How cats lap

We studied the lapping of the domestic cat ({\it Felis catus}) by combining high-speed photography with a laboratory model of lapping. We found that {\it Felis catus} laps by a subtle mechanism based on water adhesion to the dorsal side of the tongue and the creation of a liquid column, exploiting inertia to defeat gravity and pull liquid into the mouth. The competition between inertia and gravity controls the pinch-off time of the column, determining the optimal lapping frequency, $f$. {\it Felis catus} was found to operate near the optimum and theoretical analysis yielded a scaling, $f \sim M^{-1/6}$, of lapping frequency with animal mass, $M$. This prediction was verified by measuring lapping frequency across felids, from ocelots to lions, suggesting that the lapping mechanism is conserved among felines.