any marine mollusc of the class Cephalopoda, characterized by well-developed head and eyes and a ring of sucker-bearing tentacles. The group also includes the octopuses, squids, cuttlefish, and pearly nautilus
Any of various marine mollusks of the class Cephalopoda, having long tentacles around the mouth, a large head, a pair of large eyes, and a sharp beak. Cephalopods have the most highly developed nervous system of all invertebrates. Many cephalopods squirt a cloud of dark inky liquid to confuse predators. Cephalopods include the octopus, squid, cuttlefish, and nautilus, and the extinct ammonites, belemnites, and other nautiloids.