Scientists have discovered, through DNA research, the the Giant Squid species came close to extinction at some point in the past, for unknown reasons.   All modern Giant Squid share nearly the exact DNA, meaning that they all derive from only a few ancestors.

  "The fearsome sea monster of Greek and Norse tales — and the creature that fought Captain Nemo in 20,000 Leagues Under the Sea — was once driven close to extinction, gene sequencing suggests. The genetic uniformity of giant squid across distant oceans hints at a past evolutionary bottleneck, but also at low resiliency toward future crises.

The finding comes from an analysis of tissue samples from 43 giant squid (Architeuthis spp.) from around the world. The samples came mostly from dead squid that had been found washed up on beaches or floating on the ocean surface, although a few came from animals that were accidentally caught by deep-sea trawlers."

And in other giant squid news, the destroyer USS Stein was apparently attacked while on a cruise back in the 70's by an unknown breed of giant squid.

   "She (the USS Stein) is noteworthy as a U.S. Navy vessel that has apparently been attacked by an unknown species of giant squid. In 1978, the "NOFOUL" rubber coating of her AN/SQS-26 SONAR dome was damaged by multiple cuts over 8 percent of the dome surface. Nearly all of the cuts contained remnants of sharp, curved claws found on the rims of suction cups of some squid tentacles. The claws were much larger than those of any squid that had been discovered at that time."

You know squid are bad azz when they are more than willing to go after a United States warship!  Fearsome indeed!