How shrimp move backwards?

Shrimp move backwards using their pleopods, which are paddle-like appendages located on the underside of their abdomen. These pleopods have long, feathery setae arranged in a fringe to allow for efficient sweeping in a backwards direction. By quickly flexing and extending their pleopods, shrimp can create a backward propulsive force. Additionally, they employ their swimmerets or abdominal legs to assist in maneuvering and reversing their swimming direction. Each pleopod performs a powerful stroke against the surrounding water, generating a thrust that pushes the shrimp backward with great agility. This rapid and alternating contraction of pleopods provides a high level of control and precision for backward movement. The ability to swiftly retreat in the opposite direction serves as a vital defense mechanism for shrimp to evade predators and navigate effectively in their underwater environments.