COMPREHENSIVE LECTURE NOTES IN ZOOLOGY

Module 1. ZOOLOGY AS A SCIENCE. SUBKINGDOM PROTOZOA

Section 1.2. Subkingdom Protozoa (Protista). General Characteristics

Topic 1.2.1. Phylum Sarcomastigophora

General characteristics of the phylum. Origin, evolution, paleontological records, contemporary diversity, geographical distribution, and Significance in nature and human life. Overview of major taxonomic groups important for human life and the functioning of natural ecosystems. Subphylum Mastigophora (Flagellates). Class Phytomastigophorea (Plant flagellates). Class Zoomastigophorea (Animal flagellates). Subphylum Opalinata. Subphylum Sarcodina. Superclass Rhizopoda

(Rhizopoda). Class Lobosea. Subclass Gymnamoebia (Naked amoebas). Subclass Testacialobosia (Testate amoebas). Class Acrasea. Class Eumycetozoea (Slime Molds). Class Plasmodiophorea. Class Filosea. Class Granuloreticulosea. Class Xenophyophorea. Superclass Actinopoda. Class Heliozoea (Heliozoans). Biodiversity of the Dnipropetrovsk Region.

Over 25,000 species; existing in an amoeboid or flagellate state.

Subphylum Mastigophora, or Flagellata. In fresh and saline Water bodies, parasitism. Over 8,000 species. Polyphyly. Presence of flagella; pseudopodia are present permanently or temporarily. The flagellum resembles those of plants and Multicellular animals in Structure; it is more complex than in Bacteria. 11 microtubules—9 peripheral doublets and 2 single microtubules along the central axis. Kinetosome (basal body). In Kinetoplastida, the kinetoplast is a modified portion of the mitochondrion. Specialized Cytoskeleton; Plasmalemma composed of Cellulose, Glycoproteins, chitinoid, or siliceous scales. Protein plates. Pellicle. Most plant-like flagellates are autotrophs, whereas animal-like ones are heterotrophs. Euglena exhibits mixotrophy.

Class Phytomastigophorea (Plant flagellates). Chromatophores with chlorophyll, and other pigments: red, yellow, black. A few heterotrophs (saprophages, parasites, predators (Noctiluca)). Studied by both zoologists and botanists.

Order Euglenida. Over 1,000 species, predominantly freshwater; autotrophs or mixotrophs, some are heterotrophs, saprophages, or parasites of rotifers, frogs, and gill-breathing fish. Striated pellicle with protein plates; peristaltic waves; mode of locomotion involves metaboly. Two flagella, one of which is reduced; originating in a flagellar pocket at the anterior end. The body "screws" its way through water. A gullet is located near the Base of the flagella. Contractile vacuole. Parabasal body sensitive to illumination. Stigma consisting of an accumulation of lipid droplets with carotenoid pigments; it is not sensitive to light itself, but acts as a reflector for the parabasal body. Chromatophores contain chlorophylls a and b, carotenes, and xanthophylls. Paramylon (a polysaccharide) is found in the endoplasm. A single Nucleus is situated in the posterior region of the body. Asexual reproduction. Mitosis. Euglena viridis, E. sanguinea, Phacus. Used as food for fish fry, for the biological purification of water bodies, and in cytological and biochemical research.

Order Dinoflagellida (Dinoflagellates). Freshwater and marine plankton. Autotrophic, less commonly heterotrophic. Large nucleus; Chromosomes lack Histones (as in prokaryotes). Underneath the membrane lies the theca, composed of Proteins and sugars, forming a system of flattened vesicles that maintain body shape. Contractile vacuoles are absent. The surface bears 2 furrows (one equatorial and one perpendicular to it). They house 2 flagella of unequal length. In the plankton of warm seas, Noctiluca miliaris occurs. It measures 2 mm, lacks furrows and a cellulosic shell. Heterotrophic. Cell Mouth and digestive vacuoles. Feeds on Protozoa and unicellular Algae. Emits light when mechanically stimulated (the lipid-like substance luciferin is broken down by the enzyme luciferase). Many dinoflagellates are intracellular symbionts of Ciliates, radiolarians, hydras, and corals (contributing to The formation of the calcareous Skeleton).

