Octopus Recorded More Than One Mile Deeper Than Previously Sighted
The deepest-ever sighting of an octopus has been recorded in the Sunda Trench (also called the Java Trench), increasing the known habitable range of cephalopods across the world's oceans, according to a report published in the online journal Marine Biology.
Two specimens of the Grimpoteuthis genus, commonly known as 'Dumbo octopuses' because the fins that are located just above its eyes resemble the ears of the Disney cartoon elephant, made an appearance during two separate deployments of a deep-sea 'HD video lander' during 'The Five Deeps' Expeditions of 2019. The landers, a metal frame with camera and bait attached, were deployed from the research vessel DSSV Pressure Drop under the direction of the study's lead author Alan J Jamieson, of the School of Natural and Environmental Sciences at Newcastle University in the UK.
According to the paper's abstract, 'Cephalopoda are not typically considered characteristic of the benthic fauna at hadal depths.' In other words, they are not generally thought to be found on the sea-bed deeper than a depth of 6,000m – the hadal zone. The previous deepest photographic record of an octopus was taken at 5,145m (3.2miles) of depth, however, samples taken from deep-sea trawl nets implied that cephalopods might exist as deep as 8,000m.
The two specimens recorded by Dr Jamieson and his colleagues were sighted at 5,760m (3.6 miles) and 6,957m (4.3 miles) respectively, increasing the known depth range of the entire cephalopod class by 1,812m (1.1 miles) and expanding the areas of the ocean where they may be found from 75 to 99 per cent of the global seafloor. In both cases, the octopus seemed to ignore both the lander and the bait, but spent time foraging in the sea bottom, possibly taking advantage of the unexpected light source.
Where the depth range of octopuses and other members of the cephalopod class has been inconclusive in the past, partly due to the immense difficulty in observing live specimens in situ, the new paper provides 'unequivocal' proof that they are capable of existing much deeper than previously reported.
'The laws of marine ecology and marine biology are actually much the same,' said Dr Jamieson in an interview with the BBC, 'and we need the Dumbo octopus out there to blur that line between the depths we think we care about and the depths we don't. This idea that only animals in a kind of Victorian freak show live at depth isn't right.'
The original paper 'First in situ observation of Cephalopoda at hadal depths (Octopoda: Opisthoteuthidae: Grimpoteuthis sp.)' by Jamieson, A.J. and Vecchione, M. is published in Marine Biology under a Creative Commons license at https://doi.org/10.1007/s00227-020-03701-1