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July 23, 2019

The Scaly-foot Snail Formally Listed as Endangered: the First Step toward Deep-Sea Biodiversity Conservation Using the IUCN Red List

1. Key Points

The Scaly-foot Snail (Chrysomallon squamiferum), a deep-sea snail endemic to deep-sea hydrothermal vents, has been formally listed as an Endangered species in the International Union for Conservation of Nature (IUCN) Red List.
Japanese research efforts, including those of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC), provided materials and scientific knowledge that facilitated the assessment of this Red List assessment.
This is the first case in the IUCN Red List where deep-seafloor resource development has been taken into consideration, and it clearly indicates the importance of evaluating the effects of anthropogenic impacts on deep-sea organisms.


The International Union for Conservation of Nature (IUCN), a global authority on conservation, issued an update to its renowned IUCN Red List of Threatened Species on July 18th. The Scaly-foot Snail (Chrysomallon squamiferum; Figure 1), a unique species with iron-infused scales endemic to deep-sea hydrothermal vents of the Indian Ocean, has been newly added to the Red List as Endangered (EN [B2ab (iii)]). Research initiatives that ultimately resulted in this classification were largely led by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC), using numerous research vessels and submersibles, in cooperation with other research institutions within and outside Japan, to investigate seafloor hydrothermal activity in the Indian Ocean from the 1990s to date. Chong CHEN, a member of the SUGAR Program, X-STAR, JAMSTEC, contributed his valuable research findings across multiple fields, including the physiology, evolution, and ecology of this species that facilitated complete assessment of this species for the IUCN Red List.

The Scaly-foot Snail is known from only three hydrothermal vents, totaling about two soccer fields in size (Figures 3 and 4). Hydrothermal vents are facing surging interests in seafloor sulfide mining, and two of these three vents (Kairei and Longqi) are currently under mining exploration licenses issued by the International Seabed Authority. The limited number of suitable habitat sites, restricted extent of its specialized habitat, inferred infrequent dispersal interactions among populations, as well as concerns regarding disruption to its habitat by future seafloor resource development, have all contributed to the evaluation of the Scaly-foot Snail as Endangered (EN [B2ab (iii)]).

This new addition to the Red List serves as an important case study, showing how the IUCN Red List can be applied to species inhabiting deep-sea habitats that remain largely unexplored when sufficient information is gathered, and how the IUCN Red List can be used as a key tool in deep sea conservation. An article highlighting this new development in deep-sea biodiversity conservation was published in Nature Ecology & Evolution on July 23rd, 2019 (JST).

Title: Red Listing can protect deep-sea biodiversity
Authors: Julia D. SIGWART1、Chong CHEN2*、Elin A. THOMAS1、A. Louise ALLCOCK3、Monika BÖHM4、Mary SEDDON5
1. Queen’s University Belfast, Marine Laboratory 2. X-STAR, JAMSTEC 3. National University of Ireland, Galway 4. Zoological Society of London 5. IUCN SSC Mollusc Specialist Group

Figure 1

Figure 1.The Scaly-foot Snail (Chrysomallon squamiferum), newly listed as Endangered in the IUCN Red List. Each snail is approximately 5 cm in shell length.

Figure 2

Figure 2. Summary of IUCN Red List Categories.

Figure 3

Figure 3. (a) Hydrothermal vent fields in the Indian Ocean, with vents found through the efforts of JAMSTEC indicated by stars, and others marked with circles. The three vents from which the Scaly-foot Snail is known are highlighted by larger symbols. (b) Bathymetry map showing the Solitaire Field and its surrounding area; (c) Representation of the total habitat area of the Scaly-foot Snail.

Figure 4

Figure 4. The Kairei Field showing a black smoker chimney behind a robotic arm of the JAMSTEC remotely operated vehicle KAIKO.


(For this study)
Chong CHEN, Scientist, Super-cutting-edge Grand and Advanced Research (SUGAR) Program, Institute for Extra-cutting-edge Science and Technology Avant-garde Research (X-STAR)

Shinsuke KAWAGUCCI, Scientist, Super-cutting-edge Grand and Advanced Research (SUGAR) Program, Institute for Extra-cutting-edge Science and Technology Avant-garde Research (X-STAR)
(For press release)
Public Relations Section, Marine Science and Technology Strategy Department
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