Squid, Cuttlefish, Octopus

The cephalopod group are the most advanced of the molluscs, with their mantle turned into a muscular body wall and the remnants of their shell within (the term means “head-foot”: the foot muscle is near the head). The octopus, species of Octopus and Cistopus, has eight arms clustered around its mouth with which it clambers along the bottom and seizes prey; the coastal-bottom cuttlefish (species of Sepia) and open-ocean squid (species of Loligo, Todarodes, Ilex) have short arms and two long tentacles.