Cephalopods can inflict a nasty bite. On their underside, at the conjunction of their arms, they have a structure called the beak which does look rather like a bird’s beak, and which can close with enough force to crush shellfish. Many also dribble toxins into the wound that can cause pain, tissue necrosis, and paralysis. They aren’t the best animals to play with.
If you think about it, though, cephalopods don’t have a rigid internal skeleton. How do they get the leverage to move a pair of sharp-edged beaks relative to one another, and what the heck are they doing with a hard beak anyway? There’s a whole paper on the anatomy of just the buccal mass, the complex of beak, muscle, connective tissue, and ganglia that powers the cephalopod bite.