Hundreds of metres beneath the waves off the Tasmanian coast, the crew aboard CSIRO research vessel RV Investigator filmed a tentacled sneak attack recently.

The CSIRO team has been exploring the area to document species diversity, and down at around 456 feet (139m) their bait line lured in a hungry squid – which lured in another hungry assailant just seconds later.

"On the loose and well-armed," the CSIRO team joked on Facebook. 

Exactly which squid species we're looking at is not clear at this point, but many of these animals, including the notorious giant squid, are known to dine on their own kin. Not only does snacking on your relatives come in handy when other food is scarce, but it's also a way to potentially eliminate hunting competition. 

Until recently, the only proof we had of such cannibalistic tactics came from the stomach contents of dead squid. A study conducted off the coast of California, however, found the behaviour was even more common than we thought. 

Several commenters online have asked whether this cephalopod clash was actually an attempt at mating. It's a reasonable hunch, but marine biologist Dr Dana Staaf, who has studied the reproductive habits of Humboldt squid, seems to have set the record straight.

"The 'mating or cannibalism?' question is always a good one to raise," she wrote on YouTube. "Sometimes an interaction can result in both! But in this case, it looks like straight predation to me. Spermatophore transfer usually occurs in the mouth/head region, so mating is more likely to take place in a head-to-head position."

The CSIRO team will be updating us as more information about this interaction comes to light, so watch this space!

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Top header image: Illustration of the squid Bathyteuthis abyssicolaCarl Chun/Wikimedia Commons