Answer: Haemocoels
Step-by-step explanation:
In the open circulatory system found in arthropods and mollusks, the heart pumps blood into a blood vessel which branches and opens in an internal structure called Haemocoels.
The haemocoel is a highly functional part because it allows
- organs and tissues to be bathed in blood,
- for exchange of materials to occur between the body cells and the blood.
- blood to eventually flows back to the heart.