Didnium

Eaters of the Dead…

Dead paramecium that is!

I began experimenting with a pure culture of Paramecium which looked like this, --virtually nothing but the torpedo-shaped paramecia.

Now, after only one day, it looks like this -- virtually all the organisms to be found are a more spherical ciliate with two bands of cilia.

The organism that has wiped out all the paramecia is Didinium, a predator that feeds on only one

kind of prey -- Paramecium. Now there are a lot of Didinium -- and they are starting to get hungry.

This presents an excellent opportunity to study and record

their feeding behavior.

The Capture:

I add some paramecia back to the culture dish. Didinium speeds around in a random way, nose first. When it hits a Paramecium, poison darts fire automatically. Didinium then begins opening its nose, which becomes its mouth, and it begins to swallow the much larger cell.

Notice the cilia all around the didnium and the paramecium. The nose hairs paralyze the paramecium.

The Pig Out

*I was able to observe an interesting aspect of Didinium’s swallowing technique.

*With part of the Paramecium engulfed, Didinium expands, thereby sucking cytoplasm from the part still extending from its mouth.

*If the prey was hit in the middle, Didinium expands its mouth and folds the paramecium in order to cram it all in.

The Didnium is over the top of the paramecium.

Engulfment by folding prey.

Sometimes they must share.

Parts to look for in Didnium:

*Cell Membrane

*Nucleus

*2 rows of cilia

*Oral Cavity

*Describe locomotion