Why a Closed Circulatory System Would Benefit Earthworms

Earthworms have an open circulatory system. A closed system would offer:

• More efficient oxygen delivery via continuous blood vessels
• Higher blood pressure and flow for rapid nutrient/gas/hormone transport
• Blood protection within vessels, reducing loss and contamination
• Capillary filtration for waste/toxin removal
• Enhanced homeostasis against external temperature/solute fluctuations

Understanding these advantages highlights the evolutionary benefits of closed circulation.