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.
Goose barnacles, also called stalked barnacles or gooseneck barnacles, are filter-feeding crustaceans that live attached to hard surfaces of rocks and flotsam in the ocean intertidal zone. Goose barnacles formerly made up the taxonomic order Pedunculata, but research has resulted in the classification of stalked barnacles within multiple orders of the infraclass Thoracica.
Isopoda is an order of crustacean, which includes woodlice and their relatives. Members of this group are called Isopods and include both terrestrial and aquatic species. All have rigid, segmented exoskeletons, two pairs of antennae, seven pairs of jointed limbs on the thorax, and five pairs of branching appendages on the abdomen that are used in respiration. Females brood their young in a pouch under their thorax.
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.
The family Argulidae, whose members are commonly known as carp lice or fish lice, are parasitic crustaceans in the class Ichthyostraca. It is the only family in the monotypic subclass Branchiura and the order Arguloida, although a second family, Dipteropeltidae, has been proposed. Although they are thought to be primitive forms, they have no fossil record.
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 Chthamalidae are a family of chthamaloid barnacles, living entirely in intertidal/subtidal habitats, characterized by a primary shell wall of eight, six, or four plates, lacking imbricating plate whorls, and either membraneous or more rarely calcareous basis. They are not found below immediate subtidal habitats, and more likely are found in the highest tier of shallow-water barnacle fauna. They can be found in the most rigorous wave-washed locations, and some species are found in the surf zone above high tide mark, only receiving water from wave action at high tide.
Acorn barnacle and acorn shell are vernacular names for certain types of stalkless barnacles, generally excluding stalked or gooseneck barnacles. As adults they are typically cone-shaped, symmetrical, and attached to rocks or other fixed objects in the ocean. Members of the barnacle order Balanomorpha are often called acorn barnacles.
The Acrothoracica are an infraclass of barnacles.
Facetotecta is a poorly known subclass of thecostracan crustaceans. The adult forms have never been recognised, and the group is known only from its larvae, the "y-nauplius" and "y-cyprid" larvae. They are mostly found in the north Atlantic Ocean, neritic waters around Japan, and the Mediterranean Basin, where they also survive in brackish water.
Calcinus tubularis is a species of hermit crab. It is found in the Mediterranean Sea and around islands in the Atlantic Ocean, where it lives below the intertidal zone. Its carapace, eyestalks and claws are marked with numerous red spots. C. tubularis and its sister species, C. verrilli, are the only hermit crabs known to show sexual dimorphism in shell choice, with males using normal marine gastropod shells, while females use shells of gastropods in the family Vermetidae, which are attached to rocks or other hard substrates.
Chelonibiidae is a family of turtle barnacles in the order Balanomorpha. There are at least three genera and about eight described species in Chelonibiidae.
Crustaceans are invertebrate animals of the subphylum Crustacea, a large, diverse group of mainly aquatic arthropods including decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, opossum shrimps, amphipods and mantis shrimp. The crustacean group can be treated as a subphylum under the clade Mandibulata. It is now well accepted that the hexapods emerged deep in the Crustacean group, with the completed group referred to as Pancrustacea. The three classes Cephalocarida, Branchiopoda and Remipedia are more closely related to the hexapods than they are to any of the other crustaceans.
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.
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.
Polyascidae is a family of parasitic barnacles in the class Thecostraca. There are at least two genera and about eight described species in Polyascidae.
Iblomorpha is a small order of barnacles in the class Thecostraca. There are only two families and about eight described species in Iblomorpha. In this group we find barnacles that use calcium phosphate in their shell, and species that protect themselves against predators with poison.
Verrucomorpha is an order of asymmetrical sessile barnacles in the class Thecostraca. They are typically found in deeper and deep-sea habitats. There are 2 families and more than 100 described species in Verrucomorpha.
Peltogasterellidae is a small family of parasitic barnacles in the class Thecostraca. There 4 genera and about 10 described species in Peltogasterellidae.
