Tethys fimbria

Tethys fimbria Linnaeus, 1767

Tethys fimbria @ Badalona (Spain) by Enric Madrenas










































Tethys fimbria  Linnaeus, 1767

 Classification according to Bouchet et al. (2017)
Taxonomic source: World Register of Marine Species (AphiaID: 141643).

  • Tethys cornigera Macri, 1816 
  • Tethys fimbriata 
  • Tethys leporina Linnaeus, 1758 
  • Tethys parthenopeia Macri, 1816
  • Tethys polyphylla Macri, 1816 

It is a large size species since larger animals can reach over 20 cm in length, although about 40% of its length is due to the large cephalic veil. This veil is very broad and of semicircular contour and its outer margin is provided with numerous short threadlike structures, the fimbriae, the reason for its specific name. The margin of the veil also is pigmented with a dark band, decreasing towards the posterior margin. In the lower side and the center of the head, there is the mouth, provided with two thick tuberculate lips; tubercles of mouth and buccal lips are conic shaped and under binocular microscope shows that their own surface is also tuberculate. The mouth has no radula. The general coloration of the animal is grayish-white, with some shades of cream due to the internal viscera. The head, right in the area where it attaches to the cephalic veil, has a couple of short rhinophores with a laminar portion surrounded by a tubular rhinophoric sheath with a membranous extension inside. The mantle of the animal is far smaller than the foot, widely visible from the sides and the rear side. On both sides of the back there are thick flattened cerata (called Phaenicurus) of variable size and finished in one or two tips, of the same colour of the body but with brown-blackish spots. These cerata are easily detached from the body (autotomy) when the animal is disturbed and then they are regenerated. Each cerata has nerves, blood vessels and branches of the digestive gland. Among every two papilla there are two branched appendages gill-like, the first one somewhat larger than the second. The foot is very wide and the same color as the body, with whitish streaks in its dorsal area, running along it. Ventral foot is coloured creamy yellow and in the middle and posterior zone an elongated pedia gland is clearly seen. The anal papilla is located on the front right of the dorsum. Genital orifice is located on the right of the body, slightly behind that side rhinophore; genital papilla is extended backwards by a thin membrane and the penis, about 7 mm in length, is thin and with a curved tip.

This species of nudibranch is often found living in sand and gravel bottoms from 20-30 meters deep. Commercial trawlers fishing at 70-100 m depth frequently get specimens aboard which tend to arrive without any cerata, as they are very easily autotomized. After the cerata detach from the animal they tend to continue moving alone; this led to the belief that those loose cerata were considered as an independent animal species (flatworms, worms, parasites) and described as such, eg under the generic name Phaenicurus.

In 1844 Forbes wrote in his report “On Aegean Invertebrata”: “The characteristic Nudibranc of the Mediterranean, a giant among its tribe, Tethys leporina, was only met with once, swimming foot up on the surface of the sea in the Gulf of Smyrna, in an exhausted state, its sides being infested by that extraordinary parasite the Vertumnus tethydicola.”

This is a carnivorous and voracious nudibranch, which usually captures its preys by projecting its immense cephalic veil over them; thus it is able to capture and feed on amphipods, isopods, small decapods, echinoderms, worms, other molluscs and even small fish. This is a species that has a good swimming ability by body contouring movements, by using its cephalic veil and even using the membranes of the rhinophoric sheaths. Schmekel & Portmann (1982) state that the spawn is a long strip with egg capsules containing several pink eggs of about 89 microns in diameter.


  • Tethys (also Tetis). In Greek mythology is the goddess of Creation, goddess of the Sea. Mother of all Gods and all creatures. (Robert Graves, Los mitos griegos. Alianza editorial. Madrid. 1985).
  • Fimbria. From Latin homonymous word fimbrĭa: extremity, the last part or the end of something. Lower edge of a dress or mantle. Strip or ornament in a dress.

This species is distributed from Iberian Atlantic shores down to the Gulf of Guinea and also in the Mediterranean Sea. American reports should be validated. In the Iberian Peninsula it has been observed in Portugal, the Atlantic coast of Andalusia and around the Mediterranean, including the Balearic islands. It is also cited in the Canaries islands. In Catalonia it is known from the commercial trawler fishing grounds located off Tossa de Mar, Lloret and Blanes but it has also been found in shallow water in the beach of Badalona.

