''Sacculina'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

barnacle A barnacle is a type of arthropod constituting the subclass 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 erosiv ...

s that is a parasitic castrator of

crab Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all th ...

s. They belong to a group called ''

Rhizocephala 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 Thoracic ...

''. The adults bear no resemblance to the barnacles that cover ships and piers; they are recognised as barnacles because their

larval A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...

forms are like other members of the barnacle

class Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used differently ...

Cirripedia A barnacle is a type of arthropod constituting the subclass 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 erosiv ...

. The prevalence of this crustacean parasite in its crab host can be as high as 50%.

Habitat

''Sacculina'' live in a marine environment. During their larval stage they are pelagic, but as they form into adults they live as

ectoparasites Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson ha ...

on crabs. Their primary host is the green crab, which is native to the Eastern Atlantic Ocean. Though these crabs have spread to other bodies of waters, it is not believed that ''Sacculina'' barnacles have traveled with them to these new localities.

Anatomy

The body of the adult parasite can be divided into two parts: one part is called the "externa" where the bulbous reproductive organ of the parasite sticks out of the abdomen of the host. The other part is called the "interna" which is inside the host's body. This part is composed of root-like tendrils that wrap themselves around the host's organs, which gives its group name of Rhizocephala, meaning "root-head". Through microCT scans, these roots have been discovered to wrap around certain organs of the body, with most around the hepatopancreas of crustaceans. This area is primarily for absorbing nutrients, which would explain why most concentrate in that region. In a similar species called ''Briarosaccus'' roots were seen extending to the brain and central nervous system, which could help explain how parasites like these can manipulate their hosts' behavior.

Life cycle

The female ''Sacculina''

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...

finds a crab and walks on it until she finds a joint. She then

molt In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is the manner in which an animal routinely casts off a part of its body (often, but not always, an outer ...

s into a form called a kentrogon, which then injects her soft body into the crab while her

shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses ** Thin-shell structure Science Biology * Seashell, a hard o ...

falls off. The ''Sacculina'' grows in the crab, emerging as a sac, known as an ''externa'', on the underside of the crab's rear

thorax The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the c ...

, where the crab's eggs would be incubated. Parasitic ''Sacculina'' destroy a crab's genitalia, rendering the crab permanently infertile. After this invasion of the ''Sacculina'', the crab is unable to perform the normal function of molting. This results in a loss of nutrition for the crab, and impairs its overall growth. The natural ability of regrowing a severed

claw A claw is a curved, pointed appendage found at the end of a toe or finger in most amniotes (mammals, reptiles, birds). Some invertebrates such as beetles and spiders have somewhat similar fine, hooked structures at the end of the leg or tarsus ...

that is commonly used for defense purposes is therefore lost after the infestation of ''Sacculina''. The male ''Sacculina'' 'larva' looks for a female ''Sacculina'' on the underside of a crab. He then implants his cells into a pocket in the female's body called the "testis", where the male cells then produce spermatozoa to fertilize eggs. When a female ''Sacculina'' is implanted in a male crab, it interferes with the crab's hormonal balance. This sterilizes it and changes the bodily layout of the crab to resemble that of a female crab by widening and flattening its abdomen, among other things. The female ''Sacculina'' then forces the crab's body to release hormones, causing it to act like a female crab, even to the point of performing female mating dances. If the parasite is removed from the host, female crabs will normally regenerate new ovarian tissue, while males usually develop complete or partial ovaries instead of testes. Although all energy otherwise expended on reproduction is directed to the ''Sacculina'', the crab develops a nurturing behavior typical of a normal female crab. The natural hatching process of a crab consists of the female finding a high rock and grooming its brood pouch on its abdomen and releasing the fertilized eggs in the water through a bobbing motion. The female crab stirs the water with her claw to aid the flow of the water. When the hatching larvae of ''Sacculina'' are ready to emerge from the brood pouch of female ''Sacculina'', the crab performs a similar process. The crab shoots them out in pulses, creating a large cloud of ''Sacculina'' larvae. The crab uses the familiar technique of stirring the water to aid in flow.

