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a suborder of crustaceans of the order Cirripedia. They are internal parasites of crabs, hermit crabs, and shrimp. Their structure is extremely simple. The saclike unsegmented body is filled with ova and genital organs and is attached to the abdomen of the host by means of a thin stem with ramified appendages that pierce the host’s body. Limbs and an alimentary canal are absent. Rhizocephala are classified as crustaceans because they have free-swimming larvae, the nauplius and cypris. The infestation of new hosts is done by the larvae. Members of the suborder live primarily in the sea. Some Rhizocephala are hermaphrodites; others produce dwarfed males. A typical representative of the suborder is Sacculina.