This document provides an overview of invertebrate animals. It states that invertebrates lack a backbone, lay eggs, breathe through their skin as they do not have lungs or gills, and have cold blood. Their body parts and number of legs varies by species. They live in various habitats on land and in water. The document then lists and provides some key details about different phyla of invertebrates, including arthropods, molluscs, echinoderms, and worms. It notes characteristics of insects, arachnids, and crustaceans.