Tubifex - Tubifex

A general term for aquatic earthworms of the family Tubifexidae of the class Oligochaeta of the phylum Annelida, and the name of one species in the same family. The species, Tubifex tubifex , has a long, slender body of 70-100 mm, which can coil up in a spiral when stimulated. It has 85-100 segments, and mature individuals have a well-developed annulus. The setae are distributed in two rows on the dorsal and ventral surfaces. It lives in wastewater with a high organic content, such as sewage, and leaves the front half of its body in the mud and brings the rear half out into the water to shake it around, so that when it grows in colonies, the surface of the mud appears bright red. It is commonly called peach nightshade or lily flower. For a long time, the scientific name T. hattai was used, but it is now considered to be the same species as T. tubifex , which is widely distributed around the world. There are approximately 150 species of Tubifex worms in the world, and about 10 species are known from Japan, including the Tubifex worm, the Yurimizumi worm (also known as the Gotouitomizu worm), the Shiroito worm, and the Gill worm.

[Masao Ohno]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

環形動物門貧毛綱イトミミズ科の水生ミミズの総称、および同科に属する1種名。種名のイトミミズTubifex tubifexは、体は細長く70～100ミリメートル、刺激を与えるとこの体を螺旋(らせん)状に巻く性質がある。体節数は85～100個、成熟個体では環帯が発達する。剛毛束は背面と腹面に生じ、それぞれ2列に列生する。下水など有機質の多い汚水に生息し、体の前半を泥中に残し、後半を水中に出してこれを揺り動かすため、群生するときには泥の表面が真っ赤にみえる。これを俗にモモホオズキとかユリノハナとよぶ。学名は久しい間T. hattaiが用いられてきたが、現在では世界に広く分布するT. tubifexと同種とみなされている。イトミミズ科としては世界に約150種、日本からはイトミミズのほか、ユリミミズ（別名ゴトウイトミミズ）、シロイトミミズ、エラミミズなど10種ほど知られている。

［大野正男］

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