Life in Our Local Pond

One of the things I like best about science is that it makes me aware of things about the world that are right in front of me, but easy to miss. My wife and I like to visit a little pond in the cemetery near our apartment. It's a lovely place covered in lily pads, full of frogs and goldfish, and frequented by red-winged black birds that like to sit on the cattails. It's also frequented by the occasional duck and lots of dragonflies.

A while back we decided to collect a little pond water and some algae to provide for some baby snails we'd hatched from an egg mass. In our small sample of water and pond scum, we found representatives of several animal phyla. (In the traditional system of naming, or taxonomy, an animal phylum is the largest grouping of animals below the kingdom. For example, vertebrates like us are placed within the phylum Chordata, which also includes a variety of interesting invertebrates.) Of course there were arthropods such as insects and ostracodes, and oligochaetes (worms in the same group as earthworms). But we also found lots of rotifers of different kinds, a few lovely freshwater limpets, a neat flatworm, and (moving outside the animal kingdom) lots of interesting ciliates. My favorite ciliates were some Vorticella-like ones that lived attached to each other in a colony. When disturbed, they all sprang back together into a clump. But our favorite animal finds were hydra and freshwater bryozoans. Those are so cool I'll save them for their own posts in the future.

But for now, I want to say how exciting it is to be able to see such an amazing diversity of life in this tiny pond, sitting in a very disturbed habitat in the middle of a city. In just our little sample we can see so many totally different kinds of organisms, each making a living in its own way. Thanks to several centuries of people studying nature, we have a search image that lets us see more than we otherwise would know to look for. Not only that, but we can easily learn a great deal about the creatures we are looking at from the work that those previous scientists have done. One of my favorite professors, Dr. Howard Whisler of the University of Washington, began his course on eukaryotic microorgansisms by telling us he was going to "teach us how to look at pond scum". (I don't remember his exact words, but that's as close as I can recall). That skill is one of the most valuable and beautiful things I've learned in science.