  We study the spontaneous configuration transitions of an active semi-flexible
polymer between {\it spiral} and {\it non-spiral} states, and show that the
configuration dynamics is fully described by a {\it subcritical pitchfork}
bifurcation. Exploiting the fact that active polymer barely moves in {\it
spiral} states and exhibits net displacements in {\it non-spiral} states, we
theoretically prove that the motion of the active polymer is consistent with a
{\it run-and-tumble}-like dynamics. Moreover, we find that there exists an {\it
optimal} self-propelling {\it force}, at which the probabilities of finding the
polymer in the {\it spiral} and {\it non-spiral} state become equal, that
maximizes the diffusion coefficient.
