Relationship between morphology and hydrodynamics during swimming by the hydromedusae Aequorea victoria and Aglantha digitale
Sean P. Colin, John H. Costello
Hydrodynamic forces acting upon adult swimming Aglantha digitale and Aequorea victoria were estimated by combining empirical kinematic data with the model of Daniel (1983). Forces varied in magnitude during be11 pulsation and recovery. The acceleration reaction and inertial resistance were the dominant instantaneous terms. However, the net forces (each hydrodynamic force totaled over complete pulsation cycles) were different for the two species. Ag. digitale maximized acceleration rates and minimized the acceleration reaction: drag was the dominant net force. Ae. victoria minimized acceleration rates and maximized the acceleration reaction: the acceleration reaction was its dominant net force. A new finding of this work was that oblate medusae such as Ae. victoria may be efficient for continuous swimming due to a positive net contribution of the acceleration reaction to forward motion once the medusa has begun swimming.