Order Volvocida. Found in the plankton of freshwater bodies, with some marine species as well. 2 or 4 identical flagella, Cell wall composed of cellulose. Autotrophs. Reproduction is asexual (monotomy or palintomy) and sexual (iso- or anisogamy). Vegetative and generative Cells (macrogametes, microgametes). Unicellular Chlamydomonas, colonial Gonium (16 cells), multicellular Volvox (up to 2,000 cells). Producers in aquatic ecosystems. Some species are colorless heterotrophs, serving as indicators of organic water pollution.

Class Zoomastigophorea (Animal flagellates). In fresh and saline waters, parasites of animals and plants. Pinocytosis and phagocytosis. Eight orders.

Order Choanoflagellida. Small solitary or colonial forms. The base of the flagellum is surrounded by a collar of microvilli, creating a water current between them (used for filtration and phagocytosis via pseudopodia). Free-swimming and attached species. Similar to the choanocytes of Sponges. Colonial and solitary.

Order Kinetoplastida. Mostly parasites. Free-living species exist (Bodo is freshwater). Near the base of the flagellum lie the kinetoplast and kinetosome (an accumulation of DNA within a region of the giant mitochondrion). Many possess an undulating membrane. The flagellum is located at the posterior end of The Cell. Reproduction by fission. Many exhibit a complex life cycle involving changes in hosts and morphological phases. The ancestral form is promastigote (undulating membrane absent). Amastigote, epimastigote, and trypomastigote stages. Includes numerous disease-pathogens.

In Africa, sleeping sickness is caused by Trypanosoma brucei—T. b. gambiense (chronic form of the disease) and T. b. rhodesiense (acute form). The pathogen circulates in the Blood of antelopes (reservoir hosts) without causing them harm. Transmission occurs via tsetse fly bites. In humans, it resides in Blood Plasma, Lymph, CEREBROSPINAL FLUID, and the Central Nervous system. Fatal if left untreated. Horseflies act as mechanical vectors for T. brucei brucei, which causes nagana—a disease of cattle characterized by fever, anemia, and death. In Latin America, Chagas disease is caused by T. cruzi. Blood-sucking bugs of the family Reduviidae (Triatoma and others) serve as vectors. Trypanosomes parasitize the hindgut of the bug. The bug draws blood from the mucous membranes of the eyes, Lips, or Nose, contaminating the wound with feces. The parasites invade Cells of the Heart, Blood Vessels, and nervous Tissues; symptoms include fever, hepatomegaly, psychiatric disorders, cardiac dysfunction, and gastrointestinal disturbances. Mortality in children reaches up to 14%. In North Africa, the Mediterranean, and Central Asia, T. evansi causes surra, a disease affecting horses, donkeys, and camels, mechanically transmitted by horseflies. Dourine in horses, found in various PARTS OF THE world, is caused by T. equiperdum. It is a fatal disease transmitted sexually.

Leishmania species are intracellular parasites of vertebrates and humans (amastigote stage). Vectors are sandflies, in which the promastigote stage develops. Leishmania tropica causes cutaneous leishmaniasis (Oriental sore); found in Transcaucasia and Central Asia, with rodents as reservoir hosts. L. donovani causes visceral leishmaniasis (kala-azar) in Asia, infecting cells of the Liver, Spleen, Lymph Nodes, and intestine; symptoms include fever and anemia; dogs and jackals serve as reservoir hosts. Leptomonas species inhabit the latex-bearing vessels of plants, intercellular spaces, and cell vacuoles; they are parasites of coffee plants, causing infected trees to die. Vectors are phytophagous insects (such as true bugs).

Order Diplomonadida. Predominantly parasitic. Two nuclei, eight flagella. A notable parasite of the upper human Small Intestine is Lamblia intestinalis (Giardia duodenalis). Adhesive disc. Pinocytosis in the midgut. In the hindgut, they shed their flagella and secrete a thick protective wall, forming a cyst. Diplomonads also parasitize rodents, amphibians, and other animals.

Order Trichomonadida. 4–6 flagella, a contractile rod-like organelle known as the costa; an axial supporting structure called the axostyle (located inside the cell). Mitochondria are absent. Parasitize the intestinal cavity of vertebrates. In humans, Trichomonas vaginalis (parasite of the Urogenital System) and T. hominis (intestinal parasite) are found. In the reproductive Organs of cattle, T. foetus causes Infertility and Spontaneous Abortion.

