HERNANDEZ, L.P.: Functional morphology and developmental biology of zebrafish: Reciprocal illumination from an unlikely couple

Developmental biology and functional morphology have not generally been considered fields across which a useful synergy could evolve. However, recent discoveries in vertebrate morphology have been due to adoption of techniques commonly used by developmental biologists. Furthermore, reciprocal contributions are beginning to emerge. Functional morphology is now helping to explain unique patterns of morphogenesis during early embryonic stages. As broadly defined here, developmental biology encompasses the functional aspects of early life history stages as well as molecular processes involved in embryonic pattern formation. I will first discuss the insights gained from research examining the biomechanics and kinematics of larval fish feeding in relation to established paradigms based on adults. Functional morphologists have long examined adult feeding mechanics, but have largely ignored feeding mechanics at larval stages. Larval zebrafish were shown to have significantly different kinematic profiles from adults due to both constructional constraints and Reynolds number regime. I will then address how functional studies of larval behavior are the basis for hypotheses that can be tested using the methodologies of the developmental biologist. Such functional data on larval performance are significant in identifying anatomical complexes that must undergo seamless embryogenesis to assure larval survival. For example, the emphasis on pronounced head lift and extreme hyoid depression during feeding in larval zebrafish has important implications for the developmental pathways leading to the formation of structures associated with these movements during early development.