Protozoa: Characters & Classification
The protozoa are heterogenous assemblage of some 50,000 acellular or single-cell organisms possessing typical (eukaryote) membrane bound cellular organelles. Being the simplest in structure, protozoa, are regarded most primitive or first animals (Gr. protos -first; zoon = animal) of nature. The acellular level of organization is the only characteristic by which the protozoa as whole can be described; in all other respects they display extreme display. They exhibit all types of symmetry, a great range of complexity, and adaptations for all types of enviromental 8
conditions. Protozoa were first seen by Leeuwenhoek (1677). The other pioneers, in the field of Protozoology, are Joblott (1718), Trembley (1744), Linnaeus (1758), Muller (1773), Dujardin (1845) Hackel (1862), Pasteur (1870), Butschli (1881), Ronald Ross (1898), etc. Term Protozoa was coined by Goldfuss (1817). Grassi (1952), Hall (1953), Kudo (1954), Pitelka (1953-59) and Allen (1962) have made their valuable contribution to the protozoology in present century.
GENERAL CHARACTERS
1. Protozoa occur wherever moisture is present in the sea (marine), in all type of fresh water, and in the soil, These are commensal, mutualistic, and many parasitic species. In fact the sporozoans are entirely parasitic.
2. Although
most protozoa occur as solitary individuals, there are numerous colonial forms. Some colonial forms, such as Volvox, attain such a degree of cellular interdependence that they approch a true. multicellular level of structure. Both solitary and colonial species may be either free moving or sessile: 3. The great majority of protozoa are microscopic. Anaplasma, a blood parasite, is so small that it occupies only 1/6 to 1/10th of a red blood corpuscles. On the other hand, the fresh water cilliate, Spirostomum, may reach a length of 3.0 mm. and be seen with the naked eye. A fossil foraminiferan, Nummulites, was 19 cm. across, probably the largest size that has been attained by any protozoa. 4. Body
symmetry non-radial, spherical, or bilateral.
5. The body is either naked or covered by pellicle. Sometimes an exoskeleton is also present. 6. The shape of body is usually constant but in some cases it is unstable and in other it may change with, the environment or age.
7. Their locomotory organelles are finger-line pseudopodia, flagella, cilia or absent as in sporozoans. 8. Nutrition may be holozoic (animal like), holophytic (plant like), saprozoic or parasitic. The organelles of ingestion and egestion may be present or absent. Digestion occur intracellularly inside the food vacuoles in most cases.
9. No specific respiratory and excretory organs are present. Both are carried through general body surface by diffusion Excretion sometimes carried with the help of contractile vacuole.
10. In fresh water protozoa excess water is usually eleminated by contractile vacuoles, Thus these are mainly osmoregulatory in function.
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Protozoa: Characters & Classification
11. Asexual reproduction by binary fission, multiple fission or budding occurs at some time in the life history of almost all protozoa. Meiosis, gametes formation, and fertilization have been observed in many species, but the nature of these events and their occurance in the life cycle of the organism is highly variable. Encystment is common. 722
12. Life-history is often complicated in some cases with alternation of asexual and sexual phases. 16.12 13 Their body is not distinctly differentiated into somatoplasm and germplasm, hence natural death does not take place in them. 19510 1
Special Characters
1 Their acellular body regulates all the life activities thus there is no physiological division of labour. The division of labour is restricted to the organelles which are intracellular or subcellular structures. 2. The animals give their respond to various stimuli. This is gives an indication of the beginning of the nervous system of metazoans.
3. The microconjugants and macroconjugants in the conjugation of Vorticella indicate the beginning of sexual dimorphism.
CLASSIFICATIONA
There is disagreement among Protozoologits on the ways of classifying Protozoa. Modern workers like Kazloff (1972) and Robert D.Barnes (1980) tend to believe that this group includes more than one unicellular phyla. Barnes (1980) raised the four major groups viz. Mastigophora, Sarcondina, Sporozoa and Ciliophora to the rank of independent phylum. Here we are following the classification given by "Committee on Taxonomy and Taxonomic Problems of the Protozoologists" (Honiberge et al, 1964).
According to Honiberg et al Protozoa have been classified into four subphyla.
Subphylum
Subphylum II
I
Subphylum
Subphylum
Sarcomastigophora
Sporozoa
1. Organelles of locomotion
2. Nucleus monomorphic (single type).
Cnidophora
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SUBPHYLUM-I SARCOMASTIGOPHORA DE ano wally no mund are pseudopodia or flagella.
