Association with vessel vectors

Actual evidence of being found in samples in a particular vector from any world region.

Anchor and anchor chains. Organisms found on anchors, anchor chain or within attached sediments, including anchor chain lockers.

Ballast water. Ballast water means water with its suspended matter taken on board a ship to control trim, list, draught, stability or stresses of the ship.

Biofouling. Biofouling means the accumulation of aquatic organisms such as micro-organisms, plants, and animals on surfaces and structures immersed in or exposed to the aquatic environment. Biofouling can include microfouling and macrofouling.

  • Macrofouling means large, distinct multicellular organisms visible to the human eye such as barnacles, tubeworms, or fronds of algae.
  • Microfouling means microscopic organisms including bacteria and diatoms and the slimy substances that they produce.
Biofouling comprised of only microfouling is commonly referred to as a slime layer.

Sea chest. The sea chests are cavities (an opening with protection grid) at the bottom side of the ships’ hull (an opening for pumping in and out water for, e.g., ballasting, firefighting) where aquatic organisms may settle and be transported.

Tank sediments. Matter settled out of ballast water within a ship.

Bioaccumulation association

Natural toxins. An organism that accumulates toxins naturally produced by other organisms, such as phytotoxins, in its tissues.

Anthropogenic chemical compounds. An organism that accumulates human-produced chemicals, such as pharmaceuticals, heavy metals, pesticides, dioxins, in its tissues.

Characteristic feeding method

Chemoautotroph. An organism that obtains metabolic energy by oxidation of inorganic substrates such as sulphur, nitrogen or iron.

Deposit feeder – Subsurface. Synonym: detritivore. An organism feeding on fragmented particulate organic matter in the substratum.

Deposit feeder – Surface. Synonym: detritivore. An organism feeding on fragmented particulate organic matter from the surface of the substratum.

Grazer. An organism feeding on plants (higher aquatic plants, benthic algae and phytoplankton) and/or sessile animals organisms.

Herbivore. An organism feeding on plants (higher aquatic plants, benthic algae and phytoplankton).

Mixotroph. An organism both autotrophic and heterotrophic.

Omnivore. An organism feeding on mixed diet of plant and animal material.

Parasite. Feeding on the tissues, blood or other substances of a host.

Photoautotroph. An organism that obtains metabolic energy from light by photosynthesis (e.g. seaweeds, phytoplankton).

Planktotroph. An organism feeding on plankton.

Predator. An organism that feeds by preying on other organisms, killing them for food.

Scavenger. An organism feeding on dead and decaying organic material.

Suspension feeder – Active. An organism feeding on particulate organic matter, including plankton, suspended in the water column, collecting it actively by sweeping or pumping (creating feeding currents).

Suspension feeder – Passive. An organism feeding on particulate organic matter, including plankton, suspended in the water column, utilizing the natural flow to bring particles in contact with feeding structures.

Symbiont contribution. Where some dietary component(s) are provided by symbiotic organisms (e.g. Anemonia with zooxanthellae).

Developmental trait

Brooding. The incubation of eggs either inside or outside the body. Eggs may be brooded to a variety of developmental stages. Males or females may be responsible for brooding.

Direct development. A life cycle lacking a larval stage.

Spawning. The release of gametes into the water.

Lecithotrophy. Development at the expense of internal resources (i.e. yolk) provided by the female.

Parental care. Any form of parental behaviour that is likely to increase the fitness of offspring.

Planktotrophy. Feeding on plankton.

Resting stages. The quiescent stage in the life cycle (dormancy, diapause).

Viviparous. Producing live offspring from within parental body.

Habitat modifying ability potential

Autogenic ecosystem engineers. Organisms which change the environment via their own physical structures (i.e. their living and dead tissues) such as corals, oysters, kelps, sea grasses, etc.

Allogenic ecosystem engineers. Organisms which modify the environment by causing physical state changes in biotic and abiotic materials that, directly or indirectly, modulate the availability of resources to other species (e.g. excavating deep burrows which other organisms co-occupy, damming the water flow, etc).

Keystone species. A keystone species is crucial in maintaining the organization and diversity of its ecological community, by determining the types and numbers of other species.

Life form

Neuston. Organisms that live on (epineuston) or under (hyponeuston) the surface film of water bodies.

Zoobenthos. Animals living on or in the seabed.

