13 為了彌補視力上的不足，電鰻還能透過設置低電壓的電 場以探測周圍環境 [4]，使牠們能在南美洲北部亞馬遜河和 奧里諾高河一帶混濁的死水和沼澤中生活和捕獵 [2]。當障 礙物、獵物或捕食者靠近時，魚的電場會受到干擾；而即使 是細小至每厘米一微伏（10-6 V/cm）[4] 的電場扭曲，也能 被散佈在電鰻身體上的電感受器偵測到，使電鰻能察覺四 周。 一旦電鰻偵測到類似獵物的物體，就會進入典型的攻擊 模式 [5, 6]。電鰻首先會以高電壓連續兩下放電，使躲藏的 獵物不自主地強烈抽搐。泛起的漣漪能被電鰻感知，從而揭 示獵物的位置。然後電鰻會以一連串高壓脈衝掃射獵物，使 其麻痺再把其吞下。有時為了施以更強烈的電擊，電鰻會用 口叼住獵物並捲曲身體，將獵物拉近尾部，把獵物扯進更強 烈的電場 [5]。 這驚人能力背後還有一個不解謎團：電鰻如何在放電 中保護自己免受電擊？有理論認為電鰻相對較大的體型 （可達 2.5米長！）能幫助牠們承受細小獵物無法忍受的電 流 [7, 8]。與此同時，包圍著放電器官的絕緣脂肪層 [8] 和 在水中散失的一部分電流 [7] 保護了電鰻的中樞神經系統 和心臟，避免其受自己發出的強大電流直接衝擊。儘管如 此，關於電鰻，確實還有許多東西需要進一步研究和發現。 References 參考資料： [1] SPARK Museum of Electrical Invention. (n.d.). Volta’s Fishy Invention. https://www.sparkmuseum.org/voltasfishy-invention/ [2] Chetan-Welsh, H. (n.d.) How do electric eels work? Natural History Museum. https://www.nhm.ac.uk/ discover/how-do-electric-eels-work.html [3] The University of Western Australia. (2015, February). Electrical circuits 6: Electric eels (fact sheet). https:// www.uwa.edu.au/study/-/media/faculties/science/ docs/electric-eels.pdf [4] Bennett, M. V. L. (1971). Electroreception. In W. S. Hoar, & D. J. Randall (Eds.), Fish Physiology (pp. 493–574). Academic Press. https://doi.org/10.1016/S15465098(08)60038-2 [5] Catania, K. C. (2019, April 1). Shocking Secrets of the Electric Eel. Scientific American. https://www. scientificamerican.com/article/shocking-secrets-ofthe-electric-eel/ [6] Catania, K. (2014). The shocking predatory strike of the electric eel. Science, 346(6214), 1231–1234. https://doi. org/10.1126/science.1260807 [7] Scientific American. (2005, December 5). How do electric eels generate a voltage and why do they not get shocked in the process? https://www. scientificamerican.com/article/how-do-electric-eelsgene/ [8] BBC Wildlife Magazine. (2023, July 3). How an electric eel works: You wouldn't want to be on the receiving end of its high voltage charge. https:// www.discoverwildlife.com/animal-facts/fish/how-anelectric-eel-works
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