Very little is known about giant squid, the huge, deep sea cephalopods that are incredibly hard to find.
But new data shows that all giant squids are members of the same species.
The research, conducted by an international team, observed 43 tissue samples taken from dead squid specimens. Giant squid are famously shy; no photographs of the giant cephalopod were taken until 2002. Therefore, the researchers had to observe squid that were found inside the stomachs of beached sperm whales, were caught by accident, or were stranded. Using DNA sequencing techniques, the team found that all giant squids are one, varied species.
"Your general [giant] squid is a long, scrawny beast: it's got a long thin body and long thin arms," Professor M. Thomas P. Gilbert told BBC Nature. "But off [the coast of] Japan for example, they're much shorter and stubbier. Their arms are fatter and much shorter." Gilbert works at the Natural History Museum of Denmark and conducted the research with a team from Australia, France, Ireland, Japan and Portugal and his colleagues from the University of Copenhagen.
"There's normally local distinction between [animals] genetically," he said. "Things that live in one area eventually become different from things in other areas but [giant squid] are basically identical everywhere."
Gilbert points to the squids' far-reaching migration as a reason for how a globally distributed animal's population can be so similar genetically.
"We speculate the larval stage must drift globally in currents then dive to the nearest dark, deep spot when they are large enough, thus stopping any [population] structure appearing," he said. "Instead of the adults and their young living in the same place, the young distribute to a completely new place on the Earth every time."
Scientists have also suggested that giant squids have recently experienced a population boom. This is either due to an increase in their prey's populations or because of falling predator populations.
