okay hopefully people will still pay attention to this and give me advice.
There is the chance any retractable bridge built will deconstruct when I try to retract it to drop GSWs into the lower tank. I have experimented with hatch covers, and neither cages not bridges can be placed on them for any sort of release mechanism.
I do need a two layer tank, but they need to be able to be separated. Is there a quick way to test if a GSW submerged in water will deconstruct a retractable bridge. The only thing that makes me think maybe they won't is because they are in water.
I have lined the land areas with bridges and am constructing mechanism on repeat to hook them all up to one lever. One problem is ramps at the very edge of the map can't be smoothed and can't have a bridge retract up on their side. This may allow animals in... I have tried to mitigate the problem, however.
The main issue is, there will be points when I need the whales swimming free, so they can breed. Then when a baby is born I need to retrap them so I can take the baby out of the trap and air drown it. Although letting the baby grow to adult first would be fun but that could take awhile. The upper tank is where they are released via lever, the lower tank is where they are captured and re-captured.