---
title: "What the sources say about the Giant Clam | AnimalTracks.wiki"
description: "40 claims from the Giant Clam profile, each beside the words of the source that backs it."
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# What the sources say about the Giant Clam (*Tridacna gigas*)

> 40 claims from the Giant Clam profile, each beside the words of the source that backs it. A "..." marks a cut in a quote and [brackets] an insertion.

Profile: [Giant Clam](https://animaltracks.wiki/animals/giant-clam/)

## Giant clams. Dallas World Aquarium.

https://dwazoo.com/animal/giant-clams

| The page says | The source says |
| :--- | :--- |
| The largest living bivalve gets most of its nutrients from algae living in its flesh. | This is the largest living bivalve mollusk. (note: tagline; 'most' is the source's 'majority') |
| Dallas World Aquarium says the majority of its nutrients come from a partnership with billions of algae that live in its tissues. | the majority of its nutrients are obtained by a mutually beneficial relationship with billions of algae that live in its tissues (note: tagline 'lives on their sugars' is cut to the nutrient claim; see report) |
| Plankton filtered from seawater, plus carbon by-products from the algae living in its tissues | the Giant clam filters particulate food, including microscopic marine plants (phytoplankton) and animals (zooplankton) (note: stats.diet) |
| the algae hand over the carbon by-products of photosynthesis | the clam obtains the carbon by-products of photosynthesis (note: stats.diet) |
| Hosts billions of algae in its own tissues and gets the majority of its nutrients from them | the majority of its nutrients are obtained by a mutually beneficial relationship with billions of algae that live in its tissues (note: stats.superpower) |
| In return for shelter from predators | The algae gain protection from predators |
| pale or clear spots known as windows | They also have a number of pale or clear spots on the mantle, known as ‘windows’. |
| Clear patches on the mantle let sunlight in, and the algae need that light for photosynthesis. | These ‘windows’ allow sunlight to filter in through the mantle which is necessary for photosynthesis. |
| Light passes through them into the mantle, and photosynthesis by the algae depends on it. | These ‘windows’ allow sunlight to filter in through the mantle which is necessary for photosynthesis. (note: FAQ 3) |
| It pulls seawater in through one siphon (a hole) and strains out plankton | The inhalant siphon is used to draw in seawater that is then filtered for planktonic food. |
| This is the largest living bivalve, a two-shelled mollusc like a mussel or an oyster. | This is the largest living bivalve mollusk. (note: source: largest living bivalve mollusk; shell of two valves; mussel/oyster gloss is explanatory) |
| A fully grown adult can no longer close its shell completely. | Once they are fully grown they cannot close their shell completely. |
| it is not uncommon for one to pass 100 years | it is not uncommon for them to live more than 100 years! |
| that living past 100 years is not uncommon for a giant clam, which stays in one spot from the day it settles | Giant clams are sessile, once they have settled somewhere they remain there for the rest of their life and within their environment it is not uncommon for them to live more than 100 years! (note: FAQ 2) |
| A giant clam is sessile, meaning it stays put. | Giant clams are sessile, once they have settled somewhere they remain there for the rest of their life |
| Its larvae swim and feed in the water until they are big enough to settle, then they remain in that place for the rest of their lives. | The larvae swim and feed in the water column until they are big enough to find somewhere to settle and then they begin their adult life as a sessile clam. |
| Adults release eggs and sperm into the water, and fertilisation happens there. | They release eggs and sperm into the water, where the eggs are fertilized. |
| A giant clam does not feed alone. | a mutually beneficial relationship with billions of algae that live in its tissues (note: framing of the algae partnership) |
| Those pale or clear patches are windows. | They also have a number of pale or clear spots on the mantle, known as ‘windows’. (note: FAQ 3) |
| Once a giant clam settles, it stays in that spot for the rest of its life | Giant clams are sessile, once they have settled somewhere they remain there for the rest of their life (note: vibe.reason) |
| drawing seawater in through a siphon and filtering out plankton | The inhalant siphon is used to draw in seawater that is then filtered for planktonic food. (note: vibe.reason) |