Order Hypermastigida. Intestinal symbionts of insects, digesting cellulose (termites, roaches). Numerous flagella located at the anterior end of the body or distributed across the entire cell surface. One or more axostyles. Mitochondria are absent. Uninucleate and multinucleate forms. They feed on wood, engulfing it via pseudopodia. Termite larvae feed on the feces of adult colony members, which contain the symbionts. Comprises about 200 species of termite symbionts, including Teratonympha mirabilis and Calonympha grossi.

Subphylum Opalinata. Comprises a single class, Opalinatea, with a single order, Opalinida. Inhabitants of the amphibian hindgut. Large, multinucleate (rarely binucleate) organisms. The body is covered in rows of short flagella. Nuclei are all of one type. Sexual process involves the fusion of two Gametes (copulation). Opalina ranarum is a parasite of frogs. Adult frogs harbor multinucleate individuals. During the breeding season of frogs, longitudinal and transverse divisions occur. Small cells (cysts) are released into the water, ingested by tadpoles, and undergo meiotic division to form small microgametes and large macrogametes; these fuse to form zygotes in the external environment, which then reinfect tadpoles. Inside the gut, the sexual process is repeated, initiating The Development of multinucleate trophic forms. Nearly all adult frogs harbor opalines.

Subphylum Sarcodina. Planktonic or benthic marine and freshwater forms, soil-dwellers, with a few parasites. Over 10,000 species. The amoeboid form predominates; locomotion via pseudopodia. Broad, lobe-like pseudopodia are termed lobopodia; thread-like, branched pseudopodia with anastomoses are filopodia; straight, unbranched ones with internal supporting rows of microtubules are axopodia. Divided into superclasses Rhizopoda and Actinopoda.

Superclass Rhizopoda. Characterized by lobopodia and filopodia. Includes seven classes.

Class Lobosea. Freshwater benthic organisms, occasionally parasitic, uninucleate, naked or testate. Divided into subclasses Gymnamoebia and Testacialobosia.

Subclass Gymnamoebia. Plasmalemma present, shell absent. Differentiated into ectoplasm and endoplasm. Pseudopodia function in locomotion and food capture (phagocytosis). Digestive vacuoles, Lysosomes. Pinocytosis. The endoplasm contains a contractile vacuole (involved in osmotic regulation and Respiration). A single nucleus, though binucleate forms also occur (Pelomyxa). Reproduction by binary fission (mitosis). Encystment is common. Numerous amoeba species inhabit freshwaters and soils, such as Amoeba proteus. Entamoeba histolytica causes amoebic dysentery (bloody flux/colitis)—amoebiasis. Forms quadrinucleate cysts that survive in the environment for 2–3 months. In contaminated freshwater bodies, Naegleria and Acanthamoeba can enter the human Nasal cavity during swimming and invade the Brain, resulting in death. Exhibiting both facultative and obligate parasitism.

Subclass Testate amoebas (Testacealobosia). Freshwater bodies, sphagnum bogs, soil, and some species withstand salinity (in estuaries). Over 1,000 species (with more than 200 found in Ukraine). The shell is made of a Chitin-like polysaccharide, which can be encrusted with sand grains (Difflugia), and does not adhere to the plasmalemma. Aperture. The freshwater arcella (Arcella vulgaris) has two nuclei (though mononuclear species also exist). Reproduction by fission. Participation in soil formation.

Class Acrasea (Acrasea). Absence of a cell wall, amoeboid movement, and phagocytosis. About 30 species. Found on decaying plant debris and in manure. Mononuclear amoebas with pseudopodia, phagocytosis (organic residues), reproduction by fission. In case of food shortage, they form a multicellular pseudoplasmodium. Sometimes it moves through multicellular outgrowths. Some amoebas form a stalk, while others crawl to its tip to form spore-bearing heads of various shapes. The stalk branches in a whorled manner, ending in spore heads (some amoebas become covered with coats, forming cysts). Spores are shed. Acraseans contribute to the mineralization of organics.