3. Nutrition holozoic or holophytic..
4. Asexual reproduction by binary or multiple fission.
5. Sexual reproduction by syngamy; no spore formation.
This subphylum is divided into three super classes in brigma ne
Super Class-A Mastigophora
1. Simple and primitive. Body with firm pellicle.
2. One to many flagella for locomotion.
3. Asexual reproduction by binary, more or less symmetrogenic, fission.
4. Autotrophic or heterotrophic or both.
Class-1 Phytomastigophorea
1. Mostly free-living.
2. Plant-like flagellates with or without chromoplasts.
3. Usually one or two flagella, the nucleus vesicular.
serve food as starch or paramylon.
Order. 1. Chrysomonadina
1. Small flagellates with yellow or brown chromoplast.
12
Protozoa: Characters & Classification
2. One to three flagella are present.
3. Gullet absent; stigma present.
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4. Nutrition holophytic, starch absent but leucosin and fat droplets are present. the that 5. Siliceous cysts. Marine or fresh water.
Examples. Chromulina, Synura, Ochromonas, Uroglena etc.
Order. 2. Coccolithophorida
1. Tiny marine flagellates covered by calcareous platelets-coccoliths.
2. Two flagella and yellow to brown chromoplasts.
3. No endogenous siliceous cysts.
Examples: Coccolithus, Rhabdosphaera.
Order. 3. Heterochlorida
1. Two unequal flagella and yellow-green chromoplasts. 2. Silicious cysts.
Examples: Heterochloris, Myxochloris
Order. 4. Cryptomonadida ech
1. Compressed with a rigid pellicle.ets
2. Gullet reaches upto the middle of the body.
3. They have two unequal flagella. Green, yellow, brown or colourless chromatophores which form starch.
4. Stigma often present. dd
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5. Marine or fresh water
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Examples: Chilomonas, Cryptomonas.
Order. 5. Dinoflagellida
3. Chromatophores are green, yellow, or brown.
4. Reserve food is starch or oil.
6. Some are bioluminescent.
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1. Small and planktonic. Body naked or with a thick pellicle or cellulose theca.
2. Two flagella, one lying transversely and the other pointing backwards.
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5. There are complex vacuoles which are not contractile.
7. Mostly marine, some are parasitic.
Examples: Noctiluca, Ceratium; Oodinium, Gonyaulax. Order. 6. Chloromonadida
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1. Small, with a delicate and dorso-ventrally flattened pellicle.
2. Two flagella, one trailing.
3. Chromatophores green and numerous.
4. Reserve food is oil.
5. Stigma absent; complex.
6. Contractile vacuole present.
7. Largely freshwater.
Examples: Gonyostomum, Vacularia.
Order. 7. Euglenida
1. Large with a thick and firm pellicle.
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Protozoa: Characters & Classification
4. Stigma present in coloured form.
5. Chromatophores green and numerous sometimes colourless.
6. Reserve food is paramylum and oil.
7. Mostly fresh water.
Examples: Euglena, Phacus, Peranema, Rhabdomonas. 40200
Order. 8. Volvocida
1. Small with rigid cellulose covering theca.
2. Gullet absent.
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3. Flagella usually two sometimes more.
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5. Reserve food is starch and oil.
6. Stigma present.
7. Mostly fresh water forms. Many colonial species. Examples: Volvox, Chlamydomonas, Gonium, Pandori
Class-2 Zoomastigophorea (Zoomastigina)
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5. Many commensals,
Order. 1. Choanoflagellida
1. Fresh water flagellates, with a
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2. Sessile, sometimes stalked, sometimes with lorica.d
3. Solitary or colonial.non dont guere illo lo eo supildo feribogant Examples: Codosiga, Salpingoeca, Proterospongia.
Order. 2. Bicosoecida
Order. 3. Rhizomastigida 1. Largely fresh water flagellate encased within a lorica. 2. Two flagella, one free, the other attaching posterior end of body or shell.oncept ka Examples: Bicosoeca, Poteriodendron.eusot bas goft long bevolenka
1. Small and amoeboid forms.
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2. Flagella one or more upto four. 3. Locomotion by pseudopodia and flagella. 4. Chiefly freshwater.
Examples: Mastigamoeba, DimorphaOrder. 4. Kinetoplastida
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1. Small and more or less amoeboid in forms; no gullet.
2. Flagella basically one, but up to four.
Order. 5. Retortamonadina
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3. Mostly parasitic forms, some are freshwater. Freshwater forms sessile, sometimes stalked. Examples: Bodo, ypanosoma, Leishmania.
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1. Gut parasites of insects or vertebrates.
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Protozoa: Characters & Classification
Sub class (ii) Acantharia
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1. Imperforate, nonchitinoid central capsule without pores.
2. Anisotropic skeleton of strontium sulphate.
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3. Axopodia present. Marine.
Examples: Acanthometra.
