The type of circulatory system found in arthropods and some molluscs is

Explanation

Arthropods and most molluscs have an open circulatory system.  In an open circulatory system, blood is pumped from the heart into a body cavity, called a hemocoel, instead of being enclosed in blood vessels. The blood, called hemolymph, mixes with interstitial fluid and circulates around the organs as the animal moves. The blood returns to the heart through small pores called ostia.

A closed circulatory system is a system where blood flows through a network of vessels, or tubes, that are connected to each other. The heart pumps blood through the system in a continuous loop. Many animals have a closed circulatory system, including all mammals, birds, fish, reptiles, amphibians, and some invertebrates. 

A single circulatory system is a type of circulatory system where blood passes through the heart only once during each complete circuit of the body, meaning it only travels through the heart one time before returning to it. e.g fishes, invertebrates and some amphibians etc

A double circulatory system is a system where blood passes through the heart twice during each circuit of the body. This system is found in mammals, including humans. 

There is an explanation video available .