SYSTEMATIC POSITION OF PLNKTON

Transcription

1 SYSTEMATIC POSITION OF PLNKTON

2 Chapter : 3 SYSTEMATIC POSITION OF PLANKTON Plankton are drifting organisms (most of them are microscopic) that live in fresh, marine and estuarine water. They are important component of fresh water food web. Plankton are heterogenous group of very small (tiny) organisms, confined of aquatic plants and animals. Plankton can produce 75% of the total primary productivity. Dawes 1998) During the present study total 33 plankton genus were recorded. They were identified by using various references such as identification keys, books, photographs, manuals for identification and web sites. Further they are classified on the basis of classification given in the books such as Ward and Whiple, (1945), Edmondson W. T., (1959), Battish S. K., (1992) and Prescott G. W., (1969). Out of 33 plankton sp. 27 were phytoplankton sp. and rest (i.e.6) were zooplankton. Among phytoplankton sp. 8 species each belongs to class cyanophyceae and bacillariophyceae., while 11 species belongs to chlorophyceae. Similarly total 6 zooplankton genus were recorded out of them 1 represents flagellata, 3 are representatives of copepoda and 2 are of rotifera. PHYTOPLANKTON Cyanophyceae (Blue Green Algae) It is mainly found in fresh water although numerous forms occur in sea water also. More or less of a blue-green color, free floating or living in gelatinous masses or strata. It reproduces mainly asexually by means of cell division while sexual reproduction unknown. Order: Hormogenere These are filamentous, filaments simple or branched, consisting of one or more rows of cells generally enclosed within a more or less evident sheath. Asexual reproduction by means of hormogonia and more rarely by spores. Family: Oscillatoriaceae: Filaments consisting of a single row of cells.seldom one celled, not branched,

3 heterocysts absent. Genus: Anabaena Filaments straight or circinate, nacked or enclosed in a thin sheath, free floating as single filaments or united to form a theme, slimy stratum, vegetative cells as long or somewhat longer than thick, heterocysts numerous and intercalary, spores variously disposed, born singly or rarely in short chains, (plate fig. 1a) Genus: Oscilatoria Filaments long, with more than 20 cells, filaments commonly without sharp pointed ends. Filaments composed of numerous short cylindrical cells, the end cell sometimes much attenuated, without a shealth or with an almost imperceptible one, generally showing lively creeping and oscillating movements. Found in great profusion in all kinds of wet situational, sometimes free-floating at the surface of lakes and ponds, or forming filmy growths on wet soil or rocks, (Plate Fig. 1b) Family: Nostoceae Filament simple, unbranched with heterocysts, living singly or in gelatinous masses, often of definite form. Sheaths are very delicate, mostly confluent. Genus: Nostoc Forming leathery or slimy gelatinous masses, at first spherical or oblong, later of varied form, solid or hollow, and attached or unattached; filaments contorted and curved in all directions. The gelatinous sheath sometimes sharply delimited, more often fused with the enveloping jelly. Cells are globular, barrel-shaped, or cylindrical, heterocysts intercalary, or (when young) sometimes terminal, spores globular or oblong, formed in rows in varying number between the heterocysts. Forming free floating or attached masses, on damp ground, wet rocks, etc., (Plate fig. 2a) Genus: Spirulina Filaments very narrow, consisting of a single elongated cell, sometimes of great length, regularly spirally coiled, sometimes showing rapid oscillating and rotary movement. Common in stagnant water, (Plate fig. 1d)

4 Genus: Cylindrospermum Filaments without sheath relatively short, aggregated to form an expanded film or colony of indefinite shape; vegetative cells cylindrical, longer than the diameter; heterocyst terminal; spores generally solitary, born next to the heterocyst.(plate fig. 2b) Family: Rivulariaceae Filamentous sheathed, simple or branched, attenuated from the base to the apex, which is pilliferous, heterocysts generally basal, rarely absent. Genus: Calothrix Filament simple or slightly branched, single in a thick sheath, hetrocysts basal or intercalary or in a few species absent, forming tufts or soft velvety expansions on wet or sub merged rocks.(plate fig.1e) Order: Coccogoneae One-celled plants, living either free or united into colonies by being surrounded in a common gelatinous matrix. Family: Chroococcaceae Cells generally free floating or forming a gelatinous stratum, not differentiated into base and apex. Genus: Merimospedia Cell division in two planes, spherical or oblong, forms flat, plate like colonies. Live in ponds and lakes. (Plate fig. 1f) Genus: Gloeocapsa It is either single or in group of cells. Cells together form cluster by secreting mucilaginous substance. It was secreted in a concentric manner. It reproduces asexually be mean of cell division. (Plate fig.1c) Class: Bacillariaceae (Diatoms)

