# Octopus sensu stricto
**Octopus vulgaris sensu stricto** ("in the strict sense") is the common octopus as originally described by [Georges Cuvier](https://www.edgepedia.org/georges-cuvier) in 1797, a shallow-water benthic octopus now recognized as restricted to European and North African Atlantic and Mediterranean coastlines, rather than the cosmopolitan species it was long assumed to be.[1](https://academic.oup.com/cz/advance-article-pdf/doi/10.1093/cz/zoaf023/63215720/zoaf023.pdf) The name distinguishes the true Mediterranean and northeastern Atlantic species from a set of close relatives worldwide that were historically lumped under the same name, the *Octopus vulgaris* species complex.[2](https://pmc.ncbi.nlm.nih.gov/articles/PMC10728262/)
| Key fact | Detail |
|---|---|
| Scientific name | *Octopus vulgaris* Cuvier, 1797; type species of the genus *Octopus*[3](https://opal.latrobe.edu.au/articles/thesis/Untangling_the_Octopus_vulgaris_species_complex_using_a_combined_genomic_and_morphological_approach/21854307) |
| Distribution in the strict sense | European and North African Atlantic coasts and the Mediterranean[1](https://academic.oup.com/cz/advance-article-pdf/doi/10.1093/cz/zoaf023/63215720/zoaf023.pdf) |
| Species complex | At least six closely related, morphologically similar species formerly treated as one[1](https://academic.oup.com/cz/advance-article-pdf/doi/10.1093/cz/zoaf023/63215720/zoaf023.pdf) |
| Split-off species | *O. sinensis* (East Asia), *O. americanus* and *O. insularis* (western Atlantic), *O. tetricus* and *O. djinda* (Australasia)[2](https://pmc.ncbi.nlm.nih.gov/articles/PMC10728262/) • [4](https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.1018766/full) |
| Economic role | One of the most harvested octopus species in the world and a model organism for invertebrate behavioral biology[5](https://www.frontiersin.org/journals/ecology-and-evolution/articles/10.3389/fevo.2014.00055/full) |
| Mitogenome | First complete mitogenome of the sensu stricto species sequenced from the northeastern Atlantic: 13 protein-coding genes, 22 tRNAs, and two rRNAs[2](https://pmc.ncbi.nlm.nih.gov/articles/PMC10728262/) |
## The species and its name
*Octopus vulgaris* was described by Cuvier in 1797 and serves as the type species of the genus *Octopus*, a genus of roughly 200 species found in tropical and temperate waters worldwide.[3](https://opal.latrobe.edu.au/articles/thesis/Untangling_the_Octopus_vulgaris_species_complex_using_a_combined_genomic_and_morphological_approach/21854307) • [6](https://academic.oup.com/mollus/article/87/4/eyab039/6470382) For most of its history the species was considered cosmopolitan, occurring in tropical and temperate seas across the globe.[3](https://opal.latrobe.edu.au/articles/thesis/Untangling_the_Octopus_vulgaris_species_complex_using_a_combined_genomic_and_morphological_approach/21854307) The qualifier *sensu stricto* is used in taxonomy to mark the narrow, original sense of a name; here it separates the genuine common octopus of the Mediterranean and northeastern Atlantic from the other vulgaris-like species.[1](https://academic.oup.com/cz/advance-article-pdf/doi/10.1093/cz/zoaf023/63215720/zoaf023.pdf)
**Why the name narrowed.** Beginning around two decades of research based mainly on mitochondrial DNA markers, populations previously treated as *O. vulgaris* were shown to be morphologically similar but genetically distinct, forming what is now called the *Octopus vulgaris* species complex.[7](https://www.mdpi.com/2076-2615/13/17/2708) The genus *Octopus* itself has been regarded as a "catch-all" genus, and molecular work has found it to be polyphyletic, meaning some species placed in it descend from different ancestors.[6](https://academic.oup.com/mollus/article/87/4/eyab039/6470382) Within the complex, phylogenetic analyses have shown populations carrying the name *O. vulgaris* to be paraphyletic, so the name as broadly applied does not describe a single evolutionary lineage.[8](https://pubmed.ncbi.nlm.nih.gov/24964133/)
## The *Octopus vulgaris* species complex
The complex includes at least six species: *O. vulgaris* sensu stricto, the still-undescribed *O. vulgaris* Type III, *Octopus sinensis*, *Octopus tetricus*, *O. cf. tetricus* (now *Octopus djinda*), and *O. americanus*.[9](https://www.frontiersin.org/articles/10.3389/fphys.2023.1162807/pdf) • [4](https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.1018766/full) Each occupies a distinct region:
