In the study of animal organization, animals are categorized into two main classifications based on embryonic development: diploblastic and triploblastic. Diploblastic animals, such as coelenterates, exhibit a simpler structure consisting of two primary tissue layers: the ectoderm (outer layer) and endoderm (inner layer). A non-cellular layer called mesoglea is typically found between these layers. Conversely, triploblastic animals possess a third layer, the mesoderm, which facilitates more complex structures and functions, enabling the organization into systems like organs and organ systems. This classification has significant implications for understanding the evolutionary progression and complexity of various animal taxa.