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The quest that discovered thousands of new species
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Painting of ship at sea (Credit: Stanislav Pobytov/Getty Images)
HMS Challenger spent three-and-a-half years peering into some of the remotest parts of our world’s oceans. Its groundbreaking voyage still has an impact today.
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It was once a private house, but now the imposing stone structure on Boswall Road, on the southern shore of the Firth of Forth in Edinburgh, is part of a palliative care hospice.

The building shares its name with the one of the deepest parts of the ocean and two Nasa spacecraft. One was the command module for the Apollo 17 Moon mission while the other was part of the Space Shuttle fleet, and the first of them to be lost – Challenger.

Challenger Lodge was once owned by John Murray, a famous pioneer of oceanography whose travels took him almost as far as it is possible to get from Edinburgh and still be on Planet Earth.

The vessel he lived on for three years in the 1870s is what ties together the house on the firth, the deepest part of our ocean abyss, and Nasa's spacecraft. HMS Challenger was a Royal Navy ship built in the 1850s. It has entered history thanks not to a famous fighting career but a reputation earned by something far more painstaking. A three-year-long voyage – one of scientific observation rather than naval power projection – which traversed the globe on a 68,000-nautical mile (125,900km) journey.

This voyage, which Murray was part of, changed the way we view the oceans. And along the way it discovered species living in the dark depths below. Not hundreds, but thousands.

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The oceans were the highways of the late 19th Century. With freight-carrying jet aircraft a century away, and railways yet to traverse huge swathes of the world, massive amounts of world trade relied on ships. But despite their vital place in commerce and colonial power, the deep oceans might as well have been on another planet.

The ancient Roman and Greeks had painstakingly – and fairly accurately – mapped the coastlines of the Mediterranean Sea. But while their cartography mapped the shorelines, the seas around them were regarded as a realm of ship-claiming monsters and gargantuan serpents. When the Ancient Greeks first started exploring outside the Mediterranean, some 2,900 years ago, the discovery of a strong north-to-south current made them believe they had discovered a huge river. From the Greek for river – okeanos – came the word ocean.

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 For centuries, oceanography remained in relative infancy. Coastlines were charted, species hauled up in nets were drawn and pored over, and depths recorded with weighted lines. But much of the ocean – especially its cold, invisible abyss – remained a mystery.

After the age of exploration, and Europe's violent colonisation of much of the globe, attention started turning to what lay under the surface of the sea. These early attempts were sporadic, however, and only ever explored a tiny fraction of the oceans at a time. It was only in the 1760s that the first dedicated oceanographic mission – a Danish expedition to the seas around Egypt the Arabian Peninsula – took place, gathering specimens using nets and simple dredging equipment.

The measuring equipment used by Challenger's scientists was relatively primitive but captured precise measurements (Credit: Universal History Archive/Getty Images)

The measuring equipment used by Challenger's scientists was relatively primitive but captured precise measurements (Credit: Universal History Archive/Getty Images)

The 19th Century was when what we would now call oceanography came of age. Smaller, less ambitious expeditions in the decades before the 1870s were instrumental in the Challenger setting sail, says Helen Rozwadowski, the founder of the maritime studies program at the University of Connecticut. Slowly and surely, they would provide the building blocks of a mission as ambitious as the Challenger's.

"You don't get a three-and-a-half-year circumnavigation voyage out of thin air," she says. "The antecedents are in two basic directions – one is the hydrographic works that's been done by especially British and American hydrographers." The US led the way in terms of deep sea until the 1860s. Then the Royal Navy, no longer having to support troops in Crimea, filled the vacuum left when the US fell into civil war.

Understanding more about the topography of the ocean became more pressing once telegraphy became more widespread, says Rozwadowski – the only way telegraphs could connect North American with the UK, for instance, was via cables laid along the sea floor.

[Darwin] thought there would be these fossilised things that might help us understand more about evolution – Rachel Mills

"In parallel to that, there's this tradition of marine natural history dredging, which is something that very much started in Britain, and a few other people took it up in the United States," says Rozwadowski.  "You think about Charles Darwin, when he was a student in Edinburgh, learned how to dredge."

