Invertebrates include insects, arachnids, centipedes, and crustaceans. Insects have an exoskeleton, two eyes, two antennae, and three body parts - a head, thorax, and abdomen. They have six legs and lay eggs. Arachnids have two body parts, eight eyes, eight legs, and no antennae. Centipedes have an exoskeleton, no eyes, many legs, and two antennae. Their body is divided into sections. Crustaceans have a thick exoskeleton, two eyes, eight legs, four antennae, and two claws.