SPONGES ARE SKELETONS

A ``Let's-Read-and-Find-Out'' book that's cheerful and colorful, if a bit odd: Esbensen describes the sponge as the skeleton of an animal, but gives few specifics on the live animal; she remarks that ``When the sponge was alive, it pumped sea water through its thousands of small pores,'' but never explains how. Not until page 24 does she point out that most ``sponges'' are not skeletons of animals but made in factories. Keller's charming illustrations include many softly colored underwater scenes of bath sponges, divers, and fish. But even in such a simple presentation, young readers could be told more about the 5,000-plus species of unique and ancient animals that make up the phylum Porifera. (Nonfiction. 5-9)