Earthworm anatomy diagram illustrating external features and internal circulatory system.

- The earthworm has a closed circulatory system. Blood is contained within vessels and is pumped by five pairs of aortic arches (hearts) located in segments 7–11. The dorsal blood vessel carries blood forward, while the ventral blood vessel carries it backward, distributing nutrients and oxygen throughout the body.

- Digestion in earthworms involves a complete digestive tract: food enters through the mouth, passes through the pharynx, esophagus, crop (for storage), and gizzard (for mechanical breakdown). It then moves to the intestine, where enzymes secreted by glandular cells and symbiotic bacteria break down organic matter. Nutrients are absorbed through the intestinal wall, and waste exits via the anus. The typhlosole, an internal fold of the intestine, increases surface area for absorption.