"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.