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You are here:   animal list > Pinctada margaritifera




Pinctada margaritifera

Black lipped pearl oyster

Megan Van Dyk (2011)




Fact Sheet


Brief Summary

Comprehensive Description


Physical Description

Identification Resources


Disease and Predation


Environmental Factors

Reproduction and Development

Sexual Morphology and Physiology

Spawning Seasonality

Larval Development

Evolution & Systematics

Fossil History


Morphology and Physiology

External Form and Function

Internal Anatomy and Function



Feeding Rate

Respiration and Gas Exchange

Molecular Biology & Genetics

Molecular Biology

Nucleotide Sequence

Pearl Aquaculture

Economics and Pearl Farming

Pearl Production and Formation


References & More Information

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Biomedical Terms

Names & Taxonomy

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Content Summary

Sexual Morphology and Physiology

Pinctada margaritifera are protrandrous hermaphrodites with the ratio of males to females tending to 1:1 with increasing age.  Both male to female and female to male sex changes can occasionally be seen in gonad sections where hermaphroditic phases are transitional and not functional. Change in sex can occur in all members of the genus after male maturity has been reached within the second year. No differences in shell morphology are associated with a change in sex. Gonad coloration distinguishes sex with ovaries being pinkish, creamy or yellow and granular (Tranter 1958). Testes are white and smooth (Reed 1966). The gonad is not a discrete organ but is found between the connective tissue at the base of the foot and the intestinal loop. As ripening gonads increase in size, follicles and germ cells extend through the connective tissue, filling the cavity between the foot and the byssal gland, around the retractor muscle and digestive tract. A ripe individual is identifiable superficially by the size of the gonad and microscopically by the abundant gametes and fewer germ cells in the follicles.

Spawning results from muscular contractions and oocytes are activated immediately prior to spawning in the follicle (Tranter 1958). Sperm and eggs are released into the water where fertilization takes place.

The overall pattern of reproduction in pearl oyster populations is synchronous, with male and females undergoing sequential processes that lead to a simultaneous breeding period. This is a cyclical process with three general phases:

1. Vegetative phase, during which the oysters display no evidence of sexual activity.

2. Cellular differentiation phase, during which the proliferation and differentiation of stem cells lead to mature gametes and spawning.

3. Recovery phase, during which there is degeneration of the gonad after spawning and recovery of nutrients from unspawned gametes for recycling.