The name of the genus is the Latinised form of the Ancient Greek σηπία (sēpía) "cuttlefish".

All members of Sepia share the presence of eight arms and two tentacles.

Once a prey item has been caught, the tentacles detach from it and have no other function.

The tentacles reside in sheaths that run below the eyes and behind the head, into the visceral mass, where they are reserved as coiled, spring-loaded appendages, waiting to be ejected towards a food target.

A number of extinct species have been described from the Neogene of Europe, though many of these are likely synonyms.