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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 have no gut or mouth [6] and absorb nutrients from the host's alimentary tract through their specialised neodermal cuticle, or tegument, [7] through which gas exchange also takes place. [2] The tegument also protects the parasite from the host's digestive enzymes [ 8 ] and allows it to transfer molecules back to the host.
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]
the 1 to 2 outer layers are formed of mucopolysaccharides and proteins, the middle layers consist of chitinous material and serve to give structure and mechanical resistance to the eggs, and the inner layer is composed of lipids and proteins and is useful to protect eggs from desiccation, strong acid and bases, oxidants and reductive agents as ...
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 ...
Vertebrates, the best-studied group, are hosts to between 75,000 and 300,000 species of helminths and an uncounted number of parasitic microorganisms. 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]
The predominant groups of cod parasites in the northeast Atlantic were trematodes (19 species) and nematodes (13 species), including larval anisakids, which comprised 58.2% of the total number of individuals. [3] Parasites of Atlantic cod include copepods, digeneans, monogeneans, acanthocephalans, cestodes, nematodes, myxozoans and protozoans: [3]
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.