Meeting Abstract
As organisms develop, morphological growth coincides with transitions in functional demands on the body. Little is known about how organisms adapt behaviorally through this process. In larval zebrafish, pectoral fin movements during swimming serve a respiratory function by drawing oxygenated fluid to the skin for cutaneous respiration. Pectoral fins are no longer needed for respiration by 21 days post-fertilization (dpf) when the gills have fully developed. As adults (>70 dpf), pectoral fins assume a locomotor role, raising the question of how zebrafish transition between these two different pectoral fin functions. We examined the swimming of zebrafish 6-90 dpf in order to understand how pectoral fin behavior is modified from rhythmic, alternating fin beats in larvae to adult movements. In adults, we observed that fin movements during forward swimming typically consist of a single, synchronized fin beat at initiation of swimming. The transition between these two behaviors begins at 14 dpf, when oxygen intake is dependent on both gill and cutaneous respiration. We observed a gradual decrease in number and amplitude of fin beats following initiation of swimming. The transition from larval to adult fin movements stabilizes at 20 dpf, when gills have fully developed and are necessary for respiration, but before major developmental changes in pectoral fins occur. These results demonstrate that modifications in pectoral fin motor control coincide with a gradual loss of their respiratory function and precede the fin’s morphological transformation. They support the idea that gill and fin development are tightly linked. This example of locomotor-respiratory uncoupling provides a model for better understanding the development of interacting motor systems.
