Kwame Nkrumah University Of Science & Technology Phylum Protozoa PDF

Kwame Nkrumah University of Science & Technology, Kumasi, Ghana PHYLUM PROTOZOA INVERTEBRATE ZOOLOGY BIOL 160 Name: Dr Mrs Sandra Abankwa Kwarteng Department: Theoretical and Applied Biology College: Scienc...

Kwame Nkrumah University of Science & Technology, Kumasi, Ghana PHYLUM PROTOZOA INVERTEBRATE ZOOLOGY BIOL 160 Name: Dr Mrs Sandra Abankwa Kwarteng Department: Theoretical and Applied Biology College: Science  Kingdom Protista Animal-like Plant-like Fungus-like Paramecium Euglena Slime molds Amoeba Algae Downy mildew Plasmodium www.knust.edu.gh 06/07/2022 2  Phylum Protozoa Simplest of all animals. Evolutionarily it is the lowest Phylum of the invertebrates. www.knust.edu.gh 06/07/2022 3  Phylum Protozoa Key environmental requirement for protozoans are the presence of sufficient moisture to prevent drying. Only spore- or cyst-bearing forms can withstand drying. www.knust.edu.gh 06/07/2022 4  Phylum Protozoa The organisms are mostly single celled, microscopic in size except when millions of individuals are present. There are two type: – Free-living found in several places such as fresh water, salt water and moist places depending on the species. – Parasitic protozoa have been found in almost every higher animal. Some parasitic protozoans live in the digestive tract (intestinal protozoa). Other live mainly in the blood (blood-inhabiting protozoa). www.knust.edu.gh 06/07/2022 5  Phylum Protozoa About 25 different species of protozoans live in humans. Classification of protozoans is based on the presence or absence and nature of movement organs. There are four classes: – Sacordina or Rhizopoda (Amoeba proteus, pseudopodia) – Mastigophora (Euglena viridis, flagella) – Sporozoa (Plasmodium, Monocystis, spore stage in it’s life cycle) – Infusoria or Ciliophora (Paramecium, cilia) www.knust.edu.gh 06/07/2022 6  Class Sarcodina Morphology The most primitive of all animals. Single celled. About 0.25 mm in diameter. Seen under the light microscope as an irregular colourless animated jelly constantly changing shape. They however have two distinct regions. 1. An outer colourless layer of clear cytoplasm (ectosarc) made of ectoplasm. Ectoplasm contains no granules. It is firmer than endoplasm. www.knust.edu.gh 06/07/2022 7  Class Sarcodina 2. A comparatively large central mass of granular cytoplasm (endosarc) made of endoplasm. www.knust.edu.gh 06/07/2022 8  Class Sarcodina The contractile vacuole is a clear space filled with fluid less dense than the surrounding protoplasm. It lies towards the end of the animal away from the direction of finger-like protrusions. Its function appears to be respiratory and excretory. Also in the endosarc is the nucleus and food vacuoles. www.knust.edu.gh 06/07/2022 9  Class Sarcodina The food vacuole contains particle of nutritive material. It is created when food is taken into the body. The body of Amoeba is divided into: 1. Plasmosol: a central elongated portion 2. Plasmagel: a solid layer surrounding the plasmasol 3. Plasmalemma: a very thin elastic surface layer or membrane. 4. Hyaline layer: between the plasmagel and the plasmalemma. www.knust.edu.gh 06/07/2022 10  Class Sarcodina Locomotion is by means of finger-like protrusions known as pseudopodia. Pseudopodium is formed when the ectoplasm is pushed out and enlarged until a blunt projection is formed. The endoplasm flows into it. The plasmagel contracts at the posterior end. The entire animal thus moves in that direction. www.knust.edu.gh 06/07/2022 11  Class Sarcodina Movement in Amoeba may be in response to stimuli. Movements in response to stimuli may be positive, negative and food-taking. Sources of stimuli: contact, chemicals, heat and electricity. Amoeba responds positively to weak mechanical stimulus and negatively to strong mechanical stimulus. Reacts similarly to light. www.knust.edu.gh 06/07/2022 12  Class Sarcodina Habitat The majority of their species live in marine aquatic environments but some occur in fresh water where they feed on small aquatic plants (e.g. Oscillaria). Soft wet soil, leaves and stems of aquatic plants or other surface. Some are parasitic in the intestinal tracts of vertebrates and invertebrates. www.knust.edu.gh 06/07/2022 13  Class Sarcodina The metabolic processes exhibited by amoeba are ingestion, of food digestion, absorption, circulation, assimilation, secretion, excretion