Tube feet

A thin tube extending in a row from the surface of an echinoderm's body, used for locomotion, feeding, breathing, sensation, etc. The inside of the tube is connected to the water vascular system within the body, and expands and contracts and bends according to changes in water pressure within the system and the action of the muscles in the walls of the tube foot. Most sea urchins, starfish, and sea cucumbers have suction cups at the end of their tube feet, which they use to attach to rocks and other objects to support their bodies and to crawl forward by pulling their bodies to one side. In sea lilies and brittle stars, these are often called tentacles and are not used for locomotion. The peristome tentacles and warty feet of sea cucumbers and the flower-patterned gills of some sea urchins are modified tube feet.

[Michio Shigei]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

棘皮(きょくひ)動物の体表から列をなして伸び出る細管で、体の移動、摂餌(せつじ)、呼吸、感覚などに用いられる。管の内部は体内の水管系とつながり、系内の水圧変化と管足壁の筋肉の働きによって伸縮・屈曲する。ウニ、ヒトデ、ナマコ類の多くは管足の先端に吸盤をもち、それを岩などに吸着させて体を支え、また体を片側に引っ張りながらはい進む。ウミユリとクモヒトデ類の場合は触手とよばれることが多く、体の移動には用いられない。ナマコ類の周口触手といぼ足、一部のウニ類の花紋えらは管足の変形物である。

［重井陸夫］

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