BLEPHARISMA

Blepharisma is a heterotrich ciliate and a microphagus filter feeder. It usually eats bacteria found in decomposing vegetation by drawing them into its vortex of membranelles that surround its buccal cavity (mouth). The food is then passed through the cytostome and enclosed in food vacuoles which are distended to the posterior end of the cell.

At first glance Blepharisma looks like a complicated organism especially when viewed through multiple levels under the microscope. But once the buccal cavity and all its associated structures are understood the organism as a whole is easier to view.

KEY TO UNDERSTANDING THE BUCCAL CAVITY

 

INDIVIDUAL STRUCTURES

 

Buccal overture

The opening of the structure to the cell surface

Buccal cavity

The actual structure itself that the membranes originate from

Haplokinety

LHS of the buccal overture

one layer of flagella, therefore appears very thin like cellophane paper

probably only able to see the ends of the flagella, like a skirt not a sheet

Polykineties

RHS of the buccal overture

Looks like a comb, longer and thicker than the haplokinety

Each piece is from 3 flagella

Cytostome

The cell's mouth

Contractile vacuole

Located at the most posterior end of the cell, this structure is for controlling the volume of water inside the cell and therefor the buoyancy of the cell.

Food vacuole

Few to many depending on the feeding state of the organism. They accumulate at the posterior end of the cell.

Macronuclei

Easy to identify. Appears as a chain of beads similar to the nucleosomes in coiled DNA strands. They are usually stained pink and run down the ventral side of the cell.

Micronuclei

Hard to see in slides but exist in great numbers on or near the macronuclei.

Keep in mind that you are viewing a 3dimantional structure in 2 dimensions. Remember to focus up and down through the organism to get the full 3D effect. Using what you know about the location of the buccal cavity and its related structures try to determine which view of the cell you are looking at.

Try this one

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