Lunulicardia retusa (Photo: Corey Whisson)
Shells of Lunulicardia retusa (Photo: Corey Whisson)

The Blunt Cockle

Lunulicardia retusa

Triangular outline, tending to ovate, more so than L. hemicardium, with a pronounced umbonal keel, which delineates a broad, rather flat or concave posterior. Posterior margin nearly vertical. Sculpture of ribs is low, interstices are pitted or crossed by raised transverse bars. With a wide lunule that is deeply impressed in contrast to L. hemicardium. Shells white in color internally and externally, with light red (rarely yellow) spots or blotches especially anteriorly. Thin yellow periostracum. Coloration of tissue brown due to presence of photosymbionts entrained in tissue.

Morphology

Photosymbiotic.

Evolution

This is the type species of the genus Lunulicardia. Kirkendale (2009) has shown (and others have confirmed e.g. Herrera et al. 2015) that Fragum is paraphyletic and includes Corculum and Lunulicardia, the two other wholly photosymbiotic lineages of cardiids.

Behaviour

All cockles or cardiids have short siphons. Because of this morphological constraint, infaunal cardiids live close to the sediment water interface in order to filter water. This could be considered a preadaptation for a photosymbiotic lifestyle, as it also facilitates optimal light penetration into the soft tissues in shell interior where photosymbionts are housed.

Method of reproduction

Broadcast spawner.

Habitat

Marine

Marine, intertidal to shallow subtidal.

Distribution

QLD, NT and WA in Australia, but widely distributed in the Indo-west Pacific.

Life Cycle

Short lived veliger larvae.

Taxonomy

Kingdom: Animalia
Phylum: Mollusca
Class: Bivalvia
Subclass: Heterodonta
Superorder: Imparidentia
Order: Cardiida
Superfamily: Cardioidea
Family: Cardiidae
Subfamily: Fraginae
Genus: Lunulicardia
Species: retusa
Name Published Year: 1767
Rank: species
Scientific Name Authorship: Linnaeus
Commercial Impact: 

Sought after by shell collectors

Conservation Assessment: Least Concern

Net Conservation Benefits Fund

Share
Facebook Twitter

Cite this page
Western Australian Museum Collections https://museum.wa.gov.au/online-collections/names/lunulicardia-retusa
Accessed 7 Jul 2025

Rights
We support the open release of data and information about our collections.

Text content on this page is licensed under a Creative Commons Attribution 4.0 International License.
Image content on this page is copyright WA Museum.