Bathyarca glacialis Gray, 1824
|Phylum:||Mollusca Linnaeus, 1758|
|Class:||Bivalvia Linnaeus, 1758|
|Synonyms:||Arca glacialis J.E. Gray, 1824; Barbatia glacialis (Gray, 1824)|
To size: To 15mm.
Shell Structure: Thin but not fragile, opaque. Equivalve: Slightly inequivalve, left valve slightly larger, right valve sitting inside left valve. Equilateral: Inequilateral, beaks in front of midline at about 1/3 the length of the dorsal margin from the anterior. Tumidity: A little tumid. Outline: Oblong, posteriorly expanded, umbos prominent; dorsal margin long, straight; posterior broadly rounded, ventral gently curved; anterior narrower than posterior, rounded. Contour: Dorsal area narrow, flat but rising towards junction of valves; posterior angle indistinct; median area with a shallow sinus only in smaller shells.
Sculpture: Primarily radial of numerous fine riblets, these interrupted by growth stops. Margin: Inner margin of larger left valve weakly crenulate adjacent to a submarginal groove; right valve smooth. Ligament: Duplivincular, chevrons developing from the posterior of the dorsal area. Hinge: Taxodont, teeth in two series set on a gently curved hinge plate, separated by a distinct edentulous space; anterior set with up to 6 teeth, posterior set up to 9; posterior teeth longer and set more obliquely than anterior teeth. Pallial Musculature: Anterior adductor scar about 2/3 size of posterior. Colour: Yellow-brown.
An Arctic species extending south along the shelf edge and upper slope into the Faroe-Shetland Channel. Byssally attached to gravel, stones and deep water coral debris along the continental margin and upper slope.
Depth: 100 - 2000 m