Onisome - Onisome

Japanese: オニイソメ - おにいそめ
Onisome - Onisome

A marine animal belonging to the family Isomalidae, order Polychaeta, phylum Annelida. It is found in the central and southern parts of Honshu, the western Pacific, the Indian Ocean, and the Atlantic Ocean. The largest can reach a body length of 1.5 meters and a body width of about 3 centimeters. It has around 400 segments. The back is blackish brown with a strong metallic translucency. The front edge of the prostoma is divided into four lobes, with five tentacles and two eyespots. The first segment is about three times as long as the second segment, and the second segment has a pair of short tentacles. The jaws are large and powerful. A single thread-like gill appears on the warty foot from the 8th to 10th segments, and the number increases to about 30 around the 50th segment, and they are arranged like the teeth of a comb. These gills decrease again to a single small projection at the tail. In the past, it was seen coiled under stones about 50 centimeters in diameter on the coast of the Miura Peninsula, but this is now rarely seen.

[Minoru Imajima]

Main species of worms (2) [specimen illustrations]
©Tomita Hyakushu ">

Main species of worms (2) [specimen illustrations]


Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

Japanese:

環形動物門多毛綱遊在目イソメ科に属する海産動物。本州中部以南、西太平洋、インド洋、大西洋に分布する。体長は大きなもので1.5メートル、体幅約3センチメートルになる。環節数400個内外。背面は黒褐色で強い金属的な透光がある。前口葉の前縁は4葉に分かれ、5本の感触手と2個の眼点がある。第1環節は第2環節の長さの約3倍あり、第2環節には1対の短い感触糸がある。あごは大きく強力である。第8~10環節からいぼ足の上に1本の糸状のえらが生じ、第50環節付近では30本くらいに増え、それらが櫛(くし)の歯のように配列する。これらのえらはふたたび減って尾部では1本の小突起になる。かつては三浦半島の海岸で直径50センチメートルぐらいの石の下にとぐろを巻いているのがみられたが、現在ではこのような状態はほとんどみられなくなった。

[今島 実]

ゴカイ類のおもな種類(2)〔標本画〕
©冨田百秋">

ゴカイ類のおもな種類(2)〔標本画〕


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