Question

What is the main basis of differentiation between vertebrates and invertebrates?

Answer 1

In invertebrates the notochord does not change into vertebral column but in vertebrates notochord changes into vertebral column that might be cartilaginous as in Chrondrichthyes or bony as in Osteioichthyes.

Thats why we say all vertebrates are chordates but all chordates are not vertebrates

Answer 2

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Refer to the attachment ♡~