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title: "What the sources say about the Scaly-foot Snail | AnimalTracks.wiki"
description: "46 claims from the Scaly-foot Snail profile, each beside the words of the source that backs it."
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# What the sources say about the Scaly-foot Snail (*Chrysomallon squamiferum*)

> 46 claims from the Scaly-foot Snail profile, each beside the words of the source that backs it. A "..." marks a cut in a quote and [brackets] an insertion.

Profile: [Scaly-foot Snail](https://animaltracks.wiki/animals/scaly-foot-snail/)

## Chrysomallon squamiferum. Animal Diversity Web, University of Michigan.

https://animaldiversity.org/accounts/Chrysomallon_squamiferum/

| The page says | The source says |
| :--- | :--- |
| Deep-sea hydrothermal vent fields in the Indian Ocean (Kairei, Solitaire, Longqi and others), 2,400 to 2,900 meters down | Volcano Snails (Chrysomallon squamiferum) live in 3 different deep-sea hydrothermal vent fields, all located in the Indian Ocean ... Originally found in the Kairei vent field, and later found in the Solitaire and Longqi vent fields. ... Range depth 2400 to 2900 m (note: 'and others': endosymbiont-2022 (newer) samples five vent fields, claimed below) |
| Energy supplied by sulfur-oxidizing bacteria living inside its enlarged oesophageal gland | They have a larger oesophageal gland that houses chemosynthetic bacteria, that provide energy to the snails. |
| lives at deep-sea hydrothermal vents on the floor of the Indian Ocean, 2,400 to 2,900 meters down, at vent fields including Kairei, Solitaire and Longqi | Volcano Snails (Chrysomallon squamiferum) live in 3 different deep-sea hydrothermal vent fields, all located in the Indian Ocean off the Eastern and Southern coasts of Madagascar. Originally found in the Kairei vent field, and later found in the Solitaire and Longqi vent fields. ... Range depth 2400 to 2900 m |
| It measures 5 to 45 millimeters long, 32 millimeters on average. | Range length 5 to 45 mm ... Average length 32 mm |
| Snails at the iron-rich Kairei field are black and magnetic, because their armor contains a mineral called greigite. | those in the Kairei vent field have a black color and are also magnetic because of the greigite presence |
| and are white | Those that live in the Solitaire vent field have a white color due to lack of iron |
| The scaly-foot snail is what biologists call an obligate symbiotroph: it depends on its bacteria to survive. | Volcano snails are obligate symbiotrophs, meaning they need a symbiotic relationship to survive. |
| the sulfur-oxidizing bacteria living inside it | They have a larger oesophageal gland that houses chemosynthetic bacteria |
| The sclerites and shell also defend it against predatory snails of the genus Phymorhynchus, which inject venom into their prey. | Volcano snails have their sclerites and protected shells to protect themselves from predators like the genus Phymorhynchus. They inject venom into their prey, so the volcano snail's protection prevents these attacks. |

## Sun et al. (2020). The Scaly-foot Snail genome and implications for the origins of biomineralised armour. Nature Communications.

https://doi.org/10.1038/s41467-020-15522-3

| The page says | The source says |
| :--- | :--- |
| whose foot scales and shell are often mineralised with iron sulfide | The Scaly-foot Snail, Chrysomallon squamiferum , is unique among gastropod molluscs in having dense, imbricating chitinous sclerites covering the whole distal surface of the soft foot ... These hard parts, including sclerites and the shell, are often mineralised with iron sulfide |
| Foot scales and shell often mineralised with iron sulfide | These hard parts, including sclerites and the shell, are often mineralised with iron sulfide |
| Densely packed, overlapping plates called sclerites cover its foot | The Scaly-foot Snail, Chrysomallon squamiferum , is unique among gastropod molluscs in having dense, imbricating chitinous sclerites covering the whole distal surface of the soft foot |
| both the sclerites and its shell are often mineralised with iron sulfide | These hard parts, including sclerites and the shell, are often mineralised with iron sulfide |
| That makes it the only known animal using iron as a significant part of its skeleton. | making it the only known metazoan using iron as a significant component of skeleton construction |
| iron-rich Kairei field | On its discovery in the iron-rich Kairei hydrothermal vent field in the Indian Ocean in 2001 |
| The Solitaire field has about 1/58 of Kairei's iron, and the snails there lack the iron sulfide coating | a second population lacking iron sulfide mineralisation was discovered in the Solitaire hydrothermal site 11 characterised by low concentrations of iron (1/58 of that found at Kairei 12 ) |
| The living snail supplies sulfur through nano-scale, channel-like columns in its scales, and that sulfur reacts with iron diffusing in from the vent fluid to make iron sulfide nanoparticles. | the Scaly-foot Snail mediates its scale biomineralisation by supplying sulfur through nano-scale channel-like columns in the scales, which reacts with iron ions diffusing inwards from the vent fluid to make iron sulfide nanoparticles |
| Dense, overlapping scales cover its foot | The Scaly-foot Snail, Chrysomallon squamiferum , is unique among gastropod molluscs in having dense, imbricating chitinous sclerites covering the whole distal surface of the soft foot |
| they and its shell are often mineralised with iron sulfide | These hard parts, including sclerites and the shell, are often mineralised with iron sulfide |
| built from iron in the vent fluid around it | supplying sulfur through nano-scale channel-like columns in the scales, which reacts with iron ions diffusing inwards from the vent fluid to make iron sulfide nanoparticles |

## Okada et al. (2019). The making of natural iron sulfide nanoparticles in a hot vent snail. Proceedings of the National Academy of Sciences.

https://doi.org/10.1073/pnas.1908533116

| The page says | The source says |
| :--- | :--- |
| The living snail supplies sulfur | the living animal mediates biomineralization of iron sulfide nanoparticles via a channel-like columnar organic matrix that transports sulfur, which then reacts with iron ions diffusing in from the surrounding vent fluid |

## Chen et al. (2015). The heart of a dragon: 3D anatomical reconstruction of the 'scaly-foot gastropod' (Mollusca: Gastropoda: Neomphalina) reveals its extraordinary circulatory system. Frontiers in Zoology.

https://doi.org/10.1186/s12983-015-0105-1

| The page says | The source says |
| :--- | :--- |
| with a heart that takes up about 4% of its body volume | the heart complex represents approximately 4 % of the body volume |
| and a heart that's about 4% of its body volume | the heart complex represents approximately 4 % of the body volume |
| Its oesophageal gland is huge | the body cavity is occupied by a huge oesophageal gland |
| Even its armor may serve the bacteria. The researchers who mapped its anatomy view its sclerites, its circulatory system and its high fecundity as adaptations that benefit its microbes. | all of its remarkable features—protective dermal sclerites, circulatory system, high fecundity—can be viewed as adaptations beneficial to its endosymbiont microbes |
| Those researchers infer that its elaborate circulatory system most likely evolved to oxygenate the bacteria in an oxygen-poor environment, or to supply them with hydrogen sulfide. | we infer the elaborate cardiovascular system most likely evolved to oxygenate the endosymbionts in an oxygen poor environment and/or to supply hydrogen sulfide to the endosymbionts |
| Its auricle and ventricle together take up about 4% of its body volume. | Based on the volume of the auricle and ventricle, the heart complex represents approximately 4 % of the body volume. |
| The same paper puts a healthy adult human's heart at around 1.3% of body volume: the snail's share is roughly three times bigger. | The heart of Chrysomallon is estimated at 4 % of the body volume; by contrast the heart of a healthy human is averages at around 1.3 % of the body volume (mean total heart volume of adult humans 778 ml (note: the paper's own comparison, computed from its cited inputs (778 ml / 61.05 L = 1.27%); 4 / 1.3 = 3.1) |
| Its muscular ventricle is thought to work by suction, drawing blood through the gill | We interpret the heart, and particularly the muscular ventricle, functions to create suction that draws blood through the gill (note: ctenidium is the gastropod gill; the paper uses 'gill' itself here) |
| the giant heart mainly serves the gill and the gland full of bacteria | the giant heart primarily serves the ctenidium and the oesophageal gland |
| A mouth on the underside of its snout opens into a buccal cavity holding a rhipidoglossate radula, a long toothed ribbon, though it has no jaws. | The mouth opening on the ventral side of snout leads to buccal cavity contains a rhipidoglossate radula ... There are no jaws. ... The radula ribbon is long |
| Past the mouth its gut is small: a distinct stomach | the digestive system apart from the oesophageal gland is relatively small and forms a simple loop (Fig. 5b ). The midgut is forms a clearly discernable stomach |
| then an intestine reduced to a single loop, most likely because it relies on its bacteria for food | The intestine however is reduced [ 17 ] and only has a single loop, unlike grazing peltospirids [ 25 , 26 ], most likely because of its nutritional reliance on endosymbiotic bacteria |
| It has no eyes, and a detailed reconstruction of its anatomy found no sign of even a leftover optic nerve. | There are no eyes and no evidence of even a remnant optic nerve emerging from the oesophageal nerve ring. |
| Its brain is a more or less solid lump of nerve tissue | The brain is a more or less solid neural mass without clear structure or ganglia |
| with a large nerve running out to each of its head tentacles | a large, prominent tentacular nerve projecting into the cephalic tentacles |

