Sepia officinalis

Mantle & Fins 

• Mantle broad, dorsoventrally flattened
• Fins narrow, extending full length of mantle from anterior edge

Arms & Tentacles 

• Arm suckers tetraserial
• Hectocotylus on left ventral arm, usually with 5–8 rows of reduced suckers
• Club suckers in oblique rows of 7–8, mostly small; 5–6 median suckers greatly enlarged

Cuttlebone (Roper et al., 1984)

• Outline oval; width 30–40% of length in males, 33–42% in females
• Anterior striae rounded or rounded M-shaped

© Jereb, P.; Roper, C.F.E.

Colour (Gibson-Hall & Wilson, 2018)

• Highly variable; black-brown, striped or mottled dorsally, paler to white ventrally

Vertical Distribution

This neritic, demersal species occurs from the shoreline to about 200 m (Reid et al., 2005), most commonly around 100 m. The adult cuttlebone implodes at roughly 150–200 m (Ward & Boletzky, 1984), which limits how deep the species can go. Hatchling cuttlebones implode between 50 and 100 m, restricting young animals to shallow coastal waters, and eggs are rarely laid deeper than 30–40 m (Gibson-Hall & Wilson, 2018).

Geographical Distribution

Sepia officinalis is found in the eastern Atlantic from the southern North Sea south to northwest Africa, and throughout the Mediterranean (Reid et al., 2005). Waters off Mauritania lie close to the southern limit of its range (Lin et al., 2019). Records farther south along the African coast should be treated with caution, as they may represent S. hierredda or other members of the S. officinalis species complex. In the British Isles it is recorded mainly along the south and west coasts of England and Wales, around the Channel Islands and the Isle of Man, with sporadic records farther north to Scotland. Climate models suggest the species could expand northward as waters warm (Gibson-Hall & Wilson, 2018).

Habitat

Adults occur predominantly over sandy and muddy bottoms, while juveniles favour sandy substrata for burying and seagrass beds for shelter. The species tolerates salinities of about 18–40 psu if acclimated slowly, although embryos need higher salinities to develop normally. Its temperature limits are estimated at 10–30 °C, and below 10 °C animals stop feeding and become inactive (Gibson-Hall & Wilson, 2018).

Size (Reid et al., 2005)

• Maximum about 490 mm ML and 4 kg in temperate waters; subtropical animals rarely exceed 300 mm ML and 2 kg
• Largest recorded individual 600 mm ML (Gibson-Hall & Wilson, 2018)
• Breeding males 80–450 mm ML, breeding females 120–290 mm ML (Gibson-Hall & Wilson, 2018)

Cuttlebone

• Oblong, rounded posteriorly, tapering anteriorly
• Chambered structure regulates buoyancy through the ratio of gas to liquid (Reid et al., 2005)

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Skin

• Chromatophores in three colour classes (yellow, red, brown) overlying iridophores and leucophores (Messenger, 2001)

Growth & Lifespan

Sepia officinalis grows rapidly and reproduces once before dying, with a life cycle of 12–24 months (Reid et al., 2005). In the English Channel, most animals live two years, though some males mature at one year (Gras et al., 2014). Juveniles grow faster than adults, and growth nearly stops during the winter offshore migration. In warmer waters such as the Portuguese coast, animals mature faster and live about one year, while some individuals have reached four years in culture. Males typically mature at about 13 months and females at 14–16 months (Gibson-Hall & Wilson, 2018).

Migration

Populations move offshore in autumn and return inshore in spring as coastal waters warm (Guerra, 2006). Mature males and large females are the first to arrive at inshore spawning grounds, and a single seasonal migration may exceed 100 km. Day length also plays a role, with inshore migration in the English Channel usually beginning around the spring equinox (Gibson-Hall & Wilson, 2018).

Mating

Females appear to prefer males that are not displaying zebra banding, possibly because the pattern signals aggression. Males place spermatophores on the female's buccal membrane and may guard her after mating. Females mate with multiple males and can store sperm, potentially choosing which sperm fertilise their eggs (Gibson-Hall & Wilson, 2018).

Spawning & Eggs

Females are intermittent terminal spawners, laying eggs in separate batches over weeks to months before dying. Spawning peaks at water temperatures of 13–15 °C and in the English Channel runs from February to July, extending year-round where winter waters stay above 10 °C (Gibson-Hall & Wilson, 2018). Females attach eggs to seagrass, algae and other structures in shallow water, and each egg is wrapped in an ink-stained capsule produced by the accessory genital glands and ink sac, giving clusters a dark, grape-like appearance (Cornet et al., 2015). Females also use sessile animals such as tubeworms, ropes and previously laid eggs as attachment sites. Development takes one to five months depending on temperature, stalls below about 9 °C and is optimal at 15–18 °C. Near hatching, the capsule thins and loses its ink, making the embryo more visible and more vulnerable to predators (Gibson-Hall & Wilson, 2018). Fecundity varies widely between regions, with estimates off Mauritania of roughly 1,300 to 3,400 oocytes per female (Lin et al., 2019).

