  The motion of active polymers in a porous medium is shown to depend
critically on flexibilty, activity and degree of polymerization. For given
Peclet number, we observe a transition from localisation to diffusion as the
stiffness of the chains is increased. Whereas stiff chains move almost
unhindered through the porous medium, flexible ones spiral and get stuck. Their
motion can be accounted for by the model of a continuous time random walk with
a renewal process corresponding to unspiraling. The waiting time distribution
is shown to develop heavy tails for decreasing stiffness, resulting in
subdiffusive and ultimately caged behaviour.
