Now Bruce Deagle of the University of Tasmania, Australia, and his team have analysed the gut contents of a male giant squid caught by fishermen off the west coast of Tasmania in 1999. Among the slurry of macerated prey, they found three tentacle fragments and 12 squid beaks. The beaks could not be unequivocally identified, but all of the squid DNA in the slurry, and the tentacle fragments, was found to be that of A. dux (Journal of Heredity, vol 96, p 417). "This strongly suggests cannibalism," says team member Simon Jarman of the Australian Antarctic Division in Kingston, Tasmania. The only other prey species identified was a fish, the blue grenadier.
Steve O'Shea and Kat Bolstad at the Auckland University of Technology in New Zealand were the first to find evidence of cannibalism in A. dux, in a female caught in New Zealand waters. They published their findings in the New Zealand Journal of Zoology last year. But O'Shea suspected the cannibalism was accidental.
"The male giant squid has to use a puny 15-gram brain to coordinate 150 kilograms of weight, 10 metres of length and a 1.5-metre-long penis," he says. "He physically plunges this penis into the female's arms, which are rather unfortunately right next to her beak. Because he is coordinating so much with so little, I think occasionally bits get chewed off when they inadvertently get too close to the beak."
More at the link.