Phytobenthos. Algae and higher plants living on or in the seabed.

Zooplankton. Animals living in the water column, unable to maintain their position independent of water movements.

Phytoplankton. Microscopic plankton algae and cyanobacteria.

Benthopelagos. Synonyms: hyperbenthic, benthopelagic, nektobenthic, demersal. An organism living at, in or near the bottom of the sea, but having the ability to swim.

Nekton. Actively swimming aquatic organisms able to move independently of water currents.

Parasite. An organism intimately associated with and metabolically dependent on another living organism (host) for completion of its life cycle.

Symbiont (nonparasitic). An organism living mutually with another species without harming it. Association of two species (symbionts) may be mutually beneficial.


Boring. An organism capable of penetrating a solid substrate by mechanical scraping or chemical dissolution.

Burrowing. An organism capable of digging in sediment.

Crawling. An organism moving slowly along on the substrate.

Drifting. An organism whose movement is dependent on wind or water currents.

Permanent attachment. Non-motile; permanently attached at the base. Also includes permanent attachment to a host.

Swimming. An organism capable of moving through the water by means of fins, limbs or appendages.

Temporary attachment. Temporary / sporadic attachment. Attached to a substratum but capable of movement across (or through) it (e.g. Actinia). Also includes temporary attachment to a host.

Native origin

The region the species originates from.


References should follow the standard of Biological invasions:

Journal article
Gamelin FX, Baquet G, Berthoin S, Thevenet D, Nourry C, Nottin S, Bosquet L (2009) Effect of high intensity intermittent training on heart rate variability in prepubescent children. Eur J Appl Physiol 105:731-738. doi: 10.1007/s00421-008-0955-8
Ideally, the names of all authors should be provided, but the usage of “et al” in long author lists will also be accepted:
Smith J, Jones M Jr, Houghton L et al (1999) Future of health insurance. N Engl J Med 965:325–329

Article by DOI

Slifka MK, Whitton JL (2000) Clinical implications of dysregulated cytokine production. J Mol Med. doi:10.1007/s001090000086

South J, Blass B (2001) The future of modern genomics. Blackwell, London

Book chapter
Brown B, Aaron M (2001) The politics of nature. In: Smith J (ed) The rise of modern genomics, 3rd edn. Wiley, New York, pp 230-257

Online document
Cartwright J (2007) Big stars have weather too. IOP Publishing PhysicsWeb. Accessed 26 June 2007

Trent JW (1975) Experimental acute renal failure. Dissertation, University of California

Reproductive frequency

Iteroparous. Organisms breeding more than once in their lifetime.

Semelparous. Organisms breeding once in their lifetime.

Reproductive type

Asexual. Budding, Fission, Fragmentaion, including parthenogenesis. A form of asexual multiplication in which:
a) a new individual begins life as an outgrowth from the body of the parent. It may then separate to lead an independent existence or remain connected or otherwise associated to form a colonial organism;
b) the ovum develops into a new individual without fertilization;
c) division of the body into two or more parts each or all of which can grow into new individuals is involved.

Self-fertilization. Selfing or autogamy. The union of a male and female gamete produced by the same individual.

Sexual. Permanent hermaphrodite, Protandrous hermaphrodite, Protogynous hermaphrodite, Gonochoristic.
Capable of producing both ova and spermatozoa either at the same time. A condition of hermaphroditism in plants and animals where male gametes mature and are shed before female gametes mature or vice versa.
Having separate sexes.


The exact salinity range if known (psu), else salinity zone(s) according to the Venice system:
1. Limnetic [<0.5psu]
2. β-Oligohaline [0.5-3psu]
3. α-Oligohaline [3-5psu]
4. β-Mesohaline [5-10psu]
5. α-Mesohaline [10-18psu]
6. Polymixohaline [18-30psu]
7. Euhaline [30-40psu]
8. Hypersaline [>40psu]


Colonial. Descriptive of organisms produced asexually which remain associated with each other; in many animals, retaining tissue contact with other polyps or zooids as a result of incomplete budding.

Gregarious. Organisms living in groups or communities, growing in clusters.

Solitary. Living alone, not gregarious.

Sub-species level

A geographical subset of a species showing discrete differences in morphology, coloration or other features when compared with other members of the species. Subspecies may also differ in their habitat or behavior, but they can interbreed. Often the lowest taxonomic level within a classification system.


