Frogs

Frogs and humans have interacted for many thousands of years. Toads are referred to in ancient writings, as: a "rain of toads," the "eye of toad" as part of a witch's brew, and in many other relationships.

Frogs are also used in research, and to teach biology. A core element of many high school and college biology classes in the United States might involve each student dissecting a frog. Millions of leopard frogs have been utilized in this way in schools. By the 1950s, however, it was found that their numbers in the wild had decreased drastically, particularly in the midwestern U.S. This meant that frogs had to be imported from Canada and Mexico for use in teaching biology. During the past decade or so the emphasis on dissection has been much reduced, but large numbers of frogs are still used each year in physiological experiments. The frog populations of the Midwest have not recovered, and those of Canada and Mexico have also declined greatly.

Similarly, "frog-legs" used to be a prominent dish in many restaurants. American bullfrogs (Rana catesbeiana) of the swamps of Florida and Louisiana were the major source of this food. However, because of over-hunting it became too uncommon to be exploited by frog hunters in the United States, and imported legs of Rana tigrina and other species from India became the major source of frog legs.

More recently, the poison-arrow frogs of tropical America (Dendrobatidae) have become of great interest to pharmaceutical companies. Each species has an unique mix of biochemicals that may have a role to play in the treatment of human diseases. Frogs are useful to humans in various ways, although uncontrolled hunting of them can lead to serious problems for their populations.

Many people have kept pet toads or frogs, but the recent commercial market for captive frogs is primarily in exotic species such as South American horned frogs (Ceratophrys), the African "bullfrog" (Pyxicephalus adspersus), and brightly colored poison-arrow frogs. These animals are beautiful and interesting pets, but could cause ecological harm if they were to be released and develop wild populations beyond their natural range.