Locomotion of the coelacanth Latimeria chalumnae in its natural environment

Abstract

The coelacanth Latimeria chalumnae is the only living relic of a fossil group of crossopterygian lobe-finned fish1–4. We describe observations of its locomotion in a natural environment using six individuals observed from the research submersible Geo in the Indian Ocean at a depth of between 117 and 198 m. Past speculation on the pattern of locomotion has included crawling with the paired fins on the rocky ocean bottom, stalking like a large piscivorous grouper, or even fast swimming in open water4–6. Our observations show L. chalumnae to be a nocturnal piscivorous drift-hunter, moving very slowly in up- or downwelling currents, while paired fins stabilize and correct the drift motion. Paired and unpaired lobed fins are able to generate thrust. Fast starts are performed with the large caudal fin. Paired fins were not used for locomotion along the bottom. They alternate synchronously in a pattern common in tetrapod locomotion.