Elysia atroviridis
Baba, 1955

Superfamily: ELYSIOIDEA
Family: Elysiidae


Japan (except Hokkaido, Okinawa), South Korea.


Upper: Echizen-coast, Wakasa Bay, Japan. Depth: 2 m. Length: Approx 8 mm. 2 Aug 2004. On Codiaceae kind. Photographer: Jun Imamoto. Lower: Nagashima Beach, Kagoshima prefecture, southern Japan, Pacific Ocean. Depth: about 6-10 metres. Length: 15 mm. 4 March 2003. muddy sand. Photographer: Rie Nakano

Body varies from pale to dark translucent green, with black rhinophores which are paler, almost bluish black towards the base. Body, and outer surace of a parapodia covered in scattered small white spots of variable size. Border of parapodia with white line. Reported to feed exclusively on a species of the green alga Codium. Grows to approximately 30 mm.

From messages on the Forum from South Korea, it seems possible that Elysia flavomacula Jensen, 1990, is a colour variant with a bright yellow patch on the head. On the lower photo here on the Fact Sheet, there is a faint - but quite distinct - yellow patch.

This species is of particular interest as it was the subject of one of the earliest studies on solar powered sea slugs, with a detailed report by Kawaguti and Yamasu in 1965 demonstrating the presence of algal chloroplasts, not unicellular algae, in animal cells. Electron microscopy revealed that the green structures housed in the digestive cells of Elysia atroviridis were structurally identical to the chloroplasts in the green alga Codium fragile, upon which the sea slug was observed to feed.

  • Baba, K. (1955). Opisthobranchia of Sagami Bay,  Supplement. Tokyo: Iwanami Shoten.
  • Kawaguti, S. & Yamasu, T. (1965) Electron microscopy on the symbiosis between an elysioid gastropod and chloroplasts of a green alga. Biological Journal of Okayama University, 11: 57-65. 
Authorship details
Rudman, W.B., 2005 (June 17) Elysia atroviridis Baba, 1955. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/elysatro

Related messages

  1. Elysia atroviridis from Sth Korea
    From: Dong Bum Koh, June 27, 2005
  2. Re: Japanese Elysia atroviridis with yellow spot
    From: Kathe R. Jensen, June 23, 2005
  3. Re: Japanese Elysia atroviridis with yellow spot
    From: Kathe R. Jensen, June 22, 2005
  4. Photos of Elysia atroviridis from Japan
    From: Jun Imamoto, June 19, 2005
  5. Japanese Elysia atroviridis with yellow spot
    From: Rie Nakano, June 19, 2005
  6. Koh's Elysia is Elysia atroviridis
    From: Atsushi Ono, June 17, 2005
  7. Another Elysia flavomacula?
    From: Dong Bum Koh, June 16, 2005
  8. Elysia flavomacula? from South Korea
    From: Dong Bum Koh, June 9, 2005
  9. Elysia flavomacula from Hong Kong
    From: Leslie Chan, July 24, 2001

Show factsheet and all related messages