✔ 最佳答案
For MAMMALS, there are a few plant eaters who need to digest cellulose. It is done in the CAECUM[or cecum], not the colon, although they are connected to each other.
圖片參考:
http://upload.wikimedia.org/wikipedia/commons/thumb/8/82/Stomach_colon_rectum_diagram.svg/250px-Stomach_colon_rectum_diagram.svg.png
Most herbivores have a relatively large cecum, hosting a large number of bacteria, which aid in the enzymatic breakdown of plant materials such as cellulose.
So it DOES NOT STORE dietary fibres, only micro-organisms.
The appendix have no use at all, and some people are born without appendix, and are completely healthy otherwise. Thus it is said to be vestigial [退化的, 無用的].
OK, back to your answers:
The function of the large intestine is for keeping the micro-organisms in and letting them digest cellulose in HERBIVORES ONLY. It doesn't happen to carnivores like tigers nor omnivores like dogs, or us.
But for ALL MAMMALS, the large intestine is a place for water absorption, alongside with mineral and vitamin absorption.