Como funciona o choque do peixe-elétrico?
Autor: Profª Talita M Medeiros | Publicado: 2011-09-06T21:20:00-03:00

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 <![endif]-->  Como funciona o choque do peixe-elétrico?&nbsp;Nada de carregar o celular ou acender a luz: a eletricidade desses peixes é uma forma de defesa, ataque e orientação no ambiente 
Usinas hidrelétricas, termelétricas, nucleares e eólicas. Todas elas, você já sabe, produzem energia elétrica. Agora, como um peixe pode conseguir isso? Nem pense em acender um abajur ou carregar seu celular usando o peixe-elétrico. A eletricidade emitida por esses animais é uma forma de defesa, ataque e orientação no ambiente. Vamos entender melhor esse – ai! – choque!A explicação é a seguinte: algumas espécies de peixes possuem eletrócitos, que são celulas musculares modificadas. Como assim? Bem, primeiro é preciso saber que qualquer movimento muscular está associado a geração de impulsos elétricos. Acontece que, no caso desses peixes, parte da eletricidade não é gasta no movimento do seu corpo, ficando armazenada no eletrócitos. Daí o contato com esses animais, ou apenas a proximidade deles, produzir – zumpt! – uma descarga elétrica.Essa descarga elétrica varia de intensidade de acordo com a espécie. A dona de uma das descargas mais potentes é a raia-torpedo, capaz de produzir 2.500 watts de potência – para você ter uma noção, as lâmpadas incandescentes comuns têm potência média de 60 watts. No caso da raia-torpedo, essa potência toda serve para capturar suas presas ou se proteger dos predadores.Mas será que esse choque não oferece risco ao próprio peixe? Não mesmo! O campo gerado pela descarga de eletricidade do animal situa-se ao redor do corpo do peixe. Mas isso não quer dizer que ele esteja protegido contra a descarga elétrica produzida por outro peixe elétrico...Não há registros de acidentes fatais envolvendo seres humanos, apesar da enorme potência que algumas espécies são capazes de produzir. Por via das dúvidas, é aconselhável manter distância desses peixes, até porque tomar um choque, por mais fraco que seja, não é nada divertido!&nbsp;
Por: Mateus Soares, Departamento de Zoologia, Universidade de São Paulo

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