The word "more invertebrate" refers to creatures without a backbone, such as insects, mollusks, and worms that are typically included under the category of invertebrates. The antonyms of this phrase refer to animals with a backbone, known as vertebrates. Vertebrates include mammals, reptiles, birds, amphibians, and fish, and are characterized by their skeleton system. These creatures possess a spinal cord and nerves that connect to all parts of the body, allowing for a greater level of control and mobility. While invertebrates are found in various ecosystems across the world, vertebrates form an essential part of the food chain, and their presence is crucial for the proper functioning of many ecosystems.