Class True slime molds (Eumycetozoea). Over 400 species. Found in humus-rich soil, litter, manure, and decaying wood. They feed on organic debris and capture living organisms (bacteria, other protozoa, fungal hyphae, and spores). Multinuclear plasmodium—an aggregation of mononuclear amoeboid cells—pseudoplasmodium. Spores are housed in fruiting bodies. Three subclasses.

Subclass Protostelia (Protostelia). About 20 species. Vegetative bodies are individual plasmodia; the fruiting body is a hollow stalk with a HEAD (containing one or several spores). The spore produces biflagellate zoospores that develop into amoebas. In summer on rotting leaves, one can find the white, yellow, or pink plasmodium of Ceratiomyxa fruticulosa (several centimeters in size). The surface resembles a honeycomb.

Subclass Dictyostelia (Dictyostelia). Resembling the Acrasea. Hollow sporangium stalk. Amoebas emerge from spores. Dictyostelium discoideum is easily cultured for cytophysiological and morphological experiments.

Subclass Myxogastria (Myxogastria). The majority of species in the class. The vegetative body appears as a plasmodium measuring 0.1–20 cm. It engulfs organic debris and small organisms, and avoids light. During sporulation, it exhibits positive phototaxis, forming diverse fruiting bodies with spores. The plasmodium is diploid (sporulation involves Meiosis). Spores give rise to biflagellate zoospores or myxamoebae (gametes) that undergo copulation to form a diploid myxamoeba, which develops into a new plasmodium. Gametic reduction. Under unfavorable conditions, they form a sclerotium (which can survive for decades). Zoospores and myxamoebae are capable of encystment.

Lycogala epidendrum forms a red plasmodium (several centimeters across) on stumps. Physarum polycephalum forms a yellow plasmodium on the underside of mushroom caps, feeding on spores and hyphae. Fuligo septica occurs on decaying wood (reaching several tens of centimeters), eventually becoming entirely enclosed in a coat to form spore-bearing fruiting bodies. They play a significant role in wood destruction.

Class Plasmodiophoromycetes (Plasmodwphorea). Parasites living inside plant and fungal cells. The vegetative body (multinuclear plasmodium) breaks down into biflagellate zoospores or myxamoebae. The CAUSATIVE AGENT OF clubroot in cabbage, Plasmodiophora brassicae, infects about 200 plant species. ROOT cells enlarge due to the secretion of stimulating substances, forming tumors filled with myxamoebae and plasmodia, and later small spores. The roots rot, releasing spores into the soil (where they survive for years), which germinate into zoospores (or myxamoebae) that develop pseudopodia and penetrate the plant through root hairs. The zoospores fuse while their nuclei remain haploid, forming a multinuclear plasmodium that breaks down into mononuclear gametes (morphologically indistinguishable from zoospores). These emerge into the soil and undergo pairwise copulation, though their nuclei do not fuse (pseudozygote). The binucleate cell penetrates the cabbage root and grows into a multinuclear plasmodium, where the haploid nuclei fuse in pairs (true sexual process) to form diploid nuclei. Meiosis follows, resulting in breakdown into mononuclear haploid spores. The life cycle features zygotic reduction. Spongospora solani causes potato scab (more rarely on roots), characterized by ulcers filled with masses of spore balls.

Class Filosea (Filosea). Freshwater sarcodines with thread-like, branching pseudopodia. Both naked and shelled forms exist. In peat bogs, Euglypha features an oval shell covered with transparent scales.

Class Granuloreticulosea (Granuloreticulosea). Predominantly marine benthos, with known fossil planktonic forms. About 4,000 extant species. In the Black Sea, only 26 species are found, 5 of which are endemic; in the Sea of Azov, only a single species occurs. Filopodia form an interconnected network. Three orders.

Order Foraminifera (Foraminiferida). Unilocular or multilocular shell. Most species concentrate calcium carbonate. Size ranges from 0.02 to 60 mm. The shell features microscopic pores (foramen) and an aperture. Organic shells are unilocular (globular, flask-shaped, star-shaped, or spirally coiled). The majority possess a multilocular calcareous shell (with up to hundreds of chambers). Vegetative and generative nuclei exhibit nuclear dualism. Filopodia form a trapping network (capturing bacteria, unicellular algae, and organic particles). Digestive vacuoles are formed at the sites of anastomoses.

