Arctic Megabenthos Ennucula tenuis ((Montagu, 1808), ) Phylum: Mollusca Class: Bivalvia Order: Nuculida Family: Nuculidae Genus: Ennucula Synonyms: Leionucula bellotii (A. Adams, 1856); Nucula tenuis (Montagu, 1808); Nuculoma tenuis (Montagu, 1808) To size: To 13mm. Shell Structure: Thin but not fragile. Equivalve: Equivalve. Equilateral: Inequilateral, the beaks lie approximately 20\% of dorsal margin length from posterior. Tumidity: (T:L=1:4 [4.5:18.1]) Moderately inflated. Outline: Ovate triangular: height of shell approximately 75\% of length; antero-dorsal margin very long, gently curved and sloping; postero-dorsal margin slightly curved, steeply sloping with angled junction at posterior margin; anterior and ventral margins moderately rounded; escutcheon elongate heart-shaped, projecting, generally with poorly defined edges; lunule long, lanceolate with poorly defined edges, noticeably raised. Umbo slightly swollen. Sculpture: Primary sculpture of numerous very fine, closely-spaced, concentric lines and some growth stops. Margin: Smooth. Ligament: Internal, opisthodetic, elongate triangular ligament seated in a well- developed resilifer. A thin, barely visible, external ligament lies anterior to the beaks. Hinge: Taxodont: Broad and continuous hinge plate with a well-developed resilifer. Teeth long and pointed, usually 8-10 posterior and 16-18 anterior. The teeth extend across the top of the resilifer. Pallial Musculature: Pallial line continuous with no pallial sinus. Adductor muscle scars oval, more or less equal in size and indistinct. Periostracum: Glossy, grey green, green to dark olive, often darker around the outer margin, sometimes iridescent. Colour: Yellow-green. Mud and substrates such as sand and gravel which have a muddy element. Depth: 10 - 200 m. Literature ● Филатова З.А.Класс Bivalvia (Lamellibranchiata) - Двустворчатые моллюски. В кн. Определитель фауны и флоры северных морей СССР. М. 1948. С. 405-446. ● Список видов свободноживущих беспозвоночных евразийских морей и прилежащих глубоководных частей Арктики. В серии: Исследования фауны морей. Вып. 51(59). СПб., 2001. 132 с. ● Антипова Т.В. Распределение, экология, рост и продукция двустворчатых моллюсков Баренцева и Карского морей. Диссертация на соискание ученой степени канд. биолог. наук. Мурманск 1979. 230 с. ● http://www.marinespecies.org/index.php Pic. 1 Pic. 2 Pic. 3 Pic. 4 Author: Manushin Igor E. / 28.09.2015 Last edit: Manushin Igor E. / 14.07.2017.