Loretta Voss, age ~13, of Dodge City, Kan., for her question:
A majority of frogs, including most species that live on land, mate in water. The male enters the water first and starts his call to attract mates. His call also warns other males that a certain area is occupied and that intruders are not welcome.
After a female frog enters the water, a male grasps her and clings to her back. In this position, the male fertilizes the eggs as they leave the female's body.
In the water, the eggs hatch within three to 25 days, depending on the species and the water temperature. Higher water temperatures speed up development, and lower temperatures slow it down.
Some species of frogs lay several thousand eggs at a time. But only a few of these eggs develop into adult frogs. Ducks, fish, insects and other water creatures eat many of the eggs. And even if the eggs hatch, the tadpoles that form face the danger of being eaten.
The tadpole that comes from a fertilized frog's egg resembles a tiny fish. It has no neck and so its head and body look like one round form. It has a long tail. And it breathes by means of gills.
A tadpole's form changes as the animal grows. Its tail becomes larger and enables the animal to swim about to obtain food. Tadpoles eat plants and decaying animal matter.
In time, the tadpole begins to grow legs. The hind legs appear first. Then the lungs begin to develop and the front legs appear. The digestive system changes, enabling the frog that develops to eat live animals.
Just before its change, or metamorphosis, into a frog, the tadpole loses its gills.
Finally, a tiny frog, still bearing a stump of a tail, emerges from the water. Eventually, the animal absorbs its tail and assumes its adult form.
Some tadpoles are tiny and others measure six to seven inches long.
It takes two or even three years for a bullfrog tadpole to develop into a frog. But among some species, the tadpoles change into adults within a few weeks:
After a frog becomes an adult, it may take a few months to a few years before the animal is mature enough to breed. The green frog and the pickerel frog mature in aobut three years.
Scientists do not know how long frogs live in the wilds, but in captivity a bullfrog may live more than 15 years. But most frogs probably don't live this long in nature since they are often eaten by such enemies as hawks, herons, raccoons, snakes, turtles and fish.
Adult frogs eat mainly insects including earthworms and spiders. Most frogs use their sticky tongues to capture prey. But they flip out their tongue only at moving prey.