Editing Rhizocephala (section)

=== Adults ===

[[File:Haeckel Sacculina.jpg|thumb|''[[Sacculina carcini]]'' (adult female) parasiting a crab (''[[Carcinus maenas]]''). [[Haeckel]]'s drawing shows the internal network of filaments from the parasite.]]

Adult rhizocephalans lack [[appendage]]s, [[segmentation (biology)|segmentation]], and all internal organs except [[gonad]]s, a few muscles, and the remains of the [[nervous system]]. Females have a [[Arthropod cuticle|cuticle]], which is never shed.<ref>{{cite journal |last1=Bresciani |first1=José |last2=Høeg |first2=Jens T. |title=Comparative ultrastructure of the root system in Rhizocephalan barnacles (Crustacea: Cirripedia: Rhizocephala) |journal=Journal of Morphology |date=July 2001 |volume=249 |issue=1 |pages=9–42 |doi=10.1002/jmor.1039 |pmid=11410937 |s2cid=27832764 }}</ref> Other than the minute larval stages, there is nothing identifying them as crustaceans or even arthropods in general. The only distinguishable portion of a rhizocephalan body is the externa: the reproductive portion of adult females.{{cn|date=October 2024}}