: PROTOZOA :
Its Characteristics, Classification and Kinds
General Characters
- they are microscopic animalcules
- They are the most primitive of all animals
- protoplasmic degree of organisation
- Body single-celled(unicellular), containing one or additional nuclei that are monomorphic or polymorphic
- They form loose colonies in which they still remain independent but are mostly solitary.
- body symmetry is non-existing or could be bilaterally symmetrical, radially symmetrical or spherical.
- naked body or a pellicle that provides elaborate shells or exoskeletons.
- The body form is constant but varies with changing environment and age.
- All the essential activities are performed by just one cell(as mentioned earlier that they are unicellular) therefore only the subcellular physiological division of labour is present.
- Pseudopodia act as locomotor organelle.They might be completely absent or if present they might be there as whip-like flagella / hairlike cilia.
- Varied types of nutrition such as Holozoic, holophytic, saprozoic or parasitic. Digestion is performed intracellularly inside food vacuoles.
- Respiration and excretion —-general body surface
contractile vacuoles (osmoregulation)
- Reproduction —asexually
multiple fission
budding
—–sexually
hologamy which is conjugation of
adults
syngamy which is fusion of the
gametes
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SUBPHYLUM
- PLASMODROMA
- simple, primitive protozoa.
- flagella/cilia/pseudopodia could be either present or absent.
- comprises free-living and parasitic organisms.
- Examples of plasmodroma; are amoeba, plasmodium falciparum, and opalines.
SARCOMASTIGOPHORA
- Locomotor orgenelles pseudopodia or flagella / both. Nuclei of one specific kind(monomorphic).
SUBPHYLUM: MASTIGOPHORA
~ Simple, primitive, with firm pellicle
~ Flagella is there as locomotor orgenelle.
~ Nutrition autotrophic or heterotrophic or both
- CLASS: PHYTOMASTIGOPHORA
- The presence of Chlorophyll that contains chromatophores is present.
- Nutrition is majorly holophytic by phototrophy.
- Reserve food starch or paramylon.
- flagella 1,2 or more.
ORDER: CHRYSOMONADIDA
+ small, thin pellicle, often ameboid, flagella 1 to 3
+ gullet absent. Stigma often present.
+ chromatophgores 1 or 2, yellow or brown, and discoidal.
+ starch absent. Fats and Leucosin and may be present.
+ examples
chrysameoeba, synura, dinobryon.
ORDER: CRYPTOMONADIDA
+ small, with a rigid pellicle. Flagella 2.
+ Anterior gullet extends and runs upto middle of the body.
+ Two Chromatophores, yellow, brown or colourless.
+ Reserve foodstuff are present as starch, sometimes oils.
+ Examples of cryptomonadida
chilomonas, cryptomonas.
ORDER: EUGLENIDA
+ Large, pellicle thick and firm. Flagella 1/2.
+ Anterior end with a gullet leading into a resevoir.
+ Chromatophores numerous, gleen/ colourless.
+ Reserve foodstuff is present as paramylon and oils.
+ Examples
Phacus, Copromonas.
:ORDER: VOLVOCIDA(Phytomonadida)
+ Small, with rigid cellulose covering called Theca
+ no gullet. flagella 2 to 4
+presence chromatophores green, usually cup shaped
+ Reserve foodstuff starch and oils.
+ Example of volvocida;
Chlamydomonas, Volvox
ORDER: CHLOROMONADIDA
+ small dorso ventrally flat. Pellicle delicate
+ Gullet Present
+ presence Chromatophores which green and numerous.
+ Reserve foodstuff present as oils
+Examples of chloromonida:
Vacularia, Gonyostomum.
ORDER: DINOFLAGELLIDA
+ Small, planktonic. Naked, amoeboid or with a thick cellulose theca.
+ Gullet present or absent. Flagella 2.
+ Chromatophores yellow or brown.
+ Reservefoodstoff starch and oils both.
