noun
open circulatory system; open blood-vascular system
Biological term referring to a circulatory system where blood (hemolymph) is not always contained within vessels, as seen in arthropods and most mollusks.
昆虫は開放血管系を持つ。
Insects have an open circulatory system.
開放血管系では、血液は
In an open circulatory system, blood flows directly through the tissues.