Behaviour
Behaviour is characterised by cycles of stimulus and response.
This realm could equally be called that of feeling. Behaviour and feeling are the "outside" and "inside" of ethoic phenomena.
"Ethology" commonly designates the study of animal behaviour, but "ethics" has become attached to imperative realms, so I use "ethoic" to denote this (indicative) realm.
Sentience is susceptibility to stimulus.
Feeling is the interface between stimulus and response.
Skill is a behaviour pattern arising from recurrent stimulus.