Life in a drop of water

By Al Lowe
Contributor

Have you ever looked at a still, quiet body of water? A pond, a sheltered bay on the lake, or just a puddle in a field? And you thought - how peaceful and quiet that is. Well, think again. In that peaceful bit of water, life is going on at a great rate. There are millions - maybe billions of living things in that water. There are things in there that are doing all the same things that big things do - they are eating, they are moving...they are reproducing, they are getting rid of their waste products, and so on.
But you cannot see these tiny creatures. They are small, much too small to see with your naked eye. You need to look for these tiny animals and plants with a good microscope. Many of them are only a few microns in size. (A micron is one millionth of a centimeter). They are very small, indeed!
Well, there are thousands of them. If you remember anything at all about your biology class in high school, you might recall the amoeba. There is not just one, but several different kinds of amoeba. They seem to be the dummies of the microscopic world. They don't have any definite shape. An amoeba is just a one-celled blob, about the size of the period on this page. It lives in freshwater ponds, and the like, and also in standing fresh water in your home - like your humidifier.
The amoeba has no feet, to anything like feet, so it has its own way of moving around. It pushes some of its cell membrane out to one side, then the rest of the amoeba flows into it. This extension is called a pseudopod - literally, a false foot. It can also form vacuoles to hold waste products. When the vacuole is full, the amoeba just 'spits' out into the water.
As far as reproduction is concerned, the amoeba does it without any fuss at all - it just divides into two. The amoeba feeds on microscopic plants. It simply sends out thin pseudopods. These surround the particle, and it is drawn in. Breathing is very simple indeed. Oxygen moves into the amoeba by osmosis, and carbon dioxide moves out the same way.
Another little animal that you might recall from your high school days is the paramecium. This one is not clumsy or slow at all. It can move around at a really good clip. This is because it has a multitude of tiny hairs on it. These are called cilia, and they lash around, giving this tiny animals its speed. The paramecium has a definite shape too. It is called the 'slipper' animal because that is what it looks like. It has an "oral groove" where food goes in, and an "anal spot," where waste goes out. If you have a vase of flowers, and it has been standing for a while, very likely there will be some paramecia in the water and some other stuff, too.
Speaking of "other stuff" there may very well be some other tiny animals, or plants, in that water. There are at least 10000 species of these tiny things in the world. And they have all kinds of shapes. Some look like tiny funnels, and some like tiny animals. Some have long threads attached to them and they move really fast by flailing them around. And some others are sort of long and slim and move by jerking their bodies into different shapes. Now some the these creatures have chlorophyll in them - just like green plants. So are they plant or animals? Since scientists couldn't decided, they made a new classification for them, the Protists.
Now, that is not all that can be in that water. There may be lots of spores from many kinds of plants. These are usually roundish, and do not move around at all. And there may be infinitely small worms, seem only with a microscope.
There are lots of things going on in that drop or two of water, which you wouldn't know anything about, and couldn't see at all. Very few are harmful to humans, and the ones which are, are not found in cold places like Northern Ontario.
Life come in all sizes...