Department of Zoology at ANDC/Zoology Museum/Museum specimens/Kingdom Protista

Kingdom Protista Date & Time : 22, November 2024 10:32 General Characteristics of Protista Protists are microscopic, unicellular and eukaryotic organisms. Their size commonly range from 10 to 52 micrometers, but they can grow as large as 1 mm, and are seen easily by a microscope. Many protists are free Living, found in fresh and salt water; but a number of protists are endoparasites causing pathogenic effects in their hosts. Body is surrounded by a thin plasma membrane which may be covered by pellicle (a thin layer supporting the cell membrane). They may be naked organisms or enclosed in a shell. The cytoplasm is differentiated into an outer ectoplasm and inner endoplasm. Protistans possess pseudopodia, cilia or flagella as the locomotory organelles. Nutrition may be holophytic, holozoic, saprozoic or parasitic. Respiration occurs by the diffusion of gases through body surface. Reproduction may take place by asexual or sexual means. Asexual reproduction takes place by the process of binary fission, multiple fission, sporulation or budding. Sexual reproduction takes place by conjugation (syngamy), endomixis, automixis, cytomixis or hemixis. A Few Examples Noctiluca SCIENTIFIC NAME- Noctiluca. GEOGRAPHICAL DISTRIBUTION- Commonly found in madras, atlantic and pacific oceans HABITAT-Marine and pelagic. IDENTIFYING FEATURES- large circular body measuring about 1-1.5mm in diameter. body is covered by a stout pellicle. A small flagellum and a long,stout tentacle is present. COMMON CHARACTERS- Mouth is elongated having a pouch like cytopharynx. Nucleus is single and large. Holozoic nutrition. Cytoplasm is highly vacuolated and differentiated into ectoplasm and endoplasm. Asexual reproduction by binary fission and spore formation. Euglena Geographical Distribution: Euglena is cosmopolitan in distribution. Habitat: It is found in freshwater ponds,ditches,lakes and slow running streams rich in organic matter. Identifying Features: It is oval,spindle shaped measuring about 50-100 microns in length. Body is blunt anteriorly and pointed posteriorly. Single whip like fllagelum arises from the base of reservoir. Body is covered by striated and flexible pellicle. Common Characters: Anterior end of body bears a small funnel like cytostome and a tubular cytopharynx which leads into a large spherical reservoir. Nucleus is large and spherical located toward the posterior region. Cytoplasm is differentiated into ectoplasm and endoplasm. Nutrition is holophytic or saprophytic. Reproduction is asexual by binary fission. Amoeba Geographical Distribution: Found all over the world. Habitat: Commonly found in mud, freshwater ponds, ditches, slow running streams. Identifying Features: Irregular shaped body(measuring about 0.25 mm-1 mm in diameter) appears like a colourless mass of protoplasm. Body is covered by a thin, clear, elastic and semi-permeable plasma membrane called plasmalemma. Common Characters: Cytoplasm is distinguished into ectoplasm and endoplasm. Endoplasm contains a spherical nucleus, a large contractile vacuole and various food vacuoles. Locomotion by short and blunt pseudopodia. Nutrition is holozoic. Asexual reproduction by binary fission. Paramecium SCIENTIFIC NAME-Paramecium COMMON NAME HABITAT-Freshwater ponds,pools,ditches,streams,lakes,reservoirs and rivers. Specially abundant in ponds rich in organic matter. IDENTIFYING FEATURES- Slipper shaped body about 0.3mm in length. Cilia are uniformly arranged in longitudinal rows except at posterior end of the body. On the oral side is a groove ,the oral groove or peristomial groove, running backwards obliquely to the right side of anterior end to about middle of the body. This groove ends in mouth or cytostome. COMMON CHARACTER- Locomotion by lashing of cilia. Body is covered y pellicle. Cytoplasm is clearly distinguishale into ectoplasm and endoplasm. Ectoplasm contains basal granules. Endoplasm contains two nuclei(large macronucleus,small micronucleus),two contractile vacuoles and reserved food materials. Nutrition is holozoic. Asexual reproduction is by transverse binary fission,sexual reproduction is by conjugation,endomixis,autogamy and hemixis. Vorticella SCIENTIFIC NAME- Vorticella COMMON NAME GEOGRAPHICAL DISTRIBUTION-Cosmopolitan in distribution. HABITAT-Freshwater ponds , lakes , rivers , streams attached to some objects like weeds. IDENTIFYING FEATURES- Inverted bell shaped body with a long, slender stalk for attachment. Rim of bell is thick and surrounded by cilia. Cilia are arranged in two circles,in an outer anticlockwise fashion on the rim and in inner one on the edge of disc. COMMON CHARACTERS- Body consists of pellicle,ectoplasm and endoplasm . Endoplasm contains a long horse shoe shaped macronucleus ,a small micronucleus,a single contractile vacuole and food vacuoles. medulla. Free broad end of the body is oral and the opposite end is aboral. Nutrition is holozoic. Reproduction by binary fission and conjugation.