The specimen will keep circling around and you just have to wait until they loop back inside your shooting range. At first it seems like a flaw, but it makes the game more challenging.
the point is they always (3 times in a row) split into the void without enough time for me to even start shooting them
One split to the top void and the other to the bottom. Tried very hard to herd them, even tried not killing all right when it starts. Still had to stare at the 2 cells till the end of level 3