Question

why ventricle wall is thicker than auricle

Answer 1

Since ventricles have to pump blood into various organs of the body, therefore they have thicker muscular wall than atria/ auricle.
Left ventricle has thickest muscular wall.

Hope this helps :)

Answer 2

The walls of ventricles are thicker than auricles because they pump blood out of the heart at a greater pressure when compared to the auricles