Bucephalus polymorphus

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Bucephalus polymorphus
Bucephalus EncBrit1911.png
Cercaria larva of B. polymorphus from Encyclopædia Britannica, Eleventh Edition
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Platyhelminthes
Class: Trematoda
Order: Plagiorchiida
Family: Bucephalidae
Genus: Bucephalus
Species:
B. polymorphus
Binomial name
Bucephalus polymorphus
Baer, 1827

Bucephalus polymorphus is a type of flatworm. This species is within the Bucephalidae family of Digenea, which in turn is a subclass of Trematodes within the phylum Platyhelminthes (i.e. flatworm). It is characterized by having a mouth near the middle of its body, along with a sac-like gut. The mouth opening is located in the centre of the ventral surface. This is a specific body type of cecaria known as a gastrostome.

Contents

The adults occur in the gut of marine and fresh-water fish. The metacercariae encyst in smaller fish, sometimes in the nervous system. These parasitic flatworms are dorso-ventrally flattened animals [1] characterized by a bilaterally symmetrical body enclosed within a syncytial tegument. They have a distal, anucleate later (distal cytoplasm). The distal cytoplasm contains vesicular inclusions that are Golgi derived. [2] The adults of these acoelomate worms are common in the digestive tract, but are also found in other organs of vertebrates. The adult parasite attaches via a characteristic anterior adhesive organ with tentacles. This organ is recognized as a holdfast, which helps Bucephalus to stay attached to the host's organs. [3] Bucephalus are native to North American fresh waters that parasitize freshwater bivalves. [4]

Taxonomy

Bucephalid cercaria larva from Ernst Haeckel's Kunstformen der Natur (1904). Haeckel Platodes Bucephalus.png
Bucephalid cercaria larva from Ernst Haeckel's Kunstformen der Natur (1904).

The genus Bucephalus was based on this species, which was the earliest known, initially described by Baer (1827) from its cercaria. Von Siebold (1848) believed that the adult bucephalid he named Gasterostomum fimbriatum represented an adult form of the same bucephalid, but this identity has never been proven. [5]

Life cycle

Dignetic flatworm species require more than one host to complete a full life cycle. Bucephalus polymorphus requires three hosts. Dreissena polymorpha, a small freshwater mussel, is the first intermediate host parasitized by the hatching miracidium. Within the visceral mass of Dreissena, the miracidium transforms into a mother (primary) sporocyst. Asexual reproduction produces many daughter (secondary) sporocysts which are called cecariacysts, that eventually release cercariae. Unlike most digenetic trematodes, Bucephalus Polymorphus lacks a redial stage and thus emerges as a cecaria directly from the sporocyst stage. Rapid proliferation of sporocysts results in a knotted white mass of tubules, which is found primarily in the gonads of the mussel. Released from the infected mussels, cercariae attach to fish (second intermediate host), encyst, and transforms into metacercariae. The third (definitive) hosts are predatory fish that consume the infected foraging fish. [6] It has been shown experimentally that cercarial emergence exhibits a circadian rhythm of shedding with a peak in the dark period of a light:dark 12:12 h photoperiod. [7] Bucephaluslifecycle.jpg

Influence on Host

Bucephalus polymorphus is a parasite residing exclusively in host connective tissues. The gonads of its first intermediate host, Dreissena, is the primary target of infection and sporocyst proliferation. As infection intensifies, the sporocyst develops branches through connective tissue passages, emerges from the gonads, and can spread into other body regions. Such secondary sites of infection have been previously reported to occur in the digestive glands, the gills, the bundles of adductor muscle, and the mantle epithelium lining the interior of the shells. [4] [8] [9] The study found that the digestive glands of infected bivalves appeared to be relatively normal when compared to full bodied, uninfected specimens. Within the sporocyst, the cercariae existed within a wide range of developmental stages, indicating that its development is asynchronous. It was also observed that heavy infection of the parasite led to host castration, which left the entire gonadal space often occupied by the sporocysts. By limiting the infection almost exclusively to the gonads, the parasites have developed an interesting strategy to only use the reproductive energy of their hosts, thereby minimizing the risk of host mortality. Extending the life of a bucephalus infected host is important because this allows the parasite to proliferate continuously from year to year, since infected gonads produce cercariae instead of gametes. [10] The location of the sporocyst (primarily in gonads), its overall shape, irregular branches, and the morphology of its cercariae with a bifurcated tail, distinguish B. polymorphus from other trematode parasites of zebra mussels in histological sections.

