Cavity in the body of multicellular animals, which is used for digestion (digestive system); originally a simple cavity (archenteron) with connection to the outside world (coelenterates), then an external canal (intestine canal, intestinal tract), which passes through the whole animal (intestine animals, bilaterians) from an oral opening up to an opening of the anus.

Strictly speaking the intestine is the section of the intestine canal, which begins behind the stomach and ends at the anus.

The intestine length is larger with herbivores than with carnivores (e.g. with cattle 21-times as long as the body, with the cat 4,5-time as long as the body).

In the intestine, nutrients are taken out of the fodder mash and released into the blood through the intestinal wall in order to distribute them throughout the body. The human intestine (adult) has a length from 8-9 m and is divided into small intestine, large intestine and rectum. It transports the chyme prepared in the stomach through rhythmic contraction of its longitudinal and ring-shaped muscles through all its departments to the anus.

From the sheep the duodenum, the gut skin (Jejunum) and the Appendix (Caecum) are used. The duodenum and the gut skin are used not turned inside out, but mucous membrane, muscle layer and serous coatings are removed.