Why are not all Exceeds able to transform into an anthropoid (humanlike) form?


There are several exceeds known, and as far as I can remember, only
Pantherlily and Samuel are shown to turn into human form.

![enter image description here](https://i.stack.imgur.com/VUHABl.png)

So, why can't other exceeds like Happy and Carla change into human form as
well?




I am not sure that this applies for Pantherlily and Samuel, but in chapter
421, Charle could transform into anthropoid (human-like form) because she
learned transformation magic.

![chapter 421](https://i.stack.imgur.com/Im3YA.png)

This may be the cause that Pantherlily and Samuel could transform, and
Pantherlily saying that he could maintain that form for certain time only when
he's worn out in battle because it requires magic to maintain it.

