Tylodina corticalis

Umbrella shell

Tylodina corticalis, Port Stephens, NSW, Photo: Tom Davis

Same Genus

Tylodina perversa

Distribution

Temperate Australasia

Description

Only species in the family recorded from Australia. The animal is bright chrome yellow with a wide foot, and the shell is oval-shaped and covered by a thick brown protective layer (the periostracum) with strong radial ridges. The species is very rarely seen outside the autumn months. It feeds on a yellow sponge (Pseudoceratina sp).

Information

Max Size: 10 cm

Sea Temperature Range: 12.7-21.9°C

Depth: 0â€“60 m

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 (1.8% 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.

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