Sepia australis, the southern cuttlefish, is a species of cuttlefish which is found in the eastern South Atlantic Ocean and the western Indian Ocean off the coasts of Southern Africa, possibly extending into the waters off East Africa.

Description Sepia australis has widely-separated, posteriorly rounded fins. The arms have the suckers arranged in four series with the middle series of suckers consisting of slightly larger suckers than the lateral ones, this difference being more pronounced in male. The hectocotylus is found on the left ventral arm and has two rows of normal size suckers near its base, six or seven rows of greatly reduced suckers in the middle which become normal sized towards the tip of the arm. Suckers in two of the dorsal and two of the ventral series are laterally displaced and show a gap between them. The short tentacular club is crescent-shaped and has five suckers arranged in crosswise rows, these suckers show great differences in size with 3 very enlarged suckers near the base of the club. The swimming keel of the club, extends a very short distance towards the carpus at the club's base. The dorsal and ventral protective membranes are separate and are not connected at base of club. It has an oval cuttlebone which is bluntly rounded at its anterior end and has a sharp posterior end. It shows strong ventral recurving and the dorsal surface is convex, smooth and creamy white in colour.