Giant Squid Nearly Went Extinct, New Analysis Of DNA Reveals (VIDEO)

New evidence that the world's giant squid all belong to one species also suggests that the mysterious creatures had a close call with extinction, a report from the journal Nature suggests.

The giant squid's genetic uniformity hints at a "past evolutionary bottleneck" that may have almost wiped the giant squid off the map.

Of the 43 specimens of giant squid, or Architeuthis, examined in the genetic study, researchers found surprisingly little genetic variation in the creatures, despite having collected the samples from oceans around the world, including the waters of Spain, South Africa, New Zealand and Japan.

The only other marine creature with such low genetic diversity is the basking shark, Cetorhinus maximus, which is believed to have rebounded from extinction, the report stated.

Like the basking shark, the giant squid may also have come close to extinction and then rebounded, and that event may have happened in the recent past.

"What could possibly have caused giant squid to vanish on such a global scale? And what changed that allowed them to spread again?" said Phillip Morin, a molecular geneticist at the Southwest Fisheries Science Center in La Jolla, Calif., according to the report.

Morin speculated that there may be some connection with population decline associated with the giant squid's main predator, the sperm whale.

What's fascinating is that sperm whales, a globally distributed and (formerly) abundant predator of giant squid, also exhibit extremely low genetic diversity. It would be very interesting to compare patterns and timings of this low diversity and see if they correspond to some historic event," he said.

Exactly why the population of giant squid dropped is as much a mystery to researchers as the squid themselves.

"It is really damned hard to say," said Thomas Gilbert, a geneticist at the University of Copenhagen and an author of the study, as reported by Nature. "I just can't conceive of predation being responsible. If anything, I'd put my money on changes in ocean conditions somehow altering the nutrient-rich deep waters that these animals need."

The original study is published in the journal Proceedings of the Royal Society B.