Final answer:
The muscularis tunic is a layer of smooth muscle in the alimentary canal that helps with digestion and food movement.
Step-by-step explanation:
The muscularis tunic is a layer of smooth muscle found in the alimentary canal, which includes the stomach and small intestine. It consists of two layers: the inner circular layer and the outer longitudinal layer. The contractions of these layers help promote mechanical digestion, increase the surface area for digestion and absorption, and move food along the canal through peristalsis.