Meridiastra medius

Southern six-armed star
Meridiastra medius
Meridiastra medius


Temperate Australasia


Paired surface skin papulae extending no more than halfway down each arm ridge before they become single (compared with half to three-quarters distance for M.oriens), and with fine rather than coarse spinelets along the margins. Colouration is very variable, but generally with combinations of pinks, oranges and reds.


Max Size: 8 cm

Sea Temperature Range: 12-21.6°C

Depth: 0-30m

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 (1.2% 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: Many (21 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