Beat It Primary cilia are specialized organelles that serve important sensory functions in many different tissues and cells, and defects in their structure and function underlie a variety of genetic diseases. In contrast to primary cilia, motile cilia serve a mechanical function. For example, the cilia on airway epithelia remove inhaled material from the lung. Shah et al. (p. 1131 , published online 23 July; see the cover; see the Perspective by Kinnamon and Reynolds ) now show that these classic motile cilia are also chemosensory. The motile cilia on airway epithelia contain bitter-taste receptors and their associated signaling machinery. Moreover, application of bitter substances triggers an elevation of intracellular Ca 2+ levels and increases cilia beat frequency. Thus, in airway epithelia, bitter-taste receptors may be able to detect noxious substances entering the airways and initiate an autonomous defensive mechanism designed to accelerate elimination of the offending compound.