Uropod

In crustacean anatomy, a uropod is one of the paired, flattened appendages forming the posterior-most segment of the body, also known as the telson. Uropods are typically broad and fan-shaped, flanking the telson on either side. Together, the uropods and telson often form a tail fan, which can be used for various purposes, including steering while swimming, creating a sudden backward thrust for escape, and protecting the vulnerable anus.

The morphology of uropods varies across different crustacean groups. In some species, they are simple and plate-like, while in others they are more complex, with spines, serrations, or other specialized features. They articulate with the pleotelson, the fused terminal segment of the abdomen. The structure and arrangement of the uropods are important characteristics used in crustacean identification and classification.

In many decapod crustaceans, such as shrimp and crayfish, the uropods play a significant role in the animal's ability to rapidly escape predators. By flexing the abdomen and simultaneously extending the tail fan, the crustacean can generate a powerful burst of speed, propelling itself backwards away from danger.