PARAMECIUM
PARAMECIUM is a microscopic (very small), unicellular (one cell) protozoa (animal-like protist).
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It is plentiful in freshwater ponds.
Major Parts of a Paramecium

Nucleus: “control center” (3)
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Pellicle: Thick membrane that gives the
paramecium its shape (2)
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Cytoplasm: jelly-like substance that hold all the
organelles (12)
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Cilia: hair-like projections that help it move (1)

Contractile vacuole: Remove excess water
out of the cell; works like a pump. (5)

Oral groove: takes in food (6)
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Food vacuole: digests food (8)
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Anal pore: Removes waste (9)
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Trichocyst: Protection or defense against predators (10)
Paramecium Movement
•
The outer surface of the cell is covered with many hundreds of tiny hair-like structures
called cilia.
•
Act like “microscopic oars”
•
Can swim backwards, forwards, or rotate using the cilia.
•
Moves so quickly that we have to add a thickening agent or quieting solution to the
slide to slow it down to study it.
Paramecium Feeding
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Feeding mechanism = oral groove (#6) and a funnel-shaped gullet (#7) into which food
is drawn by the combined action of cilia which cover the body and other cilia lining the
oral groove and the gullet. (Refer to picture)
•
As it moves through the water it rotates on its axis and small particles of debris and
food are collected and swept into the gullet.
•
They feed on small organisms such as bacteria, yeasts, algae and even other smaller
protozoa.
Paramecium Reproduction – Binary Fission
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Cell divides in two by a process called binary fission (asexual reproduction).
•
2 new cells are formed by splitting the original (cell then grows in size and makes
structures).
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2-3 times per day if conditions were right.
Paramecium Reproduction – Conjugation
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Can also reproduce sexually called conjugation.
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2 cells coming together to exchange nuclear material.
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The two cells then separate and continue to reproduce by simple division.
•
It is similar in some ways to sexual reproduction in more complex animals.
Paramecium Excretion
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Food waste left in a food vacuole is excreted through the anal pore (the vacuole and
pore fuse.
•
Other wastes left over from cellular activity (metabolic waste) simply diffuse through
the pellicle.
•
Excess water and some metabolic wastes are excreted through the contractile vacuole.