Effects of wave-driven water flow on the fast-start escape response of juvenile coral reef damselfishes

Soft dorsal/anal fins pairs for roll and yaw motion in robotic fish

Fish has primarily served as a model for many bio-inspired underwater robots. However, most of the work on fish-inspired robots is focused on propulsion and turning in the horizontal plane. In this paper, we present our work on the 3D motion of bio-inspired underwater robots. A pair of actuated soft fins, mimicking the soft dorsal and anal fins of a live fish, have been designed and tested to generate lateral thrusts that aim to produce both roll and yaw motions. Furthermore, they can be used to provide vertical stabilization of the forward motion in the robot. These fins comprise shape memory alloy wires embedded in silicone. We demonstrate that these fins can provide a means for 3D maneuvering. In this work, we focus on roll and yaw motions. A key feature of the proposed design is that it is lightweight, compact, and waterproof.

Increased parasite load is associated with reduced metabolic rates and escape responsiveness in pumpkinseed sunfish

Wild animals have parasites that can compromise their physiological and/or behavioural performance. Yet, the extent to which parasite load is related to intraspecific variation in performance traits within wild populations remains relatively unexplored. We used pumpkinseed sunfish (Lepomis gibbosus) and their endoparasites as a model system to explore the effects of infection load on host aerobic metabolism and escape performance. Metabolic traits (standard and maximum metabolic rates, aerobic scope) and fast-start escape responses following a simulated aerial attack by a predator (responsiveness, response latency, and escape distance) were measured in fish from across a gradient of visible (i.e. trematodes causing black spot disease counted on fish surfaces) and non-visible (i.e. cestodes in fish abdominal cavity counted post-mortem) endoparasite infection. We found that a higher infection load of non-visible endoparasites was related to lower standard and maximum metabolic rates, but not aerobic scope in fish. Non-visible endoparasite infection load was also related to decreased responsiveness of the host to a simulated aerial attack. Visible endoparasites were not related to changes in metabolic traits nor fast-start escape responses. Our results suggest that infection with parasites that are inconspicuous to researchers can result in intraspecific variation in physiological and behavioral performance in wild populations, highlighting the need to more explicitly acknowledge and account for the role played by natural infections in studies of wild animal performance.