How do I make a sealed ecosystem in a 2-liter bottle with herbivores, carnivores, plants, etc last for 2 weeks?
The project is to create a sealed ecosystem in a 2-liter bottle. It has to include plants, herbivores, carnivores, and detritivores, and it will be completely sealed for two weeks. It can be terrestrial or aquatic. I have no idea where to start in order for this to be even partially successful.
Tagged as: carnivores · detritivores · Ecosystem · liter · plants
That’s a tough one. I think I would go aquatic on this one. When designing the ecosystem, make sure to think of each participants role. First, you will need mostly plants. These will provide energy for the system and food for the herbivores. Then, you will need many more herbivores than carnivores. Make sure you get a carnivore that eats the herbivore. I’m thinking I would start with one carnivore and work my way down.
Here’s an example that may work okay.
Carnivore – one frog, spider, something of that sort
Herbivore – about 20-30 of some insect (more if you pick a small insect, but make sure it’s something that the carnivore eats). Not sure if you could do crickets (they are pretty cheap and easy to find at bait shops, but technically omnivores)
Detritivore – get some worms and put soil on the bottom.
Plants – whatever the herbivores eat. Likely grasses will be the easiest to grow and maintain the herbivore population.
You should fill the bottom with a layer of rocks and then use a good topsoil. Put some water in to cover the rocks (this should be enough to keep the soil moist but not wet or you will kill your worms). I would make sure to add in sticks or something to increase the places where your insects and carnivore can roam.
Build this all in layers. Do the rocks, water, soil, worms, and grass first. Add the insects next. Put the carnivore in last. Give the system a day or two between each section. Make sure it has sunlight, but not direct sun (you will back your ecosystem). Also, be careful about your carnivore. If you pick something too small (like a spider from your yard), the herbivore may actually attack the predator in a group and kill it (I had an experiment go poorly because my crickets ate the spider instead of the other way around).
Overall, this is a pretty complex task. You will need to carefully adjust at each point to keep the system in equilibrium
Good luck!
Aquatic will be easier, thats about all i know.
fill up the bottle, tighten the cap, stick in the microwave for 3 minutes, and store on a shelf of 3 months.
i understand for it to be a sealed ecosystem it needs to be self contained, but logically it would not survive in a 2 liter bottle because it would not have oxygen to thrive…
I would imagine that in general, aquatic is the way to go. Aquatic ecosystems are lower-productivity, in general, and I think that you’ll be able to design a much simpler system. Simplicity is also the way to go – you know those commercially-produced EcoSpheres, that last over a year? All that’s in them is shrimp, algae, and bacteria. Simple.
I would research aquatic arthropods – one small planktivore, a bunch of herbivorous plankton, and as many plants as you can throw in there without them dying from lack of nutrients (a dead plant means a bunch of dead arthropods, too, due to ammonia buildup). I would avoid fish entirely; they need a lot of oxygen, and produce a lot of nitrogenous waste, and eat a lot; even the tiniest one you can get will exhaust all its resources in two weeks.
Terrestrial might be easier, actually, for only two weeks; you wouldn’t have to worry about water quality. I would think that even a few plants, some aphids, and a ladybug would last that long. Low-productivity is the goal here; find slow-growing, small organisms, and couple that with a surplus of plants. The good thing about a terrestrial ecosystem is that a dead plant won’t mean everything else dies – in fact, that’s just more food for everyone else (though then you have to worry about oxygen levels).
Anyway, research is the key here, I think. I’d try to find out as much as I can about my organisms. What is their generational length? Are they going to reproduce? If not, are there enough to feed your predator, but still not too many to destroy your plants? How much oxygen does this organism use/produce? I would try to chart everything out with different possibilities, do my best to calculate rates of oxygen use and CO2 use, and ignore nutrient cycling entirely (your plants will be fine in potting soil for years – so you don’t need to worry about feeding the plants). Look around where you live, and try to observe how that ecosystem works. Simplify it. Use native soil and the plants that grow well in it, and see what naturally eats them, and what naturally eats the herbivores. Keep it simple.
Man, you got me all excited about your project. I hope it works out well, and I hope I was at least somewhat helpful!