Swimming Christmas Germs

We took a hike to Lake Hodges in San Diego County for a hike and picked up a few samples from the reservoir. The first I looked at was some green scum floating in one of our collection containers, and we found the creatures below.

It's funny that there are green and red variants--I didn't add any stains. The microscope is at 400x and the creatures are about 20 um in length (I finally calibrated the microscope). These appears to be protozoa rather than bacteria based on their size (bacteria are usually 0.5-5 um, protozoa are 10-50 um) and the appearance of internal structures which bacteria generally lack. (All this sound vaguely familiar from high school biology. I guess I should have paid better attention. Thank God for Wikipedia.)

In this first clip, a red and green creature hang out and spin around once in a while.



In the second clip, I chase after the green one to watch it swim. Sorry for the shaky camera work--I'm still getting used to moving the microscope stage.



Protozoa can be classified by their means of locomotion into the following four groups:

1. Flagellates - these move with one or more whip-like tails called ... wait for it ... flagella
2. Ciliates - pronounced silly-ates, these move with little hair-like thingies all around the cell
3. Amoeboids - these move around like The Blob
4. Sporozoans - they sound like something out of Scientology, but they are actually parasitic protozoa that don't have any means of locomotion

If you want to see examples of flagellates and ciliates swimming, check out this cool clip.

Since these guys swim, they must be either flagellates or ciliates. They spiral through the water when they swim, which seems like it would be the result of a whip-like tail rather than lots of little hairs. On the other hand, the Blepharisma is a ciliate and the Wikipedia entry notes that "It spirals as well as spins in a circular motion." I think I'll just name them Bob and Harold.