''Kudoa'' is a genus of

Myxozoa Myxozoa (etymology: Greek: μύξα ''myxa'' "slime" or "mucus" + thematic vowel o + ζῷον ''zoon'' "animal") is a subphylum of aquatic cnidarian animals – all obligate parasites. It contains the smallest animals ever known to have lived. O ...

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 An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environment ...

fish. ''Kudoa'' are most commonly known and studied for the negative effects the genus has on

commercial fishing Commercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice it as an industry must often ...

and

aquaculture Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. lot ...

industries.

Description

The genus ''Kudoa'' is identified by the possession of four or more shell valves composed of a fragile membrane and arranged in a quadrate or stellate pattern. The maximum number of shell valves in any described ''Kudoa'' species is 13. Each of these valves has a

polar capsule Polar capsules are structures found in the valves of Myxosporean parasites, which contain the polar filament. The polar capsule is constructed of a proteinaceous and a polysaccharide layer, both layers of which continue into the polar filament. ...

. The genus ''Kudoa'' was originally part of the genus '' Chloromyxum'' because of the distribution of their polar capsules, however, it was later determined to be a separate genus. Each ''Kudoa'' has two

sporoplasm Sporoplasm is an infectious material present in the cytoplasm of various fungi-like organisms, such as members of class ''Microsporidia''. Sporoplasm is defined as a mass of protoplasm that gives rise to or forms a spore. The protoplasmic body t ...

cells, one enclosed by the other. Most ''Kudoa'' are histozoic parasites, with a few species being described as coelzoic. Some

taxonomists In biology, taxonomy () is the scientific study of naming, defining ( circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxa (singular: taxon) and these groups are given ...

question whether these coelzoic organisms belong to a separate genus. There are approximately 100 described species of ''Kudoa'' which can be found in the

Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe an ...

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

, and Indian oceans.

Species

The following species are recognized in the genus ''Kudoa'': * ''

Kudoa aequidens ''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 stu ...

'' Casal, Matos, Matos & Azevedo, 2008 * '' Kudoa akihitoi'' Kasai, Setsuda & Sato, 2017 * '' Kudoa alliaria'' Kovaleva, Shulman & Yakolev, 1979 * ''

Kudoa amamiensis ''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 studi ...

'' Egusa & Nakajima, 1978 * ''

Kudoa azoni ''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 studi ...

'' Aseeva, 2004 * ''

Kudoa barracudai ''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 studi ...

'' Abdel-Baki, Al-Quraishy, Omar & Mansour, 2016 * ''

Kudoa boopsi ''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 studi ...

'' Kpatcha, Diebakate, Faye & Toguebaye, 1999 * ''

Kudoa bora ''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 studi ...

'' (Fujita, 1930) * ''

Kudoa camarguensis ''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 studi ...

'' Pampoulie, Marques, Crivelli & Boucherau, 1999 * ''

Kudoa cascasia ''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 studi ...

'' Sarkar & Chaudry, 1996 * ''

Kudoa caudata ''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 studi ...

'' Kovaleva & Gaevskaya, 1983 * ''

Kudoa chaetodoni ''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 studi ...

'' Burger, Cribb & Adlard, 2007 * ''

Kudoa chilkaensis ''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 studi ...

'' Tripathi, 1951 * ''

Kudoa ciliatae ''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 stu ...

'' Lom, Rohde & Dyková, 1992 * '' Kudoa clupeidae'' (Hahn, 1917) * '' Kudoa crumena'' Iversen & van Meter, 1967 * '' Kudoa cynoglossi'' Obiekezie & Lick, 1994 * ''

Kudoa dianae ''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 st ...

'' Dyková, Fajer & Fiala, 2002 * '' Kudoa empressmichikoae'' Kasai, Setsuda & Sato, 2017 * '' Kudoa funduli'' Hahn, 1915 * ''

Kudoa grammatorcyni ''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 studi ...

'' Adlard, Bryant, Whipps & Kent, 2005 * ''

Kudoa hexapunctata ''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 Parasitism, parasitize on Marine life, marine and Estuary, estuarine fish. ''Kudoa'' ...

'' Yokoyama, Suzuki & Shirakashi, 2014 * '' Kudoa histolytica'' (Pérard, 1928) * '' Kudoa hypoepicardialis'' Blaylock, Bullard & Whipps, 2004 * '' Kudoa inornata'' Dykova, de Buron, Fiala, Roumillat, 2009 * ''

Kudoa insolita ''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 st ...

'' Shulman & Kovalijova, 1979 * '' Kudoa intestinalis'' Maeno, Magasawa & Sorimachi, 1993 * ''

Kudoa islandica ''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 studi ...

'' Kristmundsson & Freeman, 2014 * ''

Kudoa iwatai ''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 studi ...

