Spineless cuttlefish (Sepiella inermis)

Classification (WoRMS)

Full classification as recorded by WoRMS: Kingdom: Animalia · Phylum: Mollusca · Class: Cephalopoda · Order: Sepiida · Family: Sepiidae · Genus: Sepiella.

Accepted name: Sepiella inermis · Authority: (A. d'Orbigny, 1835) · Taxonomic status: accepted · AphiaID: 220314.

Synonyms and superseded combinations recorded for this taxon: Sepia affinis Souleyet, 1852; Sepia inermis A. d'Orbigny, 1835; Sepia microcheirus J. E. Gray, 1849; Sepia tourannensis Souleyet, 1852.

Source: World Register of Marine Species (WoRMS) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=220314 (CC BY 4.0). Accessed 2026-09-23.

Biology and life history (SeaLifeBase)

Measured values published by SeaLifeBase for Sepiella inermis. Only fields the database actually holds for this species are shown; these are database values, not aquarium guidance.

Maximum length: 12.5 cm · Depth range: 9–160 m · Habitat zone: benthic · Vulnerability index: 10 of 100 · Fishery importance: commercial.

SeaLifeBase notes: Females grow larger than males (Ref. 3722). Feeds on small demersal fishes, crustaceans, other cephalopods (Ref. 275).

Source: SeaLifeBase species summary (SpecCode 57883) — https://www.sealifebase.se/summary/Sepiella-inermis.html (CC BY-NC 3.0 — non-commercial use only). Accessed 2026-09-23.

Distribution and occurrence records (GBIF)

131 georeferenced occurrence records for Sepiella inermis are published through GBIF from 16 countries or marine areas. The map above plots 37 distinct locations from a sample of 131 records, omitting 25 inland records that carry an institution's coordinates rather than a collection site; it shows where the species has been observed and reported, not a modelled range.

Most records by country or area: India (48); Bangladesh (31); Indonesia (21); Singapore (5); China (4); Egypt (4); Thailand (4); Japan (2); Maldives (2); Malaysia (2); Somalia (2); Viet Nam (2); Canada (1); Kuwait (1); Sri Lanka (1).

Marine regions with a valid WoRMS distribution record: Red Sea; Somali Exclusive Economic Zone; Eritrean Exclusive Economic Zone; Indo-West Pacific; FAO fishing area 51; FAO fishing area 57; FAO fishing area 61; FAO fishing area 71; Indian Ocean.

Source: GBIF Occurrence Search (taxonKey 2290906) — https://www.gbif.org/occurrence/search?taxon_key=2290906&has_coordinate=true (records CC0 / CC BY); WoRMS distribution records (MarineRegions) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=220314 (CC BY 4.0); Natural Earth 110m basemap — https://www.naturalearthdata.com/ (public domain). Accessed 2026-09-23.

Conservation status (IUCN Red List)

The IUCN Red List assesses Sepiella inermis (Van Hasselt, 1835 in Férussac & d'Orbigny 1834-1848) as Data Deficient (code DD). No trend, population estimate or threat analysis is given here, because none is available from this source without the Red List API; follow the source link for the full assessment, including its date.

Source: IUCN Red List of Threatened Species (taxon 162500) — https://www.iucnredlist.org/species/162500/0; GBIF IUCN Red List category endpoint (taxonKey 2290906) — https://api.gbif.org/v1/species/2290906/iucnRedListCategory. Accessed 2026-09-23.

Description and natural history (Wikipedia)

Sepiella inermis is a relatively small species of cuttlefish, with an average mantle length of about 50mm, with a maximum length of about 125mm. It has narrow fins and a moderately small, ovate shell that is white, with a brown and polished horny margin. The dorsal surface of S. inermis ranges in color depending on chromatophores present, ranging from gray-brown to purple, with the ventral surface being light gray or brown. The dorsolateral surface of the mantle is adorned with a series of white spots in both males and females.

Sepiella inermis is found throughout the Indo-Pacific region, from shallow water down to depths of about 40m. This species lives primarily benthically.

Sepiella inermis spawns throughout the year. Geographic location, environment, and habitat all affect seasonal peaks, causing them to be varied throughout the species. When selecting a mate, males raise a pair of dorsal arms, and display a dark brown color featuring white and orange spots on their fins. Females also display white spots along their fins when consenting to males’ advances. When S. inermis mate, their mating position is head-to-head.

When a female lays eggs, she lays approximately 400, in one to five batches. The female does not eat in between the intervals of batch release. Females prefer to lay their eggs on branch-like substrates. The egg capsules of S. inermis are black in color, dyed by ink from the female, and are round, containing a tip and a stalk. Each capsule contains one egg. The length of the embryonic period can vary, anywhere between 8 and 19 days with an average of about 13 days.

After hatching, hatchlings of S. inermis are morphologically miniature adults that have a planktonic habit. Shortly after hatching, their normal color is dark brown, white, or transparent, and their chromatophores are functional. At around 3 days of age, hatchlings enter the benthic juvenile stage, and use their arms to hold onto the sea bottom. After around 5 days, their tentacles begin to function, and they are able to attack and capture prey.

Sepiella inermis generally displays more active behavior than other sepiid cuttlefish. This species both lives benthically like other cuttlefish, as well as hovers in the water column like a pelagic organism. This species is highly tolerant to fluctuations in the environment, and because of their tendency to benthic-pelagic habitats, requires less territory than pelagic squid of a similar size.

Cuttlefish are becoming an increasingly abundant aspect of the fishing industry worldwide. Although the percentage caught varies depending on geographical location and time of year, they commonly make up a majority of all cephalopod catch. Trawlers are the main means by which cuttlefish are caught, both intentionally and as bycatch. They are exploited all year long, with the percentage catch typically decreasing in summer months because many species spawn in late spring. Even though they are consistently fished, there is still no evidence that implies overexploitation.

Source: Wikipedia: Sepiella inermis — https://en.wikipedia.org/wiki/Sepiella_inermis (CC BY-SA 4.0). Accessed 2026-09-23.