The name "cephalopod" derives from Greek for "head feet," referring to the arms that project from the head of the animals. Cephalopods include the eight-armed octopodids, ten-armed decapods, and many armed nautiluses. Cephalopods have a horny beak which is used to chop prey into small bits, moved down the gullet by the horny tongue (radula). Around the beak is a venom gland, which produces an anesthetic that helps to quickly subdue prey.

A model of a giant squid hanging at the Natural History Museum
in London. Known as Architeuthis, the giant squid is the largest
(though not longest) living invertebrate. The largest was about 63
feet long, from tail tip to tentacle tip. No one has yet observed a
live adult specimen (and lived to tell the tale). Photo by 
Dr. Robert Sprackland.