Researchers have demonstrated how a bout-and-glide swimming strategy allows aquatic animals to move through water with greater energetic efficiency [1].
This discovery is significant because it explains how diverse species, from tiny larvae to massive mammals, optimize their energy consumption during long-distance travel. By understanding these biological mechanics, engineers can develop more efficient autonomous underwater vehicles.
The strategy, also known as burst-and-coast swimming, involves alternating periods of active propulsion with phases of passive gliding [1]. This pattern is observed in a wide range of marine life, including zebrafish larvae and humpback whales [1]. Rather than maintaining a constant effort, these animals use short bursts of power to reach a certain speed and then glide to maintain momentum.
To test the advantages of this method, Liu et al. used a fish-inspired robot [1]. The robotic model allowed the team to isolate the variables of active swimming and passive gliding to measure the resulting energy expenditure. The experiments showed that the bout-and-glide approach provides a distinct advantage in efficiency over continuous swimming [1].
This biological mechanism allows animals to cover significant distances without exhausting their metabolic reserves. The robot's performance mirrors the natural behavior of aquatic species that must balance the need for speed with the necessity of energy conservation — a critical trade-off for survival in the open ocean [1].
“The strategy provides energetic efficiency by alternating active movement with passive gliding.”
The validation of the bout-and-glide strategy through robotics bridges the gap between biological observation and mechanical application. By mimicking the intermittent propulsion of animals like humpback whales, future underwater drones and sensors could operate for longer durations on a single battery charge, reducing the cost and frequency of maintenance for deep-sea exploration.