Known georeferenced records of the species: Tethys fimbria
: GROC 2010-2011
: Enric Madrenas
: João Pedro Silva
: Bernard Picton
: Manuel Ballesteros.
: M@re Nostrum
: Altres fonts
: Marine Regions


    Western Mediterranean: ★★☆☆☆
    Eastern Mediterranean: ★☆☆☆☆
    Atlantic Ocean: ★☆☆☆☆

This chart displays the monthly observation probability for Tethys fimbria based on our own records.



More pictures


    Agersborg, H. P. v. 1921. Contributions to the knowledge of the nudibranchiate mollusk, Melibe leonina (Gould). Amer. Naturalist 55(638):222-253; 12 figs.
    Avila, C. 1992. A preliminary catalogue of natural substances of opisthobranch molluscs from western Mediterranean and near Atlantic. Scientia Marina 56(4):373-382.
    Avila, C. 1995. Natural products of opisthobranch molluscs: a biological review. Oceanography and Mar Biol: an Annual Review 33: 487-559.
    Avila, C. 1993. Sustancias naturales de moluscos opistobranquios: Estudio de su estructura, origen y función en ecosistemas bentónicos. Tesis Doctoral. Universitat de Barcelona.
    Ballesteros, M. 1991. Els Opistobranquis. pp. 416-427. In: Historia Natural dels Països Catalans,  Invertebrats no artròpodes. Enciclopèdia Catalana. Barcelona.
    Ballesteros, M. 2007. Lista actualizada de los opistobranquios (Mollusca: Gastropoda: Opisthobranchia) de las costas catalanas. Spira. 2: 163–188.
    Ballesteros, M., E. Madrenas, and M. Pontes. 2016. Actualización del catálogo de los moluscos opistobranquios (Gastropoda: Heterobranchia) de las costas catalanas. Spira. 6: 1–28.
    Ballesteros, M., E. Madrenas, and M. Pontes. 2023. OPK - Opistobranquis. (https://opistobranquis.info/).
    Ballesteros, M., M. Pontes, and E. Madrenas. 2019. Els nudibranquis del mar català. Brau Edicions, Figueres.
    Barash, A., and Z. Danin. 1988. Marine Mollusca at Rhodes. Israel Journal of Zoology 35:1-74.
    Barash, A., and Z. Danin. 1992. Annotated list of Mediterranean molluscs of Israel and Sinai, viii, Fauna Palaestina, Mollusca I. ed. Israel Academy of Sciences &  Humanities.
    Barash, A., and Z. Danin. 1982. Mediterranean Mollusca of Israel and Sinai: composition and distribution. Israel Journal of Zoology, 31, 86-118.
    Barash, A., and Z. Danin. 1987. Notes on the Antilessepsian migration of Mediterranean species of mollusca into the Indo-Pacific region. Gloria Maris 26 (5) (6): 81-100.
    Barash, A., and Z. Danin. 1988. Contribution to the knowledge of Opisthobranchia of Cyprus. Bollettino Malacologico (Pubblicazione Mensile Edita dalla Societa Italiana di Malacologia) 24(9-12):243- 260.
    Barash, A., and Z. Zenziper. 1984. On the food of some opisthobranchs found in the Mediterranean waters of Israel. Levantina (Israel Malacological Society) 51:585-598.
    Barbut, J. 1794. The genera vermium exemplified by various specimens of the animals contained in the orders of the Intestina et Mollusca Linnaei, drawn from nature, xx. J. Egerton, Military  Library, London.
    Barsby, T., R. G. Linington, and R. J. Andersen. 2002. De Novo terpenoid biosynthesis by  the dendronotid nudibranch Melibe leonina. Chemoecology. 12(4):199-202.
    Bedulli, D., R. Cattaneo-Vietti, R. Chemello, F. Ghisotti, and F. Giovine. 1995. Gastropoda Opisthobranchia, Divasibranchia, Gymnomorpha, Fascicolo 15, pp. 1-23.  In: A. Minelli, A. Ruffo, & S. La Posta (Eds.). Checklist delle specie fauna italiana, Checklist delle specie della Fauna Italiana. Calderini, Bologna.
