Sepia elegans, the elegant cuttlefish, is a species of cuttlefish in the family Sepiidae from the eastern Atlantic Ocean and the Mediterranean Sea. It is an important species for fisheries in some parts of the Mediterranean where its population may have suffered from overfishing.
Description
Sepia elegans is a small species of cuttlefish which has an elongated mantle which is oval in shape and has a length that is more than two times greater than its width, with a maximum mantle length of 80mm. It has a short, broad tentacular club which is blunt towards its tip and has 6-8 suckers in oblique, crosswise rows. with three very enlarged suckers in the central part of the club. It has short arms and these are less than half the total length of the head and arms, each arm has two rows of suckers. The edge of the dorsal margin of the mantle protrudes at its anterior end in a lobe between the animal's eyes. The fins have their origin a short distance from the anterior edge of the mantle gut do not extend beyond mantle's anterior margin and they do not get wider towards the rear. The underside of the mantle has a longitudinal row of 6 narrow ridges along each side near the fins; the middle 2 pairs being larger than the posterior 2 pairs and the posterior 2 pairs.
It is coloured red through to brown on its back, however, other describers give the overall colour as reddish brown. The head has a small number of scattered chromatophores, the arms are unmarked and the pale dorsal mantle is mottled with purple-black chromatophores. The fins and the underside of the mantle are paler with the ventral mantle ridges being whitish.
The arrangement of the suckers on the arms are sexually dimorphic, in the males, arm I has two series of suckers for a few rows with the remainder being arranged in four series as are all the suckers on arms II and III on each side except for those at the arm tips which are in two series. The suckers on arms IV vary in their arrangement with 2 to 4 rows if suckers in two series. In the females most of the arms have two series of suckers near the head and four series towards the tip, there are 5 rows of suckers in two series on arms I to III, 2 to 4 rows on arms IV. The suckers of the males are larger in the middle of the arm than those at the sides. The hectocotylus is situated on the left ventral arm and has 1 or 2 rows of normal size suckers near the head, 9 to 11 rows of highly reduced very small suckers in the middle part of the arm and then it has normal sized suckers towards the tip of the arms. These suckers are in 2 dorsal and 2 ventral series which are laterally displaced.
The cuttlebone is lanceolate in shape and has a very small spine, resembling a small calcareous ridge rather than a true spine. Males have a cuttlebone which is 23-33% of its length whereas in females it is 26-35 % its length. The posterior portion of the bone narrows before a blunt, rounded posterior tip.
Distribution
Sepia elegans is found in the eastern Atlantic and the Mediterranean Sea from the Shetland Islands, Scotland in the north south along the eastern shore of the Atlantic in Europe and Africa to 15°S and possibly to the Agulhas Bank. In the Mediterranean Sea its range encompasses the Ligurian Sea, Tyrrhenian Sea, Aegean Sea, Sea of Marmara and Levantine Sea. The habitat of the elegant cuttlefish is extensive as it has been found in the Mediterranean Sea, the Black Sea, as well as the northeast, southeast, and eastern central areas of the Atlantic.
Diet
While crustaceans are the main food source of Sepia elegans, they also eat bony fish, as well as marine worms, such as Polychaeta. The preferred prey of this species of cuttlefish tends to remain constant throughout its lifetime.
Habitat and ecology
Sepia elegans occurs offshore on sandy and muddy substrates, as deep as 500m but it is very rare at depth greater than 450m. It is a sublittoral cuttlefish which spends the winter months in deeper water, at depths between 200m and 400m and in the spring it migrates into shallower water to spawn. Like other cuttlefish it is an opportunistic predator and its main prey are molluscs, small crustaceans, fish and polychaete worms. There does not appear to be any difference in prey choice between the sexes but the males and females feed at different rates. It can tolerate a wide range of salinities, occurring in brackish waters on the Sea of Marmara.