In nature, aquatic animals leverage the interaction between their soft bodies and surrounding fluid to achieve efficient locomotion; for animals with multiple limbs, this requires careful coordination among the limbs. The octopus, with its tentacles and flexible webbing, exemplifies this and serves as a compelling model for underwater robotics. Many octopus-inspired soft robots have shown locomotion capability with great maneuvrability and adaptability, however, there has been limited study of the effect of arm coupling and coordination. This paper introduces quadropus, a four-arm swimming robot with independent tentacle control where the fluid interactions are coupled through a compliant webbing, designed to enhance swimming capability. Through varied web designs and control input patterns, we examine the impact of web structure on swimming performance and demonstrate the importance of coordinated arm motion.