Pheretima hilgendorfi

Japanese: ヒトツモンミミズ（英語表記）Pheretima hilgendorfi

The order is a metagonad, the class Oligochaeta, and the family Pheretidae. It is 8-20cm long, 0.5-0.9cm wide, and has 90-120 segments. The dorsal surface is reddish brown, and the ventral surface is yellowish gray. It is named after a round pattern on the ventral side of the 8th segment, but there are many individuals with two or three patterns. The pattern is composed of many fine papillae. When it matures, the 14th to 16th segments thicken and form an annulus, and a female pore opens in the center of the ventral surface of the 14th segment. The male pore opens on the small cone-shaped protuberances on the left and right sides of the ventral surface of the 18th segment. It spawns in late autumn, and the eggs laid during this period develop inside the egg capsule, and emerge from the egg capsule in early spring the following year as small earthworms with a body length of 1.5-3.2cm. The parents all die after spawning, so it is a one-year-old species. They have a strong ability to regenerate, and even if they are cut in the middle of their body, the front and rear parts will regenerate and create a nearly complete body. However, the rear part will only regenerate a small part of the front part, but will die because it cannot form a head. They live in fields and grasslands throughout Japan.

Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information

Japanese:

環形動物門貧毛綱後生殖門目フトミミズ科。体長8～20cm，体幅 0.5～0.9cm，体節数 90～120。体の背面は赤褐色，腹面は帯黄灰色。第8体節の腹側に1個の丸い紋形があるところからその名がつけられたが，紋形が2あるいは3個ある個体も少くない。紋形は多数の微細な乳頭から構成されている。成熟すると第 14～16体節が太くなって環帯をつくり，第 14体節の腹面中央に雌性孔が開く。雄性孔は第 18体節の腹面左右の小さい円錐形の隆起上に開く。産卵期は晩秋で，この時期に産み出された卵は卵包内で育ち，翌年の早春に体長 1.5～3.2cmの小さなミミズになって卵包から出てくる。親は産卵するとすべて死ぬので一年生である。再生力が強く，体のまんなかで切られても，前片は後端部を再生してほぼ完全な体をつくる。ただし後片は，前端部がわずかに再生されるが，頭部ができないため死んでしまう。日本各地の畑，草地にすむ。

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