Final Answer:
The circulatory system in an earthworm comprises the dorsal blood vessel, ventral blood vessel, and aortic arches. These components work together to form a closed circulatory loop for efficient nutrient distribution.
Step-by-step explanation:
The circulatory system of an earthworm consists of three major components: the dorsal blood vessel, the ventral blood vessel, and the aortic arches. The dorsal blood vessel runs along the dorsal side of the earthworm, while the ventral blood vessel runs along the ventral side. These vessels are connected by a series of contractile vessels that act as hearts, pumping the blood forward.
The aortic arches, typically numbering five pairs, function as muscular pumps that help propel the blood into the dorsal vessel. Together, this system forms a closed circulatory loop, allowing for the efficient distribution of nutrients, gases, and waste products throughout the earthworm's body. This simple yet effective circulatory system reflects the earthworm's adaptation to its environment and its reliance on efficient nutrient transport.