Tunicates circulatory system comprises which of the following?

Tunicates circulatory system comprises which of the following?

• A. Only closed
• B. Only open
• C. Both closed and open
• D. No circulatory system

Answer: (C)

Tunicates show a developmental change in how their blood moves through the body. In the tadpole-like larval stage, the circulatory system is organized with vessels that keep blood contained, which is the hallmark of a closed system. After metamorphosis into the adult, the blood circulates more openly, flowing through body cavities and sinuses as the simple heart pumps it, rather than staying strictly within a network of vessels. The heart can also reverse its pumping direction, helping distribute blood through the tissues in this open arrangement. Because they use a closed system early on and an open system later, the best description is that tunicates exhibit both types of circulation across their life cycle. The other options don’t fit because they imply only one mode (or none), which doesn’t reflect this life-stage shift.

Tunicates show a developmental change in how their blood moves through the body. In the tadpole-like larval stage, the circulatory system is organized with vessels that keep blood contained, which is the hallmark of a closed system. After metamorphosis into the adult, the blood circulates more openly, flowing through body cavities and sinuses as the simple heart pumps it, rather than staying strictly within a network of vessels. The heart can also reverse its pumping direction, helping distribute blood through the tissues in this open arrangement. Because they use a closed system early on and an open system later, the best description is that tunicates exhibit both types of circulation across their life cycle. The other options don’t fit because they imply only one mode (or none), which doesn’t reflect this life-stage shift.