Write three characteristic features of the phylum to which pinworm belongs.
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Phylum Platyhelminthes
Platyhelminthes - Bedfords Flatworm
Platyhelminthes are commonly known as flatworms or tapeworms. They are a group of soft-bodied invertebrate animals. As a matter of fact, there are around 20,000 species of these animals. A few of these live as parasites on humans and other animals. Furthermore, it is because of this parasitic nature that they do cause some amount of trouble for the host animal. A few species belonging to this phylum can be a major cause of certain diseases. For example, Schistosomiasis, or bilharzia or bilharziasis, is a disease caused by these parasitic flatworms. They belong to the family Schistosomatidae.
The most distinguishing feature of these invertebrates is their flat body. As the body does not have any cavity, they are flat. The body is also not segmented and they do not have specialized systems. Around eighty percent of the flatworms are parasitic in nature, while a few free-form flatworms are also present. The free-living forms are scavengers or predators. The parasitic species feed on the tissues of the host organism in which they live.
The animals in this phylum have a diverse range in size. Some are microscopic, while a few go up to two feet long. They are also hermaphrodites, which mean that both the sexes are present in the same organism.
Pinworm, also called seat worm, or threadworm (species Enterobius, or Oxyuris, vermicularis), worm belonging to the family Oxyuridae in the order Ascaridida (phylum Nematoda). Pinworms are common human intestinal parasites, especially in children. They are also found in other vertebrates. Male pinworms are 2 to 5 mm (about 0.08 to 0.2 inch) long; females range in length from 8 to 13 mm. The long tails of the worms give them a pinlike appearance.
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Related Topics: Endoparasitism
Pinworms usually occur in the large intestine but sometimes are found in the small intestine, the stomach, or farther up the gastrointestinal tract. After the eggs are fertilized by the male, the female travels to the anus, deposits the eggs on the skin near the anal opening, and usually dies. Movements of the worm on the skin cause itching. Eggs, transferred beneath the fingernails by scratching, are passed to the mouth, from which the eggs or larvae make their way to the intestine. The life cycle requires 15 to 43 days.
Hookworm (Ancylostoma).
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This article was most recently revised and updated by John P. Rafferty, Editor.
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