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What the sources say

Pacific OysterMagallana gigas

Every figure, record and mechanism on the Pacific Oyster profile was written from a source, and this is the working table behind it: 41 claims checked word for word against these sources. The left column is what the page says. The right column is the source's own words, copied, not paraphrased; a ... marks a cut and[brackets] an insertion. Open any source and check it yourself.

Profile updated

Source
01

NOAA Fisheries

Pacific Oyster. NOAA Fisheries.

The page saysA stay-put oyster that starts life male, hears underwater sound and filters up to 50 gallons of seawater a day.
The source saysan adult Pacific oyster can filter up to 50 gallons of seawater per dayNote: tagline; the male start and the hearing have their own claims
The page saysFilter feeder that lives on plankton
The source saysPacific oysters can grow quickly, depending on plankton (food) availability and water quality conditions.Note: stats.diet; filter feeding has its own claim
The page saysFilter feeder that lives on plankton
The source saysThey are filter feeders, cleaning the water as they eatNote: stats.diet
The page saysFilters up to 50 gallons of seawater a day
The source saysan adult Pacific oyster can filter up to 50 gallons of seawater per dayNote: stats.superpower
The page saysThat is what "sessile" means.
The source saysAdult oysters are sessile—they stay in one place.
The page saysstays in one place for life once it settles
The source saysthey will grow their own shells and can live for the rest of their lives
The page saysMale oysters release their sperm by clapping their shells together, often when the water is warm and coming in with the tide.
The source saysMale oysters release their sperm by clapping their shells together, often when the water is warm and coming in with the tide.
The page saysIn their first year of life, Pacific oysters are male.
The source saysIn their first year of life, Pacific oysters are male.
The page saysAs they get older, some develop female reproductive organs while their male organs shrink.
The source saysAs they get older, some will change and develop female reproductive organs, while their male organs shrink.
The page saysA female can release anywhere from 50 to 200 million eggs in a spawning event.
The source saysa female Pacific oyster can release anywhere from 50 to 200 million eggs into the water. This is called a spawning event.
The page saysThe tiny larvae drift in the upper layers of the water.
The source saysThe tiny oyster larvae develop in the upper layers of the water and drift with the currents
The page saysAfter about 20 to 22 days they settle on a shell, rock or other suitable surface, grow their own shells and can live there for the rest of their lives.
The source saysAfter about 20 to 22 days, the oysters are ready to settle down on the bottom of the bay. They attach themselves to a shell, rock, or other suitable surface, where they will grow their own shells and can live for the rest of their lives.
The page saysNOAA says a Pacific oyster can reach 10 to 12 inches.
The source saysreaching up to 10-12 inches
The page saysIts shell is long, thick and rough, and sometimes sharp around the edges.
The source saysTheir shells—known as valves—are naturally long, thick, rough, and sometimes sharp around the edges.
The page saysOne of the two valves is cupped, which is why the animal is also called the Pacific cupped oyster. The other valve is flat.
The source saysOne of the two shells is cupped, which is why they are also called "Pacific cupped oysters," while the other is flat.
The page saysValves are the two halves of the shell.
The source saysthey have a hinged shell with two partsNote: valves; NOAA: shells known as valves
The page saysOysters are filter feeders.
The source saysThey are filter feeders, cleaning the water as they eat
The page saysAn adult can filter up to 50 gallons of seawater a day, and that filtering improves light penetration for underwater plants.
The source saysan adult Pacific oyster can filter up to 50 gallons of seawater per day. This filtering of the water improves light penetration for submerged aquatic vegetation to thrive.
The page saysOysters can also form reefs that give critical habitat to many species, including fish and invertebrates like the native Olympia oyster.
The source saysOysters can also form reefs providing critical habitat for many species including fish and other invertebrates like the native Olympia oyster.
The page saysIt lives in intertidal and subtidal areas
The source saysThey inhabit both intertidal and subtidal areas.
The page saysThe Washington State Department of Fisheries introduced it from Japan in the 1920s, and it is now a popular aquaculture species on the US West Coast.
The source saysThe Pacific oyster, introduced from Japan in the 1920’s by the Washington State Department of Fisheries, is now a popular West Coast aquaculture speciesNote: West Coast in a NOAA (US agency) page is the US West Coast; NOAA Region: Alaska, West Coast
The page saysNOAA Fisheries gives a length of up to 12 inches
The source saysLength Up to 12 inchesNote: faq 1; replaces SeaLifeBase 45 cm max (FAO 1998 via Ref. 348), which disagrees with NOAA's page updated 04/13/2026. School-ruler comparison is a 12-inch ruler, needs no claim
The page saysNOAA Fisheries lists both Crassostrea gigas and Magallana gigas for the species, which it also calls the Japanese oyster, Miyagi oyster and Pacific cupped oyster.
The source saysCrassostrea gigas; Magallana gigas Also Known As Japanese oyster, Miyagi oyster, Pacific cupped oyster
The page saysMale first, maybe female later
The source saysIn their first year of life, Pacific oysters are male.Note: heading

Source
02

SeaLifeBase

Magallana gigas summary page. SeaLifeBase.

