The recent unprecedented video footage of a giant squid filmed in its deep ocean habitat has renewed interest in the enormous — and yet still mysterious — species.
It's believed that giant squid (genus Architeuthis) can grow up to 55 feet long. The individual captured on video via a small submarine located in the North Pacific Ocean was about 30 feet long and silver and gold in color, marine biologist Edie Widder, who helped to shoot the footage, said. Her colleague Tsunemi Kubodera added that the squid was missing its two longest tentacles.
Cephalopod experts are intrigued by the world record footage.
"It was really thrilling to see the press releases concerning the filming of a living giant squid with a manned submersible," William Gilly, a professor of biology at Stanford University and the Hopkins Marine Station, told Discovery News.
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Gilly previously examined a 7-foot-long giant squid that weighed 300 pounds. It was found floating dead in Monterey Bay, Calif.
"It was missing the tentacles and its stomach had been removed through a hole in its body," he said. "Something strange must like to eat those parts, I guess!"
He also noted that the color-changing system, which functions using organelles called chromatophores that contain pigment and reflect light, was present very deep inside the giant squid's body cavity. In smaller species, this system is arranged only on the body’s outer surface.
In recent months, researchers have also learned more about giant squid eyes. The diameter of these eyes measures two to three times that of any other animal.
Dan-Eric Nilsson of Lund University determined that giant squid eyes measure 10 inches, making them about the same size as a large dinner plate. Big is optimal for sight in deep-water environments.
"For seeing in dim light, a large eye is better than a small eye, simply because it picks up more light," Nilsson said, explaining that the light isn’t from the sun, but rather from bioluminescence emitted by other deep sea species, such as huge and hungry sperm whales.
This bioluminescence, he explained, is “light produced by small gelatinous animals when they are disturbed by the whale moving through the water. It is well known that bioluminescence can reveal submarines at night, and diving sperm whales will become visible for the same reason."
Bioluminescence even played a key role during the recent filming in about 3,000 feet of water near Japan. Widder, Kubodera and their crew used a lure that mimicked the bioluminescent display of jellyfish in order to attract the giant squid’s attention.
Despite the footage and other recent research, there are still more questions than answers about giant squid.
Gilly, for example, mentioned that the following questions remain: What are their daily behavior patterns? Do they rise toward the surface at night like many other large oceanic squid, or do they remain deep all the time? How can they tolerate the very low oxygen levels at great depths? How rapidly can they swim? What do they eat, and how do they catch prey with their very long tentacles? How many of them are there in any one place? Do they travel in groups like other squid? If so, do they show group behaviors associated with hunting, mating or defense? How big and old can they get?
"These questions can, at least in theory, be answered by existing technologies, including manned and remotely-operated submersibles for filming," he said.
He added that another important tool could be video and archival electronic tags for filming interactions with other animals, monitoring swimming activity, recording migration patterns, and documenting environmental parameters — such as temperature, depth, light and oxygen — as the squid moves up and down in the water column.
Such tags are programmed to release at a certain time, permitting researchers to non-invasively study the collected data. Gilly and his colleagues are using these techniques to monitor large Humboldt squid in the Gulf of California and off the Pacific coast from Baja California to Canada. No one, though, has yet been able to successfully capture and tag a giant squid for release back into its habitat.
Gilly said Kubodera might be the one, in the future, to solve this problem. In the meantime, Gilly plans "to wait until Jan. 27 like everyone else" to see the rare giant squid footage.
Discovery Channel's Monster Squid: The Giant Is Real, premieres on Sunday, Jan. 27 at 10/9c as the season finale of Curiosity.
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