Prevalence

Infection of B. polymorphus is geographically widely distributed. However, prevalence of infection in zebra mussel population is not common. [11] A study by Lajtner et al., which surveyed the zebra mussel population in the Drava River in Croatia, found a prevalence of 21.3%. In the most extensive study conducted to date, a prevalence of 73% was recorded in zebra mussel in South-Eastern France. [12] Low rates of prevalence were also recorded: 1% (Kuperman et al. 1994), [13] 1–4% (Baturo 1977), [9] 2–5% (Smirnova and Ibrasheva 1967), [14] 9% (Malloy et al. 1996), [4] and 13–28% (de Kinkelin et al. 1968). [8] Therefore, the prevalence of Bucephalus polymorphus can vary widely depending on the ecosystem.

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<span class="mw-page-title-main">Trematoda</span> Class of parasitic flatworms

Trematoda is a class of flatworms known as flukes or trematodes. They are obligate internal parasites with a complex life cycle requiring at least two hosts. The intermediate host, in which asexual reproduction occurs, is usually a snail. The definitive host, where the flukes sexually reproduce, is a vertebrate. Infection by trematodes can cause disease in all five traditional vertebrate classes: mammals, birds, amphibians, reptiles, and fish.

<i>Clonorchis sinensis</i> Species of fluke

Clonorchis sinensis, the Chinese liver fluke, is a liver fluke belonging to the class Trematoda, phylum Platyhelminthes. It infects fish-eating mammals, including humans. In humans, it infects the common bile duct and gall bladder, feeding on bile. It was discovered by British physician James McConnell at the Medical College Hospital in Calcutta (Kolkata) in 1874. The first description was given by Thomas Spencer Cobbold, who named it Distoma sinense. The fluke passes its lifecycle in three different hosts, namely freshwater snail as first intermediate hosts, freshwater fish as second intermediate host, and mammals as definitive hosts.

<span class="mw-page-title-main">Digenea</span> Class of flukes

Digenea is a class of trematodes in the Platyhelminthes phylum, consisting of parasitic flatworms with a syncytial tegument and, usually, two suckers, one ventral and one oral. Adults commonly live within the digestive tract, but occur throughout the organ systems of all classes of vertebrates. Once thought to be related to the Monogenea, it is now recognised that they are closest to the Aspidogastrea and that the Monogenea are more closely allied with the Cestoda. Around 6,000 species have been described to date.

<i>Fasciola hepatica</i> Species of fluke

Fasciola hepatica, also known as shreya or the common liver fluke or sheep liver fluke, is a parasitic trematode of the class Trematoda, phylum Platyhelminthes. It infects the livers of various mammals, including humans, and is transmitted by sheep and cattle to humans all over the world. The disease caused by the fluke is called fasciolosis or fascioliasis, which is a type of helminthiasis and has been classified as a neglected tropical disease. Fasciolosis is currently classified as a plant/food-borne trematode infection, often acquired through eating the parasite's metacercariae encysted on plants. F. hepatica, which is distributed worldwide, has been known as an important parasite of sheep and cattle for decades and causes significant economic losses in these livestock species, up to £23 million in the UK alone. Because of its relatively large size and economic importance, it has been the subject of many scientific investigations and may be the best-known of any trematode species. F. hepatica's closest relative is Fasciola gigantica. These two flukes are sister species; they share many morphological features and can mate with each other.

<span class="mw-page-title-main">Trematode life cycle stages</span>

Trematodes are parasitic flatworms of the class Trematoda, specifically parasitic flukes with two suckers: one ventral and the other oral. Trematodes are covered by a tegument, that protects the organism from the environment by providing secretory and absorptive functions.

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<i>Echinostoma</i> Genus of flukes

Echinostoma is a genus of trematodes (flukes), which can infect both humans and other animals. These intestinal flukes have a three-host life cycle with snails or other aquatic organisms as intermediate hosts, and a variety of animals, including humans, as their definitive hosts.

