Sacculina carcini | |
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Sacculina carcini (highlighted) attached to a female Liocarcinus crab | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Thecostraca |
Subclass: | Cirripedia |
Family: | Sacculinidae |
Genus: | Sacculina |
Species: | S. carcini |
Binomial name | |
Sacculina carcini | |
Synonyms [1] | |
List
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Sacculina carcini, the crab hacker barnacle, [2] 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. [2] It can be found attached to the crab's abdomen and affects consumption rates by humans. [3]
The Kentrogonida order contains the Sacculinidae family, known for their ability to induce parasitic sterilization in crabs. The genus Sacculina established by Thompson in 1836 contains 129 species. Among these, Sacculina carcini was the first and most studied barnacle parasite. [4]
Individual Sacculina carcini differ greatly between males and females. The female barnacles look like small slugs between entering the crab and infecting it. Once they have infected their host, they begin to develop and grow tendrils. [3] This allows them to get the nutrients that it needs from their host. Over time, it can be seen hanging off the crab's abdomen filled with reproductive tissue. The male parasites are much smaller and serve only to help the female Sacculina carcini reproduce. [3]
Sacculina carcini is a monoxenic parasite of crabs, most commonly the green crab (Carcinus maenas). They have also been found to infect the Carcinus aesturarii, Liocarcinus depurator (Harbour crab), Pirimela denticulata,Necora puber (Velvet crab), and the Liocarcinus holsatus (Flying crab). [2] [3] The parasite's range largely coincides with that of this host, which is usually the coasts of Western Europe and North Africa. The green crab, however, has been expanding its range and has become established in both North and South America, Southern Africa and Australia, so it is possible that the parasite is now present outside its natural territory. [3] These crabs all live in shallow water over sandy, rocky, or muddy substrates. [2]
A female Sacculina carcini larva settles on a suitable crab host and crawls across its surface until it finds a suitable spot such as the base of a seta (bristle). It then develops into a form called a kentrogon, which inserts a stylet into the crab and pushes its way inside. In order to do this, she has to shed her outer hard shell first. [5] From there it moves through the inside of the crab, in due course pushing out a sac, known as an externa, on the underside of the crab's abdomen. The part remaining inside, the interna, develops tendrils which spread throughout the crab. They take over the stomach, intestines, and nervous system to absorb nourishment and enable the parasite to control the behavior of its host. [6] [7]
The presence of the parasite inhibits the development of the crab's gonads, which eventually atrophy; it also prevents the crab from molting, consequently preventing it from regenerating lost limbs. The parasite causes a male crab to develop certain feminine characteristics including the broadening of its abdomen, [8] while in females, the abdomen becomes narrower and the pleopods degenerate. The eggs of the parasite develop in the externa and both male and female crabs carry these eggs around, secured under their abdomen, in the way that female crabs normally care for their own brood (but males never do). If the parasite is experimentally removed from the host, female crabs will usually regenerate their ovaries, but in males, sex change takes place and they develop ovarian tissue. [7]
The eggs inside the externa are fertilized by male larvae which enter the sac through a pore. These males are tiny, never become adults and soon die. However, the female, including the externa, can live for as long as the crab host survives, perhaps one or two years. [5] Hundreds of eggs are produced every day and remain in the sac for about six weeks. When the parasite eggs are ready for release, the crab will climb onto a rock, bob about to release them and waft them on their way. [5] The cycle then continues with each generation.
The Sacculina carcini is known to control the population size of their hosts, like the Green crab, by making many of them infertile. Without reproduction, the population cannot expand and can cause a shortage for human consumption. The parasite can also cause their hosts to stop molting once infected. This can cause the crab to stop growing before it reaches a size big enough for human consumption. [3] They are known to cause parasitic castration in crabs, femininize males the most.
