
Recent research conducted by a team including experts from Aberystwyth University has unveiled surprising details about the energy expenditure of fish maintaining their position in water. Contrary to prior assumptions, fish that hover or stay still in water consume considerably more energy than previously thought. This insight has significant implications for ecological studies and the development of underwater robots, bridging biology and engineering.
Hovering is a vital behavior for many aquatic species. It enables fish to stay vigilant for predators, hunt efficiently, and access hard-to-reach resources like aquatic plants or prey trapped within crevices. To remain stationary, fish employ a combination of fin movements and body adjustments, often referred to as “hovering.” While it appears effortless to an observer, maintaining this position is energetically expensive due to inherent instabilities caused by the fish’s anatomy.
Most bony fish possess a swimbladder—a gas-filled sac that provides buoyancy. Despite its essential function, the swimbladder introduces instability because of its position relative to the fish’s center of mass. This separation causes a natural tipping tendency, making the fish inherently unstable when trying to hover. As a result, fish need continuous fin movements to stabilize themselves, which in turn requires metabolic energy.
The research involved placing 13 species of bony fish in specialized tanks outfitted with high-speed cameras and oxygen sensors. By tracking fin movements and measuring oxygen consumption, researchers determined that hovering consumes roughly twice the energy compared to resting at the bottom of the tank. Additionally, a model was developed to analyze how the fish’s body shape and size influence their energy efficiency during hovering.
The study revealed that fish with compact, deep bodies—such as goldfish—are more energy-efficient in their hovering behavior. In contrast, slender, elongated species like rummy-nose tetra require more effort to maintain stability. This variation is linked to how the body shape affects the fish’s ability to counteract instability caused by the swimbladder.
This research enhances our understanding of fish ecology, particularly their energy budgets and behavioral strategies. Knowing the energetic costs of hovering can inform models of fish behavior, predator-prey interactions, and habitat use. Furthermore, these findings have promising applications in the field of underwater robotics.
The study’s insights can be translated into the development of miniature aquatic robots that mimic fish movement. Traditionally, underwater robots are designed for stability, often sacrificing maneuverability. However, by intentionally incorporating principles of instability akin to fish hovering, engineers can create robots capable of accessing tight or complex environments. This advancement opens possibilities for underwater exploration, environmental monitoring, and resource management.
Aberystwyth University’s contribution to this interdisciplinary research underscores the importance of integrating biological understanding with engineering innovation. Further studies may explore how different species adapt their body shapes for energy-efficient hovering and how these principles can be refined for robotic applications. Additionally, such research can aid in ecological conservation efforts by providing more accurate models of fish behavior and energy expenditure in changing environments.
If you are interested in diving deeper into marine biology, ecological modeling, or robotic engineering, Aberystwyth University offers comprehensive programs and research opportunities. Engaging with cutting-edge research like this not only advances scientific knowledge but also prepares you to contribute to innovative solutions in aquatic sciences.
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