<i>Leucochloridium paradoxum</i> Parasitic flatworm

Leucochloridium paradoxum, the green-banded broodsac, is a parasitic flatworm. Its intermediate hosts are land snails, usually of the genus Succinea. The pulsating, green broodsacs fill the eye stalks of the snail, thereby attracting predation by birds, the primary host. These broodsacs visually imitate caterpillars, a prey of birds. The adult parasite lives in the bird's cloaca, releasing its eggs into the faeces.

Metagonimoides oregonensis is a trematode, or fluke worm, in the family Heterophyidae. This North American parasite is found primarily in the intestines of raccoons, American minks, frogs in the genus Rana, and freshwater snails in the genus Goniobasis. It was first described in 1931 by E. W. Price. The parasite has a large distribution, from Oregon to North Carolina. Adult flukes vary in host range and morphology dependent on the geographical location. This results in different life cycles, as well as intermediate hosts, across the United States. On the west coast, the intermediate host is freshwater snails (Goniobasis), while on the east coast the intermediate host is salamanders (Desmognathus). The parasites on the west coast are generally much larger than on the east coast. For example, the pharynx as well as the body of the parasite are distinctly larger in Oregon than in North Carolina. The reverse pattern is observed on the east coast for uterine eggs, which are larger on the west coast. In snails, there is also a higher rate of infection in female snails than in males. Research on the life history traits of the parasites have been performed with hamsters and frogs as model species.

<i>Leucochloridium variae</i> Species of fluke

Leucochloridium variae, the brown-banded broodsac, is a species of trematode whose life cycle involves the alternate parasitic infection of certain species of snail and bird. While there is no external evidence of the worm's existence within the bird host, the infection of the snail host is visible when its eye stalks become grotesquely engorged with the parasite's brood sacs. These brood sacks pulsate and move to imitate insect larva, attracting the parasite's next host, insectivore birds. The bird rips off the eye stalk and eats it, thus becoming infected. Later on, the parasite's eggs are dropped with the bird's feces. Similar life-histories are found in other species of the genus Leucochloridium, including Leucochloridium paradoxum.

<i>Nanophyetus</i> Genus of flukes

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.

<i>Echinostoma revolutum</i> Species of fluke

Echinostoma revolutum is a trematode parasite of which the adults can infect birds and mammals, including humans. In humans, it causes echinostomiasis.

<i>Heterophyes heterophyes</i> Species of fluke

Heterophyes heterophyes, or the intestinal fish fluke, was discovered by Theodor Maximaillian Bilharz in 1851. This parasite was found during an autopsy of an Egyptian mummy. H. heterophyes is found in the Middle East, West Europe and Africa. They use different species to complete their complex lifestyle. Humans and other mammals are the definitive host, first intermediate host are snails, and second intermediate are fish. Mammals that come in contact with the parasite are dogs, humans, and cats. Snails that are affected by this parasite are the Cerithideopsilla conica. Fish that come in contact with this parasite are Mugil cephalus, Tilapia milotica, Aphanius fasciatus, and Acanthgobius sp. Humans and mammals will come in contact with this parasite by the consumption of contaminated or raw fish. This parasite is one of the smallest endoparasite to infect humans. It can cause intestinal infection called heterophyiasis.

Echinostoma hortense is an intestinal fluke of the class Trematoda, which has been found to infect humans in East Asian countries such as Korea, China, and Japan. This parasite resides in the intestines of birds, rats and other mammals such as humans. While human infections are very rare in other regions of the world, East Asian countries have reported human infections up to about 24% of the population in some endemic sub-regions. E. hortense infections are zoonotic infections, which occurs from eating raw or undercooked freshwater fish. The primary disease associated with an E. hortense infection is called echinostomiasis, which is a general name given to diseases caused by Trematodes of the genus Echinostoma.

<i>Clinostomum marginatum</i> Species of fluke

Clinostomum marginatum is a species of parasitic fluke. It is commonly called the "Yellow grub". It is found in many freshwater fish in North America, and no fish so far is immune to this parasite. It is also found in frogs. Clinostomum marginatum can also be found in the mouth of aquatic birds such as herons and egrets. They are commonly present in the esophagus of fish-eating birds and reptiles. Eggs of these trematodes are shed in the feces of aquatic birds and released into water. Aquatic birds become hosts of this parasite by ingesting infected freshwater fish. The metacercariae are found right beneath the skin or in the muscles of host fish.

