Benthoctopus sp., caught with the Agassiz trawl in Pine Island bay, Amundsen Sea. BASBy Jan Strugnell, British Antarctic SurveyI am a molecular phylogeneticist at Cambridge University (funded by a Lloyd’s Tercentenary Foundation Fellowship) and I am investigating the molecular evolutionary history of Antarctic and deep sea octopus. I am therefore on board to sample any octopus we catch in our trawls for later DNA sequencing and also to preserve them for later investigation and identification. Specifically I am using octopus as model organisms to test the hypothesis that the Antarctic has acted as a centre for evolutionary innovation and radiation and as a source of taxa that have invaded the deep sea. I am also interested in investigating how past glaciation in Antarctica has effected octopus speciation, and also at the effect of the Antarctic Circumpolar Current on octopus dispersal and population genetics.
As with all other groups of animals, nothing at all is known of the octopus fauna in the Amundsen Sea as no one has sampled here previously. Therefore any octopus we catch from this region is a new record of life in the Amundsen sea! Despite the fact there are three genera (Adelieledone, Pareledone and Megaleledone) (and upwards of 20 species) of octopus which are known to be endemic to, and only found in, other regions of the Southern Ocean, I must admit that I was initially quite nervous that we would not catch any octopus! Thankfully my fears were unfounded and so far we have managed to catch a range of really interesting octopuses in the Amundsen sea.
We have caught 2 cirrate octopus both from 500 m and 1000 m depth. These are the ‘dumbo’ type octopus which have large fins on either side of the mantle and they undulate these for propulsion through the water column.
Photo: cirrate octopus specimen caught with the Agassiz trawl in Pine Island Bay, Amundsen Sea. BAS
We also caught an individual of Megaleledone setebos from 500m depth. This is by far the largest octopodid in the Antarctic, with a total length known of almost 1 metre! This individual created lots of interest from everyone on board when it was caught as it is by far the largest animal we have caught so far! This species is known to be of some ecological importance in the Southern Ocean as beaks of this species have been found in the stomach contents of Elephant Seals and Weddell Seals.
Photo: Pareledone specimen, caught with the Agassiz trawl in Pine Island Bay, Amundsen Sea. BAS
We have caught a number of individuals belonging to the genus Pareledone from 500m depth. Eight new species of Pareledone have been described in the last few years and it is highly likely that some of the individuals caught from this region will be species new to science!
From February 19th until April 10th 2008, British scientists are embarking on the British Antarctic Survey’s (BAS) research ship RRS James Clark Ross. This project is part of the BAS program known as BIOFLAME (Biodiversity, Function, Limits and Adaption from Molecules to Ecosystems). Scientists onboard are studying marine fauna from the ocean shelves and slopes from a little-known region, the Bellingshausen and Amundsen Seas. This is part of the Census of Antarctic Marine Life. Follow their route on the CAML-Cousteau Expedition tracking page.