Indeed, one of Darwin's peers, naturalist Edward Forbes, was an enthusiastic champion of marine dredging as an aid to study the life at the bottom of the sea. Darwin himself was unsure as to what might be found at such enormous depth, "but he thought there would be these fossilised things that might help us understand more about evolution", says Rachel Mills, the dean of environmental life sciences at the University of Southampton in the UK.

"You have these two parallel tracks that come together finally with Challenger," says Rozwadowski. "But there are actually two voyages before the Challenger, HMS Lightning is the first and then HMS Porcupine is second. Those are voyages organised between the Royal Society and the Navy – exactly how the Challenger would be organised, they're exactly the same group of people. Lightning and Porcupine are being sent out to see if you could do sounding and dredging to see what you might find."

With these exploratory missions achieved, the Challenger mission was approved by the British government in 1870, and the Royal Navy asked to provide a ship. Much like the Space Race a century later, the expedition owes its existence partly to national pride, says Penelope Hardy, a professor of history at University of Wisconsin La Crosse. "They are also in response to Scandinavian dredging that has found crinoids, these creatures previously been only known as fossils, and they've found them alive in the ocean. A lot of it's a technological story, part of why Challenger looks so groundbreaking is because they've reached the point where technology allows them to go deeper with this dredging than anyone has managed before.

The voyage took HMS Challenger to some of the most isolated islands in the world, such as Kerguelen (Credit: Universal History Archive/Getty Images)

The voyage took HMS Challenger to some of the most isolated islands in the world, such as Kerguelen (Credit: Universal History Archive/Getty Images)

"But one of the key things is they claim for themselves they're starting oceanography, so everyone buys that story,” Hardy says. “[American oceanographer Matthew] Maury is the first one to use the term oceanography in English. And what's important about him is he's really seeing the ocean as this system that needs to be studied together so that's what we think gof oceanography, right? Not a particular place that they're doing science but an approach.

Rozwadowski says the Challenger’s findings have only become more important, as we now fully understand the effects human activity is having on the oceans. "I argue the Challenger voyage is the culmination of decades of technology and organising and asking questions about the natural world," she says. The scientific reports that emerged from the voyage would become the "foundation for the modern science of oceanography", she argues.

When Challenger was picked by the navy for the expedition, she was little more than a decade old, having served a solid but unremarkable career. It would be science, and not war, which would make her name live on.

Most of the ship's epic journey was under sail

"They took the guns off, but they were still sailing under the naval flag," says Mills. "They were clearly confident they weren't going to be attacked, and they could swan around the world calling at any port they chose."

The Challenger's around the world journey would last 1,250 days. It would be arduous in the 21st Century, let alone in the 1870s. Though the ship had a small steam engine, this was mostly used to power the dredging platform or to keep the ship from drifting when it was making a depth sounding, rather than helping power it across the ocean. Most of the ship's epic journey was under sail.

Mills has some experience of what oceanographic voyages can be like – in the 1990s, early in her career, she took part in an expedition to the Mid-Atlantic Ridge on a Russian scientific vessel. Though some 120 years had passed, there were some similarities. "Life on board a Russian ship could be uncomfortable at times," she says. "While no-one was going to get scurvy, it's fair to say that the food we were eating was not a balanced diet."

The marathon expedition took the British crew as far afield as Japan (Credit: The Print Collector/Getty Images)

The marathon expedition took the British crew as far afield as Japan (Credit: The Print Collector/Getty Images)

Challenger set sail in December 1872 from Portsmouth, during a particularly cold and bitter British winter. The ship headed south towards Portugal, where chemist John Buchanan would later boldly claim the vessel had started an entirely new field of science. "Buchanan says in his writing later, 'the science of oceanography was born at sea', and he gives a date and a latitude and a longitude, when the Challenger does its first really deep dredge off the coast of Portugal," says Hardy. "They are absolutely claiming the origin for themselves."

