What is the difference between octopuses and mussels regarding their circulatory systems? How does that difference influence the mobility of these animals?
Cephalopod molluscs, as octopuses and squids, have a closed circulatory system with blood pumped under pressure flowing within vessels. Bivalve molluscs, as mussels and oysters, have an open circulatory system (also called as lacunar circulatory system) where blood flows under low pressure as it falls in cavities of the body and does not only circulate within blood vessels. Molluscs with closed circulatory systems are larger, agile and can actively move; molluscs with open circulatory systems are lesser, slow and some are practically sessile.