  In this work, we explore the connection between the critical curves
("shadows") and the quasinormal mode frequencies (in the eikonal limit) of Kerr
black holes. This mapping has been previously established for non-rotating
black holes. We show that, the shadow seen by an distant observer at a given
inclination angle, can be mapped to a family of quasinormal modes with
$m/(\ell+1/2)$ bounded within certain range, where $m$ is is azimuthal node
number and $\ell$ is the angular node number. We discuss the possibility of
testing such relation with space-borne gravitational wave detectors and the
next-generation Event Horizon Telescope.
