Invertebrates are a group of animals that do not possess or develop a vertebral column, commonly known as a backbone or spine, included in the phylum Chordata. This category is vast and diverse, including species ranging from simple organisms such as sea sponges and starfish to complex octopuses and crustaceans. Although the terms "Cows", "Herbivorous Mammals", and "Mammals" are not directly classified under invertebrates, they are related in the broader sense as they all fall under the kingdom Animalia. However, unlike invertebrates, these groups are characterized by the presence of a backbone and other complex structures and systems.