The two main groups of the animal kingdom are invertebrates and vertebrates.
Invertebrates are animals that lack a backbone. This group includes a wide variety of organisms such as insects, arachnids, mollusks, and cnidarians. Invertebrates make up the vast majority of animal species on Earth, showcasing an incredible diversity in form and function.
On the other hand, vertebrates are animals that possess a backbone or spinal column. This group includes mammals, birds, reptiles, amphibians, and fish. Vertebrates tend to be larger and more complex than invertebrates, featuring advanced nervous systems and structures that support a variety of lifestyles and adaptations.
Understanding these two groups helps us appreciate the vast diversity of life that exists on our planet and the evolutionary history that led to the formation of such varied organisms.