In a new study, marine biologist Valentina Di Santo has made a surprising discovery. Being able to hover in fish takes twice the amount of energy than just hanging out. This new research, published in the Proceedings of the National Academy of Sciences, finally shows us how fish hover. It examines how these mechanics can help shape the design of underwater robots. The new discoveries have potential to change the way technology imitates the swimming prowess found in nature.
Unlike taxidermy specimens, Di Santo’s study shows that fish make deliberate, tactical choices with their pectoral fins while hovering. This placement makes a huge difference in their energy efficiency. Fish with fins located more towards the rear expend less energy when holding in place. This means that greater leverage is the secret to their efficiency. The study examined the impacts on 13 swim bladder species of fish. Among the most prominent are the goldfish and the giant danio.
The Mechanics of Hovering
Di Santo explains hovering as an active balancing act, like trying to stay upright on a stationary bike. This unusual posture lets fish maneuver in intricate underwater landscapes with great precision.
“Hovering is a bit like trying to balance on a bicycle that’s not moving,” – Valentina Di Santo
The study underscores that hovering isn’t just a cozy reprieve from environmental stressors for fish. Instead, it’s a deeply energetically expensive pastime that increases agility and maneuverability in complex homes.
“What struck me was how superbly all these fishes maintain a stable posture, despite their intrinsic instability,” Di Santo remarked, underscoring the remarkable balance fish achieve while hovering.
So far, the study finds long, slender fishes like the shell-dweller cichlid have a hard time hovering. The most rotund types – like the figure-eight pufferfish — master this art with flying colors. This difference is illustrative of the ways in which body shape has adapted to maximize energy efficiency while hovering.
Implications for Robotics
That work produces important, surprising discoveries that stretch what we know about biology. These discoveries provide thrilling new opportunities for engineering, particularly in the burgeoning field of underwater robotics. Historically, underwater robots have been designed to be as small as possible – long and thin to maintain stability underwater. According to Di Santo, there are lessons to be learned from fish that can help create more agile designs.
“If you want a robot that can maneuver through tight spaces, you might have to learn from these fishes to design in some instability and then add systems that can dynamically maintain stability when needed,” – Valentina Di Santo
By integrating these principles into robotic designs, engineers may develop more efficient and responsive technologies capable of navigating challenging underwater environments.
A Closer Look at Fish Efficiency
Giant danios and red zebras, two of the study’s test species, demonstrated strong energy efficiency when hovering in place. As an example, the compact body plan of goldfish allows them to remain still with a fraction of the muscular effort their more elongated relatives would require. Knowing these dynamics helps researchers understand how fish suit their physical frameworks to energy inputs and outputs the best way possible.
Di Santo’s work calls into question long held assumptions about the behavior of fish, chief among them that hovering means sleeping.
“This changes how we see hovering. It’s not a form of rest at all,” – Valentina Di Santo
This observation now motivates us to learn about the evolutionary benefits of hovering. Perhaps most importantly, it has the potential to spur new scientific methodologies in biology and tech development.