When frogs sometimes make nests of foam, what is the foam and where does it come from? Do the babies get hurt when they drop from the nest to the water?

Jessica Christian, 11, Hartsburg

Only a handful of frog families build nests of foam. All of them are tropical al species. We have no foam nest builders in Missouri. Our frogs lay their eggs in the water, whether in a pond, stream or reservoir. Sometimes many frogs lay their eggs in the same place. We call this communal nesting, although no nest is built.

The frogs that build foam nests construct them at the water's edge or in branches of a tree overhanging the water. They make the foam by whipping up skin secretions, the way you might whip egg whites in a blender. The foam nest gradually deteriorates, and the polliwogs drop harmlessly into the water.

Do corn snakes live in the wild in Missouri? How do you tell the difference between a male and a female?

Vince Markovitz, 8, Columbia

Corn snake is the common name for the red rat snake, which lives in the southeastern U.S. It does not live in the wild in Missouri. You can tell male and female snakes apart by looking at their tails. The tail of an adult female snakes narrows rapidly past the anal plate, while an adult male snake has a swelling at the base of its tail. These are hard to spot characteristics, however.

I wondered if there were any wild horses, fillies, colts or foals in Missouri. If so, where?

Lauren Thomas, 3rd grade, St. Louis

Horses aren't native to Missouri, so there aren't any truly wild horses in Missouri. However, some horses that have descended from domestic stock now live wild in parts of Missouri. The ones we know about are in the hills and valleys near the Current River. Some people have grown fond of the idea of horses living wild in Missouri, but horses can damage the fragile Ozark river environment. They eat and uproot rare and endangered plants, and they also compete with native wildlife for food and habitat. Because of their heavy weight, horses also contribute to erosion. This threatens water quality in streams and rivers, as well as plant communities in upland areas.