There are about 2,700 known species of frogs and toads. Also, as noted on our Amphibians Page , amphibians need water in which to reproduce. The picture at the right shows the head of the frog shown above. This is a Bronze Frog, Rana clamitans clamitans . It's the southern subspecies of what in the North is called the Green Frog, Rana clamitans melanota .
Frog eyes have eyelids.
An upper eyelid, which you can't really see here, is a simple skin fold, and the lower one is a translucent membrane, which you can see here partly covering the eye. When a frog's eyeball is retracted into the eye socket, the lower lid spreads over its surface. Also notice the circular item behind the eye and about the size of the eye. When soundwaves strike this membrane, the frog hears. The membrane is larger in male frogs than in female frogs.