In comparison with the normal right ventral arm the suckers towards the tip of the left arm are markedly reduced in size, particularly on the ventral side of the arm and the ventral protective membrane is expanded and strongly ribbed. Also visible in the photograph is the mouth, situated in the centre of the brachial crown, which consists of eight arms plus two tentacles. The tentacles are used primarily in catching prey. The squid dashes up to its prey, extends the tentacles beyond the reach of the arms and clasps the prey between the suckers of the tentacular clubs. Once caught, the prey is quickly brought within reach of the arms, grasped by them and drawn towards the mouth, where is is killed by bites from the protruding beaks.
Prey consists mainly of fish or squid smaller than itself.
Cannibalism also occurs among squids. The tentacular club consists of three regions. The knobs and suckers of the carpus constitute the fixing apparatus of the clubs and enable the clubs to be locked together, the suckers of one club locking on to the knobs of the other. Locking the clubs may facilitate capture of prey, or possibly enhances the hydrodynamics of the squid when swimming backwards. Each sucker on the arms and tentacular clubs of the squid contains a chitinous ring that usually bears teeth on its free edge.