The Role of Body Shape and Size on Burst Swimming Performance in Marine Reef Fishes

One of the most important behaviors many animals possess is the ability to flee or escape from predators. In fishes, burst swimming is one of the most common strategies during a predation event. With such strong evolutionary pressure, it is noteworthy that reef fishes from the same habitat exhibit such a wide range in body and fin morphology. For the first time, studies focused on fast-start acceleration have been documented in the field, which offers a more realistic and comprehensive look at natural prey escape response to stimuli. With this level of understanding and observation of more realistic escape responses, the connections between specialist morphological traits have been re-examined and provide clearer insight into the connections between morphology and swimming performance. Field data was collected for escape responses using two orthogonally mounted cameras across multiple reef sites encompassing over 40 distinct fish species from 12 taxonomic families in their natural habitat. Body centerlines were extracted from 96 individual fish using Image J software, permitting interspecies comparison of maximum velocity, acceleration, tail beat amplitude, and tail beat frequency. Elongate body forms tended to outperform deeper body forms when comparing the extremes (p=0.011, n=17, df = 23) however generalist body forms tended to vary widely between species with insignificant correlation to body shape. Aspect Ratio (standard length / body depth) was positively correlated with maximum velocity (slope=8.73, p<0.001, df=94) and mean acceleration (slope=48.53, p=0.02, df=94) supporting the Webb’s hypothesis that elongate body forms accelerate more rapidly than deeper, laterally compressed morphologies.