Sensory hairs

This refers to hairs found in animals and plants that function as receptors. In mammals, the setae distributed on the face, like cat whiskers, are also called tentacles because they are involved in touch. They are also called blood-sinus hairs because blood accumulates in the hair follicle sheath and sensory nerves are distributed in it. In arthropods, hair-like sensilla with sensory nerves have developed on the inside of the chitinous setae, and some are related to taste and smell in addition to touch and vibration. In addition, there is a hair plate with dense sensory hairs at the joints, which serves as a proprioceptor that determines how far the joint is open. Meanwhile, in plants, the hairs on the leaves of carnivorous plants (such as Venus flytraps and algae) have a similar function and receive contact stimuli from insects and other creatures.

[Akira Murakami]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

動植物がもつ、受容器としての機能がある毛をいう。哺乳(ほにゅう)類では、ネコのひげのように、顔面に分布する剛毛で、触覚に関与するため触毛ともよぶ。また毛嚢鞘(もうのうしょう)には血液がたまり感覚神経が分布するため、血洞毛ともいう。節足動物ではキチン質の剛毛の内側に感覚神経のついた毛状感覚子が発達し、触覚、振動覚のほかに味覚、嗅覚(きゅうかく)に関係したものもある。また、関節部には感覚毛の密生した毛板があり、関節がどの程度開いた位置にあるかを知る自己受容器となっている。一方、植物では食虫植物（ハエジゴクやムジナモなど）の葉にある毛が同様の機能をもち、昆虫などによる接触刺激を受容する。

［村上　彰］

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