Multi-jet propulsion organized by clonal development in a colonial siphonophore.
Physonect siphonophores are colonial cnidarians that are pervasive predators in many neritic and oceanic ecosystems. Physonects employ multiple, clonal medusan individuals, termed nectophores, to propel an aggregate colony. Here we show that developmental differences between clonal nectophores of the physonect Nanomia bijuga produce a division of labour in thrust and torque production that controls direction and magnitude of whole-colony swimming. Although smaller and less powerful, the position of young nectophores near the apex of the nectosome allows them to dominate torque production for turning, whereas older, larger and more powerful individuals near the base of the nectosome contribute predominantly to forward thrust production. The patterns we describe offer insight into the biomechanical success of an ecologically important and widespread colonial animal group, but, more broadly, provide basic physical understanding of a natural solution to multi-engine organization that may contribute to the expanding field of underwater-distributed propulsion vehicle design.
Eugene Bell Center, Marine Biological Laboratory, Woods Hole, Massachusetts 02543, USA.|Department of Biology, Providence College, Providence, Rhode Island 02918, USA.
John H
JH
Costello
Eugene Bell Center, Marine Biological Laboratory, Woods Hole, Massachusetts 02543, USA.|Department of Marine Biology and Environmental Science, Roger Williams University, Bristol, Rhode Island 02809, USA.
Sean P
SP
Colin
Eugene Bell Center, Marine Biological Laboratory, Woods Hole, Massachusetts 02543, USA.|Department of Integrative Biology, University of South Florida, Tampa, Florida 33620, USA.
Brad J
BJ
Gemmell
School of Engineering, Stanford University, Stanford, California 94305, USA.
John O
JO
Dabiri
Oregon Institute of Marine Biology, University of Oregon, Eugene, Oregon 97403, USA.
Kelly R
KR
Sutherland
D000818:Animals; D003299:Cooperative Behavior; D037402:Hydrozoa / Q000254:growth & development / Q000502:physiology*; D013550:Swimming / Q000502:physiology*