Introduction:
Octopuses have a closed circulatory system, which means that their blood is confined to vessels and does not directly come in contact with the body tissues. This system offers several advantages over an open circulatory system, enabling octopuses to meet their unique physiological needs.

Benefits of a closed circulatory system for octopuses:

1. Efficient oxygen transport: Octopuses are highly active predators, and their closed circulatory system allows for efficient oxygen transport. Oxygen-rich blood is pumped by the heart through arteries to reach various tissues and organs. This ensures a more rapid and direct supply of oxygen to meet the high metabolic demands of an active lifestyle.

2. Precise control over blood flow: The closed circulatory system provides octopuses with precise control over blood flow to different regions of their body. By constricting or dilating blood vessels, they can regulate blood flow to specific tissues or organs as needed. This allows for efficient oxygen and nutrient delivery to actively working tissues and selective redistribution during changes in activity levels.

3. Improved waste removal: In a closed circulatory system, blood flows in a controlled manner through specialized organs, such as gills or lungs, where oxygen is taken up and carbon dioxide is released. The circulatory system also helps remove metabolic waste products, such as nitrogenous waste, from the tissues. This efficient waste removal contributes to the overall health and well-being of octopuses.

4. Maintaining blood pressure: The closed circulatory system helps maintain blood pressure within the octopus's body. This is particularly important for cephalopods like octopuses, as they lack a rigid skeleton to support their bodies. By maintaining blood pressure, the circulatory system aids in maintaining body shape and providing support to soft tissues.

5. Protection against external threats: The closed circulatory system provides an added layer of protection against external threats. Octopuses have the ability to rapidly constrict blood vessels, limiting blood loss in case of injury. This mechanism helps prevent excessive bleeding and potentially aids in the healing process.

Conclusion:
Octopuses possess a closed circulatory system to meet their high oxygen demands, maintain precise control over blood flow, efficiently remove waste products, maintain blood pressure, and protect against external threats. This circulatory system provides them with the necessary physiological adaptations to thrive in their environment as active and highly intelligent marine creatures.

Octopus have close circulatory system because that blood flows through a series of vessels to return to the heart, rather than bathing organs in the blood fluid as in open circulatory systems.