The three-spined stickleback is a fish native to most inland and coastal waters north of 30°N. It has long been a subject of scientific study for many reasons. It shows great morphological variation throughout its range, ideal for questions about evolution and population genetics. Many populations are anadromous and very tolerant of changes in salinity, a subject of interest to physiologists. It displays elaborate breeding behavior and it can be social making it a popular subject of inquiry in fish ethology and behavioral ecology. Its antipredator adaptations, host-parasite interactions, sensory physiology, reproductive physiology, and endocrinology have also been much studied. Facilitating these studies is the fact that the three-spined stickleback is easy to find in nature and easy to keep in aquaria.
Myxosporea is a class of microscopic parasites, belonging to the Myxozoa clade within Cnidaria. They have a complex life cycle which comprises vegetative forms in two hosts, an aquatic invertebrate and an ectothermic vertebrate, usually a fish. Each host releases a different type of spore. The two forms of spore are so different that until relatively recently they were treated as belonging to different classes within the Myxozoa.
Microsporidia are a group of spore-forming unicellular parasites. These spores contain an extrusion apparatus that has a coiled polar tube ending in an anchoring disc at the apical part of the spore. They were once considered protozoans or protists, but are now known to be fungi, or a sister group to fungi. These fungal microbes are obligate eukaryotic parasites that use a unique mechanism to infect host cells. They have recently been discovered in a 2017 Cornell study to infect Coleoptera on a large scale. So far, about 1500 of the probably more than one million species are named. Microsporidia are restricted to animal hosts, and all major groups of animals host microsporidia. Most infect insects, but they are also responsible for common diseases of crustaceans and fish. The named species of microsporidia usually infect one host species or a group of closely related taxa. Approximately 10 percent of the species are parasites of vertebrates —several species, most of which are opportunistic, can infect humans, in whom they can cause microsporidiosis.
A xenoma is a growth caused by various protists and fungi, most notably microsporidia. It can occur on numerous organisms; however is predominantly found on fish.
Enterocytozoon bieneusi is a species of the order Chytridiopsida which infects the intestinal epithelial cells. It is an obligate intracellular parasite.
Loma is a genus of microsporidian parasites, infecting fish. The taxonomic position of Loma in the family Glugeidae has been questioned by DNA sequencing results.
Schistocephalus solidus is a tapeworm of fish, fish-eating birds and rodents. This hermaphroditic parasite belongs to the Eucestoda subclass, of class Cestoda. This species has been used to demonstrate that cross-fertilization produces a higher infective success rate than self-fertilization.
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.
Huffmanela is a genus of parasitic nematodes, belonging to the family Trichosomoididae.
Kudoa is a genus of Myxozoa and the only genus recognized within the monotypic family Kudoidae. There are approximately 100 species of Kudoa all of which parasitize on marine and estuarine fish. Kudoa are most commonly known and studied for the negative effects the genus has on commercial fishing and aquaculture industries.
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.
Hamiltosporidium is a genus of Microsporidia, which are intracellular and unicellular parasites. The genus, proposed by Haag et al. in 2010, contains two species; Hamiltosporidium tvaerminnensis, and Hamiltosporidium magnivora. Both species infect only the crustacean Daphnia magna (Waterflea).
Ceratomyxa whippsi is a myxosporean parasite that infects gall-bladders of serranid fishes from the Great Barrier Reef. It was first found on Cephalopholis boenak.
Nematocida parisii is a parasitic species of Microsporidia fungi found in wild isolates of the common nematode, Caenorhabditis elegans. The fungus forms spores and replicates in the intestines before leaving the host.
Philasterides dicentrarchi is a marine protozoan ciliate that was first identified in 1995 after being isolated from infected European sea bass reared in France. The species was also identified as the causative agent of outbreaks of scuticociliatosis that occurred between summer 1999 and spring 2000 in turbot cultivated in the Atlantic Ocean. Infections caused by P. dicentrarchi have since been observed in turbot reared in both open flow and recirculating production systems. In addition, the ciliate has also been reported to cause infections in other flatfishes, such as the olive flounder in Korea and the fine flounder in Peru, as well as in seadragons, seahorses, and several species of sharks in other parts of the world.
František Moravec is a Czech parasitologist who specialises on the Nematodes, especially the nematodes parasites of fishes. His research is mainly in the field of taxonomy of the Nematoda.
Enterospora nucleophila is a microsporidian infecting the gilt-head bream. It develops primarily within the nuclei of rodlet cells and enterocytes, at the intestinal epithelium. It can also be found in cytoplasmic position within other cell types, including phagocytes, at subepithelial layers. It is the causative agent of emaciative microsporidiosis of gilthead sea bream, a chronic condition manifested as a severe growth arrestment, normally accompanied by trickling mortality.
Carlos José Correia de Azevedo is a Portuguese biologist specialising in microparasites of aquatic organisms, particularly Apicomplexa, Haplosporidia, Microsporidia, and Myxozoa.
