In open circulatory, system, the blood flows in open spaces like lacunae and sinuses and it bathes the cells directly, e.g., arthropods (cockroach or Periplanata), Octopus and Sepia are the cephalopods in which the circulatory system is of completely closed type. Pheretima and Hirudinana are the annelids. Annelids possess the closed circulatory system, in which the blood circulates inside the blood vessels without coming in direct contact of body cells.