As Jaylus already pointed out, there is indeed an end state. ^^ But it's only implicitly indicated (through the progress bar and the music). The game is not about "how long can you survive", but "how far can you get" (by feeding as many frogs as possible). You make an interesting point, since this goal is apparently not enough clearly indicated.
Anyway, it's cool that you still enjoyed the presentation! Thank you very much for your feedback.