Bullfrog (Rana castesbeiana)
Bullfrogs have a thick, broad body and a smooth skin that varies in color from a dullish green to brown with a few or a lot of brown spots. Female bullfrogs have a white throat and the male bullfrogs have a yellow throat. Bullfrogs have distinctive folds of skin called dorsolateral ridges that begin at the eye and go around the eardrum, ending at the front legs. You can tell if the bullfrog is male or female by looking at the eardrum. If the ear circle is larger than the eye, the bullfrog is a male. If the ear circle is about the same size or smaller than the eye, the bullfrog is a female. The bullfrog in these photographs is a male.
We have bullfrogs living in our little pond, and we love to hear their deep, throaty call, which herpetologists say can be clearly heard over distances of more than half a mile. All bullfrogs, male and female, will also make a squeaking sound if they are frightened. Adult bullfrogs range in size from 3 1/2 to 6 inches and occasionally are larger, although the bullfrogs in this area are about the same size as the other frogs. They overwinter by burrowing in the mud, either underwater or on land.
In spring the female bullfrog lays thousands of eggs encased in a clear gelatinous mass that floats on top of the water but is usually attached to a plant or a floating branch. Bullfrog tadpoles are very large compared to other tadpoles and take up to three years to mature into adult frogs. Apparently bullfrog tadpoles give off a bad taste because fish or other predators will not eat them. It is interesting to see that even in the early developmental stages, young tadpoles have the distinctive webbed back legs and dorsolateral ridges around their ears.
Written by Shirley | Filed Under Enjoying Nature
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