Elongate 4th circumoral appendage of cuttlefish and squids used to capture prey. Divided into proximal stalk and distal club. [ http://www.sil.si.edu/smithsoniancontributions/zoology/pdf_hi/sctz-0513.pdf ]
Modified 4th pair of appendages in decapodiforms that are capable of considerable extension and contraction. Although the tentacles are derived evolutionarily from the 4th pair of arms, the term, "arms IV"; is reserved for the subsequent arm pair, the ventral arms, which are evolutionarily the 5th pair of arms. Each tentacle consist of a proximal stalk usually devoid of suckers, and a distal club armed with suckers and occasionally hooks.