Is phenotypic plasticity determined by temperature and fluid regime in filter-feeding gelatinous organisms?

Abstract Some organisms can compensate for changes in the fluid environment (Re), through behavioral or morphological responses, but it is not known whether their filtering structures could respond to such changes. Among filter-feeding organisms, scyphomedusae have a feeding mechanism based on vortices produced by bell pulsations, which carry fluids toward post-bell structures (tentacles and oral arms) where food particles are retained. To understand if variations in the physical environment (temperature and viscosity) could determine functional shapes or dimensions of feeding structures to compensate for these variations, we cultivated two scyphomedusae species, Lychnorhiza lucerna and Cassiopea andromeda, in different temperatures. Bell and oral-arm filtering structures (digitata) were measured and compared among treatments. Temperature influenced the bell and digitata development (p