馬有失蹄，章魚怎麼就不會纏住自己？

Researchers observed the behavior of amputated octopus arms, which remain very active for an hour after separation. Those observations showed that the arms never grabbed octopus skin, though they would grab a skinned octopus arm. The octopus arms didn’t grab Petri dishes covered with octopus skin, either, and they attached to dishes covered with octopus skin extract with much less force than they otherwise would.

在截斷章魚的腕足後，研究人員觀察發現斷肢在離體一小時後仍相當有活力。斷肢離體後的行爲觀察顯示，斷肢不會吸附章魚皮膚，但是會吸附剝了皮的章魚腕足；斷肢也不會吸附覆蓋着章魚皮的培養皿。在吸附塗有章魚皮膚提取物的培養皿時，會比吸附空培養皿時使用更小的力量。一隻章魚的八條腕足上密佈着成百上千個吸盤，會吸附幾乎任何東西，但有一個重要的例外。這些吸盤一般不會吸附章魚自身；否則，這隻極其靈活的動物很快就會發現自己整個糾纏在了一起。

Now, researchers from the Hebrew University of Jerusalem report in the Cell Press publication Current Biology on May 15 that they have discovered how octopuses manage this feat, even as the octopuses’ brains are unaware of what their arms are doing. A chemical produced by octopus skin temporarily prevents their suckers from sucking.

現在，耶路撒冷希伯來大學的研究人員於5月15日在細胞期刊數據庫（Cell Press [i]）的期刊《現代生物》（Current Biology）上發表了他們的研究成果，並稱他們已發現章魚實現這一壯舉的原理，甚至是章魚的大腦不知情的情況下完成這一行爲。一種由章魚皮膚產生的化學物質能夠在短期內阻止其吸盤的吸附行爲。

“We were surprised that nobody before us had noticed this very robust and easy-to-detect phenomena,” says Guy Levy, who carried out the research with co-first author Nir Nesher. “We were entirely surprised by the brilliant and simple solution of the octopus to this potentially very complicated problem.”

“這個現象非常強大且易於檢測，在我們之前竟無人注意到這一點，我們感到很驚訝，”與共同第一作者尼爾-內舍（Nir Nesher）一同進行了研究後，蓋伊-列維（Guy Levy）說。“更讓我們驚訝的是章魚精彩而又簡單地解決了這本會非常複雜的問題。”

Binyamin Hochner and his colleagues had been working with octopuses for many years, focusing especially on their flexible arms and body motor control. There is a very good reason that octopuses don’t know where their arms are exactly, in the same way that people or other animals do.

本雅明-霍齊納（Binyamin Hochner）和他的同事研究章魚多年，尤其是關注他們靈活的腕足和身體運動的控制。他們發現，章魚並不能像人與其他動物一樣知道自己腕足的確切位置。

“Our motor control system is based on a rather fixed representation of the motor and sensory systems in the brain in a formant of maps that have body part coordinates,” Hochner explains.

“我們人類大腦中的感覺系統有分別對應特定身體部位的區域，而運動控制系統則是一個相對固定的感覺系統對動作的映射，”霍齊納解釋道。

That works for us because our rigid skeletons limit the number of possibilities. “It is hard to envisage similar mechanisms to function in the octopus brain because its very long and flexible arms have an infinite number of degrees of freedom,” Hochner continues. “Therefore, using such maps would have been tremendously difficult for the octopus, and maybe even impossible.”

這對於我們來說是適用的，因爲我們僵硬的骨架限制了我們活動。“在章魚大腦中也使用與之相似的機制是難以想象的，因爲它那長而靈活的腕足可以進行各種角度的運動，”霍齊納繼續說道，“因此，如果章魚大腦中也用相似的區域分佈來控制運動，會是相當困難的，甚至是不可能的。”

Indeed, experiments have supported the notion that octopuses lack accurate knowledge about the position of their arms. And that raised an intriguing question: How, then, do octopuses avoid tying themselves up in knots?

事實上，實驗結果表明章魚確實並不能掌握其腕足確切位置。這樣的結果也引出了一個有趣的問題：那麼，章魚是怎樣避免把自己纏成一團亂麻的呢？

To answer that question, the researchers observed the behavior of amputated octopus arms, which remain very active for an hour after separation. Those observations showed that the arms never grabbed octopus skin, though they would grab a skinned octopus arm. The octopus arms didn’t grab Petri dishes covered with octopus skin, either, and they attached to dishes covered with octopus skin extract with much less force than they otherwise would.

爲了找到答案，研究人員將章魚腕足截取下來，觀察其行爲，這些腕足在離體一小時後仍然相當有活力。最終觀察結果顯示，腕足斷肢不會吸附章魚皮，但是會吸附剝了皮的章魚腕足；不會吸附覆蓋着章魚皮的培養皿，但是在吸附塗有章魚皮膚提取物的培養皿時，會比吸附空培養皿時使用更小的力量。

“The results so far show, and for the first time, that the skin of the octopus prevents octopus arms from attaching to each other or to themselves in a reflexive manner,” the researchers write. “The drastic reduction in the response to the skin crude extract suggests that a specific chemical signal in the skin mediates the inhibition of sucker grabbing.”
“目前爲止，研究有了新發現：章魚皮膚能夠防止腕足間相互吸附或腕足吸附自身，”研究人員這樣寫道。“對皮膚粗提取物的反應急劇減弱說明皮膚中存在一種特定的化學信號，這種化學信號會調解對吸盤吸附的抑制作用。”

In contrast to the behavior of the amputated arms, live octopuses can override that automatic mechanism when it is convenient. Living octopuses will sometimes grab an amputated arm, and they appear to be more likely to do so when that arm was not formerly their own.

與腕足斷肢的行爲活動相比，章魚能夠在適當時候無視這種自動機制。章魚有時會吸附一個斷肢，而且如果那不是自己的斷肢，他們更有可能這麼做。

Hochner and his colleagues haven’t yet identified the active agent in the animals’ self-avoidance behavior, but they say it is yet another demonstration of octopus intelligence. The self-avoidance strategy might even find its way into bioinspired robot design.

霍齊納和他的同事們還沒能確定在動物自我回避行爲中起作用的活化劑，但是他們說這是章魚智慧的又一次完美呈現。這種自我回避策略也許將來會應用於仿生機器人的設計。

“Soft robots have advantages [in] that they can reshape their body,” Nesher says. “This is especially advantageous in unfamiliar environments with many obstacles that can be bypassed only by flexible manipulators, such as the internal human body environment.”

“柔軟的機器人的優勢在於他們可以改變身體形狀，”內舍說。“這在一個陌生的環境中是尤其有利的，這樣可以利用靈活的機械手繞過重重障礙，比如在人體的內部環境中。”

In fact, the researchers are sharing their findings with European Commission project STIFF-FLOP, aimed to develop a flexible surgical manipulator in the shape of an octopus arm. “We hope and believe that this mechanism will find expression in such new classes of robots and their control systems,” Hochner says.

事實上，研究者正在於歐洲委員會STIFF-FLOP項目共享他們的研究成果，該項目致力於研發章魚腕足形狀的手術操作臂。霍齊納說：“我們希望並且相信這個機制能夠在這種新型機器人和他們的控制系統中發光發熱。”