Valid synonyms of a species (not all of them).


Poisonous. An organism capable of producing poison that gains entry to another organism body via the gastrointestinal tract, the respiratory tract, or via absorption through intact body layers.

Venomous. An organism capable of producing poison, usually injected through another organism intact skin by bite or sting.

Not relevant. Neither poisonous nor venomous.

Public domain: Species account

Species Magallana gigas [WoRMS]
Authority (Thunberg, 1793)
Family Ostreidae  
Order Ostreida  
Class Bivalvia  
Phylum Mollusca  
Synonym (?) Crassostrea angulata (Lamarck, 1819)
Crassostrea gigas (Thunberg, 1793)
Gryphaea angulata (Lamarck, 1819)
Ostrea gigas (Thunberg, 1793)
Ostrea laperousii (Schrenk,1861)
Ostrea talienwhanensis (Crosse, 1862)

References (not structured):
Boudry, P, Heurtebise S, Collet B, Cornette F, Gérard A (1998) Differentiation between populations of the Portuguese oyster Crassostrea angulata (Lamarck) and the Pacific oyster Crassostrea gigas (Thunberg) revealed by mtDNA RFLP analysis. Journal of Experimental Marine Biology and Ecology, 226(2): 279–291.
Buroker NE, Hershberger WS, Chew KK (1979) Population genetics of the family Ostreidae. I. Intraspecific studies of Crassostrea gigas and Saccostrea commercialis. Marine Biology, 54: 157 – 169
Crassostrea gigas FAO Factsheet: Accessed 19/11/2011
Huvet A, Lapegue S, et al (2000) "Mitochondrial and nuclear DNA phylogeography of Crassostrea angulata, the Portuguese oyster endangered in Europe." Conservation Genetics 1(3): 251-262
Huvet A, Balabaud K, Bierne N, Boudry P (2001) Microsatellite analysis of 6‐hour‐old embryos reveals no preferential intra‐specific fertilization between cupped oysters Crassostrea gigas and Crassostrea angulata. Marine Biotechnology, 3: 448 – 453
Huvet A, Gérard A, Ledu C, Phélipot P, Heurtebise S, Boudry P (2002) Is fertility of hybrids enough to conclude that the oysters Crassostrea gigas and Crassostrea angulata are the same species? Aquatic Living Resources, 15: 45 – 52
Leitao A, Chaves R, Santos S, Guedes‐Pinto H, Boudry P (2004) Restriction enzyme digestion chromosome banding confirms Crassostrea angulata × Crassostrea gigas F1 hybrids. Journal of Experimental Marine Biology and Ecology, 343: 253 – 260
Lopez‐Flores I, Hérran R, Garrido‐Ramos MA, Boudry P, Ruiz‐Rejón C, Ruiz‐Rejón M (2004) The molecular phylogeny of oysters based on a satellite DNA related to transposons. Genes, 339: 181 – 188
Mathers NF, Wilkins N P, et al. (1974)"Phosphoglucose isomerase and esterase phenotypes in Crassostrea angulata and C. gigas." Biochemical Systematics and Ecology 2(2): 93-96.
Menzel R (1974) "Portuguese and Japanese oysters are the same species." Journal of the Fisheries Board of Canada 31(4): 453-456
Miossec L, Le Deuff RM, Goulletquer, P (2009) Alien species alert: Crassostrea gigas (Pacific oyster). ICES Cooperative Research Report No. 299. 42 pp
Nehring S (2006): NOBANIS – Invasive Alien Species Fact Sheet – Crassostrea gigas. – From: Online Database of the North European and Baltic Network on Invasive Alien Species - NOBANIS, Access 21/11/2011
Reece KS, Cordes JF, Stubbs JB, Hudson KL, Francis EA (2008) Molecular phylogenies help resolve taxonomic confusion with Asian Crassostrea oyster species. Marine Biology, 153: 709 – 721

