Invertebrates are animals without a backbone, encompassing a diverse group that includes insects, arachnids, mollusks, and crustaceans. Articles are a unique way for readers to learn about the world around them. In addition to building reading comprehension skills and increasing vocabulary, articles can be used for writing and research. Articles are broken into 6 single-page sections: What Is, Soft Bodies, Shells and Other Coverings, Why Important, Fun Facts, and Words to Know.