I have 6 amano shrimp split between 2 tanks, and one of those tanks doesn't have a cover. Will amanos jump (or even crawl) out? Do I need to throw a screen onto the uncovered tank?
I doubt that any species of shrimp has the leg strength to 'jump'. They can flick their tail for a quick boost, much like crayfish. Any species of shrimp is able to to climb out of an uncovered tank, if the waterline is high enough.
The only things that I've had that have decided to vacate their aquatic homes are; frogs, red crabs, and suicidal gourami, who would see how far it could leap out of the water, whenever I opened the lid to feed. I found that if I opened the lid just a bit, then closed it, making a clunk noise, it would attempt to escape and hit the lid. I could then open the lid and safely feed them. His record leap was about four and a half feet from the tank. I hung a little gold medal, with a note, to honor the achivement.