There’s Actual Iron In The Shell And Scales Of The Recently Discovered Scaly-Foot Gastropod

Some of our planet’s weirdest creatures live in incredible environments on the deep ocean floor. Take this sea creature for example. It inhabits hydrothermal vents, often one mile and more below the water’s surface. Hydrothermal vents are a relatively new discovery that first came to light in 1977, in waters near the Galapagos Islands. The natural phenomena occur when underwater volcanoes cause cracks to form in the ocean floor. Jets of seawater spurt out from these rocky “chimneys,” superheated by the molten rock.

On the face of it, these environments are deeply hostile to life. And yet, to their astonishment, scientists have discovered a wealth of life forms living around the vents, many of them previously unrecorded by science. Newly discovered organisms include species of shrimps, huge tube worms and clams.

In order to survive, the vast majority of life on Earth depends on sunlight and the energy that it provides. But life forms that cluster around hydrothermal vents actually get their energy and sustenance from bacteria. Moreover, these bacteria feed on chemical compounds like hydrogen sulfide, which is actually highly poisonous to most other animals. Nevertheless, a complex variety of undersea life is using these bacteria to thrive.

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One such hydrothermal vent was discovered in the depths of the Indian Ocean in 2000. It’s a type of vent known as a “black smoker.” And in 2001 an expedition by the scientific exploration vessel RV Knorr was sent to the site to explore its life forms in detail. The Knorr already had a reputation for successful exploration – it was the vessel that found the remains of the famous Titanic in 1985.

The vent was named the Kairei, after the ship that first found it in 2000. When scientists aboard the Knorr arrived at the site a year later, they found a wide variety of life in the waters around the Kairei Field’s black smokers. There were shoals of shrimp, flatworms, crabs and barnacles. And that’s not all.

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The scientists also observed gastropods. These creatures come from the same family as both marine and land-based snails and slugs. But there was one particular sea snail that caught their attention above all else because of its pretty unique features. In fact, the creature was totally new to science and it was christened the scaly-foot gastropod.

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The animal’s scientific name, however, is Chrysomallon squamiferum. And it was unlike anything the scientists had ever seen before. The scaly-foot gastropod lives in the Kairei Field, which has an astonishing depth of up to more than 8,000 feet, or about 1.5 miles. But that’s not why these creatures are so remarkable. They live in an environment that would kill most other creatures. Scaly-foot gastropods inhabit waters with high levels of toxic hydrogen sulfide, and very little oxygen to boot. And they look pretty remarkable too.

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Their shells are on average over an inch wide, with the largest among them stretching almost two inches. This weird looking creature also has a broad snout and a mouthpiece made up of a set of muscles arranged in a circle. Instead of eyes, a pair of pointy tentacles is mounted on its head. The snail’s foot, meanwhile, is read and so large that it can’t retract fully into the shell.

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The scaly-foot gastropod is a hermaphrodite which means that it doesn’t need to mate to produce fertile eggs. And the animal is distinctive for its huge heart too, which makes up some 4 percent of its body volume. By contrast, a human heart is only around 1.3 percent of body volume.

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Not least of the scaly-foot gastropod’s unique features is its “foot.” The gastropod uses this flattened surface to propel itself around underwater. Look at any snail and you’ll see this characteristic foot. But the scaly-foot is different. Along the edges of its foot are tiny plates and these are made up of iron sulfides. And one of those is pyrite, which is often referred to as “fool’s gold” because of its gilded appearance.

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These strange metallic additions give the gastropod’s foot extra protection. But that extra protection goes much further than that. These extraordinary beasts have shells that are composed of iron. Most snails have shells that are fairly brittle, but the scaly-foot has what is in effect an armored shell.

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This iron covered shell really makes the scaly-foot unique. There is no other animal known to science that has a skeleton with an iron content. And in fact, the scaly-foot’s shell actually has three layers. The outer layer is the iron one, but there’s also a spongy middle layer. The final layer, meanwhile, is composed of a type of calcium carbonate called aragonite, similar to the shell of a standard snail.

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Indeed, this amazing “armored” shell may very well be of interest to those engineers who are developing body armor for humans. Scientists at the Massachusetts Institute of Technology (MIT) have conducted experiments on the gastropod’s unique structure. And they think they might be able to use the snail’s three-layered shell architecture to create body armor that is stronger, without being heavier.

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In its incredible underwater home, the gastropod uses its armor plating to protect itself from predators, especially crabs. And its unique qualities may help to improve various products as well as body armor. For instance, Cristine Ortiz at MIT thinks that technology inspired by the gastropod’s shell could be used to improve the strength of everything from helmets to undersea oil pipelines.

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After the discovery of the scaly-foot gastropod at the Kairei hydrothermal vents, more were discovered at two other sites on the bed of the Indian Ocean. Scaly-foots were found at the Solitaire field in 2009 by the deep-sea submersible DSV Shinkai 6500, and at the Longqui site in 2011 by the British Royal Research Ship James Cook.

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These discoveries showed that the scaly-foots have a wide geographical distribution. Solitaire is some 430 miles from Kairei while Longqui is about 1,000 miles from Solitaire. But although the animals are found at these widely spaced sites, the actual area of the sites they occupy is just a total of around 0.008 square miles.

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As if this iron-clad snail wasn’t weird enough, the variety and downright eccentricity of some of the other species found at the Kairei black smoke chimney and other hydrothermal vents in the world’s oceans is astonishing. Indeed, it’s difficult to shake off the feeling that the fauna found at these hydrothermal vents resemble what aliens from outer space might look like.

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One particularly bizarre example was found in the Pescadero Basin in the Californian Gulf. At 12,500 feet deep, this Gulf is home to the deepest Pacific Ocean vents known to science. Large numbers of strange tube worms, packed together in tight groups, wave eerily in the current.

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In 2015, the Exploration Vehicle Nautilus was on a trip to hydrothermal vents near the Galapagos Islands when it came across a specimen of the utterly peculiar “flamboyant squid worm.” First discovered in 2007, Teuthidodrilus samae is a kind of annelid worm. And the eight waving arms at the front of the animal are actually breathing organs.

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Scientists are still exploring the hydrothermal vents found in the deep ocean, and still finding peculiar animals previously unknown to science. The scaly-foot gastropod, with its unique iron shell, is just one of these eccentric beasts of the depths. And with continuing exploration, scientists hope to learn more about how life has evolved on earth – and perhaps even beyond.

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