Anomia achaeus

Scientific Name:-
Anomia achaeus

Common Name:-
Saddle oyster

Malayalam Name:-




Golden yellow shells of maximum size: 20 mm; length 16.40-25.10 mm; width 21.50-28.15 mm. The shell of adult oyster is free, compressed, slightly unequal, sub-orbicular in shape, the height and length approximately equal, very flat, rounded and translucent with pearly inner surface. The adductor impression is at the center. Two thin ridge like teeth diverging from the umbo making a characteristic inverted V shape angle. It bears numerous concentric line of growth on the exterior consisting of slightly projecting lamellae with finger-like or spatulate processes at the margins. Laterally compressed body covered by two folds of mantle. A pair of elongated, narrow labial palps and gills present on either side of the visceral mass. Mouth lies between the labial palps. Cylindrical foot with cuplike sucker at the tip which facilitates dispersal of foreign matter settling on the body. The alimentary canal consists of a slit-like mouth, esophagus, stomach, digestive gland, well-developed pyloric caecum with crystalline style, short intestine, rectum and anus in the centre of the broad ventricle membranous collar. The vascular system consists of the heart with a ventricle and two auricle, a single aorta, the anterior aorta, arteries and venous sinuses. The nervous system consists of a pair of widely separated and asymmetric cerebral ganglia, a pedal ganglion formed by the fusion of paired pedal ganglia and single parieto-splanchnic ganglion, from which nerves lead to different parts of the body. The excretory system is composed of a pair of asymmetric nephridia connected dorsally by a short, transverse channel. The right nephridium has a long caecum posteriorly while the left one has only a short caecum. The nephidia open separately to the exterior. The gonad opens into the inter-nephridial passage by a small aperture. Sexes are separate.



The shells are used as decorative pieces and for glazing windows and doors. Poor quality pearls can be obtained.


Suspension feeding, epifaunal bivalves found in rocky and muddy shores.


Anomia achaea [sic] (misspelling)
Anomia argyritis Reeve, 1859
Anomia belesis Gray, 1850
Anomia malleata Reeve, 1859
Anomia perplexa Turton, 1932
Anomia plenilunium Reeve, 1859
Anomia problematica Turton, 1932
Anomia scabra Reeve, 1859
Anomia sol Reeve, 1859


Dholakia, A. D. (2004). Window pane oyster fishery Fisheries and aquatic resources of India Daya Books 413 pp
Ramakrishna and A. Dey. 2010. Annotated Checklist of Indian Marine Molluscs. ZSI, Kolkata, 357pp.
OBIS Indo-Pacific molluscan database Available at http://data.acnatsci.org/obis/search.php/54592

Back to the search results.