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Pinctada albina
(Lamarck, 1819)

Shark Bay Shell

Nicholai Cushing (2014)

 

 

Fact Sheet

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Summary


Physical Description


Ecology


Life History & Behaviour


Anatomy & Physiology


Evolution & Systematics


Biogeographic Distribution


Conservation & Threats


References & Links

Physical Description

Exterior appearance

Pinctada albina, as a Bivalve, has a soft body enclosed by two external calcareous valves (shells) of similar or equal size (Ruppert et al., 2004). It may be easily mistaken as a juvenile when compared to other oyster species as the shells grow to a maximum diameter of approximately 100mm (10cm) (Pearl Guide, 2011). The exterior of the shells are usually of a grayish-green coloration. Indistinct radial bands of a brownish-green colour may be seen on the exterior of the shell, but because the animal is a sessile species many other organisms also grow on the shell and can make many of the features hard to distinguish.


​Exterior of specimen. Shells are often covered with algae, barnacles and other organisms making the external shell feature difficult to identify. Darker bands are visible radiating from the lower edge of the shell.


Oysters are usually found in colonies and are attached to the substrate by a filamentous structure called a byssus (Ruppert et al., 2004). This is excreted by the byssal gland on the inside of the shell and protrudes through a small opening near the hinge ligament (Southgate and Lucas, 2008). The byssal/pedal retractor muscles can be used to pull the byssus back into the shell so that the oyster may move with the aid of the muscular foot (Southgate and Lucas, 2008).

   
Byssus protruding from the shell of a Black-lip oyster (Pinctada margaritifera) (left). The byssus appears as the blue-ish gray threads. ​Body of P. albina removed from the shell in preparation for sectioning and staining (right). The byssus is clearly visible with the byssal gland and retractor muscles located at the attachment to the visceral mass. Other key sections of the body are hard to distinguish in this form.

P. albina, as with all bivalves, has a hinged shell pivoting on the flatter dorsal surface (Ruppert et al., 2004, Southgate & Lucas, 2008). This hinge is made of a tough elastic ligament so that without the powerful adductor muscle within the shell the soft body of the animal would be exposed (Levine et al., 2008, Southgate & Lucas, 2008). This is why shells of oysters, pipis and other bivalves often form a butterfly shape when the animal has died and the shells wash up on beaches.


"Is it a Shark's Bay Shell?" - Identification Checklist

This is a basic checklist of easily identifiable characteristics in order to help identify if the organism is a Pinctada albina. The organism should have the majority of the following characteristics in order to be considered as possibly a Shark's Bay Shell. Characteristics from various sources (Gosling, 2007, Pearl Guide, 2011, Ruppert et al., 2004, Southgate & Lucas, 2008)
  • Soft mantle and body tissues
  • Hard exterior shells of equal size
  • Shells a grayish-green colour (may need to be cleaned) with radiating brown bands
  • Small size no greater than approximately 10cm
  • Byssus (may be inside shell)
  • Soft organs internal of the two shells
  • Opens shells slightly whilst feeding
  • Hinge at back of the two shells
  • Thin and flakey toward the edges of the shells
  • "Layered" appearance to the outside of the shells
Further identifiable characteristics are mainly associated with the internal anatomy, breeding cycles and gene sequence of the oysters and therefore difficult to determine through basic external observations.

Classification

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Kingdom
Animalia
Phylum
Mollusca
Class
Bivalvia
Order
Ostreida
Superfamily
Pterioidea
Family
Pteriidae
Genus
Pinctada

Synonyms

Avicula anomioides (Reeve, 1857)
Avicula atropurpurea (Dunker, 1852)
Avicula concinna (Dunker, 1872)
Avicula fimbriata (Reeve, 1857)
Avicula flexuosa (Reeve, 1957)
Avicula imbricata (Reeve, 1857 [non Pinctada imbricata Röding, 1798])
Avicula irradians (Reeve, 1857)
Avicula placunoides (Reeve, 1857)
Avicula radula (Reeve, 1857)
Avicula reentsii (Dunker, 1872)
Avicula reeveana (Dunker, 1872)
Avicula scheepmakeri (Dunker, 1872)
Avicula sugillata (Reeve, 1857)
Avicula tristis (Dunker, 1872)
Meleagrina albina (Lamarck, 1819)
Pinctada atropurpurea ((Dunker, 1852))
Pinctada perrutila (Iredale, 1939)
Pteria carchariarum (Jameson, 1901)
Pteria placunoides ()

Common Names

モスソアコヤ