Digestive systems
Most animals have "assembly line" digestive systems (a complete tube,
from mouth to anus), permitting regionally different organs to specialize
for digestion of a particular nutrient or a particular step in a multi-step process.
Meat-eaters and plant-eaters have different kinds of teeth to chew different kinds of food.
Plant-eaters often have large a large caecum where bacteria can help digest cellulose.
The intestine is a complex organ with many tissue layers in its lining.
The finger-like processes, called villi, greatly increase the
surface area for absorption of digested materials.
Absorption: Notice that the midgut epithelial cells have numerous finger-like villi.