(redirected from Crassostrea)
Also found in: Dictionary, Thesaurus, Wikipedia.


(invertebrate zoology)
A family of bivalve mollusks in the order Anisomyaria containing the oysters.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



(oysters), a family of bivalve mollusks comprising approximately 25 genera. Oysters vary in size; individuals of some species may attain a height of 45 cm, for example, Crassostrea gigas. The shell may be rounded, triangular, or elongate and wedge-shaped. The left (lower) valve, which concresces to a solid substrate, is the more convex of the two. The surface of the shell usually consists of concentric, raised thickened plates and sometimes radial ribs or folds. The hinge has no teeth. The valves are joined by an internal ligament, and a single adductor muscle passes through the central part of the body. The intestine does not penetrate the pericardium. The foot and byssus gland are reduced, owing to the concrescence of the mollusk to the substrate.

Oysters are filter feeders; an individual of the species Ostrea edulis can filter 1–3 liters of water per hour, depending on the temperature. Oysters may be dioecious or hermaphroditic. Large individuals produce several million eggs. The larvae are plank-tonic for ten to 15 days. They then attach themselves to a substrate and are referred to as spat. Most species are distributed in tropical and subtropical seas. In temperate waters they are found only where the summer temperature of the water attains 16°C, a necessary condition for reproduction. Oysters live betweeen tidal levels and in littoral shallows; however, some species are found at depths to 60 m. A number of species form solid banks, for example, Ostrea edulis in the Black Sea and Crassostrea gigas in the southern part of the Sea of Japan. Many species can tolerate severe desalination. The principal enemies of oysters are some species of starfishes, gastropod mollusks, and boring sponges.

Some species, including O. edulis, C. gigas, and C. virginica, have commercial importance. They are eaten fresh (live) and canned. The average composition of the flesh is 11 percent proteins, 2 percent fats, 6 percent carbohydrates, 3 percent ash, and 78 percent water. Oyster flesh also contains vitamin C and B-group vitamins. In European countries, the USA, Japan, and other countries, oysters are raised on farms. In France the annual harvest exceeds 1 billion. In the USSR there are large reserves of oysters in the Black Sea and the Sea of Japan.


Rukovodstvo po zoologii, vol. 2. Moscow-Leningrad, 1940.
Razin, A. I. “Morskie promyslovye molliuski Iuzhnogo Primor’ia.” Izv. Tikhookeanskogo n.-i. in-ta rybnogo khoziaistva i okeanografii, 1934, vol. 8.
Gonge, C. M. Oysters. London, 1960.
Treatise on Invertebrate Paleontology, part 6: “Mollusca.” (Bivalvia, vol. 3.) [Kansas City, Mo.] 1971.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
Mentioned in ?
References in periodicals archive ?
Phylogenetic analysis of the sequences using the EzBiocloud classifier identified 14 phyla present in the Crassostrea gigas larvae and spat samples (Acidobacteria, Actinobacteria, Bacteroidetes, Calditrichaeota, Chlamydiae, Chloroflexi, Chlorobi, Cyanobacteria, Firmicutes, Parcubacteria, Peregrinibacteria, Planctomycetes, Proteobacteria, and TM6).
Marine mollusks, such the oyster Crassostrea virginica (Gmelin, 1791) have been used worldwide as bioindicators to assess the impact of pollutants in coastal lagoons ecosystems.
Other species that display a semicontinuous spawning pattern include Crassostrea rhizophorae in Venezuela (Angell 1986), Saccostrea echinata in the Philippines (Lopez & Gomez 1982), Crassostrea madrasensis in India (Nair & Nair 1987), Crassostrea iredalei in Malaysia (Teh et al.
rhizophorae in Venezuela, recorded amounts oscillating from 0.004 to 0.149 spats [cm.sup.-2] and by GARDUNHO et al.(2012), in Para State, who observed that the average density of spats of a non-identified oyster (Crassostrea sp.) varied from (0.16 a 0.75) and (0.074 to 1.64) spats [cm.sup.-2] in collectors made of half and whole PET bottles respectively.
In other related studies, the Pacific oysters (Crassostrea gigas) were collected seasonally from regions historically associated with V.
The site is significant because the bluff is home to the large oyster, Crassostrea gigantissima.
Diploid ("wild-type") and triploid larvae of Crassostrea gigas were cultured at a commercial shellfish hatchery (Taylor Shellfish Farms, Quilcene, WA).
In August and September 2011, 450 specimens of Crassostrea rhizophorae were collected from the roots of the red mangrove (Rhizophora mangle) of three estuaries in Northeast Brazil: the Jaguaribe river (04[degrees] 27' 39,21" S, 37[degrees]47'31,68"W) in Ceara (n = 150), the Camurupim river (02[degrees]54'51"S, 041[degrees]24'58,2"W) in Piaui (n =150), and the Carnaubeiras river (02[degrees] 50'0,08"S, 041[degrees]57'36,5"W) in Maranhao (n =150).