Cephalopod limb facts for kids
All cephalopods possess flexible limbs extending from their heads and surrounding their beaks. These appendages have been termed arms, legs or tentacles.
Contents
Description
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.
Suckers
Cephalopod limbs bear numerous suckers along their ventral surface as in octopus, squid and cuttlefish arms and in clusters at the ends of the tentacles (if present), as in squid and cuttlefish.
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.
Both of these structures are thick muscles, and are covered with a chitinous cuticle to make a protective surface. Suckers are used for grasping plants, catching prey and for locomotion.
Variability
Cephalopod limbs and the suckers they bear are shaped in many distinctive ways, and vary considerably between species.
Images for kids
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Arms and buccal mass of the squid Taningia danae. As in other Octopoteuthidae, the tentacles are absent in adults.
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Oral view of the bobtail squid Semirossia tenera
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Head and limbs of the bobtail squid Rossia glaucopis
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Oral view of male Bathypolypus arcticus with hectocotylus on arm III (left)
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Cephalopod suckers and configuration of suckers on tentacular club
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Octopus suckers
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A deformed octopus sucker cluster
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A common octopus with a forked arm that was found in south Crete, Greece
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