Posterior of Corculum cardissa in situ (Photo: Lisa Kirkendale)
Uncovered Corculum cardissa (Photo: Lisa Kirkendale)

Little Heart Cockle

Corculum cardissa

Shell medium to large, thin, laterally compressed, distinctly heart shaped, variably convex and bordered by smooth to ridged or even spiny projections on shell perimeter. Distinctly 'dished' appearance. Offset umbones to facilitate valve closure. Posterior with discrete translucencies. Photosymbiotic.

Morphology

This highly sophisticated system of light transmission functions to allow protection of soft tissue by shell while still permitting light to penetrate deep to photosymbionts entrained within. Byssus present in adults.

Evolution

This is the type species of the genus Corculum. 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. The phylogeny of members of the Fraginae subfamily is in a state of flux and the taxonomy of the group is in need of attention.

Behaviour

Benthic after the larvae settles and epifaunal on coral rubble surfaces.

Method of reproduction

Broadcast spawner.

Habitat

Marine

Intertidal to shallow subtidal amongst dead coral rubble or sand, where it is also impossible to distinguish from the background, making it highly camouflaged. Exposed to sheltered areas.

Distribution

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

Life Cycle

Veliger larvae competent after 2 days in plankton (Kawaguti 1950).

Taxonomy

Kingdom: Animalia
Phylum: Mollusca
Class: Bivalvia
Subclass: Heterodonta
Superorder: Imparidentia
Order: Cardiida
Superfamily: Cardioidea
Family: Cardiidae
Subfamily: Fraginae
Genus: Corculum
Species: cardissa
Name Published Year: 1758
Rank: species
Scientific Name Authorship: Linnaeus
Commercial Impact: 

Sought after by shell collectors

Conservation Assessment: Least Concern

Net Conservation Benefits Fund

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Western Australian Museum Collections https://museum.wa.gov.au/online-collections/names/corculum-cardissa
Accessed 14 Aug 2024

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