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Scaly foot snail

Scaly foot snail is one of the species of snails where its ancestors have been known to be the earliest living types in the world and are proved to be nearly 500 million years ago. Snails have many varieties and they differ based on the terrestrial or aquatic. Before they were adapted to live in the bodies of fresh water and sea but in the later period, they live in humid areas of land.

But How many have you heard about scaly foot snails? And do you know that the shell of this snail is coated with actual iron? Most of you might have not heard but the sad news that this species is listed to be endangered. So let’s see what it is and continue reading to know more.

What is a scaly foot snail?

It is known as the pangolin of the sea and is identified as one of the metal animals on the earth. This is a small animal with a large heart which is 4 % of its body volume. This is scientifically known as Chrysomallon squaniferum and on average the shell of the adult scaly foot snail is around 32 mm to 45 mm.

The shells are spherical-like shapes and coiled tightly with 3 loops. It doesn’t have a layered structure but consists of closely spaced ribs and growth lines. This is milky white in color and seems to be thick and brown and lacks folds. Moreover, the shell is coated with a black layer of iron sulphide. The sclerites are white when they form newly but it turns black due to the iron sulphide coating. 

Chrysomallon squamiferum 2

It lacks visible pigments or eyes while having a thick and tapered snout. The muscle is large and shaped like a horseshoe and the flesh of the scaly foot snail is red. The plates of the snail cover the foot of the snail as a defense against the predatory snails and crabs. A symbiotic bacteria that live on the foot of the snail facilitates the iron sulphide crusts.

Where does it live?

These snails are found in the Indian Ocean in hydrothermal vents (like hot springs on the ocean floor) and are often found in the volcanically active places which eject the warm water heated by the molten deep rocks below the crust of the oceans. And so it is recognized as the volcanic snail. This lives in the depths of 2400 to 2900 meters and withstands the temperature up to 400 degrees Celsius. The large heart of the snail helps it live in an environment that largely lacks oxygen.

So far these species are found only in three hydrothermal vent fields south of west Indian Ridge, Kairei, and Solitaire fields on the central Indian ridge and they look very different on the vent they live. Their colors differ and are produced as a result of different compositions of the hydrothermal water in the vent.

To form their shells and plates, they take the compounds of iron-sulphide from the water and it takes chemicals such as Greigite. By absorbing these deposits of the greigite into their exoskeleton, they make themselves magnetic.

Habits of the volcano snails

Chrysomallon squamiferum 3

They have a reduced digestive system and so it obtains all the nutrition from the chemoautotrophy of the endosymbiotic bacteria.

Are they endangered?

This snail shows no sexual dimorphism (different between males and females in characteristics) and in fact, it is a simultaneous hermaphrodite which means the same organisms possess both the organs of male and female. It lacks the males organs that transfer male reproductive cells but has the primary reproductive organs of both the male and female. It lays negatively buoyant eggs that are probably lecithotrophic.

Due to the deep-sea mining, the scaly foot snails are the first animal to be officially endangered. The mining companies have great interest in hydrothermal vents as they are rich in minerals and metals. The snails have a limited distribution in the environment but the technology which makes it effective to mine the grounds of hydrothermal vents resulted in the depletion of the scaly foot snails. And so the mining rights of Kairei and Longi fields are given to China and Germany. The species can be lifted if the vents are protected against mining.

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