secernentea

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Mansonella perstans

…is a species of Spirurid nematode that is widespread in parts of sub-Saharan Africa, Central and South America, and the Caribbean. M.perstans typically parasitizes humans and is usually contracted via a biting midge (usually of the genus Culicoides). Once M.perstans enters the body cavity they will begin to develop into adults. Once they mature they will start to mate and produce microfilariae that will enter the bloodstream. A midge will then ingest them it bites a human. After ingestion the microfilariae will move to the midge’s thoratic muscles and will develop into second and third-stage larvae. The third-stage larvae will move to the midge’s proboscis and will infect a human when the midge bites one.

Phylogeny

Animalia-Nematoda-Secernentea-Spirurida-Onchoceridae-Mansonella-M.perstans

Images: dpd.cdc.gov

photo by Scenics & Science

When you think of animals, think of this nematode, Gongylonema neoplasticum. Once known as Spiroptera carcinoma this roundworm was the basis for the 1926 Nobel Prize in Medicine. Johannes Fibiger noticed that infection by this nematode lead to gastric tumors in rats, and concluded that the worms were carcinogenic. Later studies actually showed that while the worms could stimulate previously damaged cells to form tumors, they had no effect on otherwise healthy cells. The work has still been important as it was the first instance of being able to induce cancerous tumors, and one of the first demonstrations that infection and tumors can be linked.

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Dog Hookworm (Ancylostoma caninum)

….a species of hookworm restricted to temperate, tropical and sub-tropical regions worldwide. A.caninum typically infect dogs and other canids and can cause serious damage. Like other hookworms A.caninum is transmitted via feces, as the larvae grow there. If the larvae gain contact with a host they will penetrate the skin and make their way to the lungs. Once in the lungs they will ascend into pharynx and are swallowed. They will settle in the lower intestine, where they will attach to the intestinal wall and mature into adults. Eventually they will mate and their eggs will leave the body via excrement.

Dog hookworms can cause major damage to the intestines and should be treated if contracted.

Phylogeny

Animalia-Nematoda-Secernentea-Strongylida-Ancylostomatidae-Ancylostoma-A.caninum

Images: Jessica Thompson and Chelsealwood

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Pachydorylaimus schizodontus

…a species of free-living Dorylaimid nematode that is native to Costa Rica. Like other free-living nematodes this species is not really a parasite and instead spends its life in the soil feeding on bacteria.

Phylogeny

Animalia-Nematoda-Secernentea-Dorylaimida-Qudsianematidae-Pachydorylaimus-P.schizodontus

Image(s): INBio

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Odontopharynx longicaudata

…is a unique species of free-living diplogasterid nematode found in California. O.longicaudata is unique in that is predacious and will actively seek out and kill other free-living nematodes. O.longicaudata accomplishes this by using a large open stoma that contains a large dorsal tooth and 12 smaller teeth. Once it selects its prey by probing it the nematode will quickly attack its prey, drawing its cuticle into its stoma. Or if the prey is larger it will pierce the prey’s body and ingest its contents. O.longicaudata is very prey selective and will only attack certain nematodes, in one study Anguina pacificae was a favorite. It also shows favor over endoparasites over ectoparasites. 

Phylogeny

Animalia-Nematoda-Secernentea-Diplogasterida-Odontopharyngidae-Odontopharynx-O.longicaudata

Images: J. Chitamber