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Coitocaecum parvum is a digeneic trematode or flatworm (Platyhelminthes) that is parasitic to the intestine of the common bully or upland bully. The common and upland bully are freshwater fish of New Zealand that C. parvum uses as its definitive host. C. parvum is a hermaphroditic freshwater trematode that can omit its definitive host and produce eggs by selfing or progenesis inside its amphipod second intermediate host.

<i>Bucephalus</i> (flatworm) Genus of flukes

Bucephalus is the genus name for many trematode flatworms that are parasites of molluscs and fish. Like other Bucephalidae, they are found in fish both as adults and as metacercariae. In marine and freshwater teleosts, they live as parasites inside the digestive tract, especially the intestine.

<i>Alaria</i> (flatworm) Genus of flukes

Alaria is a genus of flatworms, or trematodes, in the family Diplostomidae.

<i>Metagonimus yokogawai</i> Species of fluke

Metagonimus yokogawai, or the Yokogawa fluke, is a species of a trematode, or fluke worm, in the family Heterophyidae.

References

  1. ↑ "Platyhelminthes -- Encylopedic Reference of Parasitology". Archived from the original on 2009-03-12. Retrieved 2009-05-08.
  2. ↑ G. Schmidt and L. Roberts: Foundations of Parasitology (Seventh Ed.) McGraw-Hill. New York, NY, 2005.
  3. ↑ Yamaguti, S.: Synopsis of digenetic trematodes of vertebrates Keigaku Publishing Company. Tokyo, 1971.
  4. 1 2 3 Malloy et al.: "Survey of the Parasites of Zebra Mussels (Bivalvia: Dreissenidae) in Northwestern Russia, with Comments on Records of Parasitism in Europe and North America." J. Helminthol. Soc. Wash. 63(2), 1996, pp. 251–256
  5. ↑ Gibson, David Ian (2002). Keys to the Trematoda. CABI. pp. 74–75. ISBN   0-85199-547-0.
  6. ↑ Malloy et al.: “Natural Enemies of Zebra Mussels: Predators, Parasites, and Ecological Competitors”. Dreissena: Zebra Mussel Information Clearinghouse. 7(6), Winter-Spring 1997.
  7. ↑ Smyth, J. D.; Wakelin, Derek (1994-11-24). Introduction to Animal Parasitology. ISBN   9780521428118.
  8. 1 2 de Kinkelin et al.: "Etude epizootiologique de la bucephalose larvaire a Bucephalus polymorphus (Baer 1827) dans le peuplement piscicole du bassin de la Seine." Recherches Veterinaires, 1, 77–98, 1968
  9. 1 2 Baturo B.: "Bucephalus polymorphus Baer, 1827 and Rhipidocotyle illense (Ziegler, 1883)(Trematoda, Bucephalidae): morphology and biology of developmental stages." Acta Parasitologica Polonica, 24, 203–220, 1977.
  10. ↑ Taskinen et al.: "Studies on bucephalid digeneans parasitising molluscs and fishes in Finland. I. Ecological data and experimental studies." Systematic Parasitology, 19:81-94, 1991.
  11. ↑ Lajtner et al.: "The effects of the trematode Bucephalus polymorphus on the reproductive cycle of the zebra mussel Dreissena polymorpha in the Drana River." Acta Parasitologica, 53(1), 85–92, 2008.
  12. ↑ Wallet M., Lambert A. "Enquete sur la repartition et l'evolution du parasitisme a Bucephalus polymorphus Baer, 1827 chez le mollusque Dreissena polymorpha dans le sud-est de la France." Bulletin Francais de la Peche et de la Pisciculture, 300, 19–24, 1986.
  13. ↑ Kuperman et al. "Parasites of Dreissena polymorpha (Pallas) molluscs of the Volga basin." Parazitologiya, 28, 396–402, 1994.
  14. ↑ Smirnova and Ibrasheva: "Larval trematodes from freshwater molluscs in the western Kazakhstan." Trudy Instituta Zoologii Akademii Nauk Kazakhskoy SSR, 27, 53–87, 1967.
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