and respiration. They grow by increasing in volume. Disease caused by amoeba include amebic dysentery/ amebiasis which are sometimes fatal. It enters a body from contaminated food and water. Enzymes break down intestinal wall. www.knust.edu.gh 06/07/2022 14  Class Sarcodina Reproduction When the optimum growth is reached the animal divides into two. Amoeba reproduces only by binary fission/binary division. Evidence supporting sporulation is little. Binary fission www.knust.edu.gh 06/07/2022 15  Phylum Protozoa Class Mastigophora A free living single cell found in fresh water ponds. Green in colour. Not visible to the naked eye except when a great number are together. www.knust.edu.gh 06/07/2022 16  Class Mastigophora General morphology and cytology A single elongated cell pointed at the posterior, and blunt at the anterior end. Spindle shaped body and surrounded with tough elastic membrane – the pellicle. Develops parallel thickenings that run obliquely around the animal, making it appear striated. Also possess two kinds of cytoplasm: a dense outer layer, the ectoplasm, and a central mass, endoplasm, which is more fluid. www.knust.edu.gh 06/07/2022 17  Class Mastigophora General morphology and cytology A little to one side of the center of the anterior blunt end of the body is a funnel-shaped depression known as the cytostome At the bottom of this depression is an opening which leads into a short duct called the gullet (cytopharynx). This in turn enters a large spherical vesicle, the reservoir, into which several minute contractile vacuoles discharge their contents. www.knust.edu.gh 06/07/2022 18  Class Mastigophora General morphology and cytology The mouth and gullet are not used for the ingestion of food but as a canal for the escape of fluid from the reservoir. When an euglena is feeding, it surrounds the prey through a method called phagocytosis. This method allows the organism to surround its prey and absorb it. www.knust.edu.gh 06/07/2022 19  Class Mastigophora General morphology and cytology A conspicuous structure in Euglena is the red eye spot or stigma. This is placed near the inner end of the gullet close to the reservoir. It consists of protoplasm in which are embedded a number of granules of haematochrome. The haemotochrome also has many of the characteristics of the pigments in the eyes of higher organisms. If kept in the dark, Euglena soon loses its red pigment. The anterior end of the body of Euglena is said to be more sensitive to light than any other part. Euglena contains a single oval nucleus lying in a definite position a little posterior to the centre of the body. The nucleus contains a central body which is called an endosome (functions as a division centre in mitosis). www.knust.edu.gh 06/07/2022 20  Class Mastigophora General morphology and cytology The green colour of Euglena is derived from a number of oval disks suspended in the protoplasm. These are known as chromatophores. Labelled in some diagrams as chloroplast. They contain chlorophyll. Chromatophores are arranged about a collection of granules situated in the centre of the body (arranged like a star). Chromatophores carry out photosynthesis, which is not characteristic of animals. A few more cell contents are not seen under the microscope unless properly fixed such as the Golgi bodies. www.knust.edu.gh 06/07/2022 21  Class Mastigophora General morphology and cytology A long flagellum originates from two roots on the side of the reservoir. www.knust.edu.gh 06/07/2022 22  Class Mastigophora Nutrition Holophytic: Food is manufactured as in green plants, by the aid of the chlorophyll in the chromatophores. Product of photosynthesis is paramylum, a substance close to starch. If specimens are kept in good light continually, a large amount of paramylum will be stored up for future use. Also saprophytic: Able to absorb organic substances in solution through the surface of the body. www.knust.edu.gh 06/07/2022 23  Class Mastigophora Locomotion Euglena changes its shape frequently, becoming shorter and thicker, and shows certain squirming movements. Often in a favourable specimen, the flagellum may be seen projecting from the anterior end of the body and bending to and fro, drawing the animal after it. The flagellum is more or less cylindrical and possesses a central rod-like elastic core and a much more fluid protoplasmic sheath. If the flagellum cannot