Q. What is the difference between mussels and octopuses regarding their circulatory systems? How does that difference influence the mobility of these animals?

Cephalopod molluscs like octopuses and squids have a closed circulatory system with blood pumped under pressure flowing within vessels Bivalve molluscs like oysters and mussels have an open circulatory system that also known as lacunar circulatory system where blood flows under low pressure since it falls in cavities of the body and doesn't only circulate within blood vessels. Molluscs with closed circulatory systems are larger agile and can actively move molluscs with open circulatory systems are slow, smaller and some are practically sessile.