'' Egusa & Shiomitsu, 1983 * '' Kudoa kabatai'' Shulman & Kovalijova, 1979 * ''

Kudoa kenti ''Kudoa kenti'' is a myxosporean parasite of marine fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish a ...

'' Burger & Adlard, 2009 * '' Kudoa lateolabracis'' Yokoyama, Whipps, Kent, Mizuno & Kawakami, 2004 * '' Kudoa leiostomi'' Dyková, Lom & Overstreet, 1994 * '' Kudoa lemniscati'' Miller & Adlard, 2012 * '' Kudoa leptacanthae'' Heiniger & Adlard, 2012 * '' Kudoa lethrini'' Burger, Cribb & Adlard, 2007 * '' Kudoa lunata'' Lom, Dyková & Lhotákova, 1983 * '' Kudoa lutjanus'' Wang, Huang, Tsai, Cheng, Tsai, Chen, Chen, Chiu, Liaw, Chang & Chen, 2005 * '' Kudoa megacapsula'' Yokoyama & Itoh, 2005 * ''

Kudoa miniauriculata ''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 studi ...

'' Whitaker, Kent & Sakanari, 1996 * '' Kudoa minithyrsites'' Whipps, Adlard, Bryant, Lester, Findlay & Kent, 2003 * '' Kudoa mirabilis'' Naidenova & Gaevskaya, 1991 * ''

Kudoa monodactyli ''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 st ...

'' Gunter, Cribb, Whipps & Adlard, 2006 * ''

Kudoa muscularis ''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 studi ...

'' (Cheung, Nigrellu & Ruggieri, 1983) * '' Kudoa musculoliquefaciens'' (Matsumoto & Arai, 1954) * ''

Kudoa neothunni ''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 studi ...

'' (Arai & Matsumoto, 1953) * ''

Kudoa nova ''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 st ...

'' Naidenova, 1975 * ''

Kudoa obicularis ''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 studi ...

'' Azevedo, Rocha, Matos, Oliveira, Matos, Al-Quraishy & Casal, 2015 * ''

Kudoa ovivora ''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 studi ...

'' Swearer & Robertson, 1999 * '' Kudoa paniformis'' Kabata & Whitaker, 1981 * ''

Kudoa paralichtys ''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 studi ...

'' Cho & Kim, 2003 * '' Kudoa paraquadricornis'' Burger & Adlard, 2009 * '' Kudoa parathyrsites'' Kasai, Li, Mafie & Sato, 2016 * '' Kudoa pericardialis'' Nakajima & Egusa, 1978 * '' Kudoa permulticapsula'' Whipps, Adlard, Bryant & Kent, 2003 * ''

Kudoa quadratum ''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 studi ...

'' (Thélohan, 1895) * '' Kudoa quadricornis'' Whipps, Adlard, Bryant & Kent, 2003 * '' Kudoa rosenbuschi'' (Gelormini, 1966) * '' Kudoa sciaenae'' Teran, Llicán & Lugue, 1990 * ''

Kudoa septempunctata ''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 stu ...

'' * ''

Kudoa scomberomori ''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 studi ...

'' Adlard, Bryant, Whipps & Kent, 2005 * ''

Kudoa sebastea ''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 studi ...

'' Aseeva, 2004 * '' Kudoa shkae'' Dyková, Lom & Overstreet, 1994 * '' Kudoa sphyraeni'' Narasimhamurti & Kalavati, 1979 * ''

Kudoa stellula ''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 studi ...

'' Yurakhno, 1991 * '' Kudoa tachysurae'' Sarkar & Mazumder, 1983 * '' Kudoa tetraspora'' Narasimhamurti & Kalavati, 1979 * ''

Kudoa thalassomi ''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 studi ...

'' Adlard, Bryant, Whipps & Kent, 2005 * '' Kudoa thyrsites'' (Gilchrist, 1924) *''Kudoa thunni'' (Matsukane, Sato, Tanaka, Kamata & Sugita-Konishi, 2011) Five additional species have been proposed, but are not yet widely recognized: * '' Kudoa azevedoi'' Mansour, Thabet, Chourabi, Harrath, Gtari, Omar & Hassine, 2013 * ''

Kudoa cheilodipteri ''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 studi ...

'' Heiniger, Cribb & Adlard, 2013 * '' Kudoa cookii'' Heiniger, Cribb & Adlard, 2013 * '' Kudoa gunterae'' Burger & Adlard, 2009 * '' Kudoa whippsi'' Burger & Adlard, 2009

Development

In Myxozoan development, the

Myxosporea 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 (generally an annelid but sometimes a bryozoan) ...

n life-stage develops inside a fish host, while the Actinosporean life-stage develops in an

annelid The annelids (Annelida , from Latin ', "little ring"), also known as the segmented worms, are a large phylum, with over 22,000 extant species including ragworms, earthworms, and leeches. The species exist in and have adapted to various ecol ...

host. Fully-developed Myxospores are consumed by annelids and reproduce asexually via schzogony in the gut

epithelium Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellul ...

of worms.

