Mollusca

Mollusca is a large phylum of invertebrate animals whose members are known as molluscs or mollusks ( ). Around 85,000 extant species of molluscs are recognized. The number of fossil species is estimated between 60,000 and 100,000 additional species.

Characteristics

Molluscs are the largest marine phylum, comprising about 23% of all the named marine organisms. Numerous molluscs also live in freshwater and terrestrial habitats. They are highly diverse, not just in size and in anatomical structure, but also in behaviour and in habitat. The phylum is typically divided into 9 or 10 taxonomic classes, of which two are entirely extinct.

Anatomy

Molluscs are characterized by a special type of coelom, a mantle, a radula, and a foot. The coelom is reduced to a small space surrounding the heart in adult molluscs. The mantle is a fold of the outer skin or epidermis, and it encloses the mantle cavity. The radula is a feeding organ, and the foot is used for locomotion.

Classification

The classification of molluscs has been subject to considerable revision. The system used here is the current system preferred by the Conchologists of America, which is based on the work of Winston Ponder and David Lindberg.

Ecology

Molluscs play important roles in the ecology of many environments. They are both prey and predator, and they are significant to the human economy.

Human interaction

Molluscs have been used by humans for food, tools, and as symbols and currency. They are also the cause of significant human diseases.

See also

• List of mollusc orders
• Mollusc shell
• Molluscicide

References

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External links

• Molluscs at The Living World of Molluscs
• Mollusca at University of California Museum of Paleontology