5 Color yellow, plant a single cell, sometimes united into chins, membrane silicified, with minute, definite markings. These are unicellular algae. Reproduction is by auxospores, either sexual or asexual. Order: Centrales Cells are mostely circular in top view and with ornamentation (pits, striate, etc.) radial; cell walls without raphe. Family: Coscinodiscaceae Cells single, disk shaped not forming filaments, valves flat, convex or undulating, mostly with radial rows of punctulations. Genus: Cyclotella Cells are disc shaped, Cells single, disk shaped not forming filaments, valves flat, convex or undulating, mostly with radial rows of punctulations. It is found commonly in ponds and lakes (Plate fig. 3a). Order: Pennales Cells are elongated, rectangular, crescent, key-shaped, cigar-shaped or boatshaped in valve view; wall ornamentation bilaterally symmetrical; one or both valves with a raphe or a pseudoraphe. Family: Naviculaceae Valves not arched or keeled, usually symmetrical with reference to a straight or sigmoid raphe. Central and two end nodules present. Genus: Navicula Central nodule small, rounded or slightly elongated, cell with fine transverse markings which appear as lines of dots under high magnification, (Plate fig. 2c, 2e). Genus: Amphipleura These are elongated and narrow, boat-shaped cells in valve view. The valve has minute transverse striae of punctuations, (Plate fig. 3c).

6 Family: Nitzschiaceae Valves asymmectrical with reference to longitudinal axis, in that on one margin there is a longitudinal row of bead like thickenings while on the other margin they are lacking. Genus: Nitzschia Valves linear, sometimes covered, keeled, with canal raphed, cells rhomboidal in cross section, (Plate fig. 2f). Family: Diatomaceae Valves are symmetrical with reference to a transverse axis. Cells are symmetrical with reference to both axes, borne in long chains. Family: Fragilariaceae Valves are without transverse costae. Cells are much the same structure as diatoms. Transverse striations composed of separate dots, with or without raphe and end nodules. Genus: Synedra Cells are very slender, not united in bands, either free or attached at one end, forming cluster on higher algae, (Plate fig. 3e). Family: Cymbellaceae Axial field central and small not expanded as above; frustules forming linear colonies in gelatinous tubes, lunate, with a slight swelling in the mid region of the ventral margin. Genus: Cymbella These are mostly gracefully curved, crescent-shaped cells which are slightly tumid along the concave margin in the mid region. Usually free-floating, (Plate fig. 3b). Family: Gomphonemaceae Starie composed of puncta in a single series; attached on branched stalk.

7 Genus: Gomphonema Frustules are wedge-shaped or clavate, larger at one end than the other. The elongate axial field is enlarged in midregion. The cells are usually found attached on branched, gelatinous stalks at their narrow end, (Plate fig. 2d). Class: Chlorophyceae Thallus is characteristically green in color because of the green pigment the chlorophyll. Greater number of form is found in fresh water. Order: Chlorococcales Plants unicellular or colonial, few cells united into minute families. Frequently imbedded in gelatinous substance Family: Scendesmaceae Daughter cells arrange themselves to form miniature colonies within the parent. A breakdown of the old cell wall liberates the colonies which then increase to a mature size. Genus: Scendesmus Cells are four, eight or sixteen in one or two parallel or zigzag. The cells are oval or pointed, the membrane either smooth or furnished with distinct spines at the ends. Chromatophore, single, parietal with an opening at ones side and a pyrenoid. This is one of the most common and the best known of all of the lower algae. It is being found in almost all localities where algae are ever found, (Plate fig. 4b, 4c and 4d).. Family: Hydrodictyaceae A coarse net or a concentrically arranged circular disc of cells. Formed by the joining together of zoospores while within the mother-membrane or still within the liberated inner lining of the same. Genus: Pediastrum The cells arranged either with intercellular spaces or not; marginal cells with one

