#lucinidae

A cosmopolitan genus of Lucinid clam. Probably Ctena tatei.

Aka the  ridged lucine. 

Native to SE Australian shores, but for some reason all but two of the records at ALA are limited to the New South Wales coastline.

Lucinid bivalves live in muddy sand or gravel at or below low tide mark, and like this example have rounded shells with forward-facing projections, etched with concentric rings. They do not have siphons, but the extremely long foot makes a slime-lined channel for the intake and expulsion of water.

Lucinids are also remarkable for their symbiosis with sulphur-reducing bacteria, hosted in specialized gill cells called bacteriocytes. The bivalve pumps sulfide-rich water over its gills and the bacteria use the sulphur to carbon into organic compounds, which are then transferred to the host as food.

Lucinid bivalves originated in the Silurian but did not diversify until the late Cretaceous, when seagrasses and mangroves evolved and provided much larger areas of sulphur-rich sediment. They’re pretty good for the seagrasses, too, since the lucinid-symbiont holobiont removes toxic sulfide from the sediment, and the seagrass roots provide oxygen to the bivalve-symbiont system.

In at least two species of Lucinid, the symbionts are also able to fix nitrogen gas into organic nitrogen.