With what? Is there a picture....
Sub-questions are narrower questions. They are important because they provide the 'skeleton' around which you will find information to answer your main research question.
Vestigial usually refers to traits which over evolution have lost their main function and are less useful than they once were.
In number one Hunter means that he thinks the teeth were from the ancestor whale shark but are now useless or nearly useless to the current whale shark.
