ANIMAL DIVERSITY.pptx BSc boatnay honours GE

ANIMAL DIVERSITY.pptx BSc boatnay honours GE

1. ANIMAL DIVERSITY UNIT – 1 Protista, Porifera , Radiata , Acoelomates and Pseudocoelomates BSc. Botany Honours 2 nd semester Utkal University G.E. 2.1 - Zoology

2. Topic To Be Discussed…. Time – 1hour (12:30pm-1:30pm) General Characteristics of Protozoa Life Cycle of Plasmodium General characters and canal system in Porifera General characters of cnidarians and Polymorphism General characters of Helminthes Life cycle of Taenisolium General characters of Nematohelminthes Parasitic adaptation

3. General characteristics of protozoa Protozoa are unicellular, eukaryotic, heterotrophic organisms . They are either free-living or parasites. There are around 65000 species of protozoans categorised in different groups. They lack a cell wall. There are many different cell organelles, that perform various tasks performed by different organs in higher animals, e.g. mouth, anus, intestinal tract, etc. Introduction….

4. Protozoa are a diverse group of single-celled eukaryotic organisms. They exhibit a variety of characteristics that distinguish them from other microorganisms. Here are the general characteristics of protozoa: Cell Structure : Eukaryotic: Protozoa have a well-defined nucleus enclosed within a nuclear membrane, along with other membrane-bound organelles like mitochondria, endoplasmic reticulum, and Golgi apparatus . Unicellular : Each protozoan organism consists of a single cell . Size and Shape : Protozoa vary widely in size, typically ranging from 10 to 52 micrometers, though some can be larger . They exhibit a wide variety of shapes, including spherical, oval, elongated, or irregular shapes.

5. Locomotion : Flagella: Some protozoa, like those in the group Flagellata , use one or more whip-like structures called flagella to move . Cilia : Ciliates use numerous short hair-like structures called cilia for movement . Pseudopodia : Amoeboids move by extending and retracting temporary projections of their cytoplasm called pseudopodia (false feet ). Gliding : Some protozoa exhibit a gliding type of movement without obvious structures for locomotion . Nutrition : Heterotrophic: Most protozoa are heterotrophic, meaning they obtain their food by ingesting other organisms or organic matter . Phagocytosis : They typically engulf food particles by phagocytosis . Some protozoa can absorb dissolved nutrients directly through their cell membrane.

6. Reproduction : Asexual Reproduction: Most protozoa reproduce asexually by binary fission, where the cell divides into two identical cells. Some may reproduce by budding or schizogony (multiple fission ). Sexual Reproduction: Some protozoa also exhibit sexual reproduction, which can involve the fusion of gametes (conjugation) or other forms of genetic exchange . Habitat : Protozoa are found in a wide range of habitats, including freshwater, marine environments, and soil . Many are free-living, but some are parasitic and can cause diseases in humans, animals, and plants.

7. Encystment : In adverse conditions, many protozoa can form cysts. Cysts are dormant, resistant forms that can withstand harsh environmental conditions. This process is called encystment . Cysts help protozoa survive until favorable conditions return, after which they can excyst and become active again . Ecological Role : Protozoa play a crucial role in the food web, acting as both predators and prey . They help in nutrient recycling by breaking down organic materials and releasing nutrients back into the environment.

8. Diversity : Protozoa are classified into several groups based on their movement and other characteristics. The major groups include amoeboids (e.g., Amoeba), flagellates (e.g., Trypanosoma ), ciliates (e.g., Paramecium), and sporozoans (e.g., Plasmodium ). Disease : Some protozoa are pathogenic and can cause diseases in humans and other animals. Examples include Plasmodium (malaria), Trypanosoma (sleeping sickness), and Entamoeba histolytica (amoebic dysentery).

9. Life Cycle of Plasmodium The life cycle of Plasmodium, the protozoan parasite responsible for malaria, is complex and involves two main hosts: the human (or other vertebrate) and the female Anopheles mosquito. The life cycle includes several stages : Human Liver Stage ( Exo-erythrocytic Cycle ) Human Blood Stage ( Erythrocytic Cycle ) Mosquito Stage ( Sporogonic Cycle)

10. Human Liver Stage ( Exo-erythrocytic Cycle): Infection by Mosquito Bite: When an infected Anopheles mosquito bites a human, it injects sporozoites into the bloodstream . Liver Infection: The sporozoites travel to the liver and invade hepatocytes (liver cells ). Schizogony : Inside the liver cells, the sporozoites multiply asexually through a process called schizogony , forming schizonts . Merozoites Release: The schizonts rupture, releasing merozoites into the bloodstream.