be seen in the living animal, a little iodine placed under the cover glass will help to bring it out. www.knust.edu.gh 06/07/2022 24  Class Mastigophora Behaviour Euglena swims through the water in a spiral path. Euglena is very sensitive to light. It swims toward an ordinary light such as that from a window but away from direct sunlight. When a change in the intensity of the light occurs, Euglena in most cases, stops or moves backward. Reproduction Euglena replicates by binary fission. www.knust.edu.gh 06/07/2022 25  Phylum Protozoa Class Sporozoa: Monocystis Monocystis is parasitic in earthworms. Occurs in seminal vesicles of earthworms www.knust.edu.gh 06/07/2022 21/01/2019 26 Class Sporozoa: Monocystis Life cycle The animals are transferred from one earthworm to another as spores (each containing elongated bodies called sporozoites). Each sporozoite penetrates a bundle of sperm mother cells of the earthworm, and is then termed a trophozoite. Here it lives at the expense of the cells among which it lies. The spermatozoa of the earthworm which are deprived of nourishment by the parasite, slowly shrivel up finally becoming tiny filaments on the surface of the trophozoite. www.knust.edu.gh 06/07/2022 27 Class Sporozoa: Monocystis Life cycle At this stage two trophozoites come together and are surrounded by a common two-layered cyst wall. Each then divides, producing a number of small cells called gametes. The gametes unite in pairs to form zygotes. Each zygote becomes lemon-shaped, and secretes a thin hard wall around itself. It is now known as a sporoblast. The nucleus of the sporoblast divides successively into two, four, and finally eight daughter nuclei; each of these, together with a portion of the cytoplasm, becomes a sporozoite. www.knust.edu.gh 06/07/2022 28  Phylum Protozoa Class Sporozoa: Plasmodium The malaria parasites exhibits a complex life cycle involving an insect vector (mosquito-primary/definitive hosts) and a vertebrate host (human). – The insect vector is the mosquito which is the primary/definitive hosts in which Plasmodium completes its sexual life cycle. – The parasites' intermediate hosts are human and other vertebrates. www.knust.edu.gh 06/07/2022 7/6/2022 29  Class Sporozoa The Life Cycle of Plasmodium Infection in humans begins with an infected female Anopheles mosquito taking a blood meal from human host. As it feeds, it injects saliva contaminated with the Plasmodium sporozoites into the bloodstream of the host during feeding. The sporozoites are carried by the circulatory system to the liver which quickly invade the liver cells (hepatocytes). In the liver, a pre-(or exo-) erythrocytic schizogonous cycle takes place in the parenchyma cells of the liver. This leads to formation of schizonts, containing from 2000 to 4000 merozoites per the particular Plasmodium species. www.knust.edu.gh 06/07/2022 30  Class Sporozoa The Life Cycle of Plasmodium In the red blood cells, they develop into ring forms, trophozoites and schizonts which in turn produce further merozoites. Some of the merozoites develop into schizonts, but others become sexual cells called gametocytes. Gametocytes are taken up by mosquitoes during a blood meal. Further developments take place in the female Anopheles mosquito to complete the life cycle, develop new sporozoites that will be released in another blood meal. www.knust.edu.gh 06/07/2022 31  Phylum Protozoa Class Infusoria -Paramecium Lives in freshwater ponds and streams. Appears initially as cigar-shaped. A closer view reveals a depression to the right known as the oral grove. www.knust.edu.gh 06/07/2022 21/01/2019 32  Class Infusoria -Paramecium Paramecium contains several organelles such as: Macronucleus which deals with everyday functions like metabolism. Micronucleus - deals with all of the germ line DNA (Genes which are traded during sexual reproduction). Trichocyst are the defense of the paramecium, a harpoon like structure that releases a toxin to kill or paralyze other microorganisms. www.knust.edu.gh 06/07/2022 33  Class Infusoria -Paramecium Locomotion Paramecium use cilia to move around Cilia are like little oars used to move forward, backwards, and side to side Conjugation During conjugation, two paramecium attach to each other, losing some of their cilia in the process. Conjugation is used to trade genetic information between two paramecium. www.knust.edu.gh 06/07/2022 34 21/01/2019 35