The flying crab has striking flattened legs making it a good swimmer. Its build is light and it moves readily through the water, practically flying. It also uses these paddles to burrow itself into the sandy bottom. Flying crabs catch food while swimming. They pinch rapidly and painfully. This crab doesn't always actively hunt its prey. A lazy crab just waits till its prey swims past. Flying crabs are often infected with a nasty parasite, the Sacculina carcini.