Practice question

In Mollusca ventral muscular foot displays remarkable adaptive radiation. Gastropods retain broad creeping sole for crawling, bivalves hatchet-like foot for burrowing, polyplacophorans broad adhesive disc for clinging. Cephalopoda, literally head-foot, shows most derived modification where embryonic foot migrates anteriorly around mouth, dividing into prehensile muscular arms and tentacles bearing suckers as muscular hydrostats, plus posterior funnel derived from foot for jet propulsion. This transformation supports active nektobenthic predation in squids, cuttlefish and octopuses, enabling rapid prey capture and powerful escape locomotion in open water.