Por que as lesmas derretem em contato com o sal?
Autor: Prof. Luis Henrique Trentim | Publicado: 2012-07-17T19:06:00-07:00


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As
lesmas, assim como seus parentes próximos, os caracóis terrestres, são muito
sensíveis à desidratação, ou seja, à perda de água pela superfície do corpo que
permanece exposta ao ar. O sal de cozinha, por sua vez, é uma substância
higroscópica, isto é, atrai fortemente a água. "Quando o sal é lançado
sobre esses animais, ele absorve rapidamente a água do corpo deles, causando a
destruição de células e tecidos, transformando seus corpos em uma massa
viscosa, disforme, como se estivessem derretendo", afirma o biólogo Osmar
Domaneschi, da USP. O sal, portanto, suga toda a água do corpo das lesmas, que
são mais vulneráveis que os caracóis por não terem uma concha calcária para se
proteger.

Outros
animais que enfrentam o mesmo problema com o sal - pela ação maldosa de certas
pessoas - são os sapos, as rãs e as minhocas. Apesar de frágil, esse tipo de
"pele" traz lá algumas vantagens para quem a possui. Por ser bastante
permeável, ela é uma importante via de entrada e saída de gases, ajudando a
suprir a necessidade respiratória desses animais - que nem sempre têm pulmões
capazes de dar conta do recado. Além disso, a tal "pele" permite
facilmente a excreção de substâncias que precisam ser eliminadas pelo
organismo.



Fonte: Revista Mundo Estranho