Different things cause splits.
If they are exposed to air for a length of time, it can initiate a split. A sudden change in nitrogen compound can cause a split. A change in salinity can cause a split. A change in water flow can cause a spliy. All, some, none of these can cause a split.
The real life "analog" is the anemone interpreting the change as something between a change in the tides, or a runoff/die off and ocean currents.
In an effort to survive, it will trigger in itself a multi split because it can potentially move a bunch of its genetics into further regions of the ocean by going for a ride on the change in its environment as a passage to a further distance as a much lighter, or less dense organism and get a further spread.
Cool stuff.