| Argulus coregoni | |
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Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Ichthyostraca |
| Order: | Arguloida |
| Family: | Argulidae |
| Genus: | Argulus |
| Species: | A. coregoni |
| Binomial name | |
| Argulus coregoni Thorell, 1865 | |
The carp louse Argulus coregoni is an obligate ectoparasitic branciuran species on fish. [1] It occurs in China and Japan, [2] and Scandinavia. [1] Argulus coregoni can pose a threat to fish kept in fish farms. [3] [4]
Argulus coregoni has a direct life cycle, meaning that the parasite is transmitted between individuals of the same host species without an intermediate host. At Northern latitudes, adults do not survive winter, but only the eggs attached to rocks survive throughout the winter. [1] Egg hatching occurs in May [1] [2] once water temperatures exceed 10 °C. [3] From the eggs, metanauplii emerge which actively search for a fish host to feed on. [5] These can survive up to two days without finding a host. [4] One or two generations can be completed each year, depending on environmental conditions. [3] This means that infection rates of host typically reach their peak during the summer months. [2] Females start laying eggs from July until the end of summer.
Although some differences are seen in the development between males and females, the adults generally have the same size 9–12 mm (0.4–0.5 in). This is in contrast with other dioecious crustacean species [6] The sex ratio — the ratio between males and females in the population — is generally close to 1:1, [3] [6] as expected for sexually reproducing species under Fisher's principle. Both sexes can detach from the host and find alternative hosts. However, this behaviour is more common in males as they can also switch between hosts to search for mates. [6]
Argulus coregoni mainly infect salmonids, such as rainbow trout and brook trout. [2] [3] It is, however, also able to infect other species of fish, such sweet fish. [7] [8] This is supported by evidence that larvae can successfully develop on both salmonids and cyprinids, but developmental rate and reproductive output on the latter host group is reduced. [9]
In choice experiments it shows increased host preference with maturation, [7] this likely reflects the better development on its normal salmonid hosts.
Originally from Europe, [10] A. coregoni In recent years, A. coregoni has shown a geographical expansion in Japan [8] [11] and to India [10] in recent years.
Argulus coregoni aggregate on specific parts of their hosts. The prefer attaching near the fins, in particular the pectoral and pelvic fins. Larger individuals are found towards the head of the host, but not on the head. [2] To move from one host to another it can swim freely in water column. [12] Adults can survive up to two weeks without feeding on a fish host. [4]
Argulus coregoni attaches itself to the host with suckers (maxillae) and hooks. The latter are abundant on the underside of the body. The suckers are used to tear the host skin. A. coregoni feed on the blood and mucus from the resulting wound. [4]
They bury their bodies into the scale pockets [12] and their flattened body shape allows them to sit closely against the body of the host, minimising drag and the risk of detachment. [13] The eggs of gravid females protrude from the fish scales. [12]
Like many ectoparasites, A. coregoni shows aggregation within the host population. [14] This means that some host individuals carry many parasites, but that most only carry a few. This appears to be due to differences in exposure rather than in susceptibility. [14] Indeed, it appears that host behaviour plays an important role in exposure and that certain hos behaviours make them more susceptible to infections. [15]
The antennule are divided into two parts. The abdomen has two lobes, but has no spines. [10]
Infected fish can show a range of symptoms, especially at heavier infections. The symptoms include scales peeling off, red spots at the site of infection, and reduced growth rates. [12] Fish can become weak, but Argulus coregoni does normally not cause host mortality. [12] In coinfections it can, however, increase host mortality in some host species. [16] Argulus coregoni infections do not lead to threats to natural fish populations. In fish farms the infections may case problems due to the lack of natural predators of the parasites, and the high density of fish. [4]
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.
A parasitic disease, also known as parasitosis, is an infectious disease caused by parasites. Parasites are organisms which derive sustenance from its host while causing it harm. The study of parasites and parasitic diseases is known as parasitology. Medical parasitology is concerned with three major groups of parasites: parasitic protozoa, helminths, and parasitic arthropods. Parasitic diseases are thus considered those diseases that are caused by pathogens belonging taxonomically to either the animal kingdom, or the protozoan kingdom.
Parasitology is the study of parasites, their hosts, and the relationship between them. As a biological discipline, the scope of parasitology is not determined by the organism or environment in question but by their way of life. This means it forms a synthesis of other disciplines, and draws on techniques from fields such as cell biology, bioinformatics, biochemistry, molecular biology, immunology, genetics, evolution and ecology.
Diphyllobothrium is a genus of tapeworms which can cause diphyllobothriasis in humans through consumption of raw or undercooked fish. The principal species causing diphyllobothriasis is D. latum, known as the broad or fish tapeworm, or broad fish tapeworm. D. latum is a pseudophyllid cestode that infects fish and mammals. D. latum is native to Scandinavia, western Russia, and the Baltics, though it is now also present in North America, especially the Pacific Northwest. In Far East Russia, D. klebanovskii, having Pacific salmon as its second intermediate host, was identified.
