Elysia expansa

Black-margined sea slug
Elysia expansa
Elysia expansa


Temperate Australasia


Olive green body with dark tips to the rhinophores and a thin black line along the margin of the parapodia. The parapodia are very large in comparison with those of other species in the family and have a ruffled appearance. The species occurs commonly along the southern west coast, where it feeds on species of Caulerpa.


Max Size: N/A cm

Sea Temperature Range: N/A

Depth: 0-5m

Habitat Generalization Index: N/A

Also referred to as the SGI (Species Generalisation Index), this describes the habitat niche breadth of the species. Species with values less than 15 are found in a relatively narrow range of reef habitat types (specialists), while those over 25 may be found on most hard substrates within their range (generalists). Learn more here.

Conservation and Rarity

IUCN Status: Vulnerable

Occurrence: Common (22.2% of sites)

Occurrence describes how often the species is found on surveys within its distribution. It is calculated as the % of reef sites surveyed by RLS divers across all the ecoregions in which the species has been observed

Abundance: Few (2 per transect)

Abundance is calculated as the average number of individuals recorded per RLS transect, where present.

Edit by: GJ Edgar. 2008. Australian Marine Life. New Holland, Sydney