Solar-powered sea slug (Elysia viridis)

Distribution data supplied by the Ocean Biodiversity Information System (OBIS). To interrogate UK data visit the NBN Atlas.Map Help



Elysia viridis has a delicate leaf-shaped body up to 5 cm in length which tapers posteriorly. This species is commonly vivid green, and occasionally bright red or brown. Tiny glistening red, blue or green spots are also present. Both body length and colour are determined by diet. White patches may be found on the edges of the projections of the foot (parapodium) and around the eyes, and black markings may sometimes be present on the head and body. The parapodium is broad, with lobed or frilled edges and extends almost the entire length of the body, containing visible green chloroplasts. Lateral parapodial "wings" may be outstretched or held over the body. The head bares conspicuous propodial tentacles and a pair of enrolled rhinophores that open ventrally and usually have white distal ends (anus present under right rhinophore). Digestive diverticula which contain ingested chloroplasts, ramify and can be visible through the surface of the body, parapodia and rhinophores.

Recorded distribution in Britain and Ireland

This species probably distributed throughout the British Isles, although most records are from the western coats.

Global distribution



This species can be found on the underside of macroalgal fronds in shallow water and rock pools. Elysia viridis feeds usually on Codium sp. or Cladophora sp. in European waters.

Depth range


Identifying features

  • Body up to 5 cm long.
  • Commonly vivid green, occasionally bright red or brown.
  • Tiny glistening red, blue or green spots.
  • Enrolled rhinophores.
  • Parapodia broad and extends most of body length.
  • Lateral parapodial 'wings' outstretched or folded over dorsum.

Additional information

Elysia viridis is very similar to the sea hare in its soft winged body and colouration, although Elysia sp. is flatter with no oral tentacles. Elysia viridis is known as a 'sap-sucking slug' and feeds only on a single or limited food source (stenophagous). It ingests the chloroplasts unharmed and uses them for photosynthesis which benefit the slugs food supply (a process known as klepoplasty). Chloroplasts account for the colouration of the animal.

This species has a 12-15 month life-span and is sexually mature when 1.2 cm in length. It produces benthic egg masses from April to October which hatch as planktonic veligers. This species may also tolerate low salinity levels.

Listed by

- none -


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  8. Jensen, K.R., 1989. Learning as a factor in diet selection by Elysia viridis (Montagu) (Opisthobranchia). Journal of Molluscan Studies, 55, 79-88.

  9. JNCC (Joint Nature Conservation Committee), 1999. Marine Environment Resource Mapping And Information Database (MERMAID): Marine Nature Conservation Review Survey Database. [on-line]

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  11. Trowbridge, C.D., 2000. The missing links: larval and post-larval development of the ascoglossan opisthobranch Elysia viridis. Journal of the Marine Biological Association of the United Kingdom, 80(6), 1087-1094.


  1. Centre for Environmental Data and Recording, 2018. Ulster Museum Marine Surveys of Northern Ireland Coastal Waters. Occurrence dataset accessed via on 2018-09-25.

  2. Conchological Society of Great Britain & Ireland, 2018. Mollusc (marine) data for Great Britain and Ireland - restricted access. Occurrence dataset: accessed via on 2018-09-25.

  3. Conchological Society of Great Britain & Ireland, 2018. Mollusc (marine) records for Great Britain and Ireland. Occurrence dataset: accessed via on 2018-09-25.

  4. Fenwick, 2018. Aphotomarine. Occurrence dataset Accessed via on 2018-10-01

  5. Kent Wildlife Trust, 2018. Kent Wildlife Trust Shoresearch Intertidal Survey 2004 onwards. Occurrence dataset: accessed via on 2018-10-01.

  6. NBN (National Biodiversity Network) Atlas. Available from:

  7. OBIS (Ocean Biodiversity Information System),  2024. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. Accessed: 2024-05-20


This review can be cited as:

Rowley, S.J. 2006. Elysia viridis Solar-powered sea slug. In Tyler-Walters H. and Hiscock K. Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 20-05-2024]. Available from:

Last Updated: 19/09/2006