Clonorchis sinensis, commonly known as the Human liver fluke or the Chinese liver fluke is a flatworm. Scientific classification or biological classification is how biologists group and categorize extinct and living species of organisms. ... Phyla Porifera (sponges) Ctenophora (comb jellies) Cnidaria (coral, jellyfish, anenomes) Placozoa (trichoplax) Subregnum Bilateria (bilateral symmetry) Acoelomorpha (basal) Orthonectida (flatworms, echinoderms, etc. ... Classes Monogenea Trematoda Cestoda Turbellaria The flatworms (Platyhelminthes, Greek platy: flat; helminth: worm) are a phylum of relatively simple soft-bodied invertebrate animals. ... Subclasses Aspidogastrea Digenea The Trematoda is a class within the phylum Platyhelminthes, which contains two groups of parasitic worms. ... In biology, binomial nomenclature refers to the formal method of naming species. ... Classes Monogenea Trematoda Cestoda Turbellaria The flatworms (Platyhelminthes, Greek platy: flat; helminth: worm) are a phylum of relatively simple soft-bodied invertebrate animals. ...

Life cycle

The egg of a Clonorchis sinensis (commonly: Human Liver Fluke), which contains the miracidium that develops into the adult form, floats in freshwater until it is eaten by a snail. Liver flukes are a polyphyletic group of a trematodes (a kind of flatworm). ...

Once inside of the snail body, the miracidium hatches from the egg, and parasitically grows inside of the snail. The miracidium develops into a sporocyst, which in turn house the asexual reproduction of redia, the next stage. The redia themselves house the asexual reproduction of free-swimming cercaria. This system of asexual reproduction allows for an exponential multiplication of cercaria individuals from one miracidium. This aids the Clonorchis in reproduction, because it enables the miracidium to captilatize on one chance occasion of passively being eaten by a snail before the egg dies. Asexual reproduction in liverworts: a caducuous phylloid germinating Asexual reproduction is the simplest form of reproduction and does not involve meiosis, gamete formation, or fertilization. ...

Once the redia mature, having grown inside the snail body until this point, they actively bore out of the snail body into the freshwater environment. There, instead of waiting to be consumed by a host (as is the case in their egg stage), they seek out a fish. Boring their way into the fish's body, they again become parasites of their new hosts.

Once inside of the fish muscle, the cercaria create a protective metacercarial cyst with which to encapsulate their bodies. This protective cyst proves useful when the fish muscle is consumed by a human. The acid-resistant cyst enables the metacercaria avoid being digested by the human gastric acids, and allows the metacercaria to reach the small intestine unharmed. Reaching the small intestines, the metacercaria navigate toward the human liver, which becomes its final habitat. Clonorchis feed on human bile created by the liver. In the human liver, the mature Clonorchis reaches its stage of sexual reproduction. The hemaphroditic adults produce eggs every 1 - 30 seconds, resulting in the rapid multiplication of inhabitants in the liver. Diagram showing the small intestine In biology the small intestine is the part of the gastrointestinal tract between the stomach and the large intestine (colon). ... Bile (or gall) is a bitter, greenish-yellow alkaline fluid secreted by the liver of most vertebrates. ... The liver is an organ in vertebrates, including humans. ... Sexual reproduction is a process of reproduction involving the merging of two gametes from the same species to produce a new organism. ...

Effects on human health

Dwelling in the bile ducts, Clonorchis induces an inflammatory reaction, epithelial hyperplasia and sometimes even adenocarcinoma of the bile ducts (cholangiocarcinoma), the incidence of which is high in fluke-infested areas. One adverse effect of Clonorchis is the possibility for the adult metacercaria to consume all bile created in the liver, which would inhibit the host human from digesting, especially fats. Another possibility is the overcrowding of the common bile duct. The adults deposit vast amounts of eggs into the common bile duct, which poses the risk of the common bile duct and neighboring gall bladder exploding within the human body. Hyperplasia (or hypergenesis) is a general term for an abnormal increase in the amount of the cells of an organ or tissue causing it to increase in size. ... In medicine, carcinoma is any cancer that arises from epithelial cells. ... Cholangiocarcinoma is an adenocarcinoma of the biliary duct system. ... A bile duct is any of a number of long tube-like structures that carry bile. ... The gallbladder (or cholecyst) is a pear-shaped organ that stores bile (or gall) until the body needs it for digestion. ...

References

• Gilbertson, Lance; Zoology Laboratory Manual; The McGraw-Hill Companies, Inc; ISBN 0-07-237716-X (4th edition, 1999)