Search results
Results from the WOW.Com Content Network
These can be categorized into three groups; cestodes, nematodes and trematodes. Examples include: Acanthocephala; Ascariasis (roundworms) Cestoda (tapeworms) including: Taenia saginata (human beef tapeworm), Taenia solium (human pork tapeworm), Diphyllobothrium latum (fish tapeworm) and Echinococcosis (hydatid tapeworm)
Cestodes are parasites of vertebrates, with each species infecting a single definitive host or group of closely related host species. All but amphilinids and gyrocotylids (which burrow through the gut or body wall to reach the coelom [ 6 ] ) are intestinal, though some life cycle stages rest in muscle or other tissues.
Adult trematodes lay smaller numbers of eggs compared to cestodes or nematodes. However, the egg develops into a miracidia from which thousands of cercariae, or swimming larvae, develop. This means that one egg may produce thousands of adult worms. [15]
Nematodes are very small, slender worms. Most are free-living, often less than 2.5 mm long and some only about 1 mm. Many nematodes are microscopic. Some soil nematodes can reach up to 7 mm in length, and some marine species can reach up to 5 cm. Some are parasitic and can reach lengths of 50 cm or more. [42]
There are 18,000 [1] to 24,000 [2] known species of trematodes, divided into two subclasses — the Aspidogastrea and the Digenea. Aspidogastrea is the smaller subclass, comprising 61 species. These flukes mainly infect bivalves and bony fishes. [3] Digenea — which comprise the majority of trematodes — are found in certain mollusks and ...
On average, a mammal species hosts four species of nematode, two of trematodes, and two of cestodes. [85] Humans have 342 species of helminth parasites, and 70 species of protozoan parasites. [ 86 ] Some three-quarters of the links in food webs include a parasite, important in regulating host numbers.
Telorchis is a genus of trematode parasites found in many herps, comprising around 70 species. [2] This parasite is an indirect parasite, with a snail intermediate host and a reptile or amphibian definitive host.
Other internal parasites are found living inside fish gills, include encysted adult didymozoid trematodes, [15] a few trichosomoidid nematodes of the genus Huffmanela, including Huffmanela ossicola which lives within the gill bone, [16] and the encysted parasitic turbellarian Paravortex. [17]