Range: Indian Ocean Habitat: Thermal vents Size: 1.5 inches (3.81cm) long or more Diet: Do not eat; Energy synthesized by gut bacteria Threats: Crabs, snails, and more Life span: Unknown

Transcript:

Today on Animal Fact Files we’ll be looking at literally the most metal animal on earth. For more facts on some awesome animals be sure to subscribe to the channel!

Iron snails or scaly foot gastropods, another name by which they are commonly known, are marine snails that live in the Indian Ocean inhabiting thermal vents at depths of more than 1.7 miles (2.74km). As of this recording they have been found at three thermal vent sites and this extreme environment has led to some intriguing adaptations to these snails’ physiques. When we said they are literally the most metal animal on earth, we weren’t kidding.

A scaly foot gastropod’s shell is made using iron sulfides one being pyrite, or fool’s gold, and the other being greigite which is magnetic. Yes, you heard that correctly, some iron snails are magnetic and will stick to other magnetic material. Their scientific name, Chrysomallon squamiferum, is actually derived from their extraordinary architecture with Chrysomallon meaning “golden-haired” due to the pyrite found in their shell and squamiferum meaning “scale-bearing” which we haven’t discussed and probably should since this is part of what makes them so unique.

As you’ve probably noticed from the pictures already, these ain’t your typical gastropods. They are indeed covered in armor-like scales called sclerites that make them look like something straight out of the medieval era. It’s guessed that these scales are likely used as a means of protection as it has been observed in adults that they are completely lacking in an operculum or the hard part of a snail’s foot that covers the opening to the snail shell (which is called the aperture). However, the sclerites may also be a result of detoxification from their surrounding environment as the thermal vents on which the live are highly toxic places. Currently, we aren’t entirely sure of their purpose as housing scaly foot gastropods on the surface has proved difficult, much like another deep-sea creature we’ve covered previously.

Iron snails have been observed to grow to a length of more than 1.5 inches (3.81cm) and depending on where they live may appear dark, steely grey in color to lighter tones of almost white. The lighter tones come about in scaly foot gastropods that don’t have iron found in their sclerites and these are typically found in the Solitaire vent range. They don’t have eyes and they don’t eat. Wait whaaat?! But how can that work? What these clever snails have done is formed a symbiotic relationship with bacteria who live inside their digestive tract and produce the energy the snails need in order to survive. Having bacteria living inside you seems like a small price to pay in order to avoid searching for food. Heck, not even our bacteria do that!

Scaly foot gastropods have somewhat exemplary shells since, as of this recording, they’re the only animals observed to use these iron sulfite materials in their skeleton - yes, snail shells are skeletons and they need them in order to survive; they’re not like hermit crabs who change shells as they get bigger. Their shells consist of three layers with the outermost containing the iron sulfides, the middle layer which seems to be built to dissipate heat as well as to help protect from squeezing attacks such as those performed by a crab and the inner layer which is similar to shells found in other gastropods and is milky white in color. Their foot, aka the exposed, squishy part of the snail, is typically bright red and they have both sets of reproductive organs throughout their life stages so it’s likely they self-fertilize.

They’re not currently listed to be under any threats, despite living in a rather small range as far as we’ve discovered and a large portion of this range currently being licensed for deep sea mining over the next decade. Only time will tell what the future may hold for these gorgeous gastropods.

For more facts on iron snails check out the links in the description. We’d like to thank Jethro Reading from twitter for the suggestion as we had never heard of these crazy critters until this point. We love discovering new animals! Be sure to give a thumbs up for weird creatures and thank you for watching Animal Fact Files.