Hedruris spinigera
Encyclopedia
Hedruris spinigera is a parasite belong to phylum Nematoda, commonly found in stomach of freshwater fish
. The female Hedruris spinigera attaches itself onto the epithelium
of the fishes' stomach using a hook at the curved tail. Meanwhile, the male swims freely until it finds a female that has already attached to a host, then the male curls around the body of that female so that sexual reproduction
occurs within the host. Most fishes consume Paracorophium excavatum,the intermediate host for Hedruris spinigera, however, the prevelances of Hedruris spinigera are restricted to certain host range.
crustacean
Paracorophium excavatum
. Hedruris spinigera has limited host range because some fishes failed to establish Hedruris spinigera due to lack of the proper attachment site on epithelium of fish stomach. Although most fishes consume Paracorophium excavatum, Hedruris spinigera actually distribute in only a limited host range. Scientists have found that Aldrichetta forsteri
and Retropinna retropinna
fish species are the truly suitable hosts for Hedruris spinigera. The infection site in the adult worm occurs at the stomach where the female attaches to, but parasite could also be free-living as found in rectum and intestine of fishes. As for immature Hedruris spinigera, the site of infection occurs at hemocoelomic cavity, where the worms are coiled but not encysted.
Freshwater fish
Freshwater fish are fish that spend some or all of their lives in freshwater, such as rivers and lakes, with a salinity of less than 0.05%. These environments differ from marine conditions in many ways, the most obvious being the difference in levels of salinity...
. The female Hedruris spinigera attaches itself onto the epithelium
Epithelium
Epithelium is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. Epithelial tissues line the cavities and surfaces of structures throughout the body, and also form many glands. Functions of epithelial cells include secretion, selective...
of the fishes' stomach using a hook at the curved tail. Meanwhile, the male swims freely until it finds a female that has already attached to a host, then the male curls around the body of that female so that sexual reproduction
Sexual reproduction
Sexual reproduction is the creation of a new organism by combining the genetic material of two organisms. There are two main processes during sexual reproduction; they are: meiosis, involving the halving of the number of chromosomes; and fertilization, involving the fusion of two gametes and the...
occurs within the host. Most fishes consume Paracorophium excavatum,the intermediate host for Hedruris spinigera, however, the prevelances of Hedruris spinigera are restricted to certain host range.
Morphology
Hedruris spinigera have 4 complex lips consisting of two lateral pseudolabia and two median lips. The oesophagus is not clearly divided into muscular and glandular portions. The body of Hedruris spinigera is covered by non-living cuticles. The female Hedruris spinigera has a prehensic hook at the posterior end.Immature adults within the intermediate host are similar to mature adults, except for the smaller size and absence of eggs.Geographic distribution
Hedruris spinigera are widely distributed within New Zealand, scientists found that the distribution appears to be limited within the coastal area, especially in brackish waters.The prevalence of Hedruris spinigera depends on species of fishes. The prevalence in intermediate host was found infected with one worm, but sometimes two or three worms could also be found in intermediate host.Life cycle
The intermediate host for Hedruris spinigera is the amphipodAmphipoda
Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. The name amphipoda means "different-footed", and refers to the different forms of appendages, unlike isopods, where all the legs are alike. Of the 7,000 species, 5,500 are classified...
crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
Paracorophium excavatum
Paracorophium excavatum
Paracorophium excavatum is a species of amphipod in the family Corophiidae. It has been confused with other species, such that the only reliable record is from its type locality at Brighton, Otago....
. Hedruris spinigera has limited host range because some fishes failed to establish Hedruris spinigera due to lack of the proper attachment site on epithelium of fish stomach. Although most fishes consume Paracorophium excavatum, Hedruris spinigera actually distribute in only a limited host range. Scientists have found that Aldrichetta forsteri
Yellow-eye mullet
The yellow-eye mullet, Aldrichetta forsteri, is a mullet of the family Mugilidae, the only species in the genus Aldrichetta. It is found around New Zealand, the Chatham Islands, and southern Australia, from the surface to depths of 50 m...
and Retropinna retropinna
New Zealand smelt
The New Zealand smelt, New Zealand common smelt, or New Zealand cucumber fish, Retropinna retropinna, is a smelt of the family Retropinnidae, found only in New Zealand at shallow depths in estuaries and rivers...
fish species are the truly suitable hosts for Hedruris spinigera. The infection site in the adult worm occurs at the stomach where the female attaches to, but parasite could also be free-living as found in rectum and intestine of fishes. As for immature Hedruris spinigera, the site of infection occurs at hemocoelomic cavity, where the worms are coiled but not encysted.