Meeting Abstract
Ctenophores or comb jellies are known to be important marine predators that can alter plankton community dynamics in coastal ecosystems. Open ocean ctenophores are ubiquitous but poorly understood due to their delicate, gelatinous nature. Cestum veneris, or the venus girdle, is a very unusual ctenophore that exhibits a compressed, wing-like morphology, differing greatly from other gelatinous zooplankton. This animal continuously glides through the water propelled by ciliary ctene rows at the rear of the wing. C. veneris primarily preys on hydrodynamically sensitive copepods capable of responding to minute fluid disturbances with powerful escapes. However, there is currently little information on C. veneris feeding ecology. In order to determine if the unique wing-like morphology of C. veneris is capable of masking the hydrodynamic signal given off to copepod prey, we recorded the interaction of the copepod Acartia tonsa as they approached a 3D analog of the wing in a laminar flow water channel. We found that at low simulated swimming speeds copepods always detected and avoided contact with the wing. However, as speed increased, the reaction distance of the copepods relative to the wing decreases. At naturally observed swimming speeds, direct copepod contact with the wing could be observed. Quantification of fluid deformation rates around the wing and comparison of copepod response locations suggest that at natural swimming speeds, the wing-like morphology of C. veneris provides hydrodynamic stealth to aid in capturing sensitive prey.