Sub class (iii) Heliozoia
Class-3. Piroplasmea
1. Exclusive endoparasites.
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Examples: Actinophrys, Actinosphaerium, Camptonema.
Sub class (iv) Proteomyxidia
2. Parasite in red blood corpuscles of vertebrates. 3. Do not produce spores. Examples: Babesia
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1. Spherical animal without central capsule commonly called Sun-animalcules. 2. Axpodia radiating. 1m8x3
3. Body cytoplasm is differentiated into outer vacuolated ectoplasm and inner dense endoplasm. 4. Skeleton absent (naked); if present, it is made up of siliceous scales and spines. 5. Primarily in fresh water. 19
1. Largely marine and freshwater parasites of algae and higher plants. 2. Pseudopodia are filopodia and reticulopodia.
3. Reproduction by binary or multiple fission, multiple fission in cyst. Examples: Vampyrella, Pseudospora.
SUSTE.
1. Small, round, rod-shaped or amoeboid.
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SUBPHYLUM-II SPOROZOA
Class-1. Telosporea
4. Reproduction is both asexual and sexual.
Sub class (i) Gregarinia
Sub class (ii) Coccidia
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2. The locomotory organelles are absent in adults. 3. Cilia or flagella may be present in gametes. 4. Nutrition saprozoic. 25 atsotni nedito, biod unsayisi tu Autoge allowen noitaronges fluxes ear brie zaljunda šlby, 31 Stomatsby (of eentu duel
5. Asexual reproduction by multiple fission and sexual by syngamy, followed by spore formation. 6. Sporozoites are infective stage; nucleus is of single type. We
1. Pseudopodia are absent and locomotion is by gliding or body flexion. 2. Spores without capsules or filaments, naked or encysted. 1961 1962 glimming on ysm] 3. Adult trophozoites with one nucleus. 306 30 IRS 9:0
agusi vlevizmasq thod i 1. Mature trophozoites are large and extracellular. 2. Reproduction is sexual with sporogony; spores contains eight sporozoites. 12 3. These are parasite of gut and body cavity of invertebrates. Examples: Gregarina, Monocystis. ouage to YOXA 4
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1. Mature trophozoites are small and intracellular.abos
2. Gametocytes are dimorphic.
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3. Sporzoites multiply by schizogony in tissue
Protozoa: Characters & Classification
Order 1. Eucoccida
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1. Asexual and sexual both the phases occur in life-cycle.sevinus how Mornasiond 2. They are parasite in epithelial and blood cells of invertebrates and vertebrates.de alog Sub order (a) Eimerina
1. Macrogametes and microgametes 2. Syzygy is absent. Zygote is non-motile.xolor? trusfyndazteagal bengamb coo4/ 3. Sporozoites are encased in sporocyst. da vodi aux ils son los su Examples: Eimeria. insangolsz
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Sub order (b) Haemosporina
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1. Macrogametes and microgametes develop independently. otimitiv bens voo erosal 2. Syzygy is absent. Zygote (ookinate) motile. 3. Sporozoites are naked. and Lanigan single ob milostni nonible to collemagn foot 2 SET 1
4. Schizogony in vertebrate host and sporogony in invertebrate hosts.. GYI Examples: Plasmodium. earch To ales toya aslorony
Class-2. Toxoplasmea
1. Spore formation is absent.
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2. Reproduction asexual 4 3. Cysts are formed which have many naked sporozoites. No. flagella or pseudopodia. MTEN Examples: Toxoplasma, Sarcocystis.
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Class-3. Haplosporea
1. Spores are present.
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Examples: Ichthyosporidium, Haplosporidium. SUBPHYLUM-III (ambatig of boys, moliner bou hode vi cuzo mil 1 llegada 10 de soldalist nok CNIDOSPORA occurs throughout life.
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1. Adult trophozoite has many nuclei.
2. Spore formation
3. Spores have several cells having one or more polar filaments which are coiled threads and can be shot obro n
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4. Zygote gives rise to one or more trophozoites without sporogony.
Class-1. Myxosporidea
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1. Spores develop from several nuclei and enclosed in two or three valves. Polar capsule present. Order. 1. Myxosporida
1. Spores are large with a bivalved membrane. 2. Trophozoite amoeboid and not intracellular.
3. Polar capsule 1, 2 or 4 with filaments.
Examples: Myxidium. Order. 2. Actinomyxida
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1. Spores large with a trivalved membrane. 2. Polar capsule three, each with a filament. Example: Triactinomyxon.
