Oyogi Nemushi - Oyogi Nemushi

A marine animal belonging to the phylum Nerviformes and the family Pelagonemeria. It inhabits the southern coastal waters off Japan and in the deep waters of Sagami Bay. Its body is almost colorless and transparent, its internal organs are milky white, and its digestive tract is orange-red. The anterior half of the body is broad and rounded, while the posterior half is narrow, with a horizontal tail fin at the end. The mouth is located on the ventral surface near the tip of the body, with the rostrum opening in front of it. The digestive tract runs straight down the center of the ventral side of the body and ends in an anus in the center of the tail fin. The intestine has five pairs of lateral bulges arranged symmetrically. The snout is longer than the body length, and has seven small spines lined up on a sickle-shaped base. The brain is located near the tip of the body, and one pair of lateral nerves protrude from it. There is a pair of lateral blood vessels running along the sides of the body, and a vestigial dorsal blood vessel.

[Fumio Iwata]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

紐形(ひもがた)動物門有針綱ペラゴネメルテス科に属する海産動物。日本の南方の沿岸沖合いと相模(さがみ)湾の深所に生息する。体はほとんど無色透明で、内部の諸器官は乳白色、消化管は橙紅(とうこう)色。体は前半は幅広く丸みを帯び、後部は狭く、末端に水平な尾びれがある。口は体の先端近くの腹面にあり、その前方に吻道口(ふんどうこう)がある。消化管は体の腹側中央を直走、尾びれ中央の肛門(こうもん)で終わる。腸には左右相称的に並ぶ5対の側膨出がある。吻は体長より長く、鎌(かま)形の台座上に7個の小針が並ぶ。脳は体の先端近くにあり1対の側神経が出ている。体側を走る1対の側血管と痕跡(こんせき)的な背血管がある。

［岩田文男］

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