Wildlife photography is a notoriously difficult art form, requiring patience, stamina, and serendipitous timing. A recent Twitter thread demonstrated the perils of life in the field, as did the BBC’s A Perfect Planet as it sent camera operators to some of the most inhospitable habitats on Earth. Things only get harder as you move underwater, though a recent spike in recreational blackwater diving has allowed marine scientists to lay eyes on the living artwork that is some of the ocean’s residents’ larval forms.
One deep-sea beastie whose appeal has endured since tales of the “Kraken” first began circulating in Norse mythology (yes, it's Norse, not Greek) is the giant squid, Architeuthis dux. Something of a benthic celebrity, no doubt – but filming a giant squid video has historically proven to be an unconquerable quest for many a talented underwater camera operator (unless they're already dead or stealing fish). That is until Dr Edith Widder came onto the scene.
Promachoteuthis sloani captured in brine pools near the Gulf of Mexico. Video credit: Robinson et al, 2021. CC BY-NC-ND 4.0
Dr Widder, of the Ocean Research & Conservation Association, has actually managed to get A. dux on film on several occasions and in a new study published in the journal Deep Sea Research Part I: Oceanographic Research Papers, she and her team reveal the secrets to their success. Not ones to hog the glory (as if knowing how to film giant squid was the only thing stopping us from doing it), their tell-all paper is open access and includes some jaw-dropping footage of deep-sea squid species zooming around in the dark.
At around 13 meters (43 feet) in length, giant squids are one of the largest invertebrates (that we know of) found anywhere on Earth. Its enormous size unfortunately doesn’t make it any easier to spot, given their preferred depth is over 400 meters (1,312 feet). Their enormous eyes (about the size of a dinner plate, the largest of all living creatures) come in handy here, enabling them to see in the near-pitch-black waters. This means that while remotely operated vehicles and submersibles might have believed they were sneaking up on these animals unannounced, their massive googlies probably saw them coming a mile off.
Pholidoteuthis adami squid video recorded in the Exuma Sound in The Bahamas. In the bottom center of the video, a bait crate can be seen being fed upon by several Bathynomus giganteus, giant isopods. Video credit: Robinson et al, 2021. CC BY-NC-ND 4.0
To overcome this, Widder and colleagues developed a design that used dim-red lights instead of the bright white lights usually employed in underwater exploration. The squid’s massive eye is unable to see this light, vastly improving the operator’s chances of getting a closer look. Add to this a lure (coined E-Jelly) that mimics the kind of bioluminescent prey A. dux is partial to, and you have yourself a winning combination. Out in the watery field, the tech proved effective in getting video footage of a range of deep-sea squid species including Promachoteuthis sloani and Pholidoteuthis adami, both seen in the videos above.
Giant squid video with Architeuthis dux. The spinning light is the E-Jelly lure, beneath is a bait bag containing mahi mahi Coryphaena hippurus. The squid first appears on the left of the image before heading offscreen at 0:40. It then returns at 1:06 and leaves at 1:30. At 5:22, the squid returns again and attacks the E-Jelly. Video credit: Robinson et al, 2021. CC BY-NC-ND 4.0
“It is somewhat ironic that A. dux is arguably the most iconic deep-sea species, yet almost nothing is currently known about its conservation status,” wrote the paper’s authors. “One of the largest threats A. dux, and many other deep-sea cephalopods, may face is sound pollution. Loud low-frequency sounds, such as those emitted during seismic surveys, can cause significant trauma to cephalopods and the growing global use of seismic surveys has been associated with several stranding of A. dux.
“As the methods for filming large deep-sea cephalopods are refined and this increases the efficiency at which new footage of these species can be recorded, this will eventually allow us to start answering new questions about these species.”