- *O. vulgaris* sensu stricto: European and North African Atlantic coasts and the Mediterranean[1](https://academic.oup.com/cz/advance-article-pdf/doi/10.1093/cz/zoaf023/63215720/zoaf023.pdf)
- *Octopus sinensis*: the East Asian common octopus, reinstated as a valid species name on the basis of combined molecular and morphological differences[2](https://pmc.ncbi.nlm.nih.gov/articles/PMC10728262/)
- *O. americanus* and *O. insularis*: western Atlantic lineages[2](https://pmc.ncbi.nlm.nih.gov/articles/PMC10728262/)
- *O. tetricus*: southeastern Australia and northern New Zealand; *O. djinda*, formerly *O. cf. tetricus*: southwestern Australia[4](https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.1018766/full)
- *O. vulgaris* Type III: an undescribed [Southern Hemisphere](https://www.edgepedia.org/southern-hemisphere) lineage along the South African coast and Amsterdam Island in the southern Indian Ocean[10](https://pmc.ncbi.nlm.nih.gov/articles/PMC13093632/)
A phylogenomic analysis of 338 nuclear loci together with complete mitochondrial genomes confirmed that Type III is genetically distinct from *O. vulgaris* sensu stricto and from *O. sinensis*, supporting taxonomic re-evaluation of the complex.[10](https://pmc.ncbi.nlm.nih.gov/articles/PMC13093632/) A Bayesian study of genus-wide relationships found strong statistical evidence against the monophyly of *O. vulgaris* as then defined, while supporting an *O. vulgaris* sensu stricto plus *O. tetricus* group.[11](https://scientiamarina.revistas.csic.es/index.php/scientiamarina/article/view/1340)
## How the species are told apart
Delineating cryptic species is difficult in octopus taxonomy because taxonomic characters are plastic, often giving low resolution at the species level.[12](https://onlinelibrary.wiley.com/doi/10.1111/zsc.12207) A morphological study of seven phylogenetic clades of the complex, identified using the mitochondrial gene cytochrome c oxidase subunit I (COI), succeeded in delimiting *O. sinensis*, Brazilian *O. vulgaris*, and *O. vulgaris* sensu stricto, congruent with the molecular findings.[12](https://onlinelibrary.wiley.com/doi/10.1111/zsc.12207) Male morphology proved the more reliable indicator: analyses based on males distinguished 14 of 15 total pairwise comparisons, and the characters with the greatest discriminatory power were male sexual traits.[12](https://onlinelibrary.wiley.com/doi/10.1111/zsc.12207) The same study recorded significant morphological differences among sampling localities of the same species, with phenotype correlating with local environmental data, which further complicates identification.[12](https://onlinelibrary.wiley.com/doi/10.1111/zsc.12207)
Genome-wide sequencing provides greater species-level resolution than mitochondrial DNA alone, which has highlighted the limitations of mtDNA for resolving relationships within the group.[3](https://opal.latrobe.edu.au/articles/thesis/Untangling_the_Octopus_vulgaris_species_complex_using_a_combined_genomic_and_morphological_approach/21854307) The first complete mitochondrial genome of *O. vulgaris* sensu stricto, from a specimen collected in its confirmed northeastern Atlantic range, contains 13 protein-coding genes, 22 transfer RNAs, and two ribosomal RNAs; a maximum likelihood tree placed it as sister to a group comprising *O. sinensis* and a previously published "*O. vulgaris*" mitogenome from Japan, confirming that the Japanese specimen was in fact *O. sinensis*.[2](https://pmc.ncbi.nlm.nih.gov/articles/PMC10728262/)
