All cephalopods possess flexible limbs extending from their heads and surrounding their beaks. These appendages have been termed arms, legs or tentacles.
Arms have suckers along most of their length, as opposed to tentacles, which have suckers only near their ends. Barring a few exceptions, octopuses have eight arms and no tentacles, while squid and cuttlefish have eight arms (or two "legs" and six "arms") and two tentacles. The limbs of nautiluses, which number around 90 and lack suckers altogether, are called tentacles.
Each sucker is usually circular and bowl-like and has two distinct parts: an outer shallow cavity called an infundibulum and a central hollow cavity called an acetabulum.
Cephalopod limbs and the suckers they bear are shaped in many distinctive ways, and vary considerably between species.
Cephalopod limb Facts for Kids. Kiddle Encyclopedia.