Backbones or no bones? -- Hard and soft coverings -- Sponges live in oceans -- Five parts -- Sea stingers -- Wiggly worms -- Worms in water -- Slugs and snails -- Colorful sea slugs -- Octopuses and squids -- Crusty crustaceans -- Insect invertebrates -- Spiders are not insects -- Did you know?
Summary
Animals without backbones are called invertebrates. There are millions of kinds of invertebrates on Earth.