Life span

''Sacculina'' are primarily host dependent so their life span matches that of their hosts. Crabs usually have a life span anywhere from 1 to 2 years.

Biological control agents

''Sacculina'' has been suggested to be used as a type of biological control agent to help reduce the populations of the invasive green crab. This is controversial because ''Sacculina'' can also use native crab species as their host.

Species

More than 100 species of ''Sacculina'' are currently recognised: * '' Sacculina abyssicola'' * '' Sacculina actaeae'' * '' Sacculina aculeata'' Boschma, 1928 * '' Sacculina ales'' Kossmann, 1872 * '' Sacculina americana'' Reinhard, 1955 * '' Sacculina amplituba'' Phillips, 1978 * '' Sacculina anceps'' Boschma, 1931 * '' Sacculina angulata'' * '' Sacculina anomala'' Boschma, 1933 * ''

Sacculina atlantica ''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 t ...

'' Boschma, 1927 * ''

Sacculina beauforti ''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 th ...

'' Boschma, 1949 * '' Sacculina bicuspidata'' Boschma, 1931 * '' Sacculina bipunctata'' Kossmann, 1872 * '' Sacculina boschmai'' Reinhard, 1955 * ''

Sacculina bourdoni ''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 t ...

'' Boschma, 1960 * '' Sacculina brevispina'' * '' Sacculina bucculenta'' Boschma, 1933 * '' Sacculina bursapastoris'' Kossmann, 1872 * '' Sacculina caelata'' Boschma, 1931 * '' Sacculina calappae'' * '' Sacculina calva'' Boschma, 1933 * '' Sacculina captiva'' Kossmann, 1872 * ''

Sacculina carcini ''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 w ...

'' Thompson, 1836 * '' Sacculina carpiliae'' * ''

Sacculina cartieri ''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 t ...

'' Kossmann, 1872 * '' Sacculina cavolinii'' Kossmann, 1872 * ''

Sacculina comosa ''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 t ...

'' Boschma, 1931 * '' Sacculina compressa'' Boschma, 1931 * '' Sacculina confragosa'' Boschma, 1933 * ''

Sacculina cordata ''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 th ...

'' Shiino, 1943 * ''

Sacculina crucifera ''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 th ...

'' Kossmann, 1872 * ''

Sacculina curvata ''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 th ...

'' Boschma, 1933 * '' Sacculina cuspidata'' Boschma, 1949 * '' Sacculina dayi'' Boschma, 1958 * '' Sacculina dentata'' Kossmann, 1872 * '' Sacculina docleae'' Huang & Lützen, 1998 * '' Sacculina duracina'' Boschma, 1933 * '' Sacculina echinulata'' * '' Sacculina elongata'' Boschma, 1933 * '' Sacculina eriphiae'' Smith, 1906 * '' Sacculina exarcuata'' Kossmann, 1872 * ''

Sacculina fabacea ''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 th ...

'' Shiino, 1943 * ''

Sacculina flacca ''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 t ...

'' Boschma, 1931 * ''

Sacculina flexuosa ''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 t ...

'' Kossmann, 1872 * '' Sacculina gerbei'' * '' Sacculina ghanensis'' Boschma, 1971 * '' Sacculina gibba'' Boschma, 1933 * ''

Sacculina glabra ''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 th ...

'' * ''

Sacculina globularis ''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 th ...

'' Boschma, 1970 * ''

Sacculina gonoplaxae ''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 th ...

'' * '' Sacculina gordonae'' Boschma, 1933 * '' Sacculina gracilis'' Boschma, 1931 * '' Sacculina granifera'' Boschma, 1973 * '' Sacculina granulosa'' Boschma, 1931 * '' Sacculina guineensis'' Boschma, 1971 * ''

Sacculina hartnolli ''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 t ...

'' Boschma, 1965 * ''

Sacculina herbstianodosa ''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 t ...

'' (Hesse, 1867) * '' Sacculina hirsuta'' Boschma, 1925 * '' Sacculina hirta'' Boschma, 1933 * '' Sacculina hispida'' Boschma, 1928 * '' Sacculina holthuisi'' Boschma, 1956 * '' Sacculina hystrix'' * ''

Sacculina ignorata ''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 t ...

