1. Exoskeleton: Crustaceans have a hard, external skeleton made of chitin, which is a tough, flexible carbohydrate. This exoskeleton provides protection and support, but it must be shed and regrown as the animal grows, a process called molting.
2. Biramous Appendages: Crustaceans have paired appendages that are branched, with two segments. These appendages are highly specialized and used for a variety of functions, including walking, swimming, feeding, and sensing.
3. Two Pairs of Antennae: Crustaceans are easily identified by the presence of two pairs of antennae. These sensory appendages help them detect food, navigate their environment, and communicate with other crustaceans.
These three features are unique to the crustacean group and distinguish them from other arthropods.
