PARAMECIUM

PARAMECIUM is a microscopic (very small), unicellular (one cell) protozoa (animal-like protist).

·  It is plentiful in freshwater ponds.

Major Parts of a Paramecium

·  Nucleus: “control center” (3)

·  Pellicle: Thick membrane that gives the paramecium its shape (2)

·  Cytoplasm: jelly-like substance that hold all the organelles (12)

·  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)

·  Food vacuole: digests food (8)

·  Anal pore: Removes waste (9)

·  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

•  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

•  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).

•  2-3 times per day if conditions were right.

Paramecium Reproduction – Conjugation

•  Can also reproduce sexually called conjugation.

•  2 cells coming together to exchange nuclear material.

•  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

•  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.