Whether C. gigas and C. angulata are the same species is a source of controversy (Miossec et al., 2009). Morphological, physiological and allozymic similarities support this theory alongside fertility of hybrids (Huvet et al., 2002) and some mitochondrial DNA analyses (Lopez‐Flores et al., 2004; Reece et al., 2008), however, small genetic differences also appear in mitochondrial DNA (Boudry et al., 1998; Huvet et al., 2000) and karotype (Leitao et al., 2004) analyses, proposing that the populations are genetically distant .
The two taxa have also been considered as subspecies (Menzel, 1974) with the Portuguese oyster (C. angulata) being introduced in the 16th Century and also being of Japanese origin (Boudry et al., 1998; Huvet et al., 2000).
Sub-species level (?) Crassostrea angulata
Native origin (?) Country: Japan
Country: Korea, Democratic Peoples Republic of

References (not structured):
Miossec L, Le Deuff R M, Goulletquer P. Alien species alert: Crassostrea gigas (Pacific oyster)[J]. ICES Cooperative Research Report, 2009, 299.

Shell middens of C.gigas were found in two regions: 1) Peter the Great Gulf, northwestern Sea of Japan coast, and 2) eastern coast of the Kunashir Island, an open Pacific Ocean shore.

China is known to have the biggest aquaculture production of C.gigas in the world.
Life form / Life stage (?)
 AdultJuvenileLarvaeEggsResting stage
Symbiont (non parasitic)

References (not structured):
Dridi S, Romdhane MS et al (2006) Evidence of Crassostrea gigas reproduction in the Bizert lagoon, Tunisia. Journal of Biological Research 5: 35-45

Juvenile C.gigas (spat)are often collected from the wild and can then be cultured or shipped to another country for aquaculture; the main pathway for introductions.
The resting phase is from November to January; the only period where gametogenesis does not occur.
Sociability / Life stage (?)
 AdultJuvenileLarvaeEggsResting stage

References (not structured):
Karin T (2009) PACIFIC OYSTERS IN DUTCH ESTUARIES. Belgium, 27 November 2009: VLIZ Special Publication, 43. Vlaams Instituut voor de Zee (VLIZ): Oostende, Belgium. xiii+ 221 pp

Miossec, L., R. M. Le Deuff, et al. (2009). "Alien species alert: Crassostrea gigas (Pacific oyster)." ICES Cooperative Research Report 299.

Nehring S (2006) NOBANIS – Invasive Alien Species Fact Sheet – Crassostrea gigas. – From: Online Database of the North European and Baltic Network on Invasive Alien Species - NOBANIS, Access 20/11/2011

Larvae and eggs are free-living, except when larvae settle and become highly gregarious, preferring to settle on oyster shells or in areas where other individuals are present.
Reproductive frequency (?) Iteroparous

References (not structured):
Dridi S, Romdhane MS et al (2006) Evidence of Crassostrea gigas reproduction in the Bizert lagoon, Tunisia. Journal of Biological Research 5: 35-45

Gametogenesis occurs all year round except during the resting phase from November to January.
Reproductive type (?) Sexual

Miossec L, Le Deuff RM et al (2009)Alien species alert: Crassostrea gigas (Pacific oyster). ICES Cooperative Research Report 299

C. gigas usually changed sexes during its life cycle, typically spawning first as a male and then as a female. Gametogenesis is induced at around 12° C depending on duration (degree days). At least 18 ‒ 20 ° C are needed for spawning. Fecundity is high; with females producing 20 ‒ 100 million eggs per spawn and fertilization takes place in the water column.
Developmental trait (?) Planktotrophy

Miossec L, Le Deuff RM et al (2009)Alien species alert: Crassostrea gigas (Pacific oyster).ICES Cooperative Research Report 299

C.gigas is oviparous and a free-spawner, with fertilization occurs within the water column.
Characteristic feeding method / Life stage (?)
 AdultJuvenileLarvaeEggsResting stage
Suspension feeder – ActiveXX
Suspension feeder – Passive
Deposit feeder – SurfaceXX
Deposit feeder – Sub-surface
Symbiont contribution

References (not structured):
Crisp D, Yule A et al (1985)Feeding by oyster larvae: The functional response, energy budget and a comparison with mussel larvae. Journal of the Marine Biological Association of the United Kingdom. Plymouth 65(3): 759-783

Pauley, G.B., B. Van Der Raay & D. Troutt., 1988. Species profiles: life histories and environmental requirements of coastal fishes and invertebrates (Pacific Northwest) Pacific oyster. U.S. Fish and Wildl. Serv. Biol. Rep. 82 (11.85). U.S. Army Corps of Engineers, TR EL-82.4 28 pp.

