticella
- 43. Some more ciliates 43 Podophrya Prorodon
- 44. Phylum Sarcomastigophora/ Zoomastigophora Nucleus is one type, except hereokaryotic Foraminiferans Locomotion by either pseudopodia or flagella or both Asexual reproduction, essentially syngamy when sexual Three Sub-phyla: Mastigophora, Opalinata & Sarcodina Kingdom Protozoa 44
- 45. Mastigophora (examples) Trypanosoma Euglena Noctiluca Giardia Leishmania 45
- 46. Opalinata (examples) Opalina Protoopalina 46
- 47. Sarcodina (examples) Amoeba Entamoeba Elphidium 47
- 48. 48 Phagocytosis
- 50. 50 Foraminiferans (Amoeboid Protists) Individuals secrete multi- chambered tests, generally made of calcium carbonate (CaCo3)or agglutinated sediment particles. Over 50,000 species are recognized, both living (10,000) and fossil (40,000). They are usually less than 1 mm in size, but some are much larger, the largest species reaching up to 20 cm Foram. tests
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- 53. 53 Foraminiferans Feed on diatoms and algae, very slow movers Organisms are extremely common and form ooze – White cliffs of Dover are foraminiferan tests
- 54. 54 Phylum Radiozoa/Radiolaria Defining characteristics – Body is divided into distinct zones separated by a perforated membrane or capsule Have pseudopodia supported with thin microtubules that give a spiny rayed appearance
- 56. 56 Radiolarians Have shells made of silicon dioxide that can be very intricate Feed on diatoms and other phytoplankton Benthic individuals move by use of pseudopodia – Can occur in large concentrations that form ooze as well
- 57. 57 The Flagellated Protozoans Characterized by the possession of a definite body shape and the possession of one or more flagella Most species are free-living and mobile Noctiluca
- 58. 58 Phytoflagellated Protozoans Have chlorophyll and obtain energy directly from the sunlight Some are strictly autotrophic or heterotrophic – Some are a combination of both Both the Euglena and the dinoflagellates are examples of phytoflagellated protozoans
- 60. 60 Dinoflagellates Know for bioluminescence and highly toxic red tides – Dense aggregations produce saxitoxin killing fish and crustaceans Also contaminates shellfish causing diarrheic shellfish poisoning Some benthic dinoflagellates produce a neurotoxin that accumulates in tropical fish called Ciguatera
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- 64. 64 Morphology
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- 67. 67 Zooflagellated Protozoans Free-living forms – Most individuals are sessile and have a single flagellum that beats to obtain food and nutrients Parasitic forms – 25% of zooflagellate spp. are parasitic in humans, invertebrates, and other vertebrates – Usually have complex lifecycles with intermediate hosts – Malaria is caused by the genus Plasmodium technically a member of the phylum Sporozoa
- 68. Phylum Apicomplexa/ Sporozoa All species are parasitic in nature Anterior part of the body forms an apical complex This apical complex is made up of polar rings, rhoptries, micronemes, conoid and sub pellicular microtubules Microspore present in some stages Sexual reproduction by syngamy 68
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- 72. Phylum Microspora Obligatory intracellular parasites found nearly all animal groups Spores unicellular, each with imperforate wall, containing uninucleate or dinucleate sporoplasm 72
- 73. Phylum Microspora Spore with simple or complex extrusion apparatus associated with polar tube & polar cap 73
- 74. Phylum Microspora Mitochondria absent in spores 74 • Usually dimorphic in sporulation sequence
- 76. Phylum Labyrinthomorpha Mostly marine or estuarine Trophic stage having ectoplasmic network, with spindle shaped or spherical non amoeboid cells 76 Labyrinthula
- 77. Phylum Labyrinthomorpha In some genera, amoeboid cells are move within the cytoplasmic network by gliding 77
- 78. Phylum Labyrinthomorpha Unique cell-surface organelle, associated to ectoplasmic network Saprophytic or parasitic on algae; Zoospores are produced by most species 78
- 80. Phylum Ascetospora All are parasitic. In most of the cases spores are multicellular. Spores with one or more sporoplasm. Spores without polar capsules or polar filaments. Haplosporidium, Coelosporidium, Paramyxa, Marteilia. 80
- 83. Phylum Myxozoa All species are parasitic. Spores are of multicellular origin, with one or more polar capsules and sporoplasms. Each spore with 1, 2 or 3 (rarely more) valves. Myxidium, Myxobolus, Trilospora, Triactinomyxon. 83
- 85. Phylum Myxozoa example Kingdom Protozoa 85 Myxidium