Final answer:
The tail fan of many malacostracans is made up of uropods and the telson. These structures aid in their locomotion and are distinct from other appendages like swimmerets and maxillipeds.
Step-by-step explanation:
The tail fan of many malacostracans, a group of crustaceans, is composed of uropods and the telson. These parts play a crucial role in the movement and maneuverability of these aquatic creatures. Malacostracans, which include crabs, lobsters, and shrimp, have various evolved appendages such as mandibles, maxillae, and antennae that serve for feeding, sensing, and navigation.
While swimmerets (pleopods) and maxillipeds are also important appendages, they serve different functions such as swimming and handling food, respectively.