Why are frogs food “sentinels” of the environment?
Although frogs and toads spend most of their lives on land, their eggs must be deposited in water. After being born and maturing in the water, they move onto land to live and then go back to the water to reproduce. This dependence upon both land and water to complete their life cycles makes frogs and toads excellent barometers, or sentinels, of environmental health. Likewise, their sensitive skin makes them susceptible to changes in the environment, such as by pesticides and herbicides, which is another key to their ability to serve as indicators of the environment.
