Mating Slugs: Withdrawal - Type 4 - Another Example

As always, notice the slugs' ability to freely retract and extend their cephalic tentacles. It's amazing how they can bring the tentacles entirely into their head. Why they do this during the phase following copulation, I don't know, because at all other times the action seems to be a reaction to a perceived threat, such as when a predator picks them up or touches them.

Couple 21: