Closed ecological systems: It’s tough being God
August 1, 2006, 1:05 pm by bottleman. Filed under: closed ecological systems.

Yesterday morning I got up and muddled through the morning as usual: turned on the coffee maker, let out the dog, and tried to read the paper as the baby gleefully destroyed the living room. I was grateful when he finally went down for his nap about 11:00 AM. That’s when it dawned on me that I had missed something — I had forgotten to turn on the sun. See, I’ve recently become God!

thanks to flickr member msanthea for the image, licensed under creative commons -- see

Or a god of a sort. I’ve created some “closed ecological systems” — ecosystems sealed in bottles — just to see if I could keep a little world “in balance.” Here’s the recipe… Based on sources like this and this, I’m prototyping a system that can be built with stuff from the grocery and the aquarium store for just a few dollars. I put all these things together in standard canning jars (with new lids), in various combos, and sealed the jars up:

  1. water from a well-kept freshwater aquarium
  2. aquatic plants to produce food and oxygen (hornswort and duckweed, plus unknown algae)
  3. ramshorn snails to eat algae and keep things clean
  4. washed rocks to provide some minerals and maybe carbonates
  5. a “micronaut” — actually a ghost shrimp — to run around to provide entertainment and assure me that life goes on

thanks to flickr member nycbone for the image, licensed under creative commons. see

These little worlds are stored in the basement where the temperature is stable. That means someone has to go down every day and turn on the sun — a 50 watt light bulb. Otherwise the plants can’t photosynthesize and there’ll be no oxygen. That God is me.

I’m not sure how other Gods feel, but at first I was so enchanted with my little creations. The shrimp are the show! One moment they toss their long feelers so elegantly, like fly fishermen in the still of an Idaho morning. Then they suddenly lose all class and paddle madly with their innumerable legs, like dogs on speed. In the background the snails do elevator tricks, soaring from the top to the bottom of the jar with a kind of bloated accuracy. Meanwhile the duckweed shades all with a chuppah of green. How long could this magic go on?

Quite a while, it seems. After a few days I, God, got bored. Next time I, God, looked, there had been a Cain and Abel-like tragedy in the microcosm with two shrimp. I wasn’t so enchanted after that, though I had new respect for the resiliency of my denizens. Those are some tough little buggers down there. Seems like life will do ANYTHING to go on.

I don’t think I’m a jealous God, but I can be a stupid and forgetful one. When I forgot to turn on the Sun, I felt guilt, sorrow, sheepishness — why had I roped these creatures into this? What was I thinking? What did I expect to find out?

The shrimp were a little groggy, but I made it in time. This God has resolved to pay a bit more attention to his charges. I can’t speak for any other ones out there, but I wouldn’t be surprised if once or twice, one has fallen asleep on the job.

[update: improved recipe here.]

I did this same thing while in high school. I used a 1 gallon plastic juice bottle, aquarium water, aquarium gravel, plants called hornwart and anacharis, 1 black molly (aquanaut), and several junk snails (they came with the anacharis).
Molly lived for a little over a year (i think she died of old age). The snails lived for another two years, and the collection of shells in the bottom of the tank attests to at least 20 generations of junk snails. It was setting on a bookshelf near a window for those three happy years. Tragedy struck when I had an aquarium leak and had to clean out that corner of my room. The microcosm sat forgotten, on a dark shelf for about 3 days, the anacharis wilted, and killed the snails. When I opened the bottle it smelled like dead fish and the ammonia level was almost off the scale.

Comment by coal_burner on 15.08.2006 um 4:30 am

Wow! that’s cool. Quite successful considering your aquanaut was a rather large organism. I wonder when the ammonia level rose — was it before the sunless period or during?

I know that conditions inside these things are probably pretty nasty. Imagine living in a house and never ever opening the windows, and recycling all the water you use. It’d stink.

So, on a bigger scale, does the Earth stink from its bottled-up denizens?

Comment by bottleman on 15.08.2006 um 6:24 am

you should invest in a $20 lamp timer. ;)

Comment by leah on 23.09.2006 um 6:58 pm

God is on a low budget… :(

Comment by bottleman on 24.09.2006 um 6:58 pm

Update from god please.

Comment by coal_burner on 12.04.2007 um 6:28 am

Thanks for your interest coal burner. I’ve been swamped with other projects, but I can tell you this. The ghost shrimp in these bottles didn’t last very long — maybe 5 or 6 weeks, though snails continue living and reproducing to this day. I think the ghost shrimp were just too aggressive to be in this environment — I actually saw one tangling with a snail, and then getting eaten by that snail. Sounds impossible, right? But once the shrimp’s leg got sucked into the snail’s little mouth, the snail, which was all muscle, had a lot of leverage to break the shrimp open. Wasn’t pretty.

I actually have revised this recipe using gentler “amano” shrimp and a few other touches, and the recipe will be coming out in a national tech/DIY magazine sometime real soon. Using that recipe I’ve gotten shrimp to live for 3 or 4 months. There are some general principles in the article too. Your 1 year for you black molly is great, though the techno-weenie in me wonders if the plastic bottle wasn’t leaking air (some research I learned about from a professor suggested that plastic containers could bleed oxygen). Nonetheless I haven’t gotten anywhere close to that for my shrimp. Though the snails continue living and reproducing, so they demonstrate the principles of the microcosm as good as anything. But they’re just not as entertaining.

Comment by bottleman on 12.04.2007 um 8:19 am

Any updates/thoughts? Links to other folks doing this?

I’ve wondered what recipe that commercial outfit uses. I suppose it is pretty exact.

Now I gotta find me a cool bottle…

Many thanks!

Comment by John Norris on 27.07.2007 um 8:54 pm

John, there’s a yahoo group you can join where a few hobbyists are doing this. Try

The “commercial outfit” you refer to might be one of two I can think of producing desktop-sized ecospheres. They are using a saltwater shrimp as the econaut, so this is going to be harder to replicate for a hobbyist, as that shrimp is not going to be widely available in aquarium stores… not to mention other ingredients. The MAKE mag article provides a more doable recipe for the hobbists because it’s based on freshwater (pond) stuff. Good luck!

Comment by bottleman on 28.07.2007 um 9:40 am

Thanks for the link to the group and the info. Looks like a good one. We sealed up 3 jars from the MAKE article today. So far so good :-)

Comment by John Norris on 28.07.2007 um 7:47 pm