Barnacles are arthropods of the subclass Cirripedia in the subphylum Crustacea. They are related to crabs and lobsters, with similar nauplius larvae. Barnacles are exclusively marine invertebrates; many species live in shallow and tidal waters. Some 2,100 species have been described.
Rhizocephala are derived barnacles that are parasitic castrators. Their hosts are mostly decapod crustaceans, but include Peracarida, mantis shrimps and thoracican barnacles. Their habitats range 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.
Thompsonia is a genus of barnacles which has evolved into an endoparasite of other crustaceans, including crabs and snapping shrimp. It spreads through the host's body as a network of threads, and produces many egg capsules which emerge through joints in the host's shell.
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:
The Peltogastridae are a family of barnacles belonging to the bizarre parasitic and highly apomorphic infraclass Rhizocephala. The Peltogastridae are by far the largest family of Rhizocephala. They comprise 14 genera, 3 of which were moved from the family Lernaeodiscidae.
The Bopyridae are a family of isopod crustaceans in the suborder Cymothoida. There are 1223 individual species contained in this family. Members of the family are ectoparasites of crabs and shrimp. They live in the gill cavities or under the carapace where they cause a noticeable swelling. Fossil crustaceans have occasionally been observed to have a similar characteristic bulge.
Pisa armata is a species of crab from the eastern Atlantic Ocean.
Dipterosaccus is a genus of barnacle.
Pieter Nicolaas van Kampen was a Dutch zoologist.
Atergatis floridus, the floral egg crab, green egg crab, pancake crab, or shawl crab, is a species of tropical Indo-Pacific crab from the family Xanthidae. The meat of this crab is toxic, even if cooked, and consumption often results in death.
Charybdis longicollis, the lesser swimming crab, is a species of crab from the swimming crab family, the Portunidae. It has a native range which covers the north-western Indian Ocean and it has invaded the Mediterranean Sea by Lessepsian migration through the Suez Canal.
The clade Multicrustacea constitutes the largest superclass of crustaceans, containing approximately four-fifths of all described crustacean species, including crabs, lobsters, crayfish, shrimp, krill, prawns, woodlice, barnacles, copepods, amphipods, mantis shrimp and others. The largest branch of multicrustacea is the class Malacostraca.
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.
Sylon hippolytes is a castrating parasite that infects the shrimp Pandalina brevirostris.
Sacculina carcini, the crab hacker barnacle, is a species of parasitic barnacle in the family Sacculinidae, in particular a parasitic castrator, of crabs. The crab that most often is used as a host is the green crab, the natural range of which is the coasts of Europe and North Africa. It can be found attached to the crab's abdomen and affects consumption rates by humans.
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.
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.
