The cuttlebone is oblong in shape, outline roughly rectangular; tapering to a point anteriorly and rounded and blunt posteriorly.

The bone is most calcified at the rear and there is an indistinct dorsal median rib which broadens slightly towards the head end.

On the dorsal part of the mantle there are a series of elongate papillae on either flank, situated around halfway along the base of the fins.

Their size distribution, as measured from animals caught by fisheries, shows a wider variation than for the sympatric Sepia officinalis during the summer.

[1] Sepia bertheloti is fished for by trawling off the Canary Islands and is commonly captured off the western Endeavour Bank.