| Thompsonia globosa |
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.
A barnacle is a type of arthropod constituting the infraclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in erosive settings. They are sessile (nonmobile) suspension feeders, and have four nektonic larval stages. Around 70 barnacle species are currently known. The name "Cirripedia" is Greek, meaning "curl-footed". The study of barnacles is called cirripedology.
Crustaceans form a large, diverse arthropod taxon which includes such familiar animals as crabs, lobsters, crayfish, shrimps, prawns, krill, woodlice, and barnacles. The crustacean group is usually treated as a class under subphylum Mandibulata and because of recent molecular studies it is now well accepted that the crustacean group is paraphyletic, and comprises all animals in the Pancrustacea clade other than hexapods. Some crustaceans are more closely related to insects and other hexapods than they are to certain other crustaceans.
Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen), usually entirely hidden under the thorax. They live in all the world's oceans, in fresh water, and on land, are generally covered with a thick exoskeleton and have a single pair of pincers. Many other animals with similar names – such as hermit crabs, king crabs, porcelain crabs, horseshoe crabs, and crab lice – are not true crabs.
The first scientific description of the genus was Robby Kossmann's description in 1872 of Thompsonia globosa .Kossmann named the genus after John Vaughan Thompson, the Irish naturalist who had recognised the cirripedian affinities of the Rhizocephala. The type specimens had been collected by Georg Semper in the East Indies, on the legs of the crab Lybia tessellata . Eleven species are now recognised:
Affinity (taxonomy) – mainly in life sciences or natural history – refers to resemblance suggesting a common descent, phylogenetic relationship, or type. The term does, however, have broader application, such as in geology, and similarly in astronomy
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 the sister group the Thoracica, they make up the infraclass 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 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.
Georg Semper was a German entomologist who specialised in Lepidoptera.
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%.
Alpheidae is a family of caridean snapping shrimp characterized by having asymmetrical claws, the larger of which is typically capable of producing a loud snapping sound. Other common names for animals in the group are pistolshrimp or alpheid shrimp.
Thecostraca is a subclass of marine invertebrates containing about 1,320 described species. Many species have planktonic larvae which become sessile or parasitic as adults.
Pollicipes pollicipes, known as the goose neck barnacle, goose barnacle or leaf barnacle is a species of goose barnacle, also well known under the taxonomic synonym Pollicipes cornucopia. It is closely related to Pollicipes polymerus, a species with the same common names, but found on the Pacific coast of North America, and to Pollicipes elegans a species from the coast of Chile. It is found on rocky shores in the north-east Atlantic Ocean and is prized as a delicacy, especially in the Iberian Peninsula.
The Lernaeodiscidae are a family of parasitic barnacles belonging to the bizarre and highly apomorphic superorder Rhizocephala, and therein to the less diverse of the two orders, the Kentrogonida. The Lernaeodiscidae are one of the smallish families of Rhizocephala, though the only one among the Kentrogonida. The family contains three genera: Lernaeodiscus Müller, 1862, Septodiscus Van Baal, 1937 and Triangulus Smith, 1906.
The Thompsoniidae are a family of parasitic barnacles belonging to the bizarre and highly apomorphic superorder Rhizocephala, and therein to the more diverse of the two orders, the Akentrogonida.
Dosima fascicularis, the buoy barnacle, is "the most specialised pleustonic goose barnacle" species. It hangs downwards from the water surface, held up by a float of its own construction, and is carried along by ocean currents.
Facetotecta is a poorly known infraclass 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.
Balanus nubilus, commonly called the giant acorn barnacle, is the world's largest barnacle, reaching a diameter of 15 cm (6 in) and a height of up to 30 cm (12 in), and containing the largest known muscle fibres.
Crustaceans may pass through a number of larval and immature stages between hatching from their eggs and reaching their adult form. Each of the stages is separated by a moult, in which the hard exoskeleton is shed to allow the animal to grow. The larvae of crustaceans often bear little resemblance to the adult, and there are still cases where it is not known what larvae will grow into what adults. This is especially true of crustaceans which live as benthic adults, more-so than where the larvae are planktonic, and thereby easily caught.
The Bopyridae are a family of isopod crustaceans in the suborder Cymothoida. Members of the family are ectoparasites of crabs and shrimps. 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.
The Entoniscidae are a family of marine isopod crustaceans in the suborder Cymothoida. Members of this family are parasites of brachyuran and anomuran crabs, living in their hosts' haemocoel. A small chitinised hole develops through the host's exoskeleton through which the isopod can communicate with the environment. The female isopod bears little resemblance to any free-living isopod, but the morphology of the larvae show their taxonomic affiliations.
Chelonibia is a genus of acorn barnacles in the monotypic family Chelonibiidae of the subphylum Crustacea. Its members are epizootic and live attached to manatees, turtles, marine molluscs, crabs and horseshoe crabs in all tropical and subtropical oceans. In a few instances, they have been found on sea snakes, alligators and inanimate substrates, but they are not found in the typical habitats of barnacles – on rocks, docks or boats.
The clade Multicrustacea constitutes the largest superclass of crustaceans, containing approximately four-fifths of all described crustacean species, including crabs, lobsters, shrimps, woodlice, prawns, krill, barnacles, crayfish, copepods, amphipods and others. The largest branch of multicrustacea is the class Malacostraca.
The Hexanauplia constitute a class of crustaceans, comprising three groups: the Copepoda, the Tantulocarida and the Thecostraca.
Heterosaccus is a genus of barnacles in superorder Rhizocephala. Like other taxa in this superorder, 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 superorder 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.
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.
Zoologischer Anzeiger – A Journal of Comparative Zoology is a peer-reviewed scientific journal specialising in the field of comparative zoology. It is included in a number of bibliographic databases: