Uses by humans Mollusca

molluscs, bivalves such clams , mussels, have been important food source since @ least advent of anatomically modern humans, , has resulted in overfishing. other commonly eaten molluscs include octopuses , squids, whelks, oysters, , scallops. in 2005, china accounted 80% of global mollusc catch, netting 11,000,000 tonnes (11,000,000 long tons; 12,000,000 short tons). within europe, france remained industry leader. countries regulate importation , handling of molluscs , other seafood, minimize poison risk toxins can accumulate in animals.

saltwater pearl oyster farm in seram, indonesia

most molluscs shells can produce pearls, pearls of bivalves , gastropods, shells lined nacre, valuable. best natural pearls produced marine pearl oysters, pinctada margaritifera , pinctada mertensi, live in tropical , subtropical waters of pacific ocean. natural pearls form when small foreign object gets stuck between mantle , shell.

the 2 methods of culturing pearls insert either seeds or beads oysters. seed method uses grains of ground shell freshwater mussels, , overharvesting purpose has endangered several freshwater mussel species in southeastern united states. pearl industry important in areas, significant sums of money spent on monitoring health of farmed molluscs.

byzantine emperor justinian clad in tyrian purple , wearing numerous pearls

other luxury , high-status products made molluscs. tyrian purple, made ink glands of murex shells, ... fetched weight in silver in fourth century bc, according theopompus. discovery of large numbers of murex shells on crete suggests minoans may have pioneered extraction of imperial purple during middle minoan period in 20th–18th centuries bc, centuries before tyrians. sea silk fine, rare, , valuable fabric produced long silky threads (byssus) secreted several bivalve molluscs, particularly pinna nobilis, attach sea bed. procopius, writing on persian wars circa 550 ce, stated 5 hereditary satraps (governors) of armenia received insignia roman emperor given chlamys (or cloaks) made lana pinna. apparently, ruling classes allowed wear these chlamys.

mollusc shells, including of cowries, used kind of money (shell money) in several preindustrial societies. however, these currencies differed in important ways standardized government-backed , -controlled money familiar industrial societies. shell currencies not used commercial transactions, social status displays @ important occasions, such weddings. when used commercial transactions, functioned commodity money, tradable commodity value differed place place, result of difficulties in transport, , vulnerable incurable inflation if more efficient transport or goldrush behavior appeared.

bioindicators

bivalve molluscs used bioindicators monitor health of aquatic environments in both fresh water , marine environments. population status or structure, physiology, behaviour or level of contamination elements or compounds can indicate state of contamination status of ecosystem. particularly useful since sessile representative of environment sampled or placed. potamopyrgus antipodarum used water treatment plants test estrogen-mimicking pollutants industrial agriculture.