[munificent]

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

[m-i-l]

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)