Flub of Forbes

Let’s start off with the good stuff – a short video from the dive on May 11th:

I grew up in Texas – a state where my biology teacher during my senior year of high school was forced to state that evolution was only a theory, and in no way were students forced to believe or adhere to any of the ideas presented. Growing up in this kind of environment, it always irked me how people could remain so rigid in their creationist beliefs, despite the overwhelming amount of evidence that contradicted every fiber of their argument.

evolutionlabel I used to think this kind of behavior was unique to the debate between creationism vs. evolution. But no – it’s all-encompassing; it’s human. We all have our world views, pieced together from our individual experiences and predispositions. We all tend to cherry-pick the information that suits our worldview the best, unconsciously or sometimes purposefully dismissing information that challenges it in any way. We all do this, but some people crank up the spam filter to the point of absurdity.

In 1818 in search of the Northwest Passage, Sir John Ross dropped a little contraption (what he called a “deep-sea clamm” – a sediment scoop) down 1,000 fathoms into the ocean (too generous of an estimate, but still very deep). Upon hoisting the scoop back up on the boat, Ross found the mud teeming with worms and starfish – a good indication that the deepsea may harbor life.

Fast-forward twenty years: Edward Forbes  – an aspiring artist, turned medical student, turned expert deepsea dredger – set sail as a naturalist aboard the H.M.S. Beacon. The ship’s mission was to survey the Aegean Sea, and Forbes was assigned the task of dredging the ocean’s depths up to 1380 feet (much more shallow than Ross’s dredging). Forbes noticed that the abundance of deepsea creatures decreased the deeper he dredged, and his speculative conclusions were reported to the British Association for the Advancement of Science: “the number of species and individuals diminishes as we descend, pointing to a zero in the distribution of animal life as yet unvisited.” And thus, the “azoic zone” hypothesis was born. Although Forbes himself was not adamant about his conclusions, his followers were resolute – nothing existed in the abyss. Nothing.

We the people of modern times and 20/20 hindsight can read this and giggle. Or maybe not…there is a surprisingly large fraction of people who still believe that the deepsea is an empty black space. But hey – at least we’re not in the same boat as Francois Peron who believed that the sea floor was covered with a thick layer of ice (impossible – water is more dense than ice). This idea, however, was simply the product of a time (19th century) when virtually nothing was known about the deep sea. People also thought that deepsea water was so dense that nothing could sink through it. Imagine the Titanic, suspended motionless thousands of feet below the surface – unable to sink to the ocean floor.

Forbes azoic zone hypothesis was not so ridiculous at first, but his followers’ insistence on its veracity certainly was. Decades after Forbes initial hypothesis caught fire, ships exploring routes for undersea telegraph cables were pulling up animals clinging to the sounding lines. One ship, the Bulldog, pulled up 13 starfish on their sounding line. Aghast, “azoic zone” clingers surmised that starfish at shallower depths had “convulsively braced” the sounding line while it was being pulled to the surface. Good one, guys.

Don Walsh and Jacques Piccard in Bathyscaphe Trieste

Don Walsh and Jacques Piccard in Bathyscaphe Trieste

Forbes died in 1854, a century before it was conclusively proven that the deepsea was, in fact, full of life. Ironically, Forbes is known as the father of deepsea biology, despite his hypothesis which basically dismissed the nascent field. Yet, Forbes spurred a flurry of naturalists to test his ideas. Between the mid-1800’s and the mid-1900’s, the azoic zone hypothesis steadily eroded. When Jacques Piccard and Don Walsh descended 35,800 feet to the bottom of Challenger Deep in the Mariana Trench in 1960, they looked out their submarine window to see a flatfish swimming by; Forbe’s hypothesis was officially debunked and promptly jettisoned by the scientific community.

Epibenthic sled

Epibenthic sled

Since then, numerous studies have shown the incredible amount of diversity which exists at these crushing depths. In the 1960’s, Howard Sanders and Robert Hessler used an “epibenthic sled” to gain a better understanding of species existing in mud (“infauna”) and just above mud (“epifauna”) in the deepsea. Dragging this device along the ocean floor for one hour at 4600 feet  resulted in 127 different species and 25, 242 organisms. The deeper they went, the less they brought up , affirming observations from previous research. Despite the negative correlation between depth and organism abundance, Hessler and Sanders demonstrated what an incredibly diverse world exists in the recesses of our oceans.

In the past 60 years, a good deal of research (though not nearly enough) has documented the tremendous diversity of the deepsea. One scientist, Frederick Grassle, has dedicated his life to studying the deepsea. He and his colleague Nancy Maciolek developed a sampling method which used a box core to precisely quantify species present in one square foot of the ocean floor. In one study, they took 233 box cores from a 110-mile stretch of ocean floor (7,000 feet) off the coast of New Jersey and counted 798 species. Additionally, each box core sample brought up an equal number of new species. So, think about it – box core number 233 brought up the same number of new species as box core number 1. In no way was Grassle even close to finding the number of species that existed at that depth! Thanks to Grassle’s work (and many others), it’s now thought that the deepsea may be more diverse than tropical rainforests – the most diverse ecosystem on terrestrial Earth.

I have to admit, before my first dive in the sub, I didn’t think there was much more than jellies and anglerfish (thanks Nemo). Thus far, I’ve spent no more than 20 hours in the sub and seen more creatures than in two weeks of hiking through Honduran rainforest. I think Grassle may be right…

Grassle, J.F. (1989) Species Diversity in Deep-sea Communities. Trends in Ecology and Evolution 4(1): 12-15.

Kunzig, R. (2000) Mapping the Deep. New York, W.W. Norton & Company.

Kunzig, R. (2003) Deep-Sea Biology: Living with the Endless Frontier. Science 302, p. 991.

Carson, R. (1951) The Sea Around Us. Oxford University Press.


~ by twonakedapes on June 1, 2013.

3 Responses to “Flub of Forbes”

  1. Wow! Great article A! Thanks for sharing. Well researched and entertainingly written!

    Onward and downward!!


    Paul Cell: +1 (435) 363 6131 Skype: paul.macca.mcmanus

    Sent from my phone – apologies if it’s brief!

  2. […] deep sea is devoid of life thanks to the entrenchment of Edward Forbes’ azoic theory (see my Flub of Forbes […]

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