+Examples:
Noctiluca, Ceratium.
2. CLASS: ZOOMASTIGOPHORA (ZOOFLAGELLATA)
Flagellate protozoa possess one or more thread-like flagella.
– Some also have pseudopodia.
– A flagellum passes along the body, being attached to the body by an undulating
membrane (eg. Trypanosoma, Trichomonas).
– The nucleus is usually vesicular.
– Reproduction is done by longitudinal binary fission.
– A granular blepharoplast or basal granule from which
axoneme arises acts as a neuromotor apparatus.
– Axoneme forms the axial structure of the flagellum & consists of 2 central and 9 peripheral
fibrils surrounded by a flagellar sheath, which extends to the distal end of the axoneme.
– The presence of the kinetoplast is a deeply staining granule and is located prior to the blepharoplast. The kinetoplast contains DNA & is a part of mitochondria, which in the case of trypanosomes run the whole length of the body.
ORDER: RHIZOMASTIGIDA
+ small, ameboid, chiefly freshwater.
+ locomotion—-by— 1-4 flagella and pseudopodia.
+ Example of rhizomastigida:
Mastigameoeba, Dimorpha.
ORDER: KINETOPLASTIDA
+ Includes all haemo flagellates.
+ They are leaf-like in shape/ somewhat containing a single nucleus.
+ Having a Single flagellum attached to the body by an undulating membrane, supporting the
flagellum at its outer margin.
+ The single flagellum arises from the basal granule or blepharoplast and passes anteriorly
to become free in front of the body.
+ Kinetoplant posterior to the basal granule.
+ Trypanosoma have no mouth, feed by absorption of food in solution in their
environment through the pellicle.
+ 10 genera but only two genera are important genera. Trypanosoma & Leishmania.
+They have 4 developmental stages during their life cycles. “Mastigote” a Greek word that
means whip (flagellum), has been used as new terminology for 4 types of developmental
stages
ORDER: CHOANOFLAGELLIDA
+ a round collar with a base of a single flagellum.
+ free living, solitary or colonial.
+ Examples
Proterospongia
ORDER: DIPLOMONADIDA
+ Bilateral symmetry, binucleate, with delicate pellicle and often with a cytostome.
+ flagella 3-8 often traling or forming border of an undulating membrane.
+Mostly intestinal parasite
+Examples:
Girardia
ORDER: HYPERMASTIGIDA
+ highly specialised, numerous flagella.
+ kinetosomes arranged in a circle, plate or longitudnal or spiral rows.
+ mouth absent. food ingested by pseudopodia.
+gut parsites of temites and cockroaches
+Example
Lophomonas, Trychonympha
ORDER: TRICHOMONADIDA
+ flagella 4- 6 .one flagellum trailing.
+parasites of vertebrates
+ Examples:
trichomonas
SPOROZOA
- Locomotor organelles absenyt. spores are usually present. Exclusively endoparasites
- TELOSPORA
+ spores without polar capsules and filaments naked or encysted.
+ mature trophozoites large, extracellular in host’s gut and body cavities.
sublass: coccidia
*Mature trophozoites small intracellulae
*each oocyst produces many sporozoites.
*blood or gut parasite of vertebrates.
*examples : isopora, plasmodium .
CILIOPHORA
- presence of cilia as locomotor and feeding organelles at some stages in the life cycle. Nuclei of 2 kinds(dimorphic)
- Locomotor organelles numerous hair-like cilia, present throughout life.
- cytosome (definite mouth)and gullet are present except in a few parasitic forms. Anal aperture (cytophage) permanent.
- one or more contractile vacuoles are present even in marine and parasitic life types.
- Mostly two kinds of nuclei, large macronucleus and smaller micronucleus.
- examples
balantidium, clopoda.
CNIDOSPORA
- spores large/small
- nucleus 1/many.
- spores of 2/3 valves or univalve.
- mostly parasitic.
