What is the primary function of the notochord in chordates?

The primary function of the notochord in chordates is to provide support and structure. It is a flexible rod-like structure that serves as a primary axial support during the early development of the organism. This support allows the organism to maintain its shape and resist compression while providing a surface for muscle attachment, facilitating movement.

In many chordates, particularly in embryonic stages, the notochord plays a crucial role in the development of the vertebral column in later stages. As the organism matures, the notochord can be replaced by the vertebral column in vertebrates, but it still serves as a foundational element for the surrounding structure.

In contrast, functions such as respiration, movement, and digestion are managed by other systems within the organism. Respiration is handled by specialized organs such as lungs or gills, movement involves the muscular system, and digestion is facilitated by the digestive system. Thus, while these functions are vital to the organism's survival, they are distinct from the structural support that the notochord provides.