Stiliger smaragdinus

Cactus sea slug
Stiliger smaragdinus
Stiliger smaragdinus, Coffs Harbour, NSW, Photo: Ian Shaw
Stiliger smaragdinus
Stiliger smaragdinus, Batemans Bay, NSW, Photo: Andrew Green
Stiliger smaragdinus
Stiliger smaragdinus, With eggs. Batemans Bay, NSW, Photo: Andrew Green
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Stiliger smaragdinus
Stiliger smaragdinus
Stiliger smaragdinus


Temperate Australasia, Temperate northern Pacific


Largest known Australian opisthobranch that feeds on the cell contents of green algae. The animal is lime-green in colour and has its upper surface obscured by rows of cerata. On the rare occasions when the species has been seen, it has usually been associated with the alga Caulerpa cactoides.


Max Size: 8 cm

Sea Temperature Range: 10.4-18.4°C

Depth: 0-22m

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: Not Evaluated

Occurrence: Infrequent (1.3% 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: Solitary (1 per transect)

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