How do earthworms sense activity in their habitat without eyes, ears or a nose?

Explanation

1. The Photoreceptors (sense of light) are found on the dorsal surface of the body.
2. Gustatory (sense of taste) and olfactory receptors (sense of smell) are found in the buccal cavity.
3. Tactile receptors (sense of touch), chemoreceptors(detect chemical changes) and thermoreceptors (changes in temperature) are present in the prostomium and the body wall.
4. Hence they can sense activity in their habitat easily without eyes, ears or a nose.