Two generations differ in reproductive Methods and shell Morphology. The sexual generation (gamont) consists of mononuclear haploid individuals with a macrospheric shell featuring a large primordial chamber (formed via mitosis); thousands of biflagellate haploid gametes fuse in pairs to form a diploid zygote, which secretes a microspheric shell (via mitosis) containing hundreds of diploid nuclei (both vegetative and generative). This gives rise to the asexual generation (agamont), in which reduction division of the generative nuclei (meiosis) produces numerous haploid nuclei, resulting in A large number of small mononuclear agamets (asexual reproduction) that form the macrospheric haploid generation capable of producing gametes. Alternation of sexual (haploid gamont) and asexual (diploid agamont) generations. Nuclear cycle with intermediate reduction. The empty shells accumulate on the sea floor, forming limestone and chalk deposits hundreds of meters thick. The Pyrenees, Alps, Atlas, and Himalayas are largely composed of foraminiferal limestones. Used as a building material. The British Isles were named Albion (from albus, white) due to the color of their coastal chalk and limestone cliffs.

Class Xenophyophorea (Xenophyophorea). Deep-sea marine organisms up to 50 cm in length. They form irregularly shaped, intertwining tubes. The tubes have an organic matrix mixed with sand. Inside the tubes lies a multinuclear plasmodium that can break down into individual mononuclear cells.

Superclass Actinopoda (Actinopoda). Most are marine inhabitants, predominantly planktonic forms; freshwater and parasitic species also occur. Unbranched, elastic pseudopodia known as axopodia contain an axoneme made of microtubule bundles. Axopodia are radial, aiding in locomotion through the water Column and in prey capture. Mineral skeleton. Four classes. Three of these comprise the "radiolarians" (classes Acantharea, Polycystinea, Phaeodarea). The fourth class consists of the heliozoans (Heliozoea).

Radiolarians are marine, thermophilic planktonic animals (0.04–1 mm and larger). About 8,000 species. Absent in Ukraine. An intracellular organic envelope forms the central capsule. Organelle-rich Cytoplasm is divided into an intracapsular part with one or more nuclei, and an extracapsular cytoplasm. The capsule features one large and numerous small pores. The extracapsular cytoplasm is frothy (containing mucus and oil droplets). Symbiotic plant flagellates (zoochlorellae and zooxanthellae) may inhabit the central capsule. Mononuclear species have a ploidy level of about 1,000. Axopodia, filopodia, and digestive vacuoles are present.

In the class Acantharea, the skeleton is made of strontium sulfate; in others, it is composed of silicon dioxide. Reproduction is still insufficiently studied, as these organisms cannot be kept in laboratory cultures. Both Selection/8.html">Asexual and sexual reproduction occur (isogamy and anisogamy). Certain species form spherical or elongated colonies in which many central capsules are embedded within a common extracapsular cytoplasm (1.5–2.0 cm).

Siliceous skeletons form sedimentary rock deposits known as radiolarites (siliceous clays, cherty shales, tripoli, jaspers, opals, and chalcedonies). Barbados Island in the Caribbean, Paleozoic deposits of Caucasian jasper, and siliceous deposits of the Russian Far East consist largely of tripoli. Used in polishing pastes and sandpaper. Jaspers, opals, and chalcedonies serve as gemstones. Important index fossils. The skeleton of acantharians (strontium sulfate) dissolves in seawater.

Class Heliozoea (Heliozoea). Most inhabit freshwater bodies; marine and parasitic species also exist. About 100 species. They lack a mineral skeleton, though some possess a skeleton made of silicon dioxide. Central capsule is absent. Planktonic species contain vacuoles in their ectoplasm to reduce specific gravity. Possess either a single nucleus (Actinophrys) or multiple nuclei (Actinosphaerium). Contractile vacuoles are located in the ectoplasm. Prey consists of protozoa and rotifers, which adhere to the axopodia and become immobilized. Reproduction occurs by fission. Daughter individuals of shelled species leave the old skeleton behind, and each forms a new one. Some species produce

biflagellate spores. A sexual process is present. Symbiotic plant flagellates or unicellular algae frequently inhabit the cytoplasm.