Frogs and toads are the canary in the coal mine
When it comes to pollution levels and the health of an ecosystem, there is no better alert system than frogs and toads. When their croaks go silent, the alarm bells should be ringing. Frogs have very thin, porous skin through which they can absorb water and oxygen. But this thin skin allows in more than just the chemicals they need -- it also allows them to absorb whatever pollution is lurking in the water or soil. From eggs to tadpoles to adult forms, frogs are building up concentrations of toxins in their bodies, many of which are lethal and some of which cause mutations, deformities, and reproductive problems. So when a population of frogs crashes, or turns up with too many or not enough legs and other oddities, then they've essentially alerted us to the need to test and clean up pollutants in that area. So next time you're kept awake by a chorus of frogs singing at night, you can smile to yourself knowing that all is well in this local habitat.