Sacculina carcini can be considered as a potential biological control agent for Carcinus maenas , known as the invasive green crab species. However, this idea might be unlikely due to the parasite's low host specificity. While S. carcini tends to infect post-molt green crabs, this does not exclude the possibility of it infecting non-targeted native crabs. Therefore, more assessment is needed for the biological control of S. carcini. One possible solution could be to distribute the parasite only in low populations of C. maenas, enabling a faster death rate compared to other native species. [9] [10]
A negative impact on humans would be economic damage, reducing the accessibility of crabs for consumption. [3]
Sacculina carcini does not have a conservation status. [3]
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 characterised parasites as "predators that eat prey in units of less than one". Parasites include single-celled protozoans such as the agents of malaria, sleeping sickness, and amoebic dysentery; animals such as hookworms, lice, mosquitoes, and vampire bats; fungi such as honey fungus and the agents of ringworm; and plants such as mistletoe, dodder, and the broomrapes.
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%.
The New Zealand pea crab, is a species of small, parasitic crab that lives most commonly inside New Zealand green-lipped mussels. Adult females are about the size and shape of a pea, while adult males are smaller and flatter. Adult New Zealand pea crabs are completely reliant on their host mussel for shelter and food, which it steals from the mussel's gills. The New Zealand pea crab is found throughout New Zealand and can infect up to 70% of natural populations. These crabs are of concern to green-lipped mussel aquaculture because they reduce the size and growth of mussels, although infected mussels can be harvested and consumed.
Callinectes sapidus, the blue crab, Atlantic blue crab, or regionally as the Maryland blue crab, is a species of crab native to the waters of the western Atlantic Ocean and the Gulf of Mexico, and introduced internationally.
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.
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 European green crab.
Toxocara canis is a worldwide-distributed helminth parasite that primarily infects dogs and other canids, but can also infect other animals including humans. The name is derived from the Greek word "toxon," meaning bow or quiver, and the Latin word "caro," meaning flesh. T. canis live in the small intestine of the definitive host. This parasite is very common in puppies and somewhat less common in adult dogs. In adult dogs, infection is usually asymptomatic but may be characterized by diarrhea. By contrast, untreated infection with Toxocara canis can be fatal in puppies, causing diarrhea, vomiting, pneumonia, enlarged abdomen, flatulence, poor growth rate, and other complications.
Hemigrapsus oregonensis is a small shore crab of the family Varunidae; formerly classified under the family Grapsidae. It is known under several common names, including yellow shore crab, hairy shore crab, green shore crab, mud-flat crab, bay shore crab and Oregon shore crab. Despite its common name, the crab actually has a wide variety of coloration. It is found along the West Coast of the United States and Canada, specifically along shorelines and similar geographical areas. In 2009, H. oregonensis was included on a list of animals petitioning for the endangered species label, but there was not enough scientific information available for it to be considered as such, so it remains unevaluated to the present day.
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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.
Liocarcinus holsatus, sometimes known by the common name flying crab, is a species of swimming crab found chiefly in the North Sea, Irish Sea and English Channel. It has a carapace up to 4 centimetres (1.6 in) wide, which is brownish-grey with a green tinge. It is very similar in appearance to the harbour crab Liocarcinus depurator.
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.
Pugettia producta, known as the northern kelp crab or shield-backed kelp crab, is a species of crab in the family Epialtidae.
Hemioniscus balani, a species of isopod crustacean, is a widespread parasitic castrator of barnacle in the northern Atlantic Ocean. Its range extends from Norway to the Atlantic coast of France, and as far west as Massachusetts. It is also commonly found on the Pacific coast of North America; it is not known if the Pacific and Atlantic populations are the same species, or if the Pacific population exists following human-assisted introduction.
Pisa armata is a species of crab from the eastern Atlantic Ocean.
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Loxothylacus panopaei is a species of barnacle in the family Sacculinidae. It is native to the Gulf of Mexico and the Caribbean Sea. It is a parasitic castrator of small mud crabs in the family Panopeidae, mostly in the Gulf of Mexico, the Caribbean Sea and the eastern Atlantic Ocean.
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