Why are vertebrae, specifically, so important in classification?

Question

A fundamental level of animal classification is the distinction between vertebrates and invertebrates. The vertebrata are, arguably, often classified as higher life forms than the invertebrata. But why is the presence of the spine so important? Why not use the simpler concept of internal bones as a classifier? I might be missing something, but I can't think of any creature that has an endoskeleton but no spine. Do any such creatures exist? If not, why does classification focus on the spine and not the endoskeleton?

Answer 1

Let me address the endoskeletal invertebrates first, squids, octopi, star fish, and sea urchins are all classified as invertebrates but do possess and endoskeleton. So yes, they do exist.

Next the importance of the vertebral spinal - keep in mind that the classification systems are used to differentiate life forms based on anatomical and physiological differences, in the modern age we also utilize genetic comparisons, it was the simplest way to divide vertebrates and invertebrates from one another. Additionally, the presence of a rural crest during embryonic development is unique to the phylum chordata.

Lastly, in terms of utilizing the phrase "Higher Lifeforms" is utilized to describe differences in the neural capabilities of each species based on possessing advanced brain structures.