Hi @yvesoler :)
With "animals" I mean tiny insects, they're important to mantain a certain level of cabon dioxide in jar, otherwise the plant couldn't breathe anything but oxygen at some point. Also they break down dead plant matter, releasing nutrients in the soil.
This video is about the first bottled garden, it's been alive and well for 40 years so far and I think it's fascinating
I have seen the video and love it. I always wondered around the C02 and O2 levels. I figured that since many plants reverse their breathing patterns at night, they recycled their own air. I never thought about having tiny insects in there as well. I hope it is enough room for them to have a good life. I wouldn't want them to feel trapped in what we perceive as Utopia and for them, a prison!
When I see the bottled garden that has been living for 40 years, it really brings home the fact that plants could live in this planet without us. They have no need for human intervention--it is us that needs them!
The natural habitat of springtails is compost (or anyway they live in very moist and high in organic matter soil). I didn't bought mine, they just come spontaneously in my vermicompost bin, so I thought: if they're cool living in a bucket it probably won't harm them to stay in a jar.
If it makes you feel better they're already reproducing and during night time they come out from the soil and walk around. If I will notice there is something wrong with them I would immediately open the jar and put them back into the compost :)
As long as I know plants "breath in" CO2, keep the C (=carbon) that becomes more leaves, trunks etc, and expell O2 (so oxygen) plus a little bit of carbon they weren't able to process. So with time the carbon would end without further inputs.
(Sorry for the bad english, I hope you will be able to understand anyway. If not, please just ask :) )
Plants were on this planet waaaaay before us, so yes, I guess they don't need us people in order to survive.
We mostly bother, eat, and weed them :)
About the morality issue: I feel you, I believe this kind of sadness comes from our tendency to humanize non human creatures.
So, as we wouldn't like to be locked in, we perceive it as horrible for a plant as well, while we're completely ok in seeing flowers in a pot, for example.
The fact is that the plant in a jar (if it's done properly so that you allow an ecosystem to be created) is self sufficient and in balance with the existing microfauna. They have everything they need, that is food, air, water, sun, without human intervention. While the plant in the pot will always need your intervention to survive and, unless you periodically add compost or nutrients, keep it moist and shaded, the soil will die and the microfauna living in it will die with it.
Now we are talking about morality issues, so I believe there is no right or wrong. I just wanted to share with you my personal view about this