Placuna placenta   (Linnaeus,  1758) (Oyster)
Organism information awaits expert curation
Class: Bivalvia

Image copyrights: The Malacological Society of London

Size: Maximum shell length 18 cm, commonly to 10 cm.

Color: Outside of shell silvery white with a dull finish, occasionally with pale brown or light purplish rays umbonally. Interior is nacreous white.

Shell is thin and more or less translucent, almost circular in outline. Dorsal margin somewhat flattened to widely curved, sometimes faintly protruding anteriorly and posteriorly. Valves greatly compressed laterally, the lower (right) valve flat, the upper (left) valve with slight convexity. Commissural plane is flat (rarely, if at all, subflexuous). Outer surface is nearly smooth, excepting numerous, minute radiating threads forming tenuous wrinkles on the finely lamellate concentric lines of growth. Hinge line straight and rather short, not raised. External ligament forms a ventrally undulated narrow band on both sides of the umbo. Right valve nymphs of internal ligament gradually diverge from each other, with the posterior ridge distinctly longer than the anterior. Interior of shell is smooth and glossy, with only very weak radiating lines. Inner side of anterodorsal and posterodorsal margins is often slightly rugose. The shell of adult oyster is free, very much compressed, slightly inequivalve, sub-orbicular in shape, the height and length approximately equal. The shell valves are slightly unequal, very flat, rounded and translucent. The inner surface of the valves is pearly. The adductor impression is at about the centre. The umbo is small. Two thin ridge like teeth diverge from the umbo making a characterstic inverted V shaped angle. The shell is fairly large with a diameter of 14 cm or even more. It bears numerous concentric lines of growth on the exterior consisting of slightly projecting lamellae the margins of which are minutely uneven with flnger-like or spatulate processes. The shell of the adult window-pane oyster is white in colour.

The body is very much laterally compressed and is covered by two folds of mantle. Anteriorly on either side of the visceral mass is a pair of elongated, narrow labial palps between which is the mouth. There is a pair of gills on either side of the visceral mass. The foot is cylindrical, flattened laterally and attached to the anterior surface of the visceral mass and its tip has a deep cup-like sucker which facilitates dispersal of foreign matter settling on the body. The alimentary canal consists of a slit-like mouth, oesophagus, a large stomach surrounded by the digestive gland, a well-developed pyloric caecum with crystalline style, a short intestine and a rectum which ends by anus in the centre of a broad everted membranous collar. The vascular system consists of the heart with a ventricle and two auricles, the right auricle being bigger than the left, 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 a single parietosplanchnic ganglion, from which nerves lead to different parts of the body. The excretory system is composed of a pair of asymmetric nephridia which are 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 nephridia open separately to the exterior at the ventral extremity of each renal tube near the parietosplanchnic ganglion. The gonad of the left side is suppressed and that on the right side is a highly irregular mass composed of a large lobe covering the stomach, digestive gland and coil of the intestine and a number of other lobes spread out in various directions in the right mantle. The gonad opens into the internephridial passage by a small aperture.

The sexes are separate, and the males and females are easily differentiated externally by colour of the gonad. Individuals mature at between 70 and 100 mm and fertilization is external. Larvae are planktonic for around 14 days and probably attach byssally at metamorphosis and newly settled juveniles can burrow partially into mud.

Synonym (s)
Anomia placenta Linnaeus, 1758
Placuna lincolnii (non Gray, 1849)
Ephippium transparens Roding, 1798
(Junior synonym)
Placenta orbicularis Philipsson, 1788
(Junior synonym)
Placuna ovalis Blainville, 1826
(Junior synonym)
Placenta auriculata Morch, 1853
Placenta communis Megerle von Muhlfeld, 1811
Placenta orbicularis Philipsson, 1788
Placenta placenta Rao, 1969
Placenta placenta Satyamurthi, 1956
Placenta placenta Gravely, 1941
Placuna placenta Homell, 1909a
Placuna placenta Reeve, 1873
Placuna placenta Lamarck, 1819
Placenta orbicularis Retzius, 1788

Common Name (s)
• Windowpane Oyster
• Window-pane Oyster (English)
Economic Importance and Threats
Importance:  Commercial
(Edible, shell used for decoration, glue, chalk, shellac, soldering lead and paint. Transparent shells are locally used in some areas as a substitute for window glass in houses.)
Cultured:  Yes

Habitat:  Reef Associated
Trophic Level:  Consumer
Prey:  Plankton, organic detritus


• Karnataka, Gangavali Estuary (Lat: 15.58) (Long: 74.25) INDIA
• Gujarat, Gulf of Kachchh (Lat: 22.6) (Long: 69.5) INDIA
• Orissa, Mahanadi Estuary (Lat: 20.32) (Long: 86.75) INDIA
• Andhra Pradesh, Kakinada Bay INDIA
• Goa, Zuari Estuary, Nauxim Bay (Lat: 15.43) (Long: 73.85) INDIA
• Tamil Nadu, Tuticorin INDIA (Record: 1949)
• Tamil Nadu, Kilakarai INDIA (Record: 1949)
• Maharashtra, Balapur INDIA (Record: 1949)
• Gujarat, Gulf of Kachchh, Rann Bay INDIA (Record: 1949)
• Maharashtra, Mumbai INDIA
• Andhra Pradesh, Kakinada, Corangi Bay INDIA
• Tamil Nadu, Dhanushkodi INDIA
• Gujarat, Adatra Reef INDIA
• Gujarat, Balapur Reef INDIA
• Gujarat, Gulf of Kachchh INDIA
• Gujarat, Gulf of Kachchh, Rann Bay INDIA
• Maharashtra, Mumbai Harbour INDIA
• Kerala, Malabar Coast INDIA
• Tamil Nadu, Tuticorin INDIA
• Tamil Nadu, Pulicat Lake INDIA
• Tamil Nadu, Ennore INDIA
• Tamil Nadu, Nagapattinam INDIA
• Orissa, Dhamra Estuary INDIA
• Andaman and Nicobar Islands INDIA