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Hatchlings & Juveniles

Development is direct, with no larval stage. Hatchlings are 7–8 mm long, resemble adults in morphology and basic behaviour, receive no parental care and can feed within hours of hatching. They respond to visual and odour cues immediately, suggesting embryos detect stimuli before hatching, and young animals bury themselves in sand as their main defence. Juveniles remain in inshore nursery grounds for 60–120 days before moving offshore for the winter (Gibson-Hall & Wilson, 2018).

Diet

Adults feed mainly on brachyuran crabs and demersal fishes such as gobies and pipefishes, with minor amounts of amphipods. The range of prey taken narrows as animals grow, and their saliva contains cephalotoxin, which paralyses prey (Gibson-Hall & Wilson, 2018).

Behaviour

Body patterns were first systematically described by Hanlon and Messenger (1988), and later work showed the species matches its surroundings despite being colour-blind (Mäthger et al., 2006). When rotated, it reverses its countershading so the lower surface stays pale, and it scales the intensity of its camouflage to ambient light, appearing uniformly pale in near darkness (Gibson-Hall & Wilson, 2018). Males display an intense zebra pattern during contests that signals their intentions (Adamo & Hanlon, 1996), and females use a distinct "splotch" display toward other females (Palmer et al., 2006). S. officinalis uses stereopsis to judge distance when striking at prey (Feord et al., 2020) and shows a cyclic, REM-like sleep state with rapid eye movements, arm twitches and chromatophore activity (Iglesias et al., 2019).

Sepia officinalis is the type species of Sepia, anchoring the name for the entire genus. A molecular phylogeny by Lupše et al. (2023) found that Sepia in its traditional sense was not a natural group and reassigned many species to revived or new genera. Sepia in the strict sense now contains only S. officinalis and its closest relatives, currently S. hierredda and S. vermiculata.

Within the species, Atlantic and Mediterranean populations are clearly genetically distinct, while populations from the Bay of Biscay, English Channel and southern North Sea show low differentiation. Limited gene flow is thought to result from females attaching eggs to the seafloor and the absence of a dispersing larval stage (Gibson-Hall & Wilson, 2018).

Sepia officinalis is the type species of Sepia, anchoring the name for the entire genus. A molecular phylogeny by Lupše et al. (2023) found that Sepia in its traditional sense was not a natural group and reassigned many species to revived or new genera. Sepia in the strict sense now contains only S. officinalis and its closest relatives, currently S. hierredda and S. vermiculata.

Within the species, Atlantic and Mediterranean populations are clearly genetically distinct, while populations from the Bay of Biscay, English Channel and southern North Sea show low differentiation. Limited gene flow is thought to result from females attaching eggs to the seafloor and the absence of a dispersing larval stage (Gibson-Hall & Wilson, 2018).

The IUCN lists S. officinalis as Least Concern (Barratt & Allcock, 2012). Symbiotic bacteria in the female's accessory nidamental glands turn the glands from white to bright red-orange as she becomes reproductively mature, and the species hosts the parasitic copepod Doridicola longicauda (Gibson-Hall & Wilson, 2018). Its ink was the original source of the brown pigment sepia, a word that comes from the Greek and Latin names for cuttlefish.

Similar species

S. officinalis is most easily confused with S. hierredda, which was formerly treated as a subspecies and co-occurs with it off northwest Africa (Reid et al., 2005).

The two species also differ at 13 allozyme loci. The striated zone character is not reliable for Canary Islands animals (Reid et al., 2005). In northern European waters it may also be confused with Rhombosepion elegans, which is smaller, has two rows of suckers on the arms and an acute lobe on the dorsal mantle margin (Gibson-Hall & Wilson, 2018).

FAO names are common cuttlefish (En), seiche commune (Fr) and sepia común (Sp) (Reid et al., 2005). Sepia officinalis hierredda Rang, 1837, formerly treated as a subspecies, is now recognised as a separate species, Sepia hierredda (WoRMS, 2026). Names historically applied to S. officinalis include Sepia rugosa Bowdich, 1822; S. vicellius Gray, 1849; S. zebrina Risso, 1854; S. filliouxi Lafont, 1869; S. officinalis mediterranea Ninni, 1884; and, tentatively, S. fischeri Lafont, 1871 and S. veranyi P. Fischer in Lagatu, 1888 (WoRMS, 2026).

• WoRMS species record, with current taxonomy, synonyms and sources (https://www.marinespecies.org/aphia.php?p=taxdetails&id=141444)
• IUCN Red List assessment (https://www.iucnredlist.org/species/162664/939991)
• Animal Diversity Web species account, a readable general overview (https://animaldiversity.org/accounts/Sepia_officinalis/)
• SeaLifeBase species summary, with fisheries and distribution data (https://www.sealifebase.se/summary/Sepia-officinalis.html)
• MarLIN species review, a detailed account of biology, life history and sensitivity to human pressures (https://www.marlin.ac.uk/species/detail/1098)
• NOVA, Kings of Camouflage, the PBS documentary featuring cuttlefish camouflage research (https://www.pbs.org/wgbh/nova/camo/)