SYSTEMATIC
POSITION OF
PLNKTON
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
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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.
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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,
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)
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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)
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)
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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)
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Order: Coccogoneae
One-celled plants, living either free or united into colonies by being surrounded in
a common gelatinous matrix.
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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)
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Class: Bacillariaceae (Diatoms)
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.
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Order: Centrales
Cells are mostely circular in top view and with ornamentation (pits, striate, etc.)
radial; cell walls without raphe.
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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).
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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.
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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).
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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).
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Family: Diatomaceae
Valves are symmetrical with reference to a transverse axis. Cells are symmetrical
with reference to both axes, borne in long chains.
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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).
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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).
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Family: Gomphonemaceae
Starie composed of puncta in a single series; attached on branched stalk.
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).
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Class: Chlorophyceae
Thallus is characteristically green in color because of the green pigment the
chlorophyll. Greater number of form is found in fresh water.
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Order: Chlorococcales
Plants unicellular or colonial, few cells united into minute families. Frequently
imbedded in gelatinous substance
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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).
.
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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.
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Genus: Pediastrum
The cells arranged either with intercellular spaces or not; marginal cells with one
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 mother-
membrane and within which they form a new coenobium, (Plate Fig. 4e).
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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)
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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
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 )
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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.
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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).
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Genus: Cosmarium
Cells are without radiating arms; semicells compressed or rounded, margin of
semicells furnished with or without spines or processes, (Plate fig.5b).
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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).
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Order: Volvocales
Cells arranged in a perfectly spherical colony, rolling and turning as flagella beat
in a coordinated fashion.
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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:
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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.
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Class: Mastigophora
These are simple and primitive organisms. Locomotion with the help of flagella.
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Order: Euglenales
Organisms are unicellular. Locomotion by flagella. Zoospores and gamates
lacking.
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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
and smaller micronucleus
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Class: Crustacea
Head often joined with thorax to form cephalothorax, exoskeleton chitinous, hard,
slimy, sexes usually separate.
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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.
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Family: Cyclopidae
Antennae short, never longer than cephalothorax generally much shorter and
compose of from six to seventeen segments.
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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 0.7-1.5 mm. long. Antennae are short and not longer than half the body
length. Prosoma are much larger than urosome. The 1st 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).
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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).
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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.
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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.
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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.
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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.
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)
PHOTOPLATE: 1
Plate fig.1a Anabaena sp.
Plate fig. 1c Gloecapsa sp.
Plate fig. 1e Calothrix sp.
PHYTOPLANKTON-I
Plate fig. 1b Oscilatoria
Plate fig.1d Spirulina sp.
Plate fig.1f Merismopedia sp.
PHOTOTO PLATE: 2 PHYTOPLANKTON-II
PHYTOPLANKTON
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.
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.
PHOTOPLATE: 4 PHYTOPLANKTON-IV
Plate fig. 4a Cladophora sp.
Plate fig.4c Scenedesmus sp.
Plate fig. 4e Padeastrum sp.
Plate fig. 4b Scenedesmus
Plate fig. 4d Scenedesmus sp.
Plate fig. 4f Spirogyra sp.
PHOTO PLATE: 5 PHYTOPLANKTON-V
Plate fig. 5a Tetraspora sp.
Plate fig. 5c Zygnema sp.
Plate fig. 5e Pandorina sp.
Plate fig. 5b Cosmarium sp.
Plate fig. 5d Hydrodictyon
Plate fig. 5f Ankistrodesmus sp.
PHOTO PLATE : 6 ZOOPLANKTON-II
Plate fig. 6a Cyclops sp.
Plate fig. 6c Diaptomus sp.
Plate fig. 6e Brachionus sp.
Plate fig. 6b Diacyclops sp.
Plate fig. 6d Diaptomus sp.
Plate fig. 6f Brachionus sp.
PHOTO PLATE : 7 ZOOPLANKTON-II
Plate fig. 7a Brachionus sp.
Plate fig. 7b Brachionus sp.