Biologists have published a video that captures some of the least studied inhabitants of the deep sea. We are talking about deep-sea squid from the genus Magnapinna.
Magnapinna are known for their bizarre anatomy. They have huge fins: they are much larger than other squids. Therefore, these animals are also known as large-finned squids. But what is most impressive are their tentacles. They reach eight meters (!) In length. This is several times the body length of the mollusk.
Magnapinna are also famous for their strange habit of bending the tentacles at right angles, as if the hands are at the elbow. It is not clear why they are doing this. However, little is known about large-finned squids.
The fact is that these creatures live at a depth of 1–4 kilometers, in the kingdom of eternal darkness and terrible water pressure. They never seem to float higher, so it is extremely difficult to observe them. Magnapinna has only been featured on photo and video tapes a dozen times. Scientists still do not know how these creatures live and what (more precisely, who) they eat. This is why biologists are so interested in footage taken in the Great Australian Bight off the southern coast of Australia.
Little is known about the deep-sea fauna of those places. Therefore, the researchers launched a real hunt for marine life. Scientists used cameras on unmanned underwater vehicles, as well as a camera that was towed by a surface research vessel.
For several years, underwater and surface vehicles have covered 350 kilometers along the bay and filmed 75 hours of video. And only in two places large-finned squids got into the frame.
For the first time, scientists were lucky in November 2015. They filmed two cephalopods at a depth of over 2100 meters. They appeared in the frame at an interval of 12 hours and were in the field of view of the camera for four seconds each.
The next “catch” happened in March 2017 at a depth of more than three kilometers. In a little more than a day, representatives of the genus Magnapinna got into the frame three times . The longest video, which captured the mysterious animal, lasted almost three minutes.
Accurate morphological measurements using laser beams showed that different individuals fell into the frame all five times.
Scientists emphasize that until now, large-finned squids have only been observed twice in the Southern Hemisphere, and never before off the coast of Australia.
But it’s not only that. The cameras captured behavioral strategies that were never seen in Magnapinna .
For example, biologists have observed for the first time how squid adopts their trademark “arms bent at the elbows” position in a horizontal position. Previously, it was only fixed when the body was upright. Scientists still don’t know why molluscs do this. Perhaps this is how they catch small prey.
The researchers also found that one of the squid suddenly twisted its tentacles into a spiral. Previously, this behavior was observed only in the cephalopod mollusc with the eerie name hellish vampire ( Vampyroteuthis infernalis ). Cameras have recorded other examples of the behavior of these strange creatures, the meaning of which has yet to be clarified.
Details for specialists are described in a scientific article published in the journal PLOS One.