The Back Page

Q: Do all fish have gills?
Elizabeth Maddox, Licking

A: Yes, all fish have gills. Instead of using lungs to breathe oxygen, fish use gills to get oxygen that is dissolved in water. In most cases, the gills are on each side of the fish's head beneath a bony flap called a gill cover. Each gill looks like a bony arch filled with blood vessels.

A fish "breathes" by opening its mouth and taking in water. The fish then closes its mouth, which forces the water to flow over the gills and out through an opening that looks like a slit located just behind the gill cover. This process allows the fish to remove roughly 80 percent of the oxygen from the water.

Q: How does a bat find a mosquito?
Spencer Cushing, age 6, Moscow Mills

A: To find a mosquito, a bat starts by making an ultrasonic sound-a sound so high in pitch that humans can't hear it. Just as the bat makes the sound, a tiny muscle in its ear contracts or tightens up, so the bat doesn't hear its own cry. That way, the bat only hears the echo of that cry bouncing off a mosquito or other flying insect.

In a fraction of an instant, the bat analyzes the echo and can tell the size, shape and characteristics of the surface of the mosquito's body, how far away it is, in what direction to find it and whether or not the mosquito is moving. Not only that, but the bat constantly knows its own flight speed and direction and adjusts accordingly. This technique is called echolocation.

Q: To what family of animals do armadillos belong?
Kara Ross, age 9, Aurora

A: Armadillos belong to the family dasypodidae and the order edentata, which means "toothless." Other animals in this order include South American anteaters and tree sloths. There are 20 species of armadillos that live in South and Central America and Mexico. Only nine-banded armadillos live in the United States. They were first sighted in southern Missouri in 1980, having made their way north from Texas and Oklahoma.

Of all the mammals in North America, armadillos are unique because they don't have furry coats. Instead, most of the body is covered with protective shells-or plates-of lumpy scales. A large shield or plate covers the head, and their backs are covered with nine moveable bands. Their tails are protected by a series

of hard, overlapping rings. Only their undersides have soft skin. "Armadillo" means "little armored one," a name given to these insect-eating animals by the Spanish who first came across them in South America.