'' Boschma, 1947 * ''

Sacculina imberbis ''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 th ...

'' Shiino, 1943 * ''

Sacculina inconstans ''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 th ...

'' Boschma, 1952 * '' Sacculina infirma'' Boschma, 1953 * '' Sacculina inflata'' Leuckart, 1859 * ''

Sacculina insueta ''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 t ...

'' Boschma, 1966 * ''

Sacculina irrorata ''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 th ...

'' Boschma, 1934 * '' Sacculina jamaicensis'' Boschma, 1966 * '' Sacculina lata'' Boschma, 1933 * '' Sacculina leopoldi'' Boschma, 1931 * '' Sacculina leptothrix'' Boschma, 1933 * ''

Sacculina lobata ''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 th ...

'' Boschma, 1965 * '' Sacculina loricata'' * '' Sacculina margaritifera'' Kossmann, 1872 * ''

Sacculina micracantha ''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 t ...

'' Boschma, 1931 * '' Sacculina microthrix'' Boschma, 1931 * ''

Sacculina muricata ''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 t ...

'' Boschma, 1931 * '' Sacculina nectocarcini'' * '' Sacculina nigra'' Shiino, 1943 * '' Sacculina nodosa'' Boschma, 1931 * ''

Sacculina ornatula ''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 th ...

'' Boschma, 1951 * ''

Sacculina ostracotheris ''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 th ...

'' Boschma, 1967 * '' Sacculina papposa'' * '' Sacculina pertenuis'' Boschma, 1933 * '' Sacculina phacelothrix'' Boschma, 1931 * ''

Sacculina pilosa ''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 t ...

'' Kossmann, 1872 * '' Sacculina pilosella'' * ''

Sacculina pinnotherae ''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 t ...

'' Shiino, 1943 * '' Sacculina pisiformis'' Kossmann, 1872 * ''

Sacculina pistillata ''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 t ...

'' Boschma, 1952 * ''

Sacculina pomum ''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 th ...

'' Kossmann, 1872 * '' Sacculina pugettiae'' Shiino, 1943 * '' Sacculina pulchella'' Boschma, 1933 * '' Sacculina punctata'' Boschma, 1934 * '' Sacculina pustulata'' Boschma, 1925 * '' Sacculina quadrialata'' Boyko & van der Meij, 2018 * '' Sacculina rathbunae'' Boschma, 1933 * ''

Sacculina reinhardi ''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 t ...

'' * ''

Sacculina reniformis ''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 th ...

'' Boschma, 1933 * '' Sacculina robusta'' Boschma, 1948 * '' Sacculina rotundata'' Miers, 1880 * ''

Sacculina rugosa ''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 t ...

'' * '' Sacculina scabra'' Boschma, 1931 * '' Sacculina schmitti'' Boschma, 1933 * '' Sacculina scutigera'' Huang & Lützen, 1998 * '' Sacculina semistriata'' * '' Sacculina senta'' Boschma, 1933 * ''

Sacculina serenei ''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 th ...

'' Boschma, 1954 * '' Sacculina setosa'' * '' Sacculina spectabilis'' Boschma, 1948 * '' Sacculina spinosa'' * '' Sacculina striata'' Boschma, 1931 * '' Sacculina sulcata'' * '' Sacculina surinamensis'' Boschma, 1966 * '' Sacculina teres'' Boschma, 1933 * '' Sacculina teretiuscula'' Boschma, 1931 * '' Sacculina ternatensis'' Boschma, 1950 * ''

Sacculina upogebiae ''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 th ...

'' Shiino, 1943 * ''

Sacculina vankampeni ''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 t ...

'' Boschma, 1931 * '' Sacculina verrucosa'' * ''

Sacculina vieta ''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 th ...

'' Boschma, 1933 * '' Sacculina weberi'' Boschma, 1931 * '' Sacculina zariquieyi'' Boschma, 1947

References

Sources

* *: (cites many earlier papers by Boschma and others including other sources for the above list) * * *

External links

* {{Taxonbar, from=Q150610 Barnacles Parasitic crustaceans Parasites of crustaceans Mind-altering parasites Crustacean genera