Full Fathom 5000 The Expedition of HMS Challenger and the Strange Animals It Found in the Deep Sea

Biologist Graham Bell is based at McGill University in Montreal, Canada, where he teaches, amongst others, a zoology course. Since so many of the main groups of animals live in the sea, preparing for this course meant reading marine biology literature and thus encountering the unavoidable references to the Challenger expedition. Before long, he found himself making notes about the animals discovered, tracing the voyage on a map, and scrutinizing species lists until, rather amusingly I think, "it became easier to write the book than not" (p. 2). Most literature on the expedition focuses on the shore visits in exotic places. Bell instead largely omits these and puts the animals centre stage. The result is a nicely paced and balanced book that goes through the trip chronologically, discussing notable animal discoveries. He also gives surprising insights into the trip, adds relevant digressions about what we have learned since, and presents it all with the occasional well-placed dash of humour.

In the 1800s, we had no good idea about the deep sea and whether anything lived there. A brief first part introduces, amongst others, the precursor role of Edward Forbes and his azoic hypothesis, the committees involved, the ship, the crew, and the scientists. The bulk of the book then takes you through the different legs of the cruise in 14 chapters. A menagerie of previously unknown animals was hauled up from the deep over the next 3½ years. Colonial gorgonians (deep-water corals), barnacles with extreme sexual dimorphism, tripod fish that stand above the sediment on greatly elongated fins, polychaete worms that live inside sponges, their branching body all anus and one head... There lived animals in the deep alright.

These entries alternate with scenes from life on board. Several of the scientists and officers kept journals and afterwards wrote travel narratives on which Bell draws. Next to the successes, it also shows the boredom that set in as the expedition was a rather dull, repetitive affair, taking the same measurements and samples at 348 locations around the globe. By the time they reached the Central Pacific, some 2½ years into the trip, the naturalists were ready to go home, and journal entries sometimes passed over whole legs of the trip. The ~200 crew members were virtually all illiterate, with the exception (as far as we know) of assistant steward Joseph Matkin. A trove of letters home was discovered in 1980 and published in an annotated book. Bell gratefully mines that unique source for the proverbial "unauthorized version of the voyage" (p. 37).

There is a social justice streak running through this book, with Bell pointing out issues so evident in hindsight. There was extreme income inequality between the upper echelons and the crew, making this "not exclusively a modern phenomenon" (p. 43). Workplace accidents that would grind an operation to a halt today were an accepted fact of life. Probably the most tragic incident shows the impact of social class. When two people were urgently called to meet HMS Challenger at the island of St. Vincent to replace lost crew members, they arrived on the same boat, both short of money. But whereas the new schoolmaster was denied help by the British Consul, went looking for food, got lost, and died, likely of heat and thirst; the new sublieutenant was provided with board and lodging: "he was, after all, an officer and a gentleman" (p. 117).

Bell furthermore offers interesting asides on science history. One example is the infamous Bathybius haeckeli episode. One of Challenger's goals was to confirm the existence of a purported missing link between living and non-living matter that turned out to be an inorganic precipitate that formed when seawater reacted with the preservatives used in bottles with deep-sea sediment. Another example is how the aforementioned azoic hypothesis was revised repeatedly. Though the original formulation had been decisively disproven, could there still be a much greater depth below which life could not exist? When they accidentally found one of Earth's deepest marine trenches, now called the Challenger Deep, they inexplicably deployed neither dredge nor trawl to check. Or could life perhaps survive both near the surface and at the bottom, but not in between? Just as important as what the scientists caught, is what they missed. Their equipment was rudimentary, unable to sample both very small organisms and the gelatinous creatures we now know occur throughout the water column.

Given that Bell authored the textbook The Evolution of Life, I should not have been surprised that he makes nicely formulated, thought-provoking observations on evolution. He mentions its tendency to modify existing structures rather than innovate completely novel ones. He flips the script on our perception of gelatinous creatures, arguing theirs might well be "the default option for animals" (p. 280) given the deep sea is the planet's largest habitat. Then there is the difficult question of which features to use in taxonomic classification. Bell reminds you that both ancestry and convergent evolution can result in character resemblance between different groups.

The final three chapters briefly trace what happened to the ship, the people, and the collected animals. They offer a gentle goodbye for the reader, as the trip ended rather abruptly: the crew disbanded, the six scientists never met each other again, and the ship was mothballed and unceremoniously scrapped for copper in 1921. Though the Challenger expedition could have ended up as yet another forgotten Victorian oddity, it instead became legendary. Bell sees two reasons for this. First was John Murray who played a minor role while on board but afterwards became the driving force that saw the project through to completion in 15 years, ensuring specimens were distributed globally to relevant specialists, data was analysed, and results were written up. Second was the worldwide dissemination to institutes and libraries of the massive 50-volume Challenger Report, grudgingly financed by the Admiralty.

Bell has gone to great lengths, consulting both primary and secondary literature regarding the expedition, as well as modern research on many of the animal groups discussed. In following the expedition chronologically from beginning to end, it provided the full meal that Macdougall's Endless Novelties of Extraordinary Interest did not quite give me. The two books nevertheless stand shoulder to shoulder, each providing its own interesting and worthwhile perspective on the Challenger expedition.