Deepest-dwelling squid observed at depth of 6,200 meters

A pair of researchers, one with the University of Western Australia, the other NOAA National Systematics Laboratory, has recorded on video a young bigfin squid swimming just above the seafloor at an approximate depth of 6,200 meters. In their paper published in the journal Marine Biology, Alan Jamieson and Michael Vecchione describe how they captured video of the squid while they were looking for a sunken warship.

Jamieson and Vecchione were operating a manned submersible hunting for the USS Johnston, a navy destroyer that was sunk during World War II, in the Philippine Trench. After diving to near the bottom of the trench, the researchers spotted the squid, which is relatively easy to recognize due to its distinct swimming style and the very long black fins that trail behind it as it swims. The researchers captured the squid swimming on video, though not at close range, but just close enough to confirm it was a bigfin. The finding represents a depth record for a finned octopod—the previous record-holder was another that had been spotted at approximately 4,700 meters down.

The researchers also spotted several cirrate octopuses, which are more famously known as dumbo octopuses because their fins resemble the cartoon characters' ears. They were all at nearly the same depth as the bigfin. The researchers' observation of the dumbos was only the second sighting of them swimming in such deep water. It has been suggested that the prior sighting was a fluke, but this new second sighting shows that it was not. The dumbos looked somewhat different from the others that had been swimming at such depths, which indicates they were likely a different species.

The findings show that multiple types of cephalopods live in very deep parts of the world's oceans. This raises questions about how the creatures are able to live at such depths, where pressures can be as great as 600 times that of the surface.