When she set sail, the Challenger carried more than 180 miles (291km) of Italian hemp rope, enough to stretch from London to the Channel Islands

The Challenger was led by naval captain George Nares and chief scientist Charles Wyville Thomson, who would later be knighted for his work on the expedition. It was Thomson who had persuaded the Royal Navy to lend the HMS Lightning and Porcupine for those earlier dredging operations in the deep seas off the coast of Norway. The appearance of crinoids excited Thomson. But so too was the wealth of other animals that had been brought up from the very deep ocean. Thomson wanted to know what a longer, more ambitious voyage might find in deep places around the world.

The ship carried a team of five scientists, a prosector (one who cut up bodies for dissection) and an official artist, alongside 21 naval officers and 216 crew. "It's amazing to think of all these people tied up for three-and-a-half years sailing around the world," says Judith Wolf, a scientist at the National Oceanography Centre Liverpool who is also a member of the Challenger Society.

The Challenger was filled with equipment for its new role, from glass specimen jars and preserving alcohol to barometers, dredging equipment, water thermometers and special containers to scoop up animals and debris from the ocean floor and bring it back to the surface. "All the scientific chaps are on board, and have been busy during the week stowing their gear away," wrote steward's assistant Joe Matkin to his cousin shortly before the voyage started. "There are some thousands of small air-tight bottles, and little boxes about the size of Valentine boxes packed in iron tanks for keeping specimens in, insects, butterflies, mosses, plants, etc. There is a photographic room on the main deck, also a dissecting room for carving up bears, whales, etc."

Challenger visited was St Paul's Rocks in the Atlantic, where the vessel was moored using an elaborate system of ropes (Credit: The Illustrated London News/Getty Images)

Challenger visited was St Paul's Rocks in the Atlantic, where the vessel was moored using an elaborate system of ropes (Credit: The Illustrated London News/Getty Images)

There was rope, too – lots of rope. When she set sail, the Challenger carried more than 180 miles (291km) of Italian hemp rope, enough to stretch from London to the Channel Islands.

According to the Challenger Society, each sounding was more than a simple depth reading using a weighted line. Instead they were a process for several scientific observations: The exact depth was determined, samples of silt and water were brought up from the bottom, temperatures were recorded at a series of depths, and dredging and towing nets collected fauna.

"The Challenger carried out 362 soundings during her voyage," Wolf says. "Each time they had to do a sounding, they'd also lower a dredge and then pull up whatever they could." The dredge would spill huge amounts of gloopy mud – some of it the remains of long-dead marine life – onto the ship's deck. "It was drudgery," says Wolf. "The sailors themselves called it 'drudging'."

While the thermometers were not as precise as those used today, the rigorous methods used to mark the high and low temperatures in the water are of use to scientists even today, says Mills. "The readings weren't perhaps too accurate but they were precise, so scientists today can adjust for that… the difference between the top and bottom temperatures was very precise. That in itself is very useful for scientists today."

The Challenger sailed first down to the Canary Islands before crossing the Atlantic to Bermuda and across again to Cape Verde, with a diversion as far north as Canada along the way. From Cape Verde she crossed the Atlantic again, inching her way down the coast of Brazil before reaching Tristan De Cunha near the Cape of Good Hope in October 1873.

Challenger's crew boasted they had visited every continent except Antarctica

From there, Challenger traversed the vast, empty expanses of the southern Indian and Pacific oceans, so far south she encountered icebergs. By March 1874 she was in Australia, calling into New Zealand a few months later before sailing to the scattered islands of Polynesia and taking a circuitous journey around South East Asia. Nearly a year later she docked in Yokohama in Japan, before Challenger then surveyed islands across the Pacific and the coastal waters of South America before navigating around Cape Horn in January 1876. After another five months exploring various parts of the Atlantic, she returned home in May 1876. She arrived, however, with only around 140 of her crew on board. Deaths and desertions had taken their toll.

Challenger's crew boasted they had visited every continent except Antarctica. The extremes of temperature and sea conditions are testing even today. "I try to imagine how these people managed without the hi-tech fabrics and things to keep us warm," says Hardy, who is a US Navy veteran.  

"There was some good-natured ribbing by the naval personnel towards the scientists, some of whom did have some sea-time but most of whom didn't have extensive experience, making fun of them for not knowing the terms for stuff on board. As soon as they leave port they fairly quickly run into some heavy weather and the naval officers are like 'Oh good, it's a good shake down to make sure everything is all set', and all the scientists retire to their quarters and aren't seen again until the weather gets better."

The gentleman scientists and naval officers dominate the records. Finding the voices of the ordinary sailors is much more difficult, says Hardy. Steward's assistant Matkin's letters are perhaps the best record.

"He tells a lot on anecdotal stories which suggest the crew were less thrilled about all of this," she says. "Think about it, these guys are dredging up huge amounts of mud, essentially, from the bottom of the ocean and dumping it on deck, and all these sailors are having to do all the manual labour – and then clean it all up."

It was in March 1875 that Challenger made one of her most astounding discoveries, almost completely by accident. Near Guam, the crew took one of their regular soundings. The ship just happened to be above what we now know is the Mariana Trench, a vast channel between two tectonic plates which stretches nearly 1,600 miles (2,560km).

Challenger managed to stumble across it by accident, something Mills describes as "really serendipitous". The sounding measured a depth of 4,475 fathoms (26,850ft or 8.1km) and is the deepest part of the ocean to yet be discovered. Today we know the very deepest part of the trench as Challenger Deep.

 

An oceanic whitetip shark; the crew of the Challenger were reportedly obsessed with catching sharks during the voyage (Credit: Reinhard Dirscherl/Getty Images)

An oceanic whitetip shark; the crew of the Challenger were reportedly obsessed with catching sharks during the voyage (Credit: Reinhard Dirscherl/Getty Images)

Challenger's work was painstaking, and it vastly increased human knowledge of what lived so far below the surface. New species were discovered at an incredible rate. "Everywhere they stopped, they sent back crates of specimens as often as they could," Wolf says.

The specimens Challenger collected – from tiny shellfish to large ocean-going sharks – made their way back to England, and were further dispersed among scientific institutions across the world. "They made the decision to have the taxonomic groups studied by whomever was the expert in that area, whether they were German or American or whoever," says Rozwadowski. "That's one of the reasons why the reports had the lasting power that they had. They were both written by the experts, no matter who they were or where they were, and because they were written by those people they were looked upon as authoritative."

"The building of a network and a distribution for these results can also be seen as pretty fundamental to the formation of a field [of scientific study]," Hardy says.

It grew to 50 volumes, each the thickness of a family Bible – Judith Wolf

If the voyage itself was long, it was nothing compared to the time needed to collate everything they had found. The reports took 23 years to complete; Charles Wyville Thomson died a few years into the effort, apparently from the nervous exhaustion caused by dealing with the publishers.

“It grew to 50 volumes,” says Wolf. “and each of these volumes was the thickness of a family Bible.”

Thousands of the specimens preserved by the Challenger still exist, a large bulk of them in London's Natural History Museum, but others are secreted in the archives of institutions across the globe. There is a new impetus for investigating them, says Mills that could provide new and vital information to scientists today.

The increasing amount of carbon dioxide in the atmosphere from human activity is – little by little – causing the oceans to become more acidic. The Challenger's readings and specimens have "become a baseline for the start of the Industrial Revolution", says Mills. Animals samples from the voyage are still being used to understand how the oceans have changed since that time.

"If you're studying a certain shellfish, and you know that the shells are becoming thinner because of the rising acidity of the oceans, we have that record of what they were like 150 years ago thanks to Challenger," says Mills.

It's worth bearing in mind, too, that when Challenger was plying the world's oceans, there was no plastic. All of the thousands of animals the crew collected, and every single water sample taken, are free from plastic particles.

One hundred and fifty years after it set sail, the Challenger's painstaking work is opening up new ways to glimpse how our deep oceans are changing, far beyond our sight.

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