0
$\begingroup$

This question already has an answer here:

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?

$\endgroup$

marked as duplicate by Remi.b evolution Dec 26 '17 at 16:00

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  • $\begingroup$ 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 '17 at 16:01
  • $\begingroup$ What is meant by a "necessary trait"? $\endgroup$ – user31589 Jan 3 '18 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. $\endgroup$ – Aravind k Jan 4 '18 at 3:51
2
$\begingroup$

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.

Chordate

$\endgroup$
  • $\begingroup$ What do you mean "non-embryonic humans"? $\endgroup$ – Aravind k Dec 26 '17 at 15:55

Not the answer you're looking for? Browse other questions tagged or ask your own question.