... they do? I have four cats, and I've seen them do some pretty stupid things, but nothing that seemed to suggest they have any senses we haven't discovered yet . What kind of thing did you have in mind?

Well, I've often seen my own cats suddenly go into an alert state, whip their heads around, and stare at nothing in particular, for no reason I could determine. But I've always supposed this was a consequence of having hearing outside a human range of frequency and intensity.