Creepy Cannibals: Squid Have No Qualms About Eating Their Own Kind

By Laura Geggel, Senior Writer | September 22, 2016 11:12am ET

The deep-sea diving Gonatus squid has a hearty appetite, even when it comes to eating its own kind, a new study finds.

The cannibalism finding came about during a 20-year study (1995–2015) in which marine researchers used a remotely operated vehicle (ROV) to study and video-record the eating habits of more than 100 different squid of the Gonatus genus in Monterey Submarine Canyon, off the California coast.

In particular, two species of Gonatus squid — Gonatus onyx and Gonatus berryi — showed a voracious appetite for munching on their own species, the researchers said. In fact, after looking at video they took of 109 squid eating meals, researchers found 42 percent of the prey G. onyx ate were other G. onyx squid. 

 
In addition, the researchers — Henk-Jan Hoving, an evolutionary ecologist of Marine Fishes at the Helmholtz Centre for Ocean Research Kiel in Germany, and Bruce Robison, a senior scientist and midwater ecologist at the Monterey Bay Aquarium Research Institute (MBARI) in California — never observed G. onyx feeding on G. berryi, but G. berryi routinely fed on G. onyx. 

 
Why cannibalism?
Cannibalism isn't uncommon in the deep sea, but this is the first time that scientists have proof that Gonatus squid engage in cannibalistic behavior, the researchers said.

They stressed the importance of having live-video evidence (in addition to stomach contents) of the cannibalism, since looking only at stomach contents of squid caught in trawling nets can be misleading. That's because squid and other marine creatures in trawling and jigging environments often become stressed and engage in unnatural behaviors, including cannibalism.

Though ROV lights and noises may also disturb marine creatures, in this study the researchers found that most of the prey capture happened before ROV the arrived, the researchers said.

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