Not sure, they don't seem to be falling. I thought they might be a reference to the Star Trek "whale probe" from The Voyage Home [1] but they're too small for that. Maybe just some random fun like the flying or underground jellyfish.
Those aren't underground jellyfish, they are underwater. That part of the word (west of center, where the ships are) is ocean. But yeah, it's confusing at first.
[1] http://en.memory-alpha.org/wiki/Star_Trek_IV:_The_Voyage_Hom...