Crustacean is the common name for the any of a group of mainly aquatic arthropods.
The subphylum has about 26,000 known species. Lots of crustaceans are scavengers, and they often enjoy fishes and rotting seaweed . So you probably knew that crabs, lobster, and shrimp are crustaceans. Yep, they're all crustaceans. This is a classic Chinese dip for things like shrimp balls.