Locomotor compensation in the sea: body size affects escape gait in parrotfish

► Gaits reveal how fast an animal moves relative to its potential speed. ► We studied the gaits that parrotfish use to escape an approaching snorkeller. ► Small fish swam away by undulating their tails (fast, expensive gait). ► Large fish flapped their pectoral fins (slower, cheaper gait). ► Small fish thus compensate for size-limited swimming capacity by a faster gait.