The New Passengers on the Titanic - What's a Rusticle?

In the late hours of April 14th 1912, the RMS Titanic, a luxury British ocean liner with a reputation for being "unsinkable", hit an iceberg and sank to the bottom of the Atlantic ocean. This was her maiden (first) voyage.

The Titanic departs on its maiden voyage.

Visiting Titanic's wreckage

Over 100 years later, scientists, deep-sea explorers (and the odd rich tourist!) visit the Titanic's wreckage nearly 2 and a half miles under the surface of the ocean. The broken vessel lays on the seabed, so deep that researchers must use specialised deep-sea submersibles to visit it.

Specialist submersibles

A submersible visiting the Titanic wreckage must be able to withstand the immense pressure of millions of tonnes of water pushing down upon it. We're talking around 4,000 tonnes of water pressure per square metre! If the submersible isn't strong enough, the pressure could implode the vessel in a matter of milliseconds! These journeys are not for the faint of heart. Neither are they for the claustrophobic; the submersibles are tiny and it can take around 2 and half hours just to reach the seabed.

A Submersible visits the Titanic, deep underwater.

Why do people make these journeys?

Even before the Titanic sank, people were fascinated with the "virtually unsinkable" luxury ocean-liner. The obsession with the tragedy and myths about the sinking endure to this day, tempting the odd tourist to make the voyage to the bottom of the ocean. But this isn't the only reason people visit the wreckage. Ocean researchers have a more scientific motive: Rusticles.

What are Titanic Rusticles?

Rusticles are the new passengers aboard the Titanic, 12,500 feet below the surface of the Atlantic. Rusticles are icicles of rust forming on the ships carcass on the seabed.

How are Rusticles created?

Rusticles forming on the port side of the Titanic.

Life is hard in the deep-sea environment around the Titanic; crushing pressure, scarce food, freezing temperatures and lack of sunlight make existence here nearly impossible. That's what makes Rusticles so amazing. They're created by lots of microscopic living bacteria that work together to survive at the bottom of the ocean where other creatures can't exist! Rusticles are a product made by these microscopic bacteria when they eat the iron that the Titanic is made from. This process is called biocorrosion - the break down of metal by micro creatures. The Rusticles on the Titanic are made up of lots of different species of bacteria that share metabolic (bodily) products to survive, creating unique delicate rust growths. Some scientists have discovered that these bacterial microbes don't just eat iron, they can also breathe it instead of oxygen!

The bow of The Titanic is now coated in Rusticles! Image courtesy BBC.

What do Rusticles look like?

As the name suggests, Rusticles tend to look like icicles with the brown-red colour of rust; a bit like stalactites and stalagmites in caves. But Rusticles can actually come in all sorts of shapes and sizes, including "Rustflowers" that look like the stems of flowers growing towards the Earth's magnetic field. They can also grow in the shape of sheets of paper, rose buds, branches like trees or lumped clusters.

Why are Rusticles important?

Rusticles create their own ecosystem at the bottom of the ocean. As the bacteria corrode the iron, the surrounding water is filled with iron nutrients that help other, larger creatures survive, like starfish and anemones. Researching the Rusticles gives scientists insights into deep-sea microbiology and corrosion. The main bacteria in the Rusticles on the Titanic wreckage, the Halomonas Titanicae, is a brand new lifeform that has never been discovered before. And it originates on the Titanic wreckage.

Brass fittings will remain intact, whilst the rest of the Titanic will ultimately rust into a lump. Courtesy BBC.

What will happen to the Titanic?

The bacteria in the Rusticles are slowly eating all of the iron on the Titanic wreckage. The Rusticles grow at around 1cm per year, which may seem slow to us, but its estimated that hundreds of tonnes of steel could be being consumed by the bacteria every day. With the bacteria, water pressure and ocean tides, some scientists estimate the iron of the Titanic wreckage could be reduced to a rusty-coloured lump in as little as 30 years. On the other hand, parts of the ship constructed from non-corroding materials, like brass fittings, silica tiles and porcelain bathtubs, will likely lie on the seabed forever.