Which structure comprises the earthworm's major blood vessel system?

Which structure comprises the earthworm's major blood vessel system?

• A. Aortic arches
• B. Blood vessels
• C. Segments
• D. Crop

Answer: (B)

Earthworms have a closed circulatory system, meaning blood stays within vessels as it moves through the body. The major blood vessel system is the network of blood vessels itself—the dorsal vessel travels along the back, the ventral vessel along the belly, and the connecting aortic arches act as pumps to move blood. So the structure that comprises the main blood vessel system is the vessels that transport blood. The crop belongs to the digestive system, segments are body sections, and the aortic arches are parts of the heart-like pump, not the entire transport network.

Earthworms have a closed circulatory system, meaning blood stays within vessels as it moves through the body. The major blood vessel system is the network of blood vessels itself—the dorsal vessel travels along the back, the ventral vessel along the belly, and the connecting aortic arches act as pumps to move blood. So the structure that comprises the main blood vessel system is the vessels that transport blood. The crop belongs to the digestive system, segments are body sections, and the aortic arches are parts of the heart-like pump, not the entire transport network.