Paramecium :
Paramecium is the common ciliates found everywhere in fresh water ponds , pools , streams, rivers, lakes and reservoirs. It is facially abundant in stagnant water containing decaying organic matter. They feed upon bacteria and tiny protozoa. The individuals frequently gather at the surface thus forming a white scum. There are about 10 species of paramecium.
External morphology :
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| Paramecium |
Size: Paramecium are minute organism. Just visible to the naked eye as elongated white or whitish or greys spot. The largest species is about 170-290 μ long and the smallest one is measuring 60μ .
Shape: Paramecium have a permanent body shape. Under the microscopes the groups elongated and cigar shape or slipper shape. Also they are called Slipper Animalcule.
Oral Groove: The ventral surface shows a large cells / depression. It is called Oral Groove. Posteriorly it leads into a dipper conical vestibule. Which in term communicates with a buccal cavity, having a buccal mouth or cystostone.
Pellicle: The unicellular body is externally bounded by a colourless thin, elastic membrane called pellicle. The entire body surface is covered by numerous tiny hair like processes called Cilia.
Internal structures:
Ectoplasm: The ectoplasm surrounding the inner mass of endoplasm forms a clear, dense, thin,, peripheral layer which is tough, elastic supporting and protective. It is also called the Cortex.
Endoplasm: The endoplasm is semifluid, less brainular. It shows a streaming movement for cyclosis. It contains food vacuoles, reserved food granules of stretch, glycogen and fat, mitochondria, golgi bodies, ribosomes, and various crystal and other cytoplasmic
inclusions of varying, size, shape and character.
(A) Nuclear apparatus: Paramecium is heterokaryotic as it having 2 types of nuclei. A large mega nucleus lies in the middle of the body not for from the mouth. It is granular and roughly kidney shaped or bean shaped and without a membrane. It is polyploid and possess many nucleo like and much more chromatin material. It controls the ordinary day to day metabolic activities of the cell and always divides mitotically. It is derived from the micronucleus during reproductive processes. A smaller micronucleus is located in a depression on the surface of the mega nucleus. It is usually spherical and with a definite nuclear membrane. It controls the reproductive activities of the organism and undergoes mitosis during cell division.
(B) Contractile vacuole: There are two contractile vacuoles occupying some what fix position in the endoplasm. One lying near each of the body close to the dorsal surface. These are surrounded by 6-10 long narrow spindle shaped radiating canals.
(C) Food vacuoles: Numerous non contractile food vacuoles or gastrioles can be seen moving with the streaming endoplasm, They differ in shape and size according to the nature of the ingested food particles but mostly they are rounded in form.
(A) Nuclear apparatus: Paramecium is heterokaryotic as it having 2 types of nuclei. A large mega nucleus lies in the middle of the body not for from the mouth. It is granular and roughly kidney shaped or bean shaped and without a membrane. It is polyploid and possess many nucleo like and much more chromatin material. It controls the ordinary day to day metabolic activities of the cell and always divides mitotically. It is derived from the micronucleus during reproductive processes. A smaller micronucleus is located in a depression on the surface of the mega nucleus. It is usually spherical and with a definite nuclear membrane. It controls the reproductive activities of the organism and undergoes mitosis during cell division.
(B) Contractile vacuole: There are two contractile vacuoles occupying some what fix position in the endoplasm. One lying near each of the body close to the dorsal surface. These are surrounded by 6-10 long narrow spindle shaped radiating canals.
(C) Food vacuoles: Numerous non contractile food vacuoles or gastrioles can be seen moving with the streaming endoplasm, They differ in shape and size according to the nature of the ingested food particles but mostly they are rounded in form.
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