8 or two pointed projections; inner cells angled or concave; chromatophore parietal, with one pyrenoid and performed at one side. Reproduction by means of zoospores, which are cast out together with the inner lining of the mothermembrane and within which they form a new coenobium, (Plate Fig. 4e). Family: Tetrasporaceae Cells in colonies, generally sessile and enclosed in a definite gelatinous envelop. Asexual reproduction by zoospores and sexual reproduction by isogametes. Genus: Tetraspora Colonies macroscopic or microscopic, cells arranged in fours. Isogametes with two cillia. (Plate fig. 5a) Family: oocystaceae The formation of autocolonies of unadjoined cells within mother cells, mostly colonial, are uniceliular when the colonies dissociate. Cells exhibit a great range of shape: spherical, oval, lunate, acicular, polyhedral and pyramidal. Genus: Ankistrodesmus Cells needle like or fusiform often variously curved. Found in all ponds, lakes and rivers, (Plate fig. 5f). Order: Congugle Plants unbranched, strictly fresh water organisms, unicellular and multicellular filamentous forms. Slippery or mucilaginous. Chlorophyl in spiral bands, central plates, or star shaped. Family: Zygnemaceae Plants are filamentous, cylindrical, usually found near the surface of the water. Sexual reproduction by conjugation of cells in two parallel filaments. Genus: Zygnema Conjugation either ladder-like or lateral, zygospore within one of the conjugating

9 cells for in the conjugating tube. According to Collins aplanospores may take the place of zygospores, also resting akinetes with granular contents and thickened membrane may be found. (Plate fig.5c ) Order: Zygnematales Plants unbranched, strictly fresh water,unicellular and multicellular filamentous forms, Slippery to the touch. Chlorophyll in spiral bands, central plates, or star shaped body. Family: Desmidiaceae Single celled microscopic organisms. All are fresh water forms. One-half of each cell exactly symmetrical with the other half. Genus: Closterium Cells are crescent-shaped, variously bowed, without apical spine, (Plate fig. 3f). Genus: Cosmarium Cells are without radiating arms; semicells compressed or rounded, margin of semicells furnished with or without spines or processes, (Plate fig.5b). Family: Zygnemataceae Plants filamentous, cylindrical usually found near the surface of the water. Sexual reproduction by conjugation of cells in two parallel filaments. Genus: Spirogyra Chromatophore one or several, paritel, spiral bands with many pyrenoids. Conjugation ladder like or lateral. Found in fresh water ponds, lakes, (Plate fig. 4f). Order: Volvocales Cells arranged in a perfectly spherical colony, rolling and turning as flagella beat in a coordinated fashion.

10 Family: Volvocaceae All members are colonial. Reproduction occur by cells dividing internally to form daughter colony. Genus: Pandorina Colonial spheroidal or oval; cells crowded, somewhat pyriform, with the broad ends all directed outwardly, (Plate fig. 5e). ZOOPLANKTON: Phyla: Protozoa: Protozoans are small, microscopic, simplest and most primitive organisms. Body unicellular naked or bounded by a pellicle.the single cell body performs all the essential and vital activities. Nutrition is holozoic, holophytic, saprozoic or parasitic type. Class: Mastigophora These are simple and primitive organisms. Locomotion with the help of flagella. Order: Euglenales Organisms are unicellular. Locomotion by flagella. Zoospores and gamates lacking. Family: Euglenaceae Chloroplasts many oval or irregular platelike discs, orrarely diffused, visible flagellum. Genus: Euglena Euglena is solitary metabolic flagellate. Body is slightly flexible, short or elongated, slender, simple fusiform, spinle-shaped, plump like red or green colour. The eye-spot is usually conspicuous, (Plate fig. 6f). Flagella present throughout life. Mostly two kinds of nuclei, large macronucleus

11 and smaller micronucleus Class: Crustacea Head often joined with thorax to form cephalothorax, exoskeleton chitinous, hard, slimy, sexes usually separate. Order: Copepoda Copepods range from less than 1.0 mm to several mm in length, majority being about 2-3 mm long. Parasitic forms. Body is usually pale and transparent some are brightly colored. Shape is short, cylindrical and somewhat pear-shaped. Body is distinctly segmented and consists of head, thorax and abdomen. Compound eyes are absent but median naupliar eye is typically present. Family: Cyclopidae Antennae short, never longer than cephalothorax generally much shorter and compose of from six to seventeen segments. Order: Cyclopoida Antennules are of a medium length. The abdomen is narrower than thorax. Articulation between thoracic segments 5 and 6. Mandibles are in the fifth leg.they help in chewing and biting. The fifth leg is uniramous. Genus: Cyclops It is about mm. long. Antennae are short and not longer than half the body length. Prosoma are much larger than urosome. The 1 st antennae possess 17 or more segments. Ridge present on dorsal, back side of rami. Spine of second segments of fifth feet is small and near end of segments, last three segments of female antenna without hyaline membrane, (Plate Fig.6a). Genus: Diacyclops Caudal rami are 6-7 times long as wide. Lateral spine is inserted approximate distance of 55% from the base of caudal ramus to the apex, (Plate fig. 6b).

