Jeffrey Groves, age 9, of Coventry, R.I., for his question:

IS THE PLATYPUS A REPTILE OR A MAMMAL?

Along streams on Australia's mainland and on the island of Tasmania you'll find the platypus. Often called a duckbill, the creature has a bill like a duck where other mammals have noses and lips. He uses the bill to find worms, shellfish and water insects along the bottom of streams.

The platypus is a true mammal, not a reptile. The female lays eggs instead of producing her young alive, although she will nurse her babies with milk, after they are hatched, just as other mammals do. The animals, once prized for their fur, are now protected by Australian law.

The platypus is about two feet long, which includes his six inch tail. Mother lays from one to three eggs that are soft and have leathery shells, much like those of snakes.