Today in biology class, my teacher said that all chordates have all the necessary traits, at least during the embryo stage, and we humans are chordates. So, one of these necessary traits was that they should have tails. My question is, humans don't seem to have tails, so how can they be chordates?

  • $\begingroup$ Oops.... I am always surprised when my vote to close alone is enough to actually close a question. I think @kmm answer is good (+1), I just wanted to highlight that the question can be though as a duplicate of another one. $\endgroup$
    – Remi.b
    Dec 26, 2017 at 16:01
  • $\begingroup$ What is meant by a "necessary trait"? $\endgroup$
    – user31589
    Jan 3, 2018 at 20:57
  • $\begingroup$ @MamaTank what I meant is that, a species can be called a chordate only if it has all the traits a chordate is supposed to have. $\endgroup$
    – aravk33
    Jan 4, 2018 at 3:51

1 Answer 1


The chordate trait you are describing is more precisely termed post-anal tail. It is one of the basic characteristics of all chordates, along with, among others, pharyngeal pouches, a hollow dorsal nerve tube, and a notochord. Two other traits are less commonly considered chordate traits: segmented body musculature and a thyroid gland or endostyle (the latter particularly controversial).

These characteristics are present in all chordates at some point during their ontogeny. These traits are shown below.

We can see these most clearly in embryonic forms. For the post-anal tail: in humans, there is a short "tail" that extends past the anus (end of the yellow tube). This tail does not typically persist for very long. Similarly, the notochord is absorbed into the vertebral column, and remnants of the pharyngeal pouches are not externally visible.

The key phrase is "at some point during development." Non-embryonic humans don't have a tail, but that doesn't mean humans are not chordates.


  • $\begingroup$ What do you mean "non-embryonic humans"? $\endgroup$
    – aravk33
    Dec 26, 2017 at 15:55

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