Sea worm - hurry up

A marine animal belonging to the family Nereidae, order Polychaeta, class Annelida. It has about 20 common names, such as Sandworm, Sandworm, Sandworm, and Sandworm. It lives by digging holes in the sand and mud of freshwater flowing waters between the high and low tide lines on the coast and near the mouth of a river. It is 5 to 10 centimeters long and has 90 to 130 segments. The front of the body is bluish brown, and the back from the middle is gray brown. The four pairs of sensory filaments on the peristome are longer than those of other species. The Vth segment on the lower back of the snout has one cone-shaped jawlet, and the VIth segment has a row of long jawlets. The warty feet have almost the same shape throughout the body. The reproductive season is from April to July, and at night, reproductive males and females swim in groups near the water surface to release eggs and sperm.

This species is relatively easy to raise and manage from artificial insemination to the time it becomes a larva, so it is actively farmed in Kochi and Kagawa prefectures as fishing bait. It is used as bait for black porgy, rockfish, flounder, sea bass, and Japanese whiting.

[Minoru Imajima]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

環形動物門多毛綱遊在目ゴカイ科に属する海産動物。スナイソメ、ジャリメ、スナムシ、イシゴカイなど約20ほどの俗名がある。海岸の干満潮線間から河口近くの淡水の流水域の砂泥中に穴を掘ってすむ。体長5～10センチメートルで、体節数90～130個。体の前部は青褐色で、中部より後方は灰褐色。囲口節(いこうせつ)にある4対の感触糸は他の種類に比べて長い。吻(ふん)の背面下部の第Ⅴ区には円錐(えんすい)状の小顎片(しょうがくへん)が1個、第Ⅵ区には横に長い小顎片が1横列に並んでいる。いぼ足は体の全体を通じてほぼ同一の形態をもつ。生殖時期は4～7月で、夜間に生殖型の雌雄が水面近くで生殖群泳を行って放卵、放精する。

　この種類は人工受精から幼虫になるまでの飼育管理が比較的容易なため、釣り餌(え)用として高知県や香川県では盛んに養殖が行われている。クロダイ、メバル、カレイ、スズキ、キス釣りなどの餌虫として利用される。

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