[ad_1]
The bigfin squid (Magnapinna) is one of the most elusive creatures we know.
It inhabits the dark depths of the ocean and is an extremely rare sight, with only a dozen confirmed sightings worldwide.
Now, for the first time, black tip squid has been seen off the coast of Australia not once, but five times – and each sighting was a different individual. It is not enough to call the region a Magnapinna hotspots, but new observations revealed new behaviors, underscoring the importance of capturing images of deep-sea life in its natural habitat.
“These sightings, the first from Australian waters, reinforced the hypothesis of a cosmopolitan distribution and indicated a local cluster distribution with squid that are in close spatial and temporal proximity to each other,” the researchers wrote. in their article.
Squids are strange and mysterious beasts. Their bodies look quite typical for a squid, albeit with much larger fins than usual. But their arms and tentacles are truly distinctive, with surprisingly long filament tips, causing their limbs to reach lengths of over 8 meters (26 feet), many times longer than the squid’s body. Held at an angle perpendicular to the body, the limbs also give it a strange “elbow” appearance.
Because they live in the bathing-pelagic zone, between 1,000 and 4,000 meters (3,280 and 13,120 feet) deep, it is not easy for us to study these squid. At this ocean depth, sunlight never penetrates and the water pressure is overwhelming.
However, remote-controlled vehicles can get to where humans fear trampling, and sightings have gradually increased over the past two decades.
It was the very equipment that marine scientists were using to explore the deep waters off the south coast of Australia. In a region known as the Great Australian Bight, where almost nothing was known about deep-sea fauna, scientists deployed remote-controlled vehicles and a camera towed by the Marine National Facility research vessel. Investigator as part of an intensive research program to catalog life far below the waves.
https://www.youtube.com/watch?v=hRWd3oDlUrM
On five separate occasions, coarse fin squid showed up in the images obtained from the instruments.
The towed camera captured two squid, shooting them for four seconds each at 2,110 and 2,178 meters, at a site in November 2015. The two sightings were approximately 12 hours apart.
The ROV spotted three squid at another site in March 2017 at 3,002, 3,056 and 3,060 meters below the surface. Because the ROV is more flexible, it was able to track the squid, capturing longer videos of each; the longest was just under three minutes. All three sightings occurred over a 25-hour time period.
Morphological measurements with coupled lasers suggested that each of the five squid sightings were a separate individual.
Magnapinna shot at 3,056 meters. (Osterhage et al., PLOS One, 2020)
“These sightings represent the earliest records of Magnapinna squid in Australian waters, and have more than double the known records of the Southern Hemisphere, “the researchers wrote in their paper.
Even so, sightings were rare – the survey spanned more than 350 kilometers of the Great Australian Bight and recorded 75 hours of video. The beasts were only seen in those two places in those two times.
“All Magnapinna sp. sightings in the Great Australian Bight were made in areas of predominantly soft sediment, in the ground of low-slope erosion channels and in the upper section of the underwater canyon, “the researchers wrote.
“Submarine canyons and similar etched features often support high productivity and diversity in the depths of the sea, and these locations may reflect the habitat preference of Magnapinna sp. “
Although the sightings were brief, they still provided observations of some squid behavior. There was, of course, the characteristic “elbow” pose with the tentacles extended outward, then bent at an angle of nearly 90 degrees. Previously, this was mainly observed while the squid was vertical, but the new footage showed this pose in a horizontal position.
Since the tentacles appear to be quite sticky, this could be a feeding behavior, waiting for some unfortunate creature to bump into long limbs like an insect against flypaper, but we still don’t have enough information to determine for sure.
Another behavior the team observed was the squid holding an arm perpendicular to the body as it moves from a horizontal to a vertical position. This is similar to the dorsal arm curl motion seen in a number of squid, but why bigfin squid do this is still a mystery.
In a completely new behavior, the researchers also saw one of the squid wrapping its filaments close to its body. Previously, the only cephalopod seen doing something similar was the distant relative hell Vampyroteuthis, another bath-pelagic creature that uses its filaments to feed.
“Although there are obvious differences between the filamentous appendages of devil V. is Magnapinna squid … the winding behavior may represent an efficient biomechanical solution for the retraction of such long and thin filaments, “the researchers wrote.
It’s alluring and enticing stuff: new information highlighting how little we know about these strange, silent creatures and the deep, dark underwater world they live in.
The research was published in PLOS One.
.
[ad_2]
Source link