Gamete A gamete (; , ultimately ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. In species that produce t ...

s are formed in the gut of the worm and these gametes fuse together to create eight

zygote A zygote (, ) is a eukaryotic cell formed by a fertilization event between two gametes. The zygote's genome is a combination of the DNA in each gamete, and contains all of the genetic information of a new individual organism. In multicellula ...

s. The zygotes become spores with three valves, 3 polar capsules, and a

that are released in the worm's feces and attach to the surface of a fish host. Once attached to the fish, the gamete injects the sporoplasm cell into the fish. The sporoplast divides forming a fully-developed Myxosporean.

Diet

''Kudoa'' parasitize on marine and estuarine fish. ''Kudoa'' typically feed on the

skeletal muscle Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of muscl ...

tissue, although some may feed on other parts of the body such as the

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all par ...

heart The heart is a muscular organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide t ...

intestines The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans ...

ovaries The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the body. T ...

, or

gills A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...

. Most ''Kudoa'' are histozoic parasites, however, a few species are coelzoic. The genus ''Kudoa'' attack a wide range of hosts, however, individual species only feed on specific hosts. ''Kudoa'' feed via

pinocytosis In cellular biology, pinocytosis, otherwise known as fluid endocytosis and bulk-phase pinocytosis, is a mode of endocytosis in which small molecules dissolved in extracellular fluid are brought into the cell through an invagination of the cell ...

across the host-parasite membrane. One species of ''Kudoa, K. thyrsites,'' are distributed worldwide and are believed to have been reported in over 20 different species of fish but it is possible that the species described as ''K. thyrsites'' is actually multiple different species.

Implications for the fishing industry

''Kudoa'' are most well-known for the economic loss they cause for the commercial fishing and aquaculture industries. When ''Kudoa'' attach to hosts, they leave unsightly

cyst A cyst is a closed sac, having a distinct envelope and cell division, division compared with the nearby Biological tissue, tissue. Hence, it is a cluster of Cell (biology), cells that have grouped together to form a sac (like the manner in which ...

s that lower the price fish can be sold for at market. ''Kudoa'' also release

proteolytic Proteolysis is the breakdown of proteins into smaller polypeptides or amino acids. Uncatalysed, the hydrolysis of peptide bonds is extremely slow, taking hundreds of years. Proteolysis is typically catalysed by cellular enzymes called proteases, ...

enzymes that degenerate muscle in fish to aid in their own growth and development, further decreasing the fish's value. Some species in the genus ''Kudoa'' with the most notable effects of the commercial fishing and aquaculture industries are: '' K. musculoliquefaciens'' in Broadbill Swordfish ('' Xiphias gladius''), '' K. thyrsites'' in Atlantic Salmon (''

Salmo salar The Atlantic salmon (''Salmo salar'') is a species of ray-finned fish in the family Salmonidae. It is the third largest of the Salmonidae, behind Siberian taimen and Pacific Chinook salmon, growing up to a meter in length. Atlantic salmon are ...

''), '' K. clupeidae'' in Atlantic Herring (''

Clupea harengus Atlantic herring (''Clupea harengus'') is a herring in the family Clupeidae. It is one of the most abundant fish species in the world. Atlantic herrings can be found on both sides of the Atlantic Ocean, congregating in large schools. They can ...

''), '' K. septempunctata'' in Olive Flounder (''

Paralichthys olivaceus The olive flounder (''Paralichthys olivaceus''), bastard halibut or Japanese halibut, is a temperate marine species of large-tooth flounder native to the North-western Pacific Ocean. It is often referred to as the Japanese flatfish or Korean fla ...

''), ''K. thunni'' in Yellowfin Tuna (''

Thunnus albacares The yellowfin tuna (''Thunnus albacares'') is a species of tuna found in pelagic waters of tropical and subtropical oceans worldwide. Yellowfin is often marketed as ahi, from the Hawaiian , a name also used there for the closely related bigeye t ...

'') and '' K. paniformis'' in Pacific Hake (''

Merluccius productus The North Pacific hake, Pacific hake, Pacific whiting, or jack salmon (''Merluccius productus'') is a ray-finned fish in the genus '' Merluccius'', found in the northeast Pacific Ocean from northern Vancouver Island to the northern part of the Gu ...

''). Some studies have found evidence to suggest that some species of ''Kudoa'' are linked to

food-borne illness Foodborne illness (also foodborne disease and food poisoning) is any illness resulting from the spoilage of contaminated food by pathogenic bacteria, viruses, or parasites that contaminate food, as well as prions (the agents of mad cow disease ...

in humans.

References

Encyclopedia of Life
{{Taxonbar, from1=Q16984015, from2=Q16890140 Kudoidae Cnidarian genera