    Bergh, L. S. R. 1877. Notizen uber Tethys leporina. Deutsche Malakozoologische Gesellschaft Jahrbucher 4(4):335-339.
    Bergh, L. S. R. 1875. Malacologische Untersuchungen, In: Reisen im Archipel der Philippinen von Dr Carl Gottfried Semper. Zweiter Theil. Wissenschaftliche Resultate. Band 2, Theil 1, Heft 9; pp 345-376, pls. 45-49.
    Betti, F., G. Bavestrello, and R. Cattaneo-Vietti. 2021. Preliminary evidence of fluorescence in Mediterranean heterobranchs. Journal of Molluscan Studies. 87: eyaa040.
    Bielecki, S., G. Cavignaux, J. M. Crouzet, and S. Grall. 2011. Des limaces de rêve.
    Canessa, M., G. Bavestrello, R. Cattaneo-Vietti, G. Furfaro, M. Doneddu, A. Navone, and E. Trainito. 2021. Rocky substrate affects benthic heterobranch assemblages and prey/predator relationships. Estuarine, Coastal and Shelf Science 38: 539-558. 261: 1–13.
    Cattaneo-Vietti, R. 1986. Alcune considerazioni sui molluschi opistobranchi del Mar Ligure. Lavori Societa Italiana di Malacologia 22:85-96.
    Cattaneo-Vietti, R., and G. Barletta. 1984. Elenco preliminare dei molluschi opistobranchi viventi nel Mediterraneo (Sacoglossa, Pleurobranchomorpha, Acochlidiacea, Aplysiomorpha, Nudibranchia). Bollettino Malacologico (Pubblicazione Mensile Edita dalla Societa Italiana di Malacologia) 20(9-12):195-218.
    Cattaneo-Vietti, R., and R. Chemello. 1987. Alcune considerazioni sui molluschi opistobranchi della Sicilia. Bollettino Malacologico (Pubblicazione Mensile Edita dalla Societa Italiana di Malacologia) 23(5-8):207-222.
    Cattaneo-Vietti, R., and T. E. Thompson. 1989. Mediterranean opisthobranch molluscs: a zoogeographic approach. Bollettino Malacologico (Pubblicazione Mensile Edita dalla Societa Italiana di Malacologia) 25(5-8):183-204.
    Cattaneo-Vietti, R., R. Chemello, and R. Giannuzzi-Savelli. 1990. Atlas of Mediterranean Nudibranchs. La Conchiglia, Rome, Italy.
    Cervera, J. L., G. Calado, C. Gavaia, M. A. E. Malaquías, J. Templado, M. Ballesteros, J. C. García-Gómez, and C. Megina. 2004. An annotated and updated checklist of the opisthobranchs (Mollusca: Gastropoda) from Spain and Portugal (including islands and archipelagos). Boletín Instituto Español de Oceanografía, 20 (1-4): 1-111. L.
    Cervera, J. L., J. Templado, J. C. García-Gómez, M. Ballesteros, J. Ortea, F. J. García, J. Ros, and A. A. Luque. 1988. Catálogo actualizado y comentado de los Opistobranquios (Mollusca, Gastropoda) de la Península Ibérica, Baleares y Canarias, con algunas referencias a Ceuta y la isla de Alborán. Iberus, supl. 1: 1-84.
    Cimino, G., and M. T. Ghiselin. 1999. Chemical defense and evolutionary trends in biosynthetic capacity among dorid nudibranchs (Mollusca: Gastropoda: Opisthobranchia). Chemoecology. 9: 187–207.
    Cimino, G. A., A. Crispino, V. Di Marzo, A. Spinella, and S. G. 1991. Prostaglandin 1,15-lactones of the F series from the nudibranch mollusc Tethys fimbria. Journal of Organic Chemistry 56(8):2907-2911.
    Cuvier, G. L. C. F. D. 1834. The Mollusca and Radiata arranged by the Baron Cuvier with supplementary additions to each order; pp 36-42. London.
    Cuvier, G. L. C. F. D. 1830. Le règne animal distribué d’après son organisation, pour servir de base à l’histoire naturelle des animaux et d’introduction à l’anatomie comparée. Avec figures, dessinées d’après nature. Les nudibranches (3). Deterville, Libraire, Paris.