## Lan et al. (2022). Endosymbiont population genomics sheds light on transmission mode, partner specificity, and stability of the scaly-foot snail holobiont. The ISME Journal.

https://doi.org/10.1038/s41396-022-01261-4

| The page says | The source says |
| :--- | :--- |
| and others | multiple scaly-foot snail populations dwelling in five vent fields |
| sulfur-oxidizing bacteria | relies on its sulphur-oxidising gammaproteobacterial endosymbionts for nutrition and energy |
| supply the snail's nutrition and energy | relies on its sulphur-oxidising gammaproteobacterial endosymbionts for nutrition and energy |
| From its surroundings, picked up afresh in each generation. | scaly-foot snails acquire endosymbionts through horizontal transmission from the environment at each generation |
| Comparing the snail's own DNA against its bacteria's DNA shows mismatched family trees between hosts and symbionts across five vent fields, meaning the hosts are not simply inheriting a ready-made colony from a parent. | Results of population genomics analyses reveal an incongruent phylogeny between the endosymbiont and mitochondrial genomes of the scaly-foot snails in the five vent fields sampled, indicating that the hosts obtain endosymbionts via horizontal transmission in each generation. |
| Many of the symbiont populations are genetically very alike, though, and that leaves open the chance of a parent passing some along too. | the genetic homogeneity of many symbiont populations implies that vertical transmission cannot be ruled out either |

## Sigwart, J. (2017). Deep-sea conservation and the 'scaly-foot gastropod'. Tentacle: The Newsletter of the IUCN/SSC Mollusc Specialist Group.

https://www.hawaii.edu/cowielab/Tentacle/Tentacle_25.pdf

| The page says | The source says |
| :--- | :--- |
| Assuming the snail could live anywhere within any vent site in the Indian Ocean, a generous estimate puts its total potential habitat at around 0.27 square kilometers. | an assumption that the scaly-foot could potentially live anywhere within any vent site in this ocean basin, provides a generous estimate of total global potential habitat for the scaly-foot gastropod of around 0.27 km 2 |
| In 2017, both of its high-seas sites lay under licenses for mining exploration, which could reasonably be expected to shrink that habitat further. | Tentacle No. 25—February 2017 ... Its two high seas localities are under license for mining exploration, which could reasonably be projected to lead to further reduction in habitat. (note: dated to the source (Tentacle No. 25, February 2017) rather than stated as a current state) |

## Sigwart, Chen & Thomas (2019). Chrysomallon squamiferum. The IUCN Red List of Threatened Species 2019: e.T103636217A103636261.

https://doi.org/10.2305/iucn.uk.2019-2.rlts.t103636217a103636261.en

| The page says | The source says |
| :--- | :--- |
| The IUCN Red List assesses the scaly-foot snail as Endangered | IUCN Red List category: Endangered (EN). |

## Lambert (2019). Ocean snail is first animal to be officially endangered by deep-sea mining. Nature.

https://doi.org/10.1038/d41586-019-02231-1

| The page says | The source says |
| :--- | :--- |
| in 2019 it became the first deep-sea animal declared endangered because of the threat of mining | 22 July 2019 Ocean snail is first animal to be officially endangered by deep-sea mining ... has become the first deep-sea animal to be declared endangered because of the threat of mining. (note: Nature news dated 22 July 2019; hand-cached (paywalled page, lede only)) |