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An epiphragm is a temporary structure which can be created by many species of shelled, air-breathing land snails, terrestrial pulmonate gastropod mollusks. It can also be created by freshwater snails when temporary pools dry up. In most species the epiphragm is made of dried mucus and although it is elastic, it is fairly easily torn when forcibly removing a snail from its substrate. In a few species the epiphragm is thick and quite rigid, being reinforced with calcium carbonate. This kind of epiphragm is very strong and may be difficult to break. == Function == The epiphragm is created to seal the aperture of the shell against desiccation. It is used when the snail is inactive. Most land snails are only active when the humidity is high such as after rain and at night, and become inactive during dry weather. The main function of the epiphragm is to reduce water loss through the aperture during inactivity.〔Machin J. (1968). "The Permeability of the Epiphragm of Terrestrial Snails to Water Vapor". ''Biological Bulletin'' 134(1): 87-95. (JSTOR ), (PDF ).〕 An operculum is a somewhat similar but permanent anatomical feature that is found in other clades of gastropods. The operculum serves some of the same functions as an epiphragm. Sometimes it protects the snail against predation. It protects certain species of snail if they are eaten by birds (such as Japanese white-eye). The snail can remain alive as it passes through the digestive tract because it is protected from the digestive enzymes. Snails may also benefit from being moved to new locations.〔http://news.nationalgeographic.com/news/2011/07/110719-snails-birds-feces-animals-environment-weird/〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Epiphragm」の詳細全文を読む スポンサード リンク
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