Crow and kite

Japanese: からすとんび

…
[Invertebrate Jaw]
Invertebrate jaws are generally formed by the hardening of cuticle secreted from the epidermis. Cephalopods have beak-like jaw teeth (commonly known as crows) in their oral cavity, which interlock dorsoventrally. Rotifers have a pair of tooth-like jaws on the inside of their pharynx, one on each side.

From [Squid]

...Eight arms (commonly called legs) of roughly the same size and shape are arranged in a ring around the mouth from the dorsal to ventral sides, and usually two (one pair) specially extendable tentacles emerge from between the third and fourth arms, but there are exceptions where these are missing. The mouth has a sharp, chitinous jaw plate commonly called a "karasutonbi" (crow's kite), which is used to bite and tear off food. The bottom of the mouth also has a radula, a chewing organ unique to mollusks, which is used to scrape off food like grated wasabi, but it is weaker than gastropods (snails) and the like.

From [Beak]

…the upper and lower jaws of vertebrates that protrude forward from the head and are covered by a hard, horny sheath. All birds, some reptiles, and a few primitive mammals have them. The skeleton of the upper beak of a bird consists of a pair of premaxillae, maxillae, and nasal bones. These surround a pair of external nostrils, and the internal nostrils that open into the mouth are slits in the center of the palate. In parrots and crows, there is a unique hinge joint between the nasal bones and the frontal bone. …

Octopus (Tako/Chapter fish)

…the arms of an octopus are separated by a wide skirt-like membrane. In the center of the ring of arms is a mouthpart consisting of a large, sharp jaw plate, commonly called a "crow's kite," with a radula inside the mouth.
[Ecology]
All octopuses are dioecious, and in males the right or, in some species, the left third arm is modified into a hectocota that serves to insert the spermatophore (a sac that contains the sperm) into the female's mantle cavity; the tip of this arm is tongue-like or leaf-like and is usually shorter than the pair of arms.

*Some of the terminology that refers to "karasutonbi" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…
【無脊椎動物のあご】
　無脊椎動物のあごは，一般に表皮から分泌されたクチクラ質が硬化して形成されたものである。頭足類には口腔内にくちばし状の顎歯（がくし）(俗にいうからすとんび)があり，背腹方向にかみ合わされる。輪虫類には咽頭内面に左右1対の歯列状のあごがある。…

【イカ(烏賊)】より

…腕(俗に足という)は背側から，腹側にかけて8本(4対)のほぼ同大同形のものが口を囲んで環状に配列し，さらに第3腕と第4腕の間から特別に伸縮自在の触腕が2本(1対)出るのがふつうであるが，例外的にこれを欠くものもある。口には俗に“からすとんび”といわれる鋭くとがったキチン質の顎板があり，これで餌をかみちぎる。また口腔底には軟体動物特有のそしゃく器官である歯舌をそなえ，これで餌をワサビおろしのようにこすりとって食べるが，腹足類(巻貝)などに比べると弱い。…

【くちばし(嘴)】より

…脊椎動物において，頭部の前方へ突出し，表面が固い角質の鞘（さや）に覆われた上下のあごのこと。すべての鳥類，若干の爬虫類，およびごく一部の原始哺乳類がこれをもっている。鳥類の上くちばしの骨格は各1対の前顎（ぜんがく）骨･上顎骨･鼻骨から成る。これらに囲まれて1対の外鼻孔があり，口腔に通ずる内鼻孔は口蓋（こうがい）の中央に裂け目として開く。インコ類やカラス類などでは鼻骨と前頭骨の間に独特のちょうつがい関節がある。…

【タコ(蛸∥章魚)】より

…タコ類の腕と腕との間は広いスカート状の傘膜（さんまく）になっている。腕の環の中央には俗に〈からすとんび〉といわれる大きくて鋭い顎板（がくばん）からなる口器があり，口腔内には歯舌（しぜつ）をもつ。
［生態］
　タコはすべて雌雄異体で，雄は右または種によっては左の第3腕が，精莢（せいきよう）(精子を包むふくろ)を雌の外套腔に挿入する役をする交接腕に変形していて，先端は舌状ないしは葉状になっていて，対の腕より短いのがふつうである。…

※「からすとんび」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典第２版について | 情報

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