Life, wherever you find it, is a dancing, writhing mix of atoms, molecules, and larger clumps and masses, all interactive and interconnected and interdependent, and all driven by energy from the sun. This is true of the bacteria in the soil, the ameba and the snail, a pod of Orcas, myself and my significant others, the critters in the Amazon River and in the United States Congress and on the Arctic ice cap.
Homeostatic, or negative-feedback, interactions create relatively stable sub-systems within the Earth's great life system, the biosphere. It's a staggering concept to wrap your mind around! Want to see a little chunk of it at close range? Try an Eco-Jar.
When I quit teaching biology I couldn't bring myself to discard everything in my little salt-water aquarium, populated by aquatic plants and tiny animals from the tide pools of the Maine coast.
As an experiment I washed out a Miracle Whip jar, scooped about an inch of sand and mud from the aquarium into the jar, and filled it to within an inch of the top with water from the tank. I added the 2 playing-card-sized pieces of "sea lettuce"—a kind of alga—that I had brought from the sea. Finally the animals: a small stone with several barnacles on it; a tiny starfish; a transparent sea slug the size of a date seed; and 3 snails as big as my little finger nail.
I poured melted paraffin into the metal jar lid, screwed it down airtight, and set the jar on the windowsill. It had a fresh, garden-like look. In bright sunshine, tiny bubbles of oxygen formed on the alga leaves.
For 6 months the scene in the jar kept changing. The starfish lasted 2 weeks. The barnacles quit feeding and died in about 3 weeks, as did the sea slug. The sea lettuce slowly turned brown at the edges and in 3 months was gone, but had been replaced by a fine velvety layer of green on top of the sand and thinly on the sides of the jar. One of the snails died.
At one time numerous pinhead-sized critters could be seen moving against the glass. A month later they were gone, but for a few weeks lots of hair-like nematodes, barely visible, undulated and danced just off the bottom.
Two years later, when I sold the house with the jar on the windowsill, one snail still cruised and grazed his little trails on the inner surface of the glass.
Since then I've never been without one or more of these Eco-Jars. Some fail to thrive and go "dead" in a few weeks or months. One slowly changed for about 6 months, then remained almost exactly the same, with a few little swimming creatures smaller than pinheads visible, for 12 years. Then one day they just weren't there any more.
Jars set up in June 2000.
This photo taken in March 2003.
A quart jar is a good size. Find a watery place such as a swamp, stagnant pond, or tide-pool. Either fresh or salt water will do, but don't mix them. Places where water is standing, or is moving slowly, are more likely to have plenty of little live creatures.
Dip up about half a cup of sand or mud from under the water and pour it into the bottom of your jar. Now fill the jar nearly to the top with the water, pouring gently to avoid stirring up the mud too much.
In a separate container collect one or more kinds of algae—water plants. Look for free-floating types, hair-like green strands or clumps, or ones with stems and leaves that regularly live under water.
Let the mud settle out in the jar until the water is clear. (This may take only a few minutes or overnight, depending on the kind of mud.) Now carefully add the plant material, enough so it floats free without too much crowding but fills most of the jar. This green stuff is the key to the whole system, for it is what captures the sun's energy and provides both oxygen and food for the whole jar society.
You may wish to add other creatures picked out of the pond or swamp or tide-pool—snails, mussels, tiny shrimp. But a warning: choose only very tiny animals, and not too many. Your little world will be limited, and an animal as large as a baby crab or fish would soon use up its resources and die from lack of food and oxygen.
Leaving a little air space, put the top on the jar and screw it down air-tight, and set the jar in a window. It doesn't have to be in direct sunlight, but needs full light from out of doors for most of every day.
Looking through the jar, you can probably see tiny animals swimming around, not only the ones that you added but also many that were clinging to the algae as you scooped it up. With a strong magnifying glass you may see still others.
People may ask, "Don't you ever have to open the jar to let in fresh air? Don't you have to add food and clean water?" But you can ask them, "Does the Earth's biosphere have to have fresh air and clean water added?"
You now have no control over who in the jar lives or dies, nor which species of animals or plants will thrive and which will disappear. How long the system will continue depends on many factors, and the only ones you can now control are the placement of the jar, the temperature, and the amount of available light.
The jars shown here were set up in June 2000, with stuff from two small roadside ponds, a lake, and a small creek. The photo above was taken 3 years later. The appearance has changed some since the beginning, in that most of the stem-like fronds of algae have gradually disintegrated, and in Jars 2 and 3 (numbering from the left) the water is now very turbid with green one-celled plants. Jar 1 has plenty of live duckweed floating on its surface, but no moving (animal) forms have been seen after the first year. Jars 2 and 3 still contained a few little shrimp-like animals less than a quarter inch long.
Three months after this photo, for 3 weeks a sun-shield screen was left down nearly to the tops of the jars. This, along with shade from an apple tree outside the window, apparently decreased the available light too much, and in a few days all of the jars began to appear less green, and all visible movement in all jars appeared to have ceased. However, the algae in Jar 2 rallied somewhat, and from 1 to 4 shrimp were seen at various times. The last shrimp was seen in Jar 2 in November 2005—more than 5 years after the jars were established.
In February 2006, at the time of this
photo, Jar 1 appeared totally inert; in
Jars 2 and 3 were many barely visible
dark colored dots moving about. No
other movement has been seen. The
plant material appears all but dead—
but in bright sunlight, small bubbles
of oxygen still form and rise briskly
to the surface.
The Miracle Whip Microcosm is a model of the whole earth system:
By careful and thoughtful observations of the Eco-Jars, one can find endless lessons in physics, chemistry, ecology, economics and politics.
