Question

Many nonchordates have tails. Which feature differentiates a chordate's tail from that of a nonchordate?

Answer 1

The main difference between a chordate and a non-chordate is that the former has a notochord present in at least a stage in their life cycle while the latter will not have a notochord at all. Also, the former will at some stage or even throughout their life possess a post-anal tail while the latter will never possess a post-anal tail. I think what you mean by "tail" is the hindmost part of a nonchordate like an earthworm, if so, then the difference would be that in chordates, the "tail" is located after their anus while in the non-chordates, it is just basically the structure located rearmost of the animal.

Answer 2

Some unique characteristics of the chordata are the following: Notochord is present, Dorsal hollow nerve cord is present,paired pharyngeal gill slits are present, and post anal tail is present. The differences in Nonchordates are the following: Notochord is absent, Solid nerve cord generally ventral/lateral, post anall tail is absent, pharyngeal gill slits are absent, Dorsal hear.

Answer: A) Chordates have postanal tails.

I hope it helps, Regards.