The use of biting to obtain food items attached to the substratum is an ecologically widespread and important mode of
feeding among aquatic vertebrates, which rarely has been studied. We did the first evolutionary analyses of morphology
and motion kinematics of the feeding apparatus in Indo-Pacific members of an iconic family of biters, the marine angelfishes
(f. Pomacanthidae). We found clear interspecific differences in gut morphology that clearly reflected a wide range of trophic
niches. In contrast, feeding apparatus morphology appeared to be conserved. A few unusual structural innovations enabled
angelfishes to protrude their jaws, close them in the protruded state, and tear food items from the substratum at a high
velocity. Only one clade, the speciose pygmy angelfishes, showed functional departure from the generalized and cladedefining
grab-and-tearing feeding pattern. By comparing the feeding kinematics of angelfishes with wrasses and
parrotfishes (f. Labridae) we showed that grab-and-tearing is based on low kinematics disparity. Regardless of its restricted
disparity, the grab-and-tearing feeding apparatus has enabled angelfishes to negotiate ecological thresholds: Given their
widely different body sizes, angelfishes can access many structurally complex benthic surfaces that other biters likely are
unable to exploit. From these surfaces, angelfishes can dislodge sturdy food items from their tough attachments.
Angelfishes thus provide an intriguing example of a successful group that appears to have evolved considerable trophic
diversity based on an unusual yet conserved feeding apparatus configuration that is characterized by limited functional