David Sullivan age 13, of White Plains, N.Y , for his question

WHAT IS A WATER FLEA?

A water flea is a tiny freshwater shellfish about one tenth of an inch long It is not an insect It gets its name because it skips and jumps through water like a flea using its feelers as oars These feelers are the antennae

The water flea has a transparent carapace or body covering that surrounds most of its body. Because the action of the water flea s heart and other organs can be seen directly, the animal is often used in scientific experiments on the effects of drugs

The head of the water flea narrows into a long snout which bears a pair of compound eyes. The animal also has five pair of leg parts called appendages. These appendages move continually and their motion helps the animal breathe

The appendages also sweep in food and water

Water fleas are sold as food for tropical fish In the summer millions of these tiny creatures swarm in ponds and marshes