microscopic life

In high school biology class, we learned about protozoa, single celled creatures such as

We got to see one or maybe two films in class, and we saw some drawings in books.

Well now we got YouTube. Boy howdy, there are dozens of very nice high magnification videos of all these guys. Highly recommend searching for each of those names.

I'm very impressed at the complexity of behavior they exhibit. They each actively hunt prey, be it bacteria, algae, or other protists. And they do it all with a single cell, and each kind of protist gets its food in vastly different ways.

Euglena is maybe the most animal-like of them, having a little eye-spot and a tail -- but it has chloroplasts, by which it photosynthesizes like a plant!

Something that had escaped my notice before -- there are really huge single-celled organisms. Besides stentor and spirostomum, which are visible, and on the order of a couple of millimeters in length, there are a few that grow to several centimeters in size:

All of these giant cells function by having multiple nuclei in their one cell. It's a different approach for an organism getting big.

And if you want to see something really different, check out

These critters alternate between a state of independent amoebic cells and very coordinated movement and a state of animal-like collective movement and behavior.

On similar scales, there are the multi-celled

called a "colony, microscopic crustaceans like

whose cells are a large fraction of their length, and the

each species of which has a constant number of cells in their body, and the wonderful

famous for surviving almost anything. It's just... how many ways there are for creatures to be on our planet, most of which are beyond our direct perception.