title: Propulsion in cubomedusae: mechanisms and utility.
abstract: Evolutionary constraints which limit the forces produced during bell contractions of medusae affect the overall medusan morphospace such that jet propulsion is limited to only small medusae. Cubomedusae, which often possess large prolate bells and are thought to swim via jet propulsion, appear to violate the theoretical constraints which determine the medusan morphospace. To examine propulsion by cubomedusae, we quantified size related changes in wake dynamics, bell shape, swimming and turning kinematics of two species of cubomedusae, Chironex fleckeri and Chiropsella bronzie. During growth, these cubomedusae transitioned from using jet propulsion at smaller sizes to a rowing-jetting hybrid mode of propulsion at larger sizes. Simple modifications in the flexibility and kinematics of their velarium appeared to be sufficient to alter their propulsive mode. Turning occurs during both bell contraction and expansion and is achieved by generating asymmetric vortex structures during both stages of the swimming cycle. Swimming characteristics were considered in conjunction with the unique foraging strategy used by cubomedusae.
authors: Marine Biology and Environmental Science, Roger Williams University, Bristol, Rhode Island, USA. scolin@rwu.edu
authors: Sean P
authors: SP
authors: Colin
authors: John H
authors: JH
authors: Costello
authors: Kakani
authors: K
authors: Katija
authors: Jamie
authors: J
authors: Seymour
authors: Kristen
authors: K
authors: Kiefer
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D049628:Body Size / Q000502:physiology; D037462:Cubozoa / Q000033:anatomy & histology / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology; D013550:Swimming / Q000502:physiology*; D013997:Time Factors