11. Human Blood Stage ( Erythrocytic Cycle): Invasion of Red Blood Cells (RBCs): Merozoites invade red blood cells . Trophozoite Stage: Inside the RBCs, the merozoites develop into ring-stage trophozoites . Schizogony : The trophozoites mature into schizonts , which multiply to produce more merozoites . Rupture and Release: The infected RBCs burst, releasing new merozoites that can invade more RBCs, continuing the cycle . Gametocyte Formation: Some merozoites differentiate into sexual forms called gametocytes (male and female) instead of continuing the asexual cycle.

12. Mosquito Stage ( Sporogonic Cycle): Ingestion by Mosquito: When another female Anopheles mosquito bites an infected human, it ingests the gametocytes along with the blood meal . Fertilization : Inside the mosquito's gut, the male and female gametocytes fuse to form a zygote . Ookinete Formation: The zygote becomes a motile ookinete , which penetrates the mosquito's gut wall . Oocyst Formation: The ookinete forms an oocyst under the outer lining of the gut.Sporozoite Development: Inside the oocyst , the parasite undergoes multiple divisions to produce numerous sporozoites . Release and Migration: The oocyst ruptures, releasing sporozoites that migrate to the mosquito's salivary glands . Transmission : When the mosquito bites another human, the cycle begins again with the injection of sporozoites .

13. Summary Sporozoites : Infective stage injected by the mosquito into the human bloodstream, targeting the liver . Merozoites : Result from liver schizonts , they infect RBCs . Trophozoites : Develop from merozoites within RBCs . Schizonts : Form from trophozoites and produce more merozoites . Gametocytes : Sexual forms taken up by the mosquito, leading to fertilization and formation of new sporozoites .

14. General characters and canal system in Porifera Simple Body Organization : Porifera are the simplest multicellular animals, lacking true tissues and organs . They have a cellular level of organization with specialized cells but no distinct tissues or organs . Asymmetry : Most sponges are asymmetrical, although some exhibit radial symmetry . Sessile Lifestyle : Adult sponges are sessile, meaning they are anchored to a substrate and do not move . General Characteristics of Porifera (Sponges):

15. Body Structure : Their bodies are porous, with numerous openings called ostia (small pores) and one or more larger openings called oscula (singular: osculum ). The body wall consists of an outer layer called the pinacoderm and an inner layer called the choanoderm , with a gelatinous matrix ( mesohyl ) in between . Cell Types : Choanocytes (collar cells): Flagellated cells that create water currents and capture food particles . Pinacocytes : Flat cells that cover the exterior surface and line the internal canals . Amoebocytes ( archaeocytes ): Mobile cells involved in digestion, reproduction, and secretion of skeletal elements . Porocytes : Tubular cells that form the ostia .

16. Skeleton : The skeleton is composed of spicules (made of silica or calcium carbonate) and/or spongin fibers (a form of collagen ). Reproduction : Sponges can reproduce both sexually and asexually . Sexual reproduction involves the production of eggs and sperm, with fertilization occurring internally or externally . Asexual reproduction occurs through budding, fragmentation, or the formation of gemmules (resistant structures that can develop into new sponges ). Feeding: Sponges are filter feeders, capturing small particles from the water that flows through their bodies . Choanocytes play a crucial role in trapping and phagocytizing food particles . Respiration and Excretion : Sponges rely on the flow of water through their bodies for gas exchange and the removal of waste products.

17. Canal System in Porifera : The canal system in sponges is essential for their feeding, respiration, and excretion. It varies among different classes of sponges and is categorized into three main types : Asconoid Canal System : The simplest and least common type . Water enters through numerous ostia into a large central cavity called the spongocoel , lined with choanocytes . Water exits through a single osculum . Found in small, tube-shaped sponges.

18. Syconoid Canal System : More complex than the asconoid type . The body wall is thicker and folded into radial canals lined with choanocytes . Water enters through dermal ostia into incurrent canals, passes through prosopyles (small openings) into radial canals, and then into the spongocoel . Water exits through a single osculum . This type increases the surface area for filtration.

19. Leuconoid Canal System : The most complex and efficient type . The body wall is extensively folded, creating a complex network of chambers and canals . Water enters through dermal ostia into incurrent canals, passes through prosopyles into flagellated chambers lined with choanocytes , and then into excurrent canals leading to one or more oscula . This system greatly increases the surface area for filtering water and is found in most large sponges.

20. Summary Asconoid : Simple, with a single spongocoel and osculum . Syconoid : Folded body wall with radial canals leading to a spongocoel and single osculum . Leuconoid : Highly folded body with complex chambers and multiple oscula , allowing for efficient water filtration and increased surface area.