    Cuvier, G. L. C. F. D. 1836. Le règne animal distribué d`après son organisation pour servir de base à l’histoire naturelle des animaux et d’introduction à l’anatomie comparée. Pteropoda, 2. Bruxelles (): 16-18.
    Cuvier, G. L. C. F. D. 1833. Catalogue des préparations anatomiques laissées dans le cabinet d’anatomie  comparée du Museum d’Histoire Naturelle. Nouvelles Annales du Muséum d’Histoire Naturelle, ou,  Recueil de Mémoires 2:417-508.
    Cuvier, G. L. C. F. D., and P. A. Latreille. 1831. The animal kingdom arranged in conformity with its organization. G. & C. & H. Carvill, 1831.
    De Fez, S. 1974. Ascoglosos y Nudibranquios de España y Portugal. Consejo Superior de Investigaciones Científicas, Valencia, Spain.
    Debelius, H., and R. H. Kuiter. 2007. Nudibranchs of the world. IKAN- Unterwasserarchiv, Frankfurt.
    Domènech, A., C. Ávila, and M. Ballesteros. 2006. Opisthobranch molluscs from the subtidal trawling grounds off Blanes (Girona, north-east Spain). Journal of the Marine Biological Association of U.K. 86: 383–389.
    Domínguez, M., A. Fontán, J. Rivera, and M. Ramón. 2013. Informe proyecto DRAGONSAL. Caracterización del ecosistema bentónico de la plataforma costera del área comprendida entre Sa Dragonera, Cabrera y el Cap de Ses Salines (Mallorca). Instituto Español de Oceanografía.
    Doneddu, M., B. Manunza, and E. Trainito. 1995. Opistobranchi del Nord Sardegna: censimento ed annotazioni. Biologia Marina Mediterranea II (2): 369-370.
    Furfaro, G., F. Vitale, C. Licchelli, and P. Mariottini. 2020. Two Seas for One Great Diversity: Checklist of the Marine Heterobranchia (Mollusca; Gastropoda) from the Salento Peninsula (South-East Italy). Diversity. 12: 171.
    Garcia, F. J., and H. Bertsch. 2009. Diversity and distribution of the Gastropoda Opisthobranchia from the Atlantic Ocean: A global biogeographic approach. Scientia Marina. 73: 153–160.
    García-Gómez, J. C., J. L. Cervera, F. J. García, J. A. Ortea, S. F. García-Martin, A. Medina, and L. P. Burnay. 1991. Resultados de la campaña internacional de biología marina “Algarve 88”: moluscos opistobranquios. Bollettino Malacologico 27 (5-9): 125-138.
    Göthel, H. 1994. Fauna marina del Mediterráneo. Ediciones Omega, Barcelona.
    Grande, C., J. Templado, J. L. Cervera, and R. Zardoya. 2003. Molecular phylogeny of Euthyneura (Mollusca: Gastropoda). Molecular Biology and Evolution 21 (2): 303-313. 21: 303–313.
    Hartmann, R. 1880. Uber die Organisation von Tethys fimbriata. Sitzungs-Berichte der Gesellschaft Naturforschender Freunde (1):9-12.
    Linnaeus, C. 1767. Systema Naturae. Systema Naturae, 12th ed. Laurentii Salvii: Holmiae [Stockholm, Sweden].
    List, J. H. 1887. Zur Kenntnis der Drusen im Fusse von Tethys fimbriata L. Arbeiten aus dem Zoologischen Institut zu Graz 1(6):287-305, pl 17.

    Bibliography based on the works by Steve Long, 2006. Bibliography of Opisthobranchia 1554-2000 and Gary McDonald, 2009. Bibliographia Nudibranchia, with later updates from other resources.

Further reading

Cite this article as:

Ballesteros, M., Madrenas, E. & Pontes, M. (2023) "Tethys fimbria" in OPK-Opistobranquis. Published: 17/05/2012. Accessed: 04/12/2023. Available at (https://opistobranquis.info/en/?p=647)

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