Windowpane oyster

Windowpane oyster

Windowpane oyster
A cleaned shell of the capiz ready for processing, the V-shaped ligament ridge is showing.
Scientific classification
Kingdom: Animalia
Phylum: Mollusca
Class: Bivalvia
Order: Ostreoida
Family: Placunidae
Genus: Placuna
Species: P. placenta
Binomial name
Placuna placenta
Linnaeus, 1758

The windowpane oyster, Placuna placenta, also known as capiz, is a bivalve marine mollusk in the family of Placunidae.[1] Among the species in the genus, only the P. placenta has an outer shell translucent enough for commercial use.[2]


The distribution of this species extends from the shallows of the Gulf of Aden, around India, then Malaysia to the southern South China Sea, and around the Philippines, whose province of Capiz derives its name from this shell, as it flourishes abundantly there.

These oysters can usually be found in muddy or sandy shores, in bays, coves, and lagoons to a depth of about 100 m (330 ft). Windowpane oysters are also cultivated in some areas. Like almost all other bivalves, they consume plankton filtered from the water passing through their slightly opened shell; the shell closes if the bivalve is above water during low tide.[2]


The almost-flat concave shells of the capiz can grow to over 150 mm (5.9 in) in diameter, reaching maturity between 70 to 100 mm (2.8 to 3.9 in); securing the shells is a V-shaped ligament. Male and female oysters are distinguished by the color of the gonads. Fertilization is external and larvae are free-swimming like plankton for 14 days or attached to surfaces via byssal thread during metamorphosis, eventually settling in the bottom.[3][2]

A Spanish Colonial-style house in Manila with sliding windowpanes made from capiz shells


Capiz shells industry (Samal, Bataan Town Hall).

These oysters are edible, but valued more for the shells, which are used as a raw material in the manufacture of glue, chalk, varnish, etc. The translucent capiz shells are commonly used in window panes in the Philippines, India, and other Asian countries, as they are a cheaper alternative to glass and readily abundant. Windowpane oysters are also commercially exploited pearl producers.[2]

The primary exporter of products made from the shellfish is the Philippines,[2] where it is known locally as kapis, and is used in the manufacture of decorative items such as chandeliers and lampshades, and kitchen utensils such as mats, trays, and bowls.[2][4]

A Filipino Christmas lantern called parol made from melded capiz shells

Kapis is also one of the many materials used to make lighted versions of the beloved parol, an indispensable feature of Christmas in the Philippines. The shell is dyed, cut, and set like stained glass into designs as simple as the one in the photo to larger, more complicated starbursts.


  1. ^ "Capiz". MSN Encarta U.S. English Dictionary. Retrieved on 2011-10-23.
  2. ^ a b c d e f "Fisheries and aquaculture of window-pane shells". Malacological Society of London. Retrieved on 2011-10-23.
  3. ^ "Bivalves". Retrieved on 2011-10-24.
  4. ^ "Placuna placenta". Encyclopædia Britannica Online. Retrieved on 2011-10-23.