Ruminants and birds

A cow keeps chewing even when it is not eating. Why?

The idea

A cow chews food again after swallowing it.

Cows, buffaloes and goats eat grass. They are ruminants. A ruminant swallows its grass fast. Later the partly digested food comes back to the mouth. The animal chews it again. This is rumination.

A bird has no teeth. It swallows its food whole. Food goes to the stomach, then to the gizzard. The gizzard has strong walls that squeeze the food. Small stones called grit help grind the food.

A cow chews its food again. This is rumination. A bird has no teeth. Its gizzard breaks up the food.

Try the lab to finish this lesson.