page_title: Scaly-foot snail
section_title: Distribution
hierarchical_section_title: Scaly-foot snail / Distribution
caption_attribution_description: English: Distribution map of Chrysomallon squamiferum. Coordinates: Kairei -25.3206500,070.0404833 Solitaire -19.5568833,065.8481333 Longqi -37.7837833,049.6493833. Layer: ETOPO1 Global Relief Model.
context_page_description: Chrysomallon squamiferum, commonly known as the scaly-foot gastropod, scaly-foot snail, or sea pangolin, is a species of deep-sea hydrothermal-vent snail, a marine gastropod mollusc in the family Peltospiridae. This vent-endemic gastropod is known only from deep-sea hydrothermal vents in the Indian Ocean, where it has been found at depths of about 2,400–2,900 m. Chrysomallon squamiferum differs greatly from other deep-sea gastropods, even the closely related neomphalines. In 2019, it was declared endangered on the IUCN Red List, the first species to be listed as such due to risks from deep-sea mining of its vent habitat that also produce high-quality metal ores.
  The shell is of a unique construction, with three layers; the outer layer consists of iron sulfides, the middle layer is equivalent to the organic periostracum found in other gastropods, and the innermost layer is made of aragonite. The foot is also unusual, being armored at the sides with iron-mineralised sclerites.
  The snail's oesophageal gland houses symbiotic gammaproteobacteria from which the snail appears to obtain its nourishment.
context_section_description: The scaly-foot gastropod is a vent-endemic gastropod known only from the deep-sea hydrothermal vents of the Indian Ocean, which are around 2,780 metres (1.73 mi) in depth. The species was discovered in 2001, living on the bases of black smokers in the Kairei hydrothermal vent field, 25°19.239′S 70°02.429′E, on the Central Indian Ridge, just north of the Rodrigues Triple Point. The species has subsequently also been found in the Solitaire field, 19°33.413′S 65°50.888′E, Central Indian Ridge, within the Exclusive Economic Zone of Mauritius and Longqi (means "Dragon flag" in Chinese) field, 37°47.027′S 49°38.963′E, Southwest Indian Ridge. Longqi field was designated as the type locality; all type material originated from this vent field. The distance between Kairei and Solitaire is about 700 km (430 mi). The distance between Solitaire and Longqi is about 2,500 km (1,600 mi). These three sites belong to the Indian Ocean biogeographic province of hydrothermal vent systems sensu Rogers et al. (2012). The distance between sites is large, but the total distribution area is very small, less than 0.02 square kilometres (0.0077 sq mi).
  Peltospiridae snails are mainly known to live in Eastern Pacific vent fields. Nakamura et al. hypothetized that the occurrence of scaly-foot gastropods in the Indian Ocean suggests a relationship of the hydrothermal vent faunas between these two areas.
  Research expeditions have included:
  2000 – an expedition of the Japan Agency for Marine-Earth Science and Technology using the ship RV Kairei and ROV Kaikō discovered the Kairei vent field, but scaly-foot gastropods were not found at that time. This was the first vent field discovered in the Indian Ocean.
  2001 – an expedition of the U.S. research vessel RV Knorr with ROV Jason discovered scaly-foot gastropods in the Kairei vent field.
  2007 – an expedition of RV Da Yang Yi Hao discovered the Longqi vent field.
  2009 – an expedition of RV Yokosuka with DSV Shinkai 6500 discovered the Solitaire field and sampled scaly-foot gastropods there.
  2009 – an expedition of RV Da Yang Yi Hao visually observed scaly-foot gastropods at Longqi vent field.
  2011 – an expedition of the British Royal Research Ship RRS James Cook with ROV Kiel 6000 sampled the Longqi vent field.
caption: Distribution map of the scaly-foot gastropod
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