16. Open Circulatory Systems
Insects have an open circulatory system, meaning their hemolymph (insect blood) flows freely within body cavities rather than through a network of blood vessels.
This fluid directly bathes organs, delivering nutrients and removing wastes.
Unlike vertebrates, which use closed circulatory systems with veins and arteries, insects rely on the movement of their bodies to help circulate hemolymph.
It’s a simple yet effective system, perfectly matched to their small size and active lifestyles.