This may be the most common species of opisthobranch on the Pacific side of Mexico and Central America. One of the “solar sea slugs”, it is a sacoglossid and feeds on algae, retaining living chloroplasts in its tissue. This species derives double benefit from this feeding preference as it also harvests the by-products manufactured as chloroplasts carry on photosynthesis.
This is likely the reason this species is always found in shallow, well lit waters. In sunlight specimens can be seen to open their mantle exposing their chloroplast laden tissue to the greatest amount of solar insolation. Depending on your location, depth and light conditions, specimens may vary in color.
E. diomedea has a sister species in the Caribbean, Elysia crispata . Some speculate these two species evolved separately after closure of the Panama land bridge.
Like many other species of Sacoglossa, E. diomedea lays a flat spiral egg ribbon .
If you have ever wondered just how many species live in the waters of the Gulf of California and coastal Mexico, may I refer you to a new book – Opistobranquios de Mexico – by Alicia Hermosillo, Eduardo Rios Jara and yours truly. This full color guide, while in Spanish, does contain 234 species, many with multiple photos showing the color variation and egg masses.
Opisthobranquios de Mexico
2006. Alicia Hermosillo, David Behrens & Eduardo Rios Jara
This new guide (in Spanish) covers every known species of sea slugs from the U.S. Border to Guatemala, along the Pacific Coast of Mexico. All Gulf species are included. Multiple color photos of each of the 234 species are included.
Dimensions: 6 3/4 x 8 1/2
Contact Dave at firstname.lastname@example.org
Ali Hermosillo and Dave Behrens
Pacific Coast Nudibranchs and Nudibranch Behavior
Send Dave mail at email@example.com