Photo Observation(s) of the Month of November - The Elusive Elysia

Congratulations to Karolyn Landat for their Photo Observation(s) of the Month of November of the sea slug from the Elysia genus at Camp Cove in southern Sydney Harbour, also observed on the same day here. This genus of colourful sea slugs is nested within the Plakobranchidae family, but do not be fooled! Even though they superficially resemble nudibranchs, they are not closely related to them at all. Instead they are sacoglossans, sometimes referred to as the solar-powered sea slugs.

At least some species of Elysia sea slugs have extraordinary feeding strategies. When nibbling on their primary food source of algae, they often retain the associated chloroplasts in the lining of their digestive tract, enabling them to survive solely by photosynthesis (without further feeding) for several months at a time. Other species of this genus can be stressed to sadistic extremes. Indeed, some Elysia are capable of regenerating their entire body anew from a severed head (gasp!!!). The observation by Karolyn Landat may be the elusive Elysia australis, but this will require a few more experts providing identification suggestions on iNaturalist given that there are over 100 species in the genus, many with ambiguous taxonomy.

This journal post was written by project leader and iNaturalist member, Dr Joseph DiBattista.