Species Account

Thyasira (Thyasira) sarsi (Philippi, 1845)

Thyasiroidea : Thyasiridae

Tebble name: n/a
Smith & Heppell name: Thyasira sarsi (Philippi, 1845)

To size: To 25mm. Shell Structure: Thin. Equivalve: Equivalve. Equilateral: Equilateral. Tumidity: Not inflated. Outline: Subcircular; anterior dorsal (lunule) margin short weakly depressed; anterior broadly rounded with a weak angulation or truncation at junction with lunule margin; ventral broadly rounded; posterior weakly bisinuate. Contour: Auricle low, long extending to almost complete length of submarginal sulcus; first posterior fold low, rounded; second fold weak, rounded; posterior area weakly sulcate.

Sculpture: Growth line and stops. Margin: Smooth. Ligament: External, sunken but clearly visible and extending for 3/4 length of auricle. Hinge: Weak, RV with a rudimentary cardinal peg or protuberance; LV with indistinct corresponding depression. Pallial Musculature: Muscle scars obscure. Periostracum: Often persistent, silky. Colour: Shell white. Additional Characters: 2 demibranchs.

Distribution & Ecology

In British waters from the north-central North Sea 80-220m. Also from the Norwegian shelf and fjords. Chemosymbiotic, in Norwegian fjords associated with detritus rich sediments but in British waters associated with hydrocarbon enriched sediments around drilling platforms. Also associated with methane seeps in the Skagerrak. Appears to be more dependent on enriched substrates than T. flexuosa. Gills have 2 demibranchs and highy adapted for bacterial symbiosis.
Gill anatomy – Dufour, 2005
Symbiosis – Southward, 1986; Dando & Southward, 1986; Dando & Spiro, 1993; Dando, Austin, Burke et al, 1991; Dando, Bussmann, Niven, et al, 1994

Depth Range
Continental Shelf (to 200m)

Additional Information & Related Species


Listed are literature citing Thyasira (Thyasira) sarsi (Philippi, 1845). Reference containing the species Type Description is highlighted.

Dando P R & Southward A J 1986. Chemoautotrophy in the bivalve molluscs of the genus Thyasira. Journal of the Marine Biological Association of the United Kingdom. 66: 915-929.
Dando P R & Spiro B 1993. Varying nutritional dependence of the thyasirid bivalves Thyasira sarsi and T. equalis on chemoautotrophic symbiotic bacteria, demonstrated by isotope ratios of tissue carbon and shell carbonate. Marine Ecology Progress Series . 92: 131-158.
Dando P R, Austen M C, Burke Jr R A, Kendall M A, Kennicutt M H, Judd A G, Moore D C, O’Hara S C M, Schmaljohann R & Southward A J. 1991. Ecology of a North Sea pockmark with an active methane seep. Marine Ecology Progress Series . 70: 49-63.
Dando P R, Bussmann I, O’Hara S C M, Schmaljohann R & Taylor L J. 1994. A methane seep in the Skageraak, the habitat of the pogonophore Siboglinum poseidoni and the bivalve mollusc Thyasira sarsi. Marine Ecology Progress Series . 107: 157-167.
Dufour S C 2005. Gill anatomy and the evolution of symbiosis in the bivalve family Thyasiridae. Biological Bulletin. 208: 200-212.
Oliver P G & Killeen I J 2002. The Thyasiridae (Mollusca: bivalvia) of the British continental shelf and North Sea Oilfields. Studies in Marine Biodiversity and Systematics from the National Museum of Wales. BIOMOR Reports. 3: 1-73.
Payne C.M. & Allen J.A. 1991. The morphology of deep-sea Thyasiridae (Mollusca: Bivalvia) from the Atlantic Ocean. Philosophical Transactions of the Royal Society of London Series B. 334: 481-566.
Philippi R A 1845. Kritische Bemerkungen über einige Trochus- Arten und die Gattung Axinus. Zeitschrift für Malakozoologie. 1845: 87-91.
Southward E C 1986. Gill symbionts in thyasirids and other bivalve molluscs. Journal of the Marine Biological Association of the United Kingdom. 66: 889-914.
Taylor J D, Williams S T & Glover E A 2007. Evolutionary relationships of the bivalve family Thyasiridae (Mollusca: Bivalvia), monophyly and superfamily status. Journal of the Marine Biological Association of the United Kingdom. 87: 565-574.


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Record last modified: 17/05/2016