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Comment by AKifer | Hacker News Reader

Did anyone try introduce an animal in such a closed system, insects for instance. Does it self sustain ?

I saw a shop selling these once: https://www.ecospheres.co.uk/ . They contain small marine shrimp, and "The only care the sphere requires is a source of indirect natural or artificial light" and they "have an average life expectancy of 2-3 years however it is not uncommon for them to survive for 7 to 10 years"[0].

[0] https://www.ecospheres.co.uk/what-is-an-ecosphere/

If you read up on this, you'll find a lot of not-very-nice things said about ecospheres.

The shrimp inside are ʻōpaeʻula [0] which evolved to live in volcanic tide pools filled by rainwater. Sort of a feast or famine environment where the salinity and nutrients available are very volatile. Because of that, the shrimp have evolved to handle a wide range of temperatures, salinity, and scarcity of food.

The latter means they can go surprisingly long without sufficient food without realizing it. In other words, there's a good chance (according to some) that the shrimp in your ecosphere are actually slowly starving to death and aren't in anything approaching a stable ecosystem.

(Also, they aren't brine shrimp, which are an entirely different class of animal.)

[0]: https://en.wikipedia.org/wiki/Halocaridina_rubra

Thanks for this. I wasn't too keen on them to be honest because they reminded me of little fleas jumping around. But it is sad to read "These shrimp are social creatures, but the Ecosphere starts with only four (often less, with one or more dead on arrival), and eventually only a single one is left to swim around alone, perhaps for years"[0]. I had assumed that they would reproduce within the ecosystem, but apparently not.

[0] https://en.wikipedia.org/wiki/Ecosphere_(aquarium)

I have one of these sitting on the table right in front of me. We've had it for a couple months, and the brine shrimp are swimming around happily still. I figure it has a 50-50 chance of being broken by my kids before the shrimp die.

On a larger scale, wouldn't this be Earth?

Complete with the "put it in a spot with enough sun light". Except the atmosphere leaks a little http://www.esa.int/Our_Activities/Space_Science/Cluster_watc...

On such a significantly larger scale that it would bear only passing resemblance

https://en.m.wikipedia.org/wiki/Biosphere_2

It's pretty normal to introduce springtails (small arthropods) to sealed terrariums. Their main purpose is to to eat mold, but they presumably also help with the carbon cycle.

How about humans:

https://en.wikipedia.org/wiki/Biosphere_2

Yeah, my brother did this. He made a self sustaining garden with some bugs in it. The bugs eventually stopped reproducing, possibly because of inbreeding? The plants lasted quite a while until my parents moved and couldn't take it with them.

https://en.wikipedia.org/wiki/Ecosphere_(aquarium)

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