Silent predators in the sea such as the giant squid are hardly documented in their mesopelagic habitat. However, marine scientists have unveiled their hunting behavior for the first time.
A 'first-of-its-kind' video shows how this enigmatic giant squid stalks and attacks its prey in the deep sea, as reported by Science Alert. Thanks to new robotic technology, humans are able to dive underwater without really diving into the hostile environment of crushing pressures and darkness of the ocean depths.
These new devices also surpass underwater vehicles which are only best suited to studying slow or immobile organisms. For the sensitive, low-light-eyed squid, these vehicles can cause discomfort and scare them off. Which is why a team of researchers led by Nathan Robinson of the Oceanographic Foundation in Spain devised a different solution.
It Paid Off
The deep-sea platform equipped with a camera has served its purpose and was able to record several encounters with large squids at depths between 557 and 950 meters (1,827 and 3,117 feet) in the Gulf of Mexico and in Exuma Sound near the Bahamas.
The first encounters were in 2004 and 2005 with two large animals that may have been Promachoteuthis sloani, a species of squid from the northern Atlantic Ocean, at a mantle length of 1.0 meters.
As the team continued to update their platform, they were able to capture Pholidoteuthis adami or scaled squid, with a mantle length of 0.5 meters, in 2013. Finally, they filmed Architeuthis dux, the giant squid itself, clocking in at a mantle length of 1.7 meters (excluding the tentacles), in 2019.
While proven to be challenging to study in the wild, the encounters strongly suggest that the large squids are in favor of visual signals than sound.
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Giant Squid's 'Fascinating' Hunting Behavior
The research published in Deep Sea Research Part I: Oceanographic Research Papers described the behavior of the first live giant squid as perhaps the "most fascinating".
"The legend of the "kraken" has captivated humans for millennia, yet our knowledge of the large deep-sea cephalopods that inspired this myth remains limited," the authors of the paper wrote, noting that conventional methods for exploring the deep ocean had not been primarily suited for predators.
Using unobtrusive camera-platforms, the team observed that giant squids appear to be active and engaged in hunting using visual cues with their humongous eyes, and more of a stalker than ambush predators as previously put forward in several papers.
Although the encounters were few, each one of them shed light and provided new information about the range and distribution of the giant species. Using passive platforms also suggests that the tools are extremely helpful in observing these elusive creatures, especially if refined and optimized for specific encounters, the researchers said.
"We recommend that future studies assess the value of using low-light systems or optical lures in a more scientifically-robust manner," the team noted.
"For example, while the bioluminescence-mimicking E-Jelly appears to be an effective tool for attracting cephalopod species, future studies could assess whether lures of differing intensities, colors, or light patterns vary in their capacity to attract various taxa of deep-sea cephalopods."
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