Frogs: a vital link in the food and health chain The populations of frogs have been declining at an alarming rate worldwide, with nearly one-third of the world’s amphibian species threatened with extinction. Since 1980 nearly 200 species have altogether disappeared. This is not a normal precedent as  amphibians naturally go extinct at a rate of only about one species every 250 years. The amphibian population is faced with massive environmental problems such as pollution, infectious diseases,  habitat loss, invasive species, climate change and over-harvesting for the pet and food trades.
Frogs are vital not just to the food chain but also for a host of other issues. Frogs produce a wide array of skin secretions, many of which have significant potential to improve human health through their use as pharmaceuticals. Approximately 10% of Nobel Prizes in Physiology and Medicine have resulted from investigations which used frogs. When a frog species disappears, so does any promise it holds for improving human health.
Tadpoles keep waterways clean by feeding on algae. Adult frogs eat large quantities of insects, including disease vectors that can transmit fatal illnesses to humans (i.e. mosquitoes/malaria). Frogs also serve as an important food source to a diverse array of predators, including dragonflies, fish, snakes, birds, beetles, centipedes and even monkeys. Thus, the disappearance of frog populations disturbs an intricate food web, and results in negative impacts that cascade through the ecosystem.
Most frogs require suitable habitat in both the terrestrial and aquatic environments, and have permeable skin that can easily absorb toxic chemicals. These traits make frogs especially susceptible to environmental disturbances, and thus frogs are considered accurate indicators of environmental stress: the health of frogs is thought to be indicative of the health of the biosphere as a whole. Frogs have survived in more or less their current form for 250 million years, having survived countless ice ages, asteroid crashes, and other environmental disturbances, yet now one-third of amphibian species are on the verge of extinction. This should serve as an alarm call to humans that something is drastically wrong in the environment.