What is the transport system found in arthropods and mollusks?

Arthropods and mollusks have an open circulatory system, where blood (hemolymph) is not confined exclusively to vessels but bathes the organs directly in a hemocoel. In arthropods, such as insects and crustaceans, a dorsal heart pumps hemolymph through vessels into the body cavity, while in mollusks, the heart pumps hemolymph through a series of sinuses. This system allows for efficient nutrient and gas exchange despite the lack of a closed network. However, some cephalopod mollusks, like octopuses, possess a closed circulatory system for more efficient oxygen transport.