Suction cup - kyuuban

This is an organ that animals use to attach to other animals or objects. It has a hollow space surrounded by a soft, raised periphery, and it presses this space firmly against the object, then contracts the surrounding muscles to create negative pressure inside and attach to the object. The shape, number, and purpose of attachment vary depending on the type of animal. Internal parasitic trematodes such as Schistoma have suction cups on their mouth and abdomen, which attach to the intestines and other organs of the host to prevent them from being expelled. Leeches have suction cups at the front and back ends of their bodies, and move by alternately attaching to and releasing other objects, and their anterior suckers also serve the purpose of sucking blood. Suction cups in cephalopods such as squids and octopuses are arranged in a certain order on the tentacles and are used to obtain food. In insects, the male diving beetles have suction cups on the last segment of their forelimbs (tarsus) to hold the female during mating. In vertebrates, the common suction cup has an oval-shaped suction cup on the back of its head, which attaches to the ventral surface of sharks and other large fish and moves around. Tree frogs have suction cups on the tips of their fingers, while geckos have suction cups on the palmar surfaces of their fingers, allowing them to move easily over trees and walls.

[Masayuki Uchibori]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

動物が他の動物や物体に吸着するための器官をいう。柔らかく盛り上がった周縁に囲まれた中に空所をもち、これを他物に強く押し付け、次に周囲の筋肉を収縮させて内部を陰圧にして吸着する。その形や数、また吸着の目的は動物の種類によってさまざまである。ジストマなど内部寄生をする吸虫類では口と腹部に吸盤があり、宿主から排出されないように腸その他の器官に吸着する。ヒル類では体の前後両端にあり、他物に交互にくっつけたり放したりして移動するが、さらに前吸盤は吸血の役目を果たす。イカ、タコなどの頭足類の吸盤は触手上に一定の配列を示し、食物をとるために利用している。昆虫ではゲンゴロウ類の雄の前肢最終肢節（跗節(ふせつ)）に、交尾時に雌を抱くための吸盤がある。脊椎(せきつい)動物ではコバンイタダキの頭部背面に小判形の吸盤があり、サメその他の大形魚の腹面にくっつき移動する。アマガエルでは指先に、ヤモリでは指の掌面に吸盤があり、樹木や壁を簡単に移動する。

［内堀雅行］

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