Dew, Johnny (2012) Mollusca (animal phylum). White Word Publications, Delhi, India. ISBN 9788132341895
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Abstract
The Mollusca, common name molluses or mollusks, is a large phylum of invertebrate animals. There are around 85,000 recognized extant species of molluscs. This is the largest marine phylum, comprising about 23% of all the named marine organisms. Numerous molluscs also live in freshwater and terrestrial habitats. Molluscs are highly diverse, not only in size and in anatomical structure, but also in behavior and in habitat. The phylum Mollusca is typically divided into nine or ten taxonomic classes, of which two are extinct. The gastropods (snails and slugs) include by far the most classified species, accounting for 80% of the total. Cephalopod mollusks such as squid, cuttlefish and octopus are among the most neurologically advanced invertebrates. Either the giant squid or the colossal squid is the largest known species of animal without a backbone. The two most universal features of the body structure of molluscs are a mantle with a significant cavity used for breathing and excretion, and the organization of the nervous system. Because of the great range of anatomical diversity, many textbooks base their not all classes within the Mollusca. descriptions on a hypothetical "generalized mollusc", with features common to many but there is good evidence for the appearance of gastropods, cephalopods and bivalves in the Cambrian period 542 to 488 3 million years ago. However, the evolutionary history both of the emergence of mollusks from the ancestral group Lophotrochozoa, and of their diversification into the well-known living and fossil forms, is still vigorously debated. The most abundant metallic element in molluscs is calcium. Mollusks have for many centuries been the source of important luxury goods, notably pearls, mother of pearl, Tyrian purple dye, and sea silk. Their shells have also been used as money in some pre-industrial societies. There is a risk of food poisoning from toxins that accumulate in molluscs under certain conditions, and many countries have regulations that aim to minimize this risk.
| Item Type: | Book |
|---|---|
| Subjects: | S Agriculture > SF Animal culture |
| Divisions: | Electronic Books |
| Depositing User: | Esam @ Hisham Muhammad |
| Date Deposited: | 02 Jan 2023 02:02 |
| Last Modified: | 18 Apr 2023 02:19 |
| URI: | http://odlsystem2.utm.my/id/eprint/3860 |
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