Literature Source(s)
  • Tikadar, BK; Daniel, A and Subbarao, NV (1986) Sea shore animals of Andaman and Nicobar Islands The Director, ZSI, Kolkatta 188 Available at - ZSI, Pune
  • Subba Rao, NV and Dey, A (2000) Catalogue of marine molluscs of Andaman and Nicobar Islands Occasional paper no 187 Records of the Zoological Survey of India ZSI 1-323 Available at - NCL, Pune
  • (1995) Hugali Matla estuary: West Bengal ZSI, Kolkatta 1-542
  • Venkatraman, K; Srinivasan, M; Satyanarayana, CH and Prabhakar D (2002) Faunal diversity of Gulf of Mannar biosphere reserve Conservation area series 15 ZSI 77 pp; VIII pla Available at - NCL, Pune
  • (2001) Fauna of Godavari estuary, Andhra Pradesh Estuarine ecosystem series 4 ZSI, Kolkata 1-166 Available at - ZSI, Pune
  • Zoological Survey of India (Eds.) (1998) Fauna Of Mahanadi estuary, Orissa Estuarine ecosystem series no 3 ZSI, Kolkata 1-218 Available at - ZSI, Pune
  • Dhargalkar, V and Ingole, B (2005) Survey of inventorization of coastal biodiversity at three estuarine sites along the central west coast of India 1 Available at - NCL, Pune
  • Subba Rao, NV and Sastry, DRK (2005) Fauna of Marine National Park, Gulf of Kuchchh (Gujarat) ZSI 79 pp Available at - NCL, Pune
  • Campbell, C Fisheries and aquaculture of window pane shells Mini review The Malacological Society of London: Bulletin Available at -
  • Hosseinzadeh, H; Daghoghi, B and Rameshi, H (2001) Atlas of the Persian Gulf molluscs Oman sea fisheries research center, Oman 208 Available at - NIO, Goa
  • Sealifebase Available at -
  • Poutiers, JM (1998) Bivalves FAO species identification guide for fishery purposes. The living marine resources of the western central Pacific. Volume 1: Seaweeds, corals, bivalves and gastropods FAO, Rome 1 686 pp Available at -
  • Society for the Management of European Biodiversity Data (2009) World Register of Marine Species (WoRMS) Available at -
  • Rao, NVS; Rao, KVS and Manna, RN (1995) Mollusca Wetland ecosystem series 1: Fauna of Chilka lake ZSI, Calcutta 391-468 Available at - NIO, Goa
  • Raut, D; Ganesh, T; Murty, NVSS and Raman, AV (2005) Macrobenthos of Kakinada Bay in the Godavari delta, East coast of India: comparing decadal changes Estuarine, Coastal and Shelf Science Elsevier 62(4) 609-620 Available at -
  • Ingole, B.S., Clemente, S. (2006) Status of windowpane oyster Placuna placenta (Linnaeus) population in Goa Glimpses of marine archaeology in India. Proceedings of the Seventh Conference on Marine Archaeology of Indian Ocean Countries, 6-7 October 2005. Society for Marine Archaeology, NIO, Dona Paula, Goa 130-133 Available at - NIO, Goa
  • Sealifebase Available at -
  • Bouillon, S; Raman, AV; Dauby, P and Dehairs, F (2002) Carbon and Nitrogen stable isotope ratios of subtidal benthic invertebrates in an estuarine mangrove ecosystem (Andhra Pradesh, India) Estuarine, Coastal and Shelf Science. Elsevier 54 901–913 Available at -
  • Alagarswami, K and Narasimham, KA (1973) Clam, cockle and oyster resources of the indian coasts Living resources of the seas around India CMFRI, Cochin 648-658 Available at -
  • Samuel, VD; Chacko, D and Edward, JKP (2005) Preliminary study on the molluscan diversity of “the lost world’’– Dhanushkodi, east coast of India Proceedings of the National Seminar on Reef Ecosystem Remediation SDMRI Special Research Publication No.9 54-58 Available at -
  • Gopalakrishnan, P (1970) Some observations on the shore ecology of the Okha Coast Journal of the Marine Biological Association of India Cochin, India 120(1&2) 15-34 Available at - NIO, Goa
  • Rao, KS (1974) Other commercial molluscs The commercial molluscs of India Bulletin Of Central Marine Fisheries Research Institute CMFRI, Cochin 25 141-151 Available at -
  • Dutta, SK (2007) Biodiversity assessment of Dhamra port site and surrounding areas, Orissa Greenpeace India 4-38 Available at -
  • Das, AK and Roy, MKD (1989) A general account of the mangrove fauna of Andaman and Nicobar islands Fauna of conservation areas Zoological survey of India 1-152 Available at - NIO, Goa

Page last updated on:2011-07-04

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