National Introduced Marine Pest Information System (NIMPIS), 2002. Crassostrea gigas species summary. National Introduced Marine Pest Information System (Eds: Hewitt C.L., Martin R.B., Sliwa C., McEnnulty, F.R., Murphy, N.E., Jones T. & Cooper, S.). (Web publication)

Karin T (2009) PACIFIC OYSTERS IN DUTCH ESTUARIES. Belgium, 27 November 2009: VLIZ Special Publication, 43. Vlaams Instituut voor de Zee (VLIZ): Oostende, Belgium. xiii+ 221 pp

Planktonic larvae feed on a variety of micro-algae in the water column and are partially selective by size via the gills.

Adults ingest bacteria, protozoa, a wide variety of diatoms, larval forms of other invertebrate animals, and detritus.
Mobility / Life stage (?)
 AdultJuvenileLarvaeEggsResting stage
Temporary attachment
Permanent attachmentXX

References (not structured):
Miossec L, Le Deuff RM et al (2009)Alien species alert: Crassostrea gigas (Pacific oyster).ICES Cooperative Research Report 299

Most of life cycle is spent as a sessile benthic organism, however gametes are released into the water and the larvae are free-living until settlement.
Salinity tolerance range (?) Exact range: 10 - 34

Hsieh H.L., Kao W.Y., Chen C.P., Liu P.J., 2000. Detrital flows through the feeding pathway of the oyster (Crassostrea gigas) in tropical shallow lagoon: δ13C signals. Marine Biology 136:677-684
Habitat modifying ability potential (?) Keystone species

Cocito S (2004) Bioconstruction and biodiversity: their mutual influence. Scientia Marina 68(S1): 137-144
Guo X, Wang Y et al(2008) Oysters. Genome Mapping and Genomics in Fishes and Aquatic Animals: 163-175
Gutiérrez JL, Jones CG et al (2003) Mollusks as ecosystem engineers: the role of shell production in aquatic habitats. Oikos 101(1): 79-90
Miossec L, Le Deuff RM et al (2009) Alien species alert: Crassostrea gigas (Pacific oyster). ICES Cooperative Research Report 299
Tagliapietra D, Sigovini M Biological diversity and habitat diversity: a matter of Science and perception.

Ecosystem engineer
Perennial habitat former (Anna)

Form oyster reefs and can overgrow any other benthic organisms such as the blue mussel, Mytilus edulis. Some believe this to offer suitable habitats for other organisms and food resources however, some claim them to reduce biodiversity.
Toxicity / Life stage (?) Not entered
Bioaccumulation association (?) Not entered
Association with vessel vectors (?) Anchor and anchor chains
Ballast waters

Eno, N. C., A. Robin, and C.W.G. Sanderson. 1997. Non-native marine species in British waters: a review and directory. Joint Nature Conservation Committee Monkstone House, City Road Peterborough PE1 1JY UK.

Gollasch S, Macdonald E, Belson S, Botnen H, Christensen JT, Hamer JP, Houvenaghel G, Jelmert A, Lucas I, Masson D, McCollin T, Olenin S, Persson A, Wallentinus I, Wetsteyn LPMJ, Wittling T (2002) Life in Ballast Tanks In: Invasive aquatic species of Europe - distribution, impact and management. Leppäkoski, E., S. Gollasch & S. Olenin (eds). Kluwer Academic Publishers: 217-231
Diederich S, Nehls G, Beusekom JEE, Reise K (2005)Introduced Pacific oysters (Crassostrea gigas) in the northern Wadden Sea: invasion accelerated by warm summers? Helgoland Marine Research, Volume 59, Issue 2, 97 - 106

In the North Sea imports of C. gigas started in 1964 in the Netherlands, followed by transports to England, France, and Germany. Whereas only sporadic natural spatfalls occurred in Great Britain, wild oyster populations are growing fast in France as well as in the Netherlands. The spread of the Pacific oyster in the northern Wadden Sea began 5 years after the first German oyster farm had started its business off the island of Sylt in 1986.
Molecular information Available

GenBank (
Barcode Of Life Data Systems (BOLD)

Genome sequencing and DNA barcoding is available in a number of online databases. Other molecular data is available for C.gigas to determine its phylogeny and to describe other characteristics, such as composition.
Last update byAleksas Narščius, 2019-03-12