Illustration by Alex Hanson
Off the coast of Norway and Greenland lies the memory of the hopefully-fictional Kraken, a Giant Squid capable of snapping a galleon sailing ship in two. The storybook sea monster takes up the ocean, its tentacles reaching for unassuming sailors and its heart set on destruction. If the Kraken had been real—if it had existed today, alongside its brethren of very-real Giant Squid—eager scientists would call it a cephalopod.
The oceans are a cephalopod’s stomping ground—squid, octopus, and cuttlefish can be found in the waters of the Pacific, Atlantic, Indian, Southern, and Arctic oceans. They’re feisty and adaptable, adorable and terrifying, and according to a study published last week in Current Biology, our squishy, tentacled friends are thriving.
The study started in response to declining numbers of the Australian Giant cuttlefish in South Australia. An international team, headed by researchers at the University of Adelaide, wanted to check in on cephalopods around the globe to see how they were fairing—and it turns out, they were better than alright. (Unleash the dancing octopuses!)
From 1953 to 2013, in all of the major oceanic regions listed above, cephalopod populations have been experiencing a steady incline. This includes 35 species and six families, from the common cuttlefish to the flapjack octopus more commonly known as Adorable (see also: Pearl from Finding Nemo).
Lead author and Research Fellow at the University of Adelaide, Zoë Doubleday, said the increase was “remarkably consistent” across the board. Cephalopod populations were increasing while many of their fish pals/meals fell by the wayside—in 2015 the World Wildlife Fund (WWF) found a 49 percent decline in marine vertebrae from 1970 to 2012. But during that time, cephalopods appear to have been laying back, kicking up their tentacles, and quietly ruling the high seas.
The squid, octopus, and cuttlefish can be fierce fighters and nifty scavengers, experts at camouflage and hiding, and their quick growth and short lifespans mean they’re able to cope with changes to their environment. But—though their resiliance is as good an explanation as any as to how these populations are surviving—researchers can only speculate on how cephalopods are not only surviving, but flourishing. So why are they doing so well? Tell us your secrets, you squirmy inkfish!
Well, an educated guessing-game led researchers to two probable reasons behind the cephalopods good fortune: rising ocean temperatures and overfishing.
Throughout the last century the ocean has warmed about 0.18° Fahrenheit, or 0.1° Celsius, which has been widely regarded as a bad move for the marine ecosystem—BUT, because of their short lifespans and ability to adapt, cephalopods have been able to avoid major harm. They’re in a Goldilocks zone: the warmer temperatures accelerate their lifespans (making way for newer, more resilient squids, octopuses, and cuttlefish), but the change in temperature doesn’t exceed their own optimal range or impact their ability to find food.
And, simply put, overfishing has knocked out the class’ predators and competitors—according the WWF “the global fishing fleet is 2.5 times larger than what the oceans can sustainably support.” What is bad news for many marine species, and even humans, seems to be good news for cephalopods. At least for the time being.
Things are even looking up for the Giant Australian cuttlefish, whose declining population led to the discovery of the rising global trend of cephalopods. From 2013 to 2015, the cuttlefish population in South Australia went from 13,500 to around 130,771.
Though researchers have their likely culprits—rising ocean temperatures and overfishing—they’re yet to confirm anything for sure. And as well as trying to pinpoint the reasoning, they’re trying to project the impact of all the squids, octopuses, and cuttlefish now swimming around in the ocean. Doubleday said the ramifications “are likely to be complex”.
So, although the Kraken was never confirmed as fact, it seems the cephalopods are making a collective effort to take over the ocean.