Why do pigs have spiral colons and not colons like humans?

Question

So I am writing a conclusion on a fetal pig vs human anatomy and the colons are different (human's frames the small intestines, pancreas, etc. and the pig's is just a spiral shape). Why is it like that? What benefit does it have for the pig to be like that?

Answer 1

Not a direct answer but some ideas to consider under general "Form follows Function" rule.

1. Function: Human colon absorbs water and salts but doesn't perform digestion. Pig colon performs anaerobic digestion of cellulose by microbes. This requires more time,therefore more length and more surface area for nutrient absorption. 5m in a pig vs. 1.5M in a human. Body conserves space via coiling. Another example is the brain that increases surface area by folding/coiling when learning something new.
2. Evolutionary embryology: pigs are quite far removed from humans so the early migration and specialization of types of cells/tissues that is needed for the functions above are set in motion very shortly after fertilization.
3. Clade diagram: https://upload.wikimedia.org/wikipedia/commons/a/a5/The_Ancestors_Tale_Mammals_cladogram.png

Glad to hear other ideas - you've gotten me curious!

ann