Meeting Abstract
Skull mobility, including the iconic ability to protrude the upper jaw, is a classic feature of teleost feeding systems. However, the broader relationship between cranial mobility and the many strategies teleost fishes use to capture their prey is unclear. Coral reef fishes show exceptional trophic diversity, ranging from algal scraping in parrotfishes to hyper-extended suction of invertebrates in slingjaw wrasses, and thus make an excellent system to explore how feeding ecology has affected the evolution of cranial mobility. We assembled a dataset from high speed video recordings of suction feeding strikes in 34 species of coral reef fishes that span a range of reliance on suction to biting. We used landmark morphometrics to quantify cranial kinesis as a trajectory of skull shape change during the feeding strike from the initial closed mouth to maximum gape. Species that rely on biting have consistently lower kinesis than habitual suction feeders. Among suction feeders, we find differentiation between suction strikes characterized by high buccal expansion, commonly piscivores, and those characterized by high jaw protrusion, commonly zooplanktivores, indicating that the challenges specific to feeding on different prey can lead to modifications to the mobility of different components of the feeding apparatus. In contrast, most fishes that primarily rely on biting in their natural feeding behavior show low levels of kinesis, which may reflect adaptations that result in enhanced stability of jaw elements for force transmission and loss of skeletal mobility. Overall, we find evidence for reduced kinesis in fishes that rely on biting and that among suction feeders, prey type may affect evolution of skull mobility.
