''Sacculina'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

barnacle Barnacles are arthropods of the subclass (taxonomy), subclass Cirripedia in the subphylum Crustacean, Crustacea. They are related to crabs and lobsters, with similar Nauplius (larva), nauplius larvae. Barnacles are exclusively marine invertebra ...

s that is a

parasitic castrator Parasitic castration is the strategy, by a parasite, of blocking reproduction by its host, completely or in part, to its own benefit. This is one of six major strategies within parasitism. Evolutionary strategy The parasitic castration strateg ...

crab Crabs are decapod crustaceans of the infraorder Brachyura (meaning "short tailed" in Greek language, Greek), which typically have a very short projecting tail-like abdomen#Arthropoda, abdomen, usually hidden entirely under the Thorax (arthropo ...

s. They belong to a group called

Rhizocephala 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 w ...

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

larval A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

forms are like other members of the barnacle

class Class, Classes, 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 d ...

Cirripedia 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 water ...

. 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 (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The en ...

on crabs. Their primary host is the

green crab ''Carcinus maenas'' is a common littoral crab. It is known by different names around the world. In the British Isles, it is generally referred to as the shore crab or green shore crab. In North America and South Africa, it bears the name Europe ...

, which is native to the Eastern Atlantic Ocean. Though these crabs have spread to other bodies of water, 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 The hepatopancreas, digestive gland or midgut gland is an organ of the digestive tract of arthropods and molluscs. It provides the functions which in mammals are provided separately by the liver and pancreas, including the production of digestive ...

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 is a hypothesis to help explain how parasites like these can manipulate their hosts' behavior.

Life cycle

The female ''Sacculina''

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

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 a process by which an animal casts off parts of its body to serve some beneficial purpose, either at ...

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 Science Biology * Seashell, a hard outer layer of a marine ani ...

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 (: thoraces or thoraxes) or chest is a part of the anatomy of 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 di ...

, where the crab's

egg An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the ...

s 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 Arthro ...

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

. This is controversial because ''Sacculina'' can also use native crab species as their host and there would be no way to control or stop them from attacking native species.

Species

More than 100 species of ''Sacculina'' are currently recognised: * ''

Sacculina abyssicola ''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, whales, and piers; they are recognised as barnacles becau ...

'' * ''

Sacculina actaeae ''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, whales, and piers; they are recognised as barnacles becau ...

'' * ''

Sacculina aculeata ''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, whales, and piers; they are recognised as barnacles becau ...

'' Boschma, 1928 * ''

Sacculina ales ''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, whales, and piers; they are recognised as barnacles becau ...

'' Kossmann, 1872 * ''

Sacculina americana ''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, whales, and piers; they are recognised as barnacles becau ...

'' Reinhard, 1955 * ''

Sacculina amplituba ''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, whales, and piers; they are recognised as barnacles becau ...

'' Phillips, 1978 * ''

Sacculina anceps ''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, whales, and piers; they are recognised as barnacles becau ...

'' Boschma, 1931 * '' Sacculina angulata'' * '' Sacculina anomala'' Boschma, 1933 * '' Sacculina atlantica'' Boschma, 1927 * '' Sacculina beauforti'' Boschma, 1949 * '' Sacculina bicuspidata'' Boschma, 1931 * '' Sacculina bipunctata'' Kossmann, 1872 * ''

Sacculina boschmai ''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, whales, and piers; they are recognised as barnacles becau ...

'' Reinhard, 1955 * '' Sacculina bourdoni'' Boschma, 1960 * '' Sacculina brevispina'' * '' Sacculina bucculenta'' Boschma, 1933 * '' Sacculina bursapastoris'' Kossmann, 1872 * '' Sacculina caelata'' Boschma, 1931 * '' Sacculina calappae'' * ''

Sacculina calva ''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, whales, and piers; they are recognised as barnacles becau ...

'' 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'' Kossmann, 1872 * '' Sacculina cavolinii'' Kossmann, 1872 * '' Sacculina comosa'' Boschma, 1931 * '' Sacculina compressa'' Boschma, 1931 * '' Sacculina confragosa'' Boschma, 1933 * '' Sacculina cordata'' Shiino, 1943 * '' Sacculina crucifera'' Kossmann, 1872 * '' Sacculina curvata'' 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'' Shiino, 1943 * '' Sacculina flacca'' Boschma, 1931 * '' Sacculina flexuosa'' Kossmann, 1872 * '' Sacculina gerbei'' * '' Sacculina ghanensis'' Boschma, 1971 * '' Sacculina gibba'' Boschma, 1933 * '' Sacculina glabra'' * '' Sacculina globularis'' Boschma, 1970 * '' Sacculina gonoplaxae'' * '' Sacculina gordonae'' Boschma, 1933 * '' Sacculina gracilis'' Boschma, 1931 * '' Sacculina granifera'' Boschma, 1973 * '' Sacculina granulosa'' Boschma, 1931 * '' Sacculina guineensis'' Boschma, 1971 * '' Sacculina hartnolli'' Boschma, 1965 * '' Sacculina herbstianodosa'' (Hesse, 1867) * '' Sacculina hirsuta'' Boschma, 1925 * '' Sacculina hirta'' Boschma, 1933 * '' Sacculina hispida'' Boschma, 1928 * '' Sacculina holthuisi'' Boschma, 1956 * '' Sacculina hystrix'' * '' Sacculina ignorata'' Boschma, 1947 * '' Sacculina imberbis'' Shiino, 1943 * '' Sacculina inconstans'' Boschma, 1952 * '' Sacculina infirma'' Boschma, 1953 * '' Sacculina inflata'' Leuckart, 1859 * '' Sacculina insueta'' Boschma, 1966 * '' Sacculina irrorata'' Boschma, 1934 * '' Sacculina jamaicensis'' Boschma, 1966 * '' Sacculina lata'' Boschma, 1933 * '' Sacculina leopoldi'' Boschma, 1931 * '' Sacculina leptothrix'' Boschma, 1933 * '' Sacculina lobata'' Boschma, 1965 * '' Sacculina loricata'' * '' Sacculina margaritifera'' Kossmann, 1872 * '' Sacculina micracantha'' Boschma, 1931 * '' Sacculina microthrix'' Boschma, 1931 * '' Sacculina muricata'' Boschma, 1931 * '' Sacculina nectocarcini'' * '' Sacculina nigra'' Shiino, 1943 * '' Sacculina nodosa'' Boschma, 1931 * '' Sacculina ornatula'' Boschma, 1951 * '' Sacculina ostracotheris'' Boschma, 1967 * '' Sacculina papposa'' * '' Sacculina pertenuis'' Boschma, 1933 * '' Sacculina phacelothrix'' Boschma, 1931 * '' Sacculina pilosa'' Kossmann, 1872 * '' Sacculina pilosella'' * '' Sacculina pinnotherae'' Shiino, 1943 * '' Sacculina pisiformis'' Kossmann, 1872 * '' Sacculina pistillata'' 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, whales, and piers; they are recognised as barnacles becau ...

'' 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 reniformis'' Boschma, 1933 * '' Sacculina robusta'' Boschma, 1948 * '' Sacculina rotundata'' Miers, 1880 * '' Sacculina rugosa'' * '' Sacculina scabra'' Boschma, 1931 * '' Sacculina schmitti'' Boschma, 1933 * '' Sacculina scutigera'' Huang & Lützen, 1998 * '' Sacculina semistriata'' * '' Sacculina senta'' Boschma, 1933 * '' Sacculina serenei'' 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'' 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, whales, and piers; they are recognised as barnacles becau ...

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