Proboscidea - Chobirui

A general term for animals belonging to the order Proboscidae in the class Mammalia. Members of this order Proboscidae are the largest of all terrestrial mammals, with a long, freely movable snout (nose and upper lip joined together) that they use to carry food to their mouths and splash water on their bodies. They have a large head, a short neck, and long, columnar limbs, with five fingers and hoof-like flat claws on their digitigrade feet. They have a pair of nipples on the prothorax. They have no scrotum. The pair of upper incisors continues to grow throughout their life, reaching up to 3 meters. They have six pairs of molars on each side, one on each side, and they appear one at a time. The structure of the upper carpal bone resting on the lower one and the placenta (band-like) are similar to those of hyraxes and sirenians. They grow slowly, reaching maturity at 13 to 14 years of age. They have a gestation period of 22 months, and only one baby is born per litter. Their life span is 60 to 80 years. Extant species belong to the elephantidae family, with one species found in Africa and one in South Asia.

[Yoshinori Imaizumi]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

哺乳(ほにゅう)綱長鼻目に属する動物の総称。この目Proboscidaeの仲間は、陸生哺乳類でもっとも体が大きく、自由に動く長い鼻（鼻と上唇が一体となったもの）をもち、これで食物を口に運び、体に水をかける。頭は大きく、頸(くび)が短く、四肢は柱状で長く、指行性の足には5本の指とひづめ状の平づめがある。乳頭は前胸に一対。陰嚢(いんのう)がない。上の一対の門歯は終生伸び続け3メートルに達する。臼歯(きゅうし)は上下とも六対あり、1個ずつ現れる。上の手根骨が下のそれの上にのるところや胎盤（帯状）の構造は、ハイラックスや海牛類に似る。成長が遅く、13～14歳で成熟する。妊娠期間22か月、1産1子。寿命は60～80年。現生種はゾウ科に属し、アフリカと南アジアに各1種がある。

［今泉吉典］

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