Monogastric
Monogastricians (from gr . : γαστήρ, gastēr - stomach) are living beings that have only one stomach or whose stomach is made of one piece.
Since vertebrates do not have an enzyme that breaks down cellulose , they rely on the help of microorganisms to digest the energy they contain.
In some monogastric animals (for example the equine) the appendix takes over this function. Game animals improve their energy yield by eating their droppings one more time. With hoatzin , the goiter is used to digest cellulose. Other monogastricians such as humans and pigs do not use cellulose as a source of food, so together with hemicellulose , pectin and lignin it forms the main part of the dietary fiber for them .
Polygastric
In contrast to the monogastric animals , ruminants camels , langurs and red giant kangaroos have chambered stomachs ( polygastric animals ). Part of it, in ruminants it is the rumen , serves to digest the cellulose by microorganisms.