The researchers detail their findings in the March 12 issue of the journal Marine Ecology Progress Series. "We propose that jumbo squid are more susceptible to predation while they are recovering at depth immediately after a deep nighttime dive," Gilly said. Surface waters might stress the squid out, Gilly suggests, perhaps due to the heat, which at up to 82 degrees Fahrenheit is sweltering for squid, or due to the high oxygen content. "Perhaps it's the only way they can catch them, but no one has ever seen a sperm whale feeding in the wild, so nobody really knows how they capture their food."Ĭuriously, squid often made rapid nighttime dives from the surface to depths that whales frequent. The electronics tags revealed whales spent three-quarters of their time ranging from 600 to 1,300 feet day and night, "whether squid are there or not," Davis said. Such small marine prey species typically migrate toward the surface after dusk to feed on phytoplankton, or photosynthetic sea life, and return to deeper waters during the day to escape tuna and other predators that rely on eyesight to hunt nearer the surface. The main prey of octopuses are shellfish and crustaceans, while sharpshooters like cuttlefish.
![are squids carnivores are squids carnivores](http://www.divedownbelow.com/wp-content/uploads/2010/07/cuttlefish-04.jpg)
One likely explanation for this rise at night is that they were following prey such as bioluminescent lanternfish and krill and other crustaceans. Squid are important because they both compete with and serve as prey for higher carnivores, and thus must be carefully considered.