Fat digestion can only occur at the surface of fat globules. Lipase in the small intestine works at the surface of the globs and releases glycerol and 3 fatty acids. These are absorbed, then reassembled into triglycerides inside intestinal cells. The triglycerides are then packaged into membranes, transported to golgi then into vesicles into lymph into blood. Absorption Occurs in jejunum and ileum.
Absorption requires lots of surface area.
The length of intestine is related to diet - the more meat in the diet the diet the shorter the intestine because plant material is more resistant to digestion and needs a longer period in the digestive tract.