12 Family: Diaptomidae Antennae long, commonly nearly or quite as long as the whole animal and compose of 23, 24 or 25 segments. Genus: Diaptomus There are five setae on each caudal ramus. Process on the third segment from the end of the right antenna has a broad hyaline lamella that extends past the end of the segment. Organism is approximately 1.2 to 2.4 mm long. Endopodites of first swimming feet composed of two segments, of third and fourth swimming feet compose of three segments, furcal rami short, (Plate fig. 6c, 6d). Phylum: Rotifera: Microscopic, Cilia on oral disk. Body is elongated, cylindrical and divided into head, trunk and foot. The head is often separated from the large trunk. The body has a cuticular covering. Class: Monogonata Swimming or sessile Rotifera, with a single germovitellarium; males usually present, with one testis; lateral antennae present; foot present or absent, when present with 2 toes or without toes. Order: Ploima Bodyshape vermiform, dorso-ventrally flattened. Free swimming organisms, never fixed. Corona without long antenna-like bristles and setigerous prominences, foot when present, with toes. Family: Brachionidae Most of the form is heavily loricated; corona often with several dorso-transverse prominences bearing tufts of strong cilia. Mouth is funnel-like, situated in buccal field. Foot present or absent, when present with two toes. Foot projects from posterior end.

13 Genus: Brachionus Heavily loricate forms; lorica broad and covers the trunk completely; may be one or two piece. Antero-dorsal edge is always with spines. Postero-median spines mostly present and flank the foot. Lorica very convex dorsally, (Plate Fig. 6e, 7a, 7b)

14 PHOTOPLATE: 1 PHYTOPLANKTON-I Plate fig.1a Anabaena sp. Plate fig. 1b Oscilatoria Plate fig. 1c Gloecapsa sp. Plate fig.1d Spirulina sp. Plate fig. 1e Calothrix sp. Plate fig.1f Merismopedia sp.

15 PHOTOTO PLATE: 2 PHYTOPLANKTON-II Plate fig. 2a Nostoc sp. Plate fig. 2b Cylindrospermum sp. Plate fig. 2c Navicula sp. Plate fig. 2d Gomphonema sp. Plate fig. 2e Navicula sp. Plate fig. 2f Nitzschia sp.

16 PHOTOPLATE: 3 PHYTOPLANKTON-III Plate fig. 3a Cyclostella sp. Plate fig. 3b Cymbella sp. Plate fig. 3c Amphiplura sp. Plate fig. 3d Fragillaria sp. Plate fig. 3e Synedra sp. Plate fig. 3f Clostorium sp.

17 PHOTOPLATE: 4 PHYTOPLANKTON-IV Plate fig. 4a Cladophora sp. Plate fig. 4b Scenedesmus Plate fig.4c Scenedesmus sp. Plate fig. 4d Scenedesmus sp. Plate fig. 4e Padeastrum sp. Plate fig. 4f Spirogyra sp.

18 PHOTO PLATE: 5 PHYTOPLANKTON-V Plate fig. 5a Tetraspora sp. Plate fig. 5b Cosmarium sp. Plate fig. 5c Zygnema sp. Plate fig. 5d Hydrodictyon Plate fig. 5e Pandorina sp. Plate fig. 5f Ankistrodesmus sp.

19 PHOTO PLATE : 6 ZOOPLANKTON-II Plate fig. 6a Cyclops sp. Plate fig. 6b Diacyclops sp. Plate fig. 6c Diaptomus sp. Plate fig. 6d Diaptomus sp. Plate fig. 6e Brachionus sp. Plate fig. 6f Brachionus sp.

20 PHOTO PLATE : 7 ZOOPLANKTON-II Plate fig. 7a Brachionus sp. Plate fig. 7b Brachionus sp.