Amphibians are a unique group of vertebrates that are distributed across the globe. Sadly, nearly one-third of the world’s over 7,300 species are threatened. Frogs are the most speciose of three orders of amphibians, which also includes salamanders and worm-like caecilians.
Use these cards to help you focus on the key traits and behaviors that make different frogs species unique. Drawings, photographs and notes or recordings of vocalizations are a great way to supplement your field notes as you explore the diversity of these amazing animals.
Most people learn about the basics of frog reproduction in elementary school. Frogs lay eggs in water, and the eggs hatch into tadpoles that grow into frogs. Only about half of all frogs follow these exact steps, but there are a few rules of thumb about frog reproduction. All frogs reproduce sexually, and all hatch from eggs.
In almost all frogs, egg fertilization happens outside the female's body instead of inside. The female releases her eggs and the male releases his sperm at the same time. In order to make sure that the sperm reach the eggs, the male and female get into a mating posture called amplexus. The male climbs onto the female's back and clasps his forelegs around her middle. Frogs can stay in amplexus for hours or even days as the female releases as few as one or as many as several hundred eggs.
Sometimes, it's easy to tell male frogs from female frogs. Many species are sexually dimorphic, meaning that there are differences between the bodies and colors of males and females. But in some species, males and females are hard to tell apart. In such species, male frogs often produce a release call when clasped by another male. During mating season, researchers can use release calls to tell which frogs are male and which are female.
All frogs' eggs require moisture to develop, and most frogs abandon their eggs once they're fertilized. But not all eggs incubate underwater or without parental care. A few species carry their eggs in their vocal sacs or their abdomens. Others lay eggs in dry areas and keep the eggs moist with water or urine. Depending on the frog's species and the climate in which it typically lives, the eggs can hatch in a few days to a few weeks.
In a few species, fully formed froglets hatch from the eggs, but most of the time the frog starts its life as a tadpole. While adult frogs are carnivores, tadpoles can be vegetarians or omnivores. Some are filter feeders that eat algae, and others have teeth and can eat anything from rotting vegetation to other tadpoles. Either way, tadpoles tend to be voracious eaters -- it takes a lot of energy to complete their metamorphosis into frogs.
The Frog Finder is a unique smartphone guide for searching worldwide frog and toad distributions. It is designed for amphibian researchers, naturalists, educators, hobbyists and anyone interested in knowing species that might occur—or may have once occurred—in specific locations.
Download the free Frog Finder iPhone app.
The Frog Finder was created by Seungkeol Choe and Jeff Rice, with support from the University of Utah J. Willard Marriott Library in conjunction with the Western Soundscape Archive and the Encyclopedia of Puget Sound at the University of Washington.
The Frog Finder is a unique smartphone guide for searching worldwide frog and toad distributions. It is designed for amphibian researchers, naturalists, educators, hobbyists and anyone interested in knowing species that might occur—or may have once occurred—in specific locations.
Download the free Frog Finder iPhone app.
The Frog Finder was created by Seungkeol Choe and Jeff Rice, with support from the University of Utah J. Willard Marriott Library in conjunction with the Western Soundscape Archive and the Encyclopedia of Puget Sound at the University of Washington.
