INVERTEBREATE ZOOLOGY

Invertebrate means lacking a spinal column. Animals in this category include species of the following: protozoans, annelids, cnidarians, echinoderms, flatworms, nematodes, molluscs, and arthropods. Invertebrates make up 90% of the Earth's animals. They range in size from minute to extremely large. They possess soft bodies and external skeletons.