The azoic hypothesis
The deep sea is teeming with a wide variety of flora and fauna that are specially adapted to live in the extreme conditions. Before the 20th century nothing was known about life in the deep. It was presumed that the enthronement was devoid of life, in the 5th century Socrates wrote “…Only caverns and sand and measureless mud, and tracts of slime wherever there is earth as well, and nothing is in the worthy to be judged beautiful by our standards.” This was confirmed in 1843 when Edward Forbes set sail in the Aegean sea concluding that there was no life bellow 300 fathoms (550 meters). He wrote “As we descend deeper and deeper in this region its inhabitants become more and more modified, and fewer and fewer, indicating our approach towards an abyss where life is either extinguished, or exhibits but a few sparks to mark its lingering presence.”
Poor Experimental Design
One of the reasons Forbes failed to recover samples for the deep collected data during his expedition is because water in the Aegean sea is very oligotrophic (nutrient poor) therefore the depths are particularly barren. Instead he should have sampled a variety of different oceans before making such a broad conclusion.
Another problem with the design was that the scientific sampling for the deep ocean at the time was poorly adapted from commercial fishing gear. Forbes adapted oyster fishing baskets that would quickly fill up with sediment
Ignoring Other Evidence
Before Forbes went to the Aegean sea there was already evidence that life existed bellow 300 fathoms. Risso found life in the Gulf of Genoa at 1,000 m 70 years earlier. More evidence to the contrary was collected by Captain John Ross who was instructed to collect samples from as deep as 850-200 meters whilst captaining the HMS Erebus and HMS Terror between1839 and 1843.
The azoic hypothesis was accepted by scientific community many people disagreed with it. Sir James Clarke Ross, a navy captain, wrote “Although contrary to the general belief of naturalists, I have no doubt that from however great a depth we may be enabled to bring up the mud and stones of the bed of the ocean, we shall find them teaming with animal life; the extreme pressure at the greatest depth does not appear to affect these creatures…”
Why was this evidence ignored by the scientific community? Forbes did examine Captain John Ross’s samples, however, Forbes notes have been lost so we will never know what he thought of them was known to be unreliable. He reported his findings to be from 800 fathoms (approximately 1465 meters) but they were actually from 600 fathoms (approximately 1095 meters) due to poorly managed equipment. This was just a mistake on Ross’s part but he was also known to be purposely deceptive, reporting a range of fictitious mountains blocking Lancaster Sound.
Disproving the Hypothesis
25 years after Forbes published, Norwegian zoologist Michael Sars dredged of the Scandinavian coast and discovering hundreds of new species between 200 and 300 fathoms. Despite this the scientific community still stood by the azoic hypothesis, the depth was considered to be too shallow to disprove Forbes. George Charles Wallich and Captain Sir Leopold McClintock on the HMS Bulldog dredging at 1260 fathoms near Iceland, but still the azoic hypothesis was accepted.
Wyville-Thomson and Carpenter dredged in deep waters off the coast of the UK, Spain, and The Medeterain. They modified Forbes dredges by adding ropes and making the mouth of the net much larger. This proved “‘beyond question that animal life is varied and abundant, represented by all the invertebrate groups, at depths in the ocean down to 650 fathoms at least.” Finally the azoic hypothesis was disproved.
Between Forbes expedition and Wyville-Thomson and Carpenters there was a vast amount of contradicting the azoic hypothesis but the prejudice and biases of the scientific community meant that this evidence was not accepted. How creatures survived in the deep became one of the biggest mysteries in the field until the Challenger expedition of 1872–1876.