## Fisheries and research significance
The common octopus is one of the most widely distributed members of its genus as historically understood, an important commercially harvested species, and a model organism for the behavioral biology of invertebrates.[5](https://www.frontiersin.org/journals/ecology-and-evolution/articles/10.3389/fevo.2014.00055/full) Octopuses exported globally under the name *O. vulgaris* carry extremely high fisheries market value, and the recognition that multiple vulgaris-like species are treated under a single name has implications for naming and conservation of the harvested members of the complex throughout their ranges.[12](https://onlinelibrary.wiley.com/doi/10.1111/zsc.12207) Poor taxonomic resolution and catch under-reporting at regional and species level could contribute to overexploitation of octopus populations, as has occurred for certain members of the complex such as *O. sinensis*.[4](https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.1018766/full) Because of a lack of widespread awareness of the updated taxonomy, misidentification of western Atlantic species such as *O. americanus* and *O. insularis* persists in the scientific literature and in fisheries designations.[1](https://academic.oup.com/cz/advance-article-pdf/doi/10.1093/cz/zoaf023/63215720/zoaf023.pdf)
## References
1. [Octopus vulgaris sensu stricto distribution and species complex, Journal of Zoology (2025)](https://academic.oup.com/cz/advance-article-pdf/doi/10.1093/cz/zoaf023/63215720/zoaf023.pdf)
2. [The complete mitochondrial genome of Octopus vulgaris, PMC](https://pmc.ncbi.nlm.nih.gov/articles/PMC10728262/)
3. [Untangling the Octopus vulgaris species complex using a combined genomic and morphological approach, La Trobe University thesis](https://opal.latrobe.edu.au/articles/thesis/Untangling_the_Octopus_vulgaris_species_complex_using_a_combined_genomic_and_morphological_approach/21854307)
4. [Projecting future climate change impacts on the distribution of the 'Octopus vulgaris species complex', Frontiers in Marine Science (2022)](https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.1018766/full)
5. [An integration of historical records and genetic data to the assessment of global distribution and population structure in Octopus vulgaris, Frontiers in Ecology and Evolution (2014)](https://www.frontiersin.org/journals/ecology-and-evolution/articles/10.3389/fevo.2014.00055/full)
6. [Solving the identity of the common shallow-water octopus of the Colombian Caribbean, Journal of Molluscan Studies (2021)](https://academic.oup.com/mollus/article/87/4/eyab039/6470382)
7. [Insights on the Evolutionary History and Genetic Patterns of Octopus vulgaris in the Northeastern Atlantic, Animals (2023)](https://www.mdpi.com/2076-2615/13/17/2708)
8. [Allopatric Speciation within a Cryptic Species Complex of Australasian Octopuses, PLOS ONE (2014)](https://pubmed.ncbi.nlm.nih.gov/24964133/)
9. [Genetic confirmation of Octopus insularis in South Florida, Frontiers in Physiology (2023)](https://www.frontiersin.org/articles/10.3389/fphys.2023.1162807/pdf)
10. [Genomic Divergence Between Octopus vulgaris and Its Undescribed Sister Species, PMC (2025)](https://pmc.ncbi.nlm.nih.gov/articles/PMC13093632/)
11. [A contribution to the understanding of phylogenetic relationships among species of the genus Octopus, Scientia Marina (2011)](https://scientiamarina.revistas.csic.es/index.php/scientiamarina/article/view/1340)
12. [Amor et al. (2017). Morphological assessment of the Octopus vulgaris species complex, Zoologica Scripta 46(3): 275-288](https://onlinelibrary.wiley.com/doi/10.1111/zsc.12207)
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*Topic: Encyclopedia › Life and health › Animals › Invertebrates › Molluscs › Cephalopods › Octopuses › Octopus species › Octopus sensu stricto residual species*
*Initially written Sep 17, 2026 · Reviewed: Sep 30, 2026; Oct 21, 2026 · Edited: Oct 15, 2026; Oct 21, 2026 · Last review: Oct 21, 2026*
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License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license