The page saysShallow brackish and coastal waters of the northwest Pacific, from Hong Kong to Kamchatka; introduced across the rest of the Pacific, Atlantic and Indian Oceans and the Mediterranean
The source saysNorthwest Pacific: from Hong Kong, east to Taiwan, and north to Kamchatka, Russia. Introduced in the rest of the Pacific, Atlantic, Indian Ocean and the Mediterranean.Note: stats.habitat
The page saysShallow brackish and coastal waters
The source saysBenthic; brackish; depth range 0 - 15 mNote: stats.habitat
The page saysNot Evaluated
The source saysIUCN Red List Status (Ref. 130435 : Version 2025-2 (Global)) Not EvaluatedNote: stats.conservationStatus. No Red List assessment exists for Magallana gigas or Crassostrea gigas (GBIF has no category, Crossref no assessment DOI), so no IUCN reference is cited. SeaLifeBase prints the same status.
The page saysThe species is native to the northwest Pacific, from Hong Kong east to Taiwan and north to Kamchatka, Russia.
The source saysNorthwest Pacific: from Hong Kong, east to Taiwan, and north to Kamchatka, Russia.
The page saysSeaLifeBase lists it as introduced across the rest of the Pacific, the Atlantic, the Indian Ocean and the Mediterranean.
The source saysIntroduced in the rest of the Pacific, Atlantic, Indian Ocean and the Mediterranean.
The page saysSeaLifeBase gives a depth range of 0 to 15 meters and a temperature range of 15 to 30 degrees Celsius.
The source saysdepth range 0 - 15 m (Ref. 348 ). Subtropical; 15°C - 30°C

Source
03

AnAge: The Animal Ageing and Longevity Database

Crassostrea gigas. AnAge: The Animal Ageing and Longevity Database.

The page saysAnAge lists a maximum of 7 years in the wild.
The source saysMaximum longevity 7 years (wild)
The page saysThe longest AnAge records in the wild is 7 years, and it rates that figure as resting on a small sample.
The source saysMaximum longevity 7 years (wild) Source ref. 1307 Sample size SmallNote: faq 2

Source
04

Charifi et al. 2017

Charifi et al. (2017). The sense of hearing in the Pacific oyster, Magallana gigas. PLOS ONE.

The page saysoysters briefly shut their valves when they were played loud enough sounds from 10 hertz to just under 1,000 hertz
The source saysAt high enough acoustic energy, oysters transiently closed their valves in response to frequencies in the range of 10 to <1000 Hz
The page saysTheir sensitivity peaked between 10 and 200 hertz.
The source sayswith maximum sensitivity from 10 to 200 Hz
The page saysfive oysters with shells 70 to 75 millimeters long weighed 72 grams on average
The source saysThe analysis was performed on 5 oysters (shell length 70–75 mm, weight 72.4 ± 10.7 gNote: 72.4 g is the stated mean (m ± sd), sd 10.7; scoped to the five test oysters
The page saysin a lab test, oysters briefly shut their valves to loud enough sounds from 10 hertz to just under 1,000 hertz
The source saysAt high enough acoustic energy, oysters transiently closed their valves in response to frequencies in the range of 10 to <1000 HzNote: vibe.reason
The page saystheir sensitivity peaked between 10 and 200 hertz
The source sayswith maximum sensitivity from 10 to 200 HzNote: vibe.reason

Source
05

Charifi et al. 2018

Charifi et al. (2018). Noise pollution limits metal bioaccumulation and growth rate in a filter feeder, the Pacific oyster Magallana gigas. PLOS ONE.

The page saysIn a 14-day test with cadmium, a metal pollutant, in the water, oysters exposed to cargo ship noise grew 2.6 times slower than oysters that heard no ship noise.
The source saysFour oyster-groups were studied during a 14-day exposure period. ... Oysters exposed to Cd in the presence of cargo ship-noise accumulated 2.5 times less Cd in their gills than did the controls without ship noise and their growth rate was 2.6 times slower.Note: Cd is cadmium; the abstract names it as the metal in the water
The page saysThey also stayed shut more during the day.
The source saysIn the presence of ship noise, oysters were closed more during the daytime
The page saysAn oyster that can hear a cargo ship
The source saysShipping has increased dramatically in recent decades and oysters can hear them.Note: heading
The page saysYet it can hear.
The source saysShipping has increased dramatically in recent decades and oysters can hear them.

How the table was made: a writer drafted the profile from these sources and logged each claim with its quote, a reviewer with nothing but this table checked every sentence said no more than its quote, and a script confirmed each quote appears word for word in the source. The method is in the site'sAbout page.