3. Digestion in the Intestine
The stomach leads to the intestines which in sharks, is referred to as the spiral valve. The intestines are short but have a large surface area due to the infolding of the inner surface, some are arranged in folds, and some are in a spiral pattern. The digestive tract leads to the rectum and to the cloaca. The cloaca is a common opening for the urinary, digestive, and reproductive systems. Human intestines contain villi and microvilli, just like the spiral valves are arranged in folds or spirals to increase surface area and nutrient absorption. Both digestive tracts also contain a rectum however humans have an anus instead of a cloaca.