In exocytosis, the membrane package fuses with a transport proteina gap junctionthe nucleusthe cell membrane

Exocytosis is a procedure by which a cell transports secretory items through the cytoplasm to the plasma film. Secretory items are bundled into transport vesicles. In exocytosis, the one that fuses with the membrane package is the cell membrane. The membrane is transported to the cell membrane and the water molecules are released into the extracellular environment. 

Predator instincts is what causes it