Overview
Brief Summary
Historical importance
Ecology
Local Distribution and Habitats
Biogeographical Distribution
Life History
Behaviour
Cyclicity
Evolution & Systematics
Systematics or Phylogenetics
Morphology and Physiology
External Morphology
Anatomy
Conservation
Threats
Wikipedia
References & More Information
Bibliographies | Cyclicity
The life history of cowries can be split into three stages: the first being the juvenile larva stage where shell volume increases, secondly the callus-building bulla stage whereby the shell is thickened and lastly the adult stage where no further growth occurs and sexual maturity is reached (Irie & Iwasa 2003, Burgess 1986).
Reproduction and Growth
In cowries, the sexes are seperate and they practice copulation (Burgess 1986, Walls 1987). Fertilisation is internal and subsequently the female deposits her eggs which are embedded in a circular gelatinous mass. The mother will then brood the egg mass for up to four weeks and after a period of approximately 14 days the eggs will rupture and larvae are released (Wilson 1985, Renaud 1971). Depending on the species, the veliger is planktotrophic and will then spend some time in the water column before settling to the bottom where a new shell whorl is secreted and they transform into an olivoform ("bulla" stage) (Wilson 1985). This juvenile stage possess a thin shell , which grows by addition of new shell material by the outer lip. Generally, the sex of the animal is related to shell size and female cowries have been shown to be larger than males in majority of species (Burgess 1986). |
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