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Protozoa: Characters & Classification
Class-2. Microsporidea
1. Spores small, with a univalved membrane.play 2. Polar capsule absent or present with 1 or 2 filaments. Examples: Nosema. why i dag on her fine black ES () tahtoa 1
Pastaneyors I SUBPHYCUM-IV CILIOPHORANO 1. The ciliates comprise the largest subphylum of Protozoa. Some 8000 species have been described and many groups are still not well known. They are also like the most animal and exhibit a very high level of organelle development.
2. The shape of body is definite. The body wall is a complex living pellicle, containing alveoli, trichocysts and other organelles, in addition to infraciliature.
3. The body surface is covered with uniform cilia which function in locomotion.OKLA 4. The cilia around the cytostome region have become specialized as compound ciliary organelles called membranelles and undulating membranes in many ciliates that employ filter feeding. 5. Most of them have two types of nuclei-larger macronucleus and smaller micronucleus. S 6. One or more contractile vacuoles are present in fresh water forms.
7. Reproduction asexual by transverse binary fission.
8. Conjugation also takes place with fusion of nuclei.
9. The anal aperture or cytopyge is a permanent aperture. 10. No alternation of generation in the life cycle.ge boxsu vasin sadku nw ben of 912 H Class-1. Ciliata 19752, 49040 3
1. Cilia are present during the whole or a part of their life cycle. 2. Mouth or cytostome and cytophanynx are often present. 3. Nutrition is holozoic.
4. Reproduction takes place asexually by binary fission or budding and sexually by conjugation. 5. Mostly free living in fresh water, marine but parasites, colonial and sedentary forms also occur. Class Ciliata is divided into four subclasses : A
Sub class (i) Holotrichia
1. Cilia usually short and uniform, arranged in longitudinal rows all over the body.
2. No adoral spiral of long cilia or membranelles.
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3. Buccal ciliature either absent or, if present, usually inconspicuous. The subclass Holotrichia is divided into following orders: 13 10 M 10
Order. 1. Gymnostomatida
1. Chiefly large ciliates with no oral ciliature.
2. Cytostome opens directly to outside.
Examples: Didinium, Nassula, Coleps.
Order. 2. Trichostomatida
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1. With vestibular but not buccal ciliature. 2. Free living and parasitic forms.
Examples: Colpoda, Balantidium.
Order. 3. ChonotrichidaProtozoa: Characters & Classification
Order. 4. Apostomatida
1. Body with spirally arranged ciliation.
2. Cytostome mid-ventral.
3. Marine parasite. Life cycle complex usually involving two hosts, one of which is crustacean, Examples: Hyalophysa. Order. 5. Astomatida 1. Body ciliation uniform. nopfvesst we
2. Cytostome absent.
3. Commensals or endoparasites living in the gut and body cavity of oligochaete worms. Apie Examples: Hoplitophrya, Anoplophrya. and almos
Order. 6. Hymenostomatida
1. Mouth usually lies on the side of the body at the end of peristome, remains permanently open and leads into cytopharnx.
2. Buccal cavity present with membranes.
3. Small body with uniform cilia.
Example: Paramecium
Order. 7. Thigmotrichida
1. A small group of fresh and marine water ciliates found in association with bivalve molluses. 2. Anterior end of body bears a tuft of thigmotactic cilia. 2 no obmeld")
1 Example: Boveria, Thigmophrya. #beb zengwe net buot plnotumoo inmins petifoz Sub class (ii) Peritricha llogah own ad 11 seolah to abew-los donds and baba woman 1. Adults without body cilia.olda beqare quel sonsesiqol suby a vbod uslooboom
2. The apical end of the body typically bears a conspicuous buccal ciliaturelioolt tona 26 bod 1-toala convicted not 3. Mostly sessile bearing a stalk. PORT d get to suidwa who hrbe out sgole afford og sdt si naft It bears a single order-Peritrichida.
Examples: Vorticella, Carchesium.
Sub class (iii) Suctoria
1. Sessile and stalked body.
2. Young with cilia. Adult with few to many tentacles.
3. Adult completely devoid of any ciliature. This subclass bears only one order-Suctorida. Examples: Ephelota, Podophrya, Acineta.
Sub class (iv) Spirotricha
1. Reduced body cilia.
2. Well developed conspicuous buccal ciliature.
Order. 1. Heterotrichida
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1. With uniform body cilia or body encased in a lorica and body cilia absent. Examples: Stentor, Halteria.
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Order. 2. Oligotrichida
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1. Body cilia reduced or absent.
2. Conspicuous buccal membranelles, commonly extending around apical end of body. Examples: Halteria, Strombidium. Day. al
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1. Vase-shaped ciliates lacking body cilia.
2. A funnel at the free end of the body bears vestibular 3. Chiefly marine and ectocommensel on crustaceans.
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Examples: Spirochona, Chilodochona.
