What is a scaly-foot snail?

Earlier this year, the scaly-foot snail became the first species to be listed as endangered due to the threat of deep-sea mining. This marine mollusc might not have the charisma of the orangutans and pandas of this world, but a closer look reveals that it’s just as special.

First off, this is a small animal with a big heart – approximately 4 per cent of its body volume, to be precise. This makes it the largest heart – relative to body size – in the entire animal kingdom, helping the snail to live in an environment that’s largely devoid of oxygen.

So far, the snail has been found in only three locations – all hydrothermal vents in the Indian Ocean, as much as three kilometres below the surface. These vents provide food for the snail, via a farm of microbes (called ‘chemoautotrophs’) that it keeps in a special pocket in its gut. The microbes break down the chemicals that leak from the volcanic vents, creating food in the process.

The scaly-foot snail is the only organism known to incorporate metals (in the form of iron sulphides) into its ‘skeleton’, both into its shell, and into the hundreds of external scales which give it its name. It’s the RoboCop of the ocean world, but this unique armour will provide little defence against the mining projects that threaten its deep-sea habitat.

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