Sacculina is a genus of barnacles that is a parasitic castrator of crabs. They belong to a group called Rhizocephala. The adults bear no resemblance to the barnacles that cover ships and piers; they are recognised as barnacles because their larval forms are like other members of the barnacle class Cirripedia. The prevalence of this crustacean parasite in its crab host can be as high as 50%.
Barnacles are a type of arthropod constituting the subclass Cirripedia in the subphylum Crustacea, and are hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in erosive settings. Around 1,000 barnacle species are currently known.
Rhizocephala are derived barnacles that parasitise mostly decapod crustaceans, but can also infest Peracarida, mantis shrimps and thoracican barnacles, and are found from the deep ocean to freshwater. Together with their sister groups Thoracica and Acrothoracica, they make up the subclass Cirripedia. Their body plan is uniquely reduced in an extreme adaptation to their parasitic lifestyle, and makes their relationship to other barnacles unrecognisable in the adult form. The name Rhizocephala derives from the Ancient Greek roots ῥίζα and κεφαλή, describing the adult female, which mostly consists of a network of thread-like extensions penetrating the body of the host.
Thecostraca is a class of marine invertebrates containing over 2,200 described species. Many species have planktonic larvae which become sessile or parasitic as adults.
The Balanidae comprise a family of barnacles of the order Balanomorpha. As a result of research published in 2021 by Chan et al., the members of the family Archaeobalanidae were merged with this family.
In the past, Lernaeodiscidae has been considered a family of barnacles. Research published in 2021 by Chan et al. resulted in the genera of Lernaeodiscidae being merged with that of Peltogastridae, which now contains the members of both families. As an exception, the species Triangulus galatheae was moved to the genus Paratriangulus in the family Triangulidae.
The Sacculinidae are a family of barnacles belonging to the bizarre parasitic and highly apomorphic infraclass Rhizocephala. The Sacculinidae is one of the two larger families of Rhizocephala, containing six genera:
Dipterosaccus is a genus of barnacle.
Pieter Nicolaas van Kampen was a Dutch zoologist.
Heterosaccus is a genus of barnacles in infraclass Rhizocephala. Like other taxa in this group, they parasitize crabs. Geoffroy Smith circumscribed the genus in 1906; he initially only included H. hians. Smith circumscribed a genus distinct from Sacculina due to a difference of the mesentery; in Heterosaccus, the mesentery does not stretch down to the mantle opening but rather only is present on the ring of attachment.
Polyascus is a genus of barnacles in infraclass Rhizocephala. It was circumscribed in 2003 by Henrik Glenner, Jørgen Lützen, and Tohru Takahashi. They included three species, all transferred from Sacculina. The generic name polyascus refers to the typical presence of multiple external sac-like female bodies, known as externae. In Polyascus species, these originate from asexual reproduction.
Clistosaccidae is a family of parasitic barnacles belonging to the bizarre and highly apomorphic infraclass Rhizocephala, which is part of the barnacle subclass Cirripedia.
Clistosaccus is a genus of barnacles which are parasitic on hermit crabs. It is a monotypic genus, and the single species is Clistosaccus paguri, which is found in the northern Atlantic Ocean and the northern Pacific Ocean.
Akentrogonida was formerly a suborder of barnacles belonging to the group Rhizocephala, now an infraclass. In research published by Chan et al. in 2021, the suborders Akentrogonida and Kentrogonida were removed from the infraclass Rhizocephala, leaving 13 families as children of Rhizocephala without intermediate orders or suborders.
Kentrogonida was formerly a suborder of barnacles belonging to the group Rhizocephala, now an infraclass. In research published by Chan et al. in 2021, the suborders Kentrogonida and Akentrogonida were removed from the infraclass Rhizocephala, leaving 13 families as children of Rhizocephala without intermediate orders or suborders.
Chthamalophilidae is a family of barnacles belonging to the infraclass Rhizocephala.
Peltogasterella is a genus of parasitic barnacles in the family Peltogasterellidae. There are at least four described species in Peltogasterella.
Loxothylacus is a genus of parasitic barnacles in the family Sacculinidae. There are more than 20 described species in Loxothylacus.
Triangulus is a genus of parasitic barnacles in the family Triangulidae, the sole genus of the family. There are at least four described species in Triangulus.