## True Giant Clam. NOAA Fisheries.

https://www.fisheries.noaa.gov/species/true-giant-clam

| The page says | The source says |
| :--- | :--- |
| Shallow reefs, atoll lagoons and fringing reefs of the Indo-Pacific, from Myanmar to Kiribati | The geographic range of T. gigas spans the shallow waters of the Indo-Pacific and the Great Barrier Reef, from Myanmar in the west to the Republic of Kiribati in the east (note: stats.habitat) |
| Shallow reefs, atoll lagoons and fringing reefs | can be found in many habitats, including high- and low-islands, atoll lagoons, and fringing reefs (note: stats.habitat; the source lists these among many habitats) |
| NOAA ranks Tridacna gigas as the biggest of all the giant clam species, growing to more than a metre wide and more than 496 pounds (225 kg). | is the largest of all the giant clam species, growing to sizes over a meter wide and weights in excess of 496 pounds (225 kg) |
| from Myanmar to Kiribati and from the Ryukyu Islands of Japan down to Queensland, Australia | from Myanmar in the west to the Republic of Kiribati in the east, and from the Ryukyus Islands of Japan in the north to Queensland, Australia in the south |
| NOAA places the species across the Indo-Pacific and the Great Barrier Reef | spans the shallow waters of the Indo-Pacific and the Great Barrier Reef |
| coral reefs, atoll lagoons and fringing reefs, typically 6 to 65 feet down, often among hard coral or on bare sand | Individuals are typically found between the depths of 6 to 65 feet, often among hard coral communities, hard reef substrata, or on bare sand. |
| decades of heavy, unregulated collecting have made it very scarce across much of its range | Decades of intense, unregulated harvest has driven T. gigas to very low abundance throughout much of its range. |
| catching it for meat and shells is the main threat | Past and ongoing harvest for meat and shells is the primary threat to this and other giant clam species. |
| In 2024 NOAA Fisheries proposed listing it as endangered under the US Endangered Species Act | NOAA Fisheries has completed a status review for Tridacna gigas and is proposing to list the species as endangered throughout its range under the Endangered Species Act (note: 2024: the NOAA page stating the proposal was last updated 07/24/2024; dated rather than present tense because the rule may since be final) |
| it is on CITES Appendix II | CITES Appendix II Throughout Its Range |
| Biggest of its kind | is the largest of all the giant clam species (note: heading) |
| weightKg: 225 | weights in excess of 496 pounds (225 kg) (note: large adult; the 500 kg record is an outlier) |

## Neo & Li (2024). Tridacna gigas. The IUCN Red List of Threatened Species 2024: e.T22137A119167161.

https://doi.org/10.2305/iucn.uk.2024-2.rlts.t22137a119167161.en

| The page says | The source says |
| :--- | :--- |
| Critically Endangered | IUCN Red List category: Critically Endangered (CR). (note: stats.conservationStatus; assessed 2024; GBIF copy of the Red List) |
| The IUCN Red List assessed it as Critically Endangered in 2024. | IUCN Red List category: Critically Endangered (CR). (note: year from the 2024-2 assessment DOI) |
| The IUCN Red List's 2024 assessment of Tridacna gigas rates it Critically Endangered. | IUCN Red List category: Critically Endangered (CR). (note: FAQ 4) |

## Li et al. (2024). The genome sequence of the giant clam, Tridacna gigas (Linnaeus, 1758). Wellcome Open Research.

https://doi.org/10.12688/wellcomeopenres.21136.1

| The page says | The source says |
| :--- | :--- |
| every giant clam species has this partnership with algae called Symbiodiniaceae | All species within the subfamily form a photosymbiotic partnership with Symbiodiniaceae dinoflagellates |
| The genome team reports the largest individual as 137 cm long and 500 kg. | with the largest individual measuring an impressive 137 cm in length and weighing a remarkable 500 kg |
| The biggest on record weighed 500 kg and measured 137 cm in length, the figures given in the 2024 paper that sequenced its genome. | with the largest individual measuring an impressive 137 cm in length and weighing a remarkable 500 kg (note: FAQ 1; 2024 is the genome paper's publication year (Wellcome Open Research 2024)) |

## Bonham (1965). Growth Rate of Giant Clam Tridacna gigas at Bikini Atoll as Revealed by Radioautography. Science.

https://doi.org/10.1126/science.149.3681.300

| The page says | The source says |
| :--- | :--- |
| A 1965 study of a 52 cm clam from Bikini Atoll counted bands in its shell, read them as yearly rings, and put it in its 9th year. | The regular banding seen in the sections is interpreted as annular in nature. One annulus precedes the 1956 layer of radioactivity, two intervene in 1958, and six follow to the time of collection, so that this clam (length, 52 centimeters) was in its 9th year of life. (note: 1965 is the paper's publication year) |