Kingdom Protista – Animal like Protists or Protozoans
Table of Contents
Table of Contents
· Animal like Protists or Protozoans are the organisms which are heterotrophs and live as predators or parasites.
· They are believed to be primitive relatives of animals, hence included in Kingdom Protista in Five Kingdom Classification.
· They are heterotrophic organism which are almost found in every habitat. Some of them also show symbiotic nutrition.
· They are free living or exists as parasites in animals.
· They are acellular and microscopic organisms.
· Parasitic Protozoa produce some of the most deadly diseases. Such as Malaria etc.
Classification of Animal like Protists or Protozoa
· There are four major groups of protozoan, on the basis of their locomotory organs –
1. Flagellated Protozoans or Zooflagellates
2. Ciliated Protozoans or Ciliates
3. Amoeboid Protozoans or Sarcodina
4. Parasitic Protozoans or Sporozoans
· Most Primitive. They are acellular or non-cellular having protoplasmic level of organisation.
· They possess one or more flagella for locomotion.
· They may be free living or parasitic.
· Zooflagellates are generally uninucleate, occasionally multinucleate.
· The body is covered by a firm pellicle. They lack Cell Wall.
· Nutrition is holozoic, saproboic and parasitic.
· Asexual reproduction is by binary fission.
·Trypanosome – The parasite of sleeping sickness. It was first observed by Forde in 1901. Fruce discovered that the parasite of sleeping sickness is transmitted by tse-tse fly.
· Leishmania – it causes Kala azar, a severe Liver infection.
· Trichonymph – Inhabitant of gut of Termites capable of Digesting Cellulose.
· This group consists of Amoeba and their shelled relatives.
· Sarcodines are mostly free living, found in fresh water, sea water and on damp soil. Only a few are parasitic.
· Nutrition is Holozoic.
· The cytoplasm is differentiated into outer layer of clear plasmagel called Ectoplasm and inner granular mass plasmasol known as Endoplasm.
· The Various cell organelles floats in endoplasm such as Contractile Vacoules, Nucleus etc.
· They develop pseudopodia which are temporary protoplasmic outgrowths. They are of four types- lobopodia (broad and blunt), filppodia (slender, unsupported, and independent), axpodia (slender with axial support) and reticulopodia (slender, reticulate).
· Pseudopodia are used for locomotion and engulfing food articles.
· The body may be covered with plasmalemma or a shell.
· Reproduce Asexually by Binary Fission.
· Amoeba proteus – The Proteus Animalcule. Amoeba was discovered by Russel Von Rosenhoff in 1755.
· Entamoeba histolytica – Lamble (1859) discovered Entamoeba histolytica. It resides in the upper part of the human large intestine and causes the disease known as amoebic dysentery or amoebiasis.
· All Sporozoans are endoparsites.
· Uses spores to pass from one host to another.
· Locomotory organelles (cilia, flagella, pseudopodia, etc.) are absent.
· Nutrition is parasitic (absorptive).
· The body is covered with an elastic pellicle or cuticle.
· Contractile vacuoles are absent.
· Asexual reproduction occurs through syngamy followed by formation of haploid Spores called Sporozoids.
· Complex Life cycle consisting of two distinct asexual and sexual phases. They may be passed in one (monogenetic) or two different hosts (digenetic).
· Plasmodium – causative agent of Malaria.
· Regarded as highly evolved Protozoans.
· Ciliates are protozoan protists which develop a number of cilia during a part or whole of the life cycle.
· Cilia are used for locomotion and driving food.
· Most ciliates are free living individuals in fresh and marine waters. A few are parasitic.
· There is a high degree of morphological and physiological specialization.
· They have micronucleus which is repository for Genetic information and macronucleus which contains multiple copies of Genetic material found in micronucleus.
· The body is covered by a pellicle.
· Nutrition is holozoic except in the parasitic forms.
· There are definite regions for ingestion and egestion. The region of ingestion consists of an oral groove, cytostome (mouth) and gullet.
· They reproduce asexually by Binary Fission and Sexually by Conjugation.
· Paramecium– The slipper organism. Paramecium is a free living ciliate which is found in fresh water.
So, this was all about the Kingdom Protista – Animal like Protists or Protozoans and their Characteristics. In the next post (Click here), we will discuss about the Kingdom Fungi of Five Kingdom Classification by R.H. Whittaker in detail.
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