After capturing Captain Nemo's submarine Nautilus with its frightening tentacles, dragging generations of readers to "Twenty Thousand Leagues Under the Seas", the legendary giant squid is finally ready to reveal its secrets: this time not from the pages of a book by adventure but of a scientific journal, GigaScience, where the entire sequence of its genome is published for the first time.
The giant squid in an illustration of 'Twenty Thousand Leagues Under the Seas' (source: Alphonse de Neuville)
It was analyzed by an international research group led by the University of Copenhagen, which thus aims to solve many of the mysteries concerning the anatomy and evolution of this bizarre marine animal.
The study shows that the giant squid (Architeuthis dux) has an equally titanic DNA: it is estimated that it contains 2.7 billion base pairs (the 'pegs' of the DNA double helix), equal to about 90% of the size of the human genome.
"Speaking of genes, we discovered that the giant squid is very similar to other animals: this means that we can study it to understand more about ourselves," explains Caroline Albertin, a researcher at the Marine Biological Laboratory, in the United States, who in the 2015 led the sequencing of the first genome of a cephalopod, an octopus to be exact.
Just by comparing the giant squid's DNA with that of man and that of four other cephalopod species, the researchers found that the sea monster has become as big as a bus without resorting to genome duplication, a strategy that evolution has instead adopted long ago to increase the size of vertebrates.
"The genome - Albertin underlines - is the first step to answer many questions about the biology of these strange animals". The researchers intend to understand how they developed the largest brain ever seen in invertebrates, as well as agility, sophisticated behaviors and almost instantaneous camouflage.
