How to Distinguish Between a Bullfrog and a Green Frog

Bullfrogs lack a dorsal-lateral ridge.

Green frogs (Rana clamitans) and bullfrogs (Rana catesbeiana) are very similar in appearance. There are, however, a few characteristics that you can use to tell the difference between the two species. These include a frog's size, the length of its dorsal-lateral folds and its voice.

Things You'll Need

• green frog or bullfrog

Instructions

1. Examine your frog's size. Bullfrogs can grow much larger than green frogs. Bullfrogs reach lengths of more than 6 inches, but green frogs are typically anywhere from 2 to 4 inches long.

2. Look at the dorsal-lateral folds or ridges. This is the most important distinguishing feature that separates green frogs from bullfrogs. The green frog has ridges of skin extending along the length of its back. In the bullfrog, these folds of skin curve around the tympanum membrane (ear) and do not extend down the body.

3. Listen to the sounds the frog makes. Bullfrog calls are deep and sound like "barrrum barrrum barrum." Green frog calls are higher pitched and shorter in duration.

Tips & Warnings

• Bullfrogs and green frogs are very difficult to capture because of their long, strong jumping legs. You may want to use a net.

References

• New York State Department of Environmental Conservation: Bullfrog
• University of Rhode Island: American Bullfrog