Ceratonova shasta is a myxosporean parasite that infects salmonid fish on the Pacific coast of North America. It was first observed at the Crystal Lake Hatchery, Shasta County, California, and has now been reported from Idaho, Oregon, Washington, British Columbia and Alaska.
Tetracapsuloides bryosalmonae is a myxozoan parasite of salmonid fish. It is the only species currently recognized in the monotypic genus Tetracapsuloides. It is the cause of proliferative kidney disease (PKD), one of the most serious parasitic diseases of salmonid populations in Europe and North America that can result in losses of up to 90% in infected populations.
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.
The Pentastomida are an enigmatic group of parasitic arthropods commonly known as tongue worms due to the resemblance of the species of the genus Linguatula to a vertebrate tongue; molecular studies point to them being highly-derived crustaceans.
Sea lice are copepods of the family Caligidae within the order Siphonostomatoida. They are marine ectoparasites that feed on the mucus, epidermal tissue, and blood of host fish. The roughly 559 species in 37 genera include around 162 Lepeophtheirus and 268 Caligus species.
Acanthocephalus is a genus of parasitic worms. One of the species in this genus is Acanthocephalus anguillae, a fish parasite. Acanthocephalans are also found in humans and primates, causing a common zoonotic infection called "human acanthocephaliasis". While pathogens can be transferred among animals and humans, the main source of human acanthocephaliasis is the diet of infected raw fish and insects. Because they are lacking circulatory, respiratory, and digestive systems, Acanthocephalus are exceptionally well-adapted to a symbiotrophic existence.
Paleoparasitology is the study of parasites from the past, and their interactions with hosts and vectors; it is a subfield of paleontology, the study of living organisms from the past. Some authors define this term more narrowly, as "Paleoparasitology is the study of parasites in archaeological material." K.J. Reinhard suggests that the term "archaeoparasitology" be applied to "... all parasitological remains excavated from archaeological contexts ... derived from human activity" and that "the term 'paleoparasitology' be applied to studies of nonhuman, paleontological material." This article follows Reinhard's suggestion and discusses the protozoan and animal parasites of non-human animals and plants from the past, while those from humans and our hominid ancestors are covered in archaeoparasitology.
Nanophyetus salmincola is a food-borne intestinal trematode parasite prevalent on the Pacific Northwest coast. The species may be the most common trematode endemic to the United States.
Like humans and other animals, fish suffer from diseases and parasites. Fish defences against disease are specific and non-specific. Non-specific defences include skin and scales, as well as the mucus layer secreted by the epidermis that traps microorganisms and inhibits their growth. If pathogens breach these defences, fish can develop inflammatory responses that increase the flow of blood to infected areas and deliver white blood cells that attempt to destroy the pathogens.
Argulus is a genus of fish lice in the family Argulidae. There are about 140 accepted species in the genus Argulus. They occur in marine, brackish, and freshwater environments. They sit tightly against the host body, this minimises risk of detachment. As juveniles, these species feed on mucous and skin cells of their host. With age they become blood feeders because the parasite moves from feeding on the fins to feeding on the body of the fish, causing the feeding change. At least some species can have severe impacts on their host populations.
Diseases and parasites in salmon, trout and other salmon-like fishes of the family Salmonidae are also found in other fish species. The life cycle of many salmonids is anadromous, so such fish are exposed to parasites in fresh water, brackish water and saline water.
Argulus foliaceus, also known as the common fish louse, is a species of fish lice in the family Argulidae. It is "the most common and widespread native argulid in the Palaearctic" and "one of the most widespread crustacean ectoparasites of freshwater fish in the world", considering its distribution and range of hosts. It can cause the severe disease state argulosis in a wide variety of fish species. It is responsible for epizootic outbreaks that have led to the collapse of aquaculture operations. Fish lice are not related to lice, which are insects.
Argulus japonicus, also known as the Japanese fish louse, is a species of crustacean in the family Argulidae. This species is light brown in colour and may be between 4 and 9 mm long and 3 to 6 mm wide. It has a stumpy tail, and is shaped somewhat like a round shield. The female and male are phenotypically distinct, categorizing them as a dioecious species. Although they are not drastically different, their transparent skin highlights the minor differences such as the different copulatory accessories.
Acanthocephalus dirus is a species of parasitic worm in the Echinorhynchidae family. Instead of having its eggs expelled from the host in feces, the gravid female detaches itself from the host's digestive tract and sinks to the bottom, where her body is consumed by the species' intermediate host, Caecidotea intermedius, a species of isopod. Upon hatching, the larvae begin to alter their host's behavior. This will manifest in lighter pigmentation and an increased attraction to predators, such as A. dirus' primary hosts.
Diphyllobothrium dendriticum is a large pseudophyllid cestode of the family Diphyllobothriidae.
Chonopeltis is a genus of fish lice in the subclass Branchiura. These crustaceans are ectoparasitic freshwater fish host. Species of this genus are exclusively found in rivers in Africa.
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