Practice question

Cephalopods differ from other molluscs in circulatory physiology because they have closed circulatory system whereas most molluscs retain open sinuses with hemocoel pooling. Closed system with systemic heart and two branchial hearts generates high blood pressure channeling hemolymph through continuous vessels and capillary beds, enabling rapid oxygen delivery to large brain, sophisticated eyes and powerful mantle jet muscles for escape. Radula present, head well developed with arms derived from foot, gills present as ctenidia. Closed circulation correlates with active predatory lifestyle, elevated metabolic rate and intelligence convergent with vertebrates, marking highest molluscan advancement.