Aplysia depilans

Aplysia depilans Gmelin, 1791

Aplysia depilans by Enric Madrenas




































Aplysia depilans  Gmelin, 1791

 Classification according to Bouchet et al. (2017)
Taxonomic source: World Register of Marine Species (AphiaID: 138754).

  • Aplysia juliana var. quoyana Engel & Eales, 1957
  • Aplysia leporina Delle Chiaje, 1828
  • Aplysia major Lankester, 1875
  • Aplysia melanopus Couch, 1870
  • Aplysia petersoni Gray J.E., 1828
  • Aplysia poli Delle Chiaje, 1824
  • Aplysia poliana Delle Chiaje, 1824
  • Aplysia sandvichensis Sowerby G.B. II, 1869
  • Aplysia woodi Bergh, 1908
  • Dolabella fragilis Lamarck, 1822
  • Dolabella laevis de Blainville, 1819
  • Dolabella lepus Risso, 1826
  • Syphonota bipes Pease, 1860
  • Tethys capensis O’Donoghue, 1929

Together with A.fasciata this is one of the biggest sea hares in European waters, it is cited to reach up to 30 cm in length (Eales, 1960) and a weight of about 1 kg. The body is wide and very variable in color, ranging from brown to green, often with several white or yellow spots. The oral tentacles are broad and the rhinophores are auriculate. The parapodia are fused in the back, as in A.punctata. The dorsal mantle foramen has a small diameter, and it is the origin of several fine radial striations. The surface of the internal shell can be seen through the foramen, it is thin, flat and semi-transparent. Multiple opaline gland pores are located in the front right area of the mantle cavity. The foot is wide and rounded in the back zone, where it also has an adherent circular zone, called metapodial suction cup, that allows the animal to remain attached to the substrate. In the genital tract the penis is dark, almost black, and the cuticle has penial thorns.

Like other European species of the genus, A.depilans lives in shallow waters of the coast where photophilous algae grow, as it feeds on them. There is evidence that this sea hare eats different species of algae as Dictyota, Ulva and various pheophyceans. The parapodia joined in the back side prevents it from making swimming motions, although it has been reported that Mediterranean specimens can swim. Due to the presence of the metapodial suction cup, animals are strongly attached to the substrate by the back of the foot, while the whole body can stand almost upright. When specimens are abruptly disturbed they are capable of secreting a whitish, pungent odor, defensive fluid through the holes in the opaline gland. As in other species of the genus, during reproduction time many individuals copulate reciprocally forming chains; the first individual in the chain has the role of female, being fertilized by animal behind, the animal at the end of the chain plays the role of male fertilizing the animal in front of it, and all the intermediate individuals in the chain have a role of both male and female both, impregnating the front animal and being fertilized by the animal on their back. In Asturias it has been studied the annual cycle of a population of A.depilans in an intertidal zone of the beach of Las Llanas (Martínez, 1995) and results show that the spawning period is from late June to late September and that the life cycle lasts less than a year, adults disappearing from the beach during the winter months. The spawn, as in other species of the genus, is shaped like a very long cord rolled into a compact mass of yellow-orange color that can be up to 80 times longer than the body size. Within the cord there are egg capsules containing an average of 25 eggs about 100 microns in diameter, accounting for more than 3 million eggs in the whole ovigerous mass (Bebbington & Thompson, 1968). In the outer parts of the body of A.depilans various secondary metabolites called aplyolides have shown repellency to predation and ichthyotoxic properties (Martinez, 1995).


  • Aplysia. Derived from Greek word for dirty
  • depilans = depilatory, ancient belief about touching the animal provokes a hair loss.

It is a species that is distributed along the coasts of Europe, from the British Isles to the Mediterranean, and is also cited in the Canary Islands, Madeira, Azores and Cape Verde archipelagos. In the Iberian Peninsula it has been cited in all both Spanish and Portuguese coastal areas and in Catalonia it has been observed in the north and south of Costa Brava, the Medes Islands, Maresme, Costa Dorada and along the coast of Tarragona down to Sant Carles de la Ràpita.

Known georeferenced records of the species: Aplysia depilans
: 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 Aplysia depilans based on our own records.



More pictures


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    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) "Aplysia depilans" in OPK-Opistobranquis. Published: 15/05/2012. Accessed: 04/03/2024. Available at (https://opistobranquis.info/en/?p=367)

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