Green Frog vs Bullfrog
Green Frogs and Bullfrogs sometimes overlap in size, especially juveniles of each species, and young female Bullfrogs and large male Green Frogs. Luckily, there is one characteristic that is completely failsafe for telling these two species apart. Both have a ridge that extends from behind the eye and curves down around the eardrum, or typanum. In the Green Frog, there is an extension of this, called the dorsolateral ridge, that runs straight back along the body to the hip (see above). This ridge is absent in Bullfrogs.