Winkelmann, from the University of Copenhagen's Natural History Museum of Denmark, and colleagues studied the mitochondrial genome of tissue samples from 43 such giant squid. "Mitochondrial" refers to a type of DNA inherited only through the female line. The squid came from all over the world, including waters off of California, Florida, Spain, Japan and New Zealand.
Incredibly, all had the same basic mitochondrial genomes. If there is just one giant squid species, as the researchers suspect, then adults must travel huge distances. Younger squid might disperse via drifting.
BLOG: Giant Squid Filmed in Pacific Depths
Giant squid might also be more plentiful than previously thought. But the lack of genetic diversity could make this species more vulnerable to human impact. Back in the day, fishermen rarely encountered the deep-dwelling squid. Now, with modern trawling equipment and huge fishing operations, the squid are more likely to become by-catch.
Pollution and climate change could also hurt the squid, as could loss of their food sources. They are thought to primarily feed on deep sea fish and other, smaller types of squid.