Muscle as active matter: How fish tune their body mechanics for effective swimming

Many fishes swim efficiently over long distances to find food or during migrations. They also have to accelerate rapidly to escape predators. These two behaviors require different body mechanics: for efficient swimming, fish should be very flexible, but for rapid acceleration, they should be stiffer. Here, I will discuss recent experiments that show that they can use their muscles to tune their effective body mechanics. Control strategies inspired by the muscle activity in fishes may help design better soft robotic devices.