"By hunting deep in this cold, hypoxic environment at night, as well as during the day, sperm whales may favor jumbo squid that are in some way compromised and thus easier to capture," the authors wrote.

"This research provided a unique opportunity to learn more about two species that are very difficult to study in their natural habitat," Davis noted. "In the future, this co-tagging approach should yield new insights into predator-prey interactions with other pelagic species that are large enough to carry electronic tags."

Added Gilly: "Although human observers at the surface of the sea must still infer what the mysterious squid and the leviathan are doing at great depths, the use of modern electronic tagging methods will surely guide those inferences, leading to insights that even Melville might not have imagined."