Studying the swift, smart, and shy: Unobtrusive camera-platforms for observing large deep-sea squid

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. Conventional methods for exploring the deep sea, including the use of nets, manned submersibles, and remotely operated vehicles (ROVs), are primarily suited for studying slow-moving or sessile organisms, and baited camera-traps tend to attract scavengers rather than predators. To address these issues, unobtrusive deep-sea camera platforms were developed that used low-light cameras, red illuminators, and bioluminescence-mimicking lures. Here, we report on several opportunistic deployments of these devices in the Wider Caribbean Region where we recorded several encounters with large deep-sea squids, including the giant squid Architeuthis dux Steenstrup 1857, Pholidoteuthis adami Voss 1956, and two large squid that may be Promachoteuthis sp. (possibly P. sloani Young et al. 2006). These species were recorded between depths of 557 and 950 m. We estimate the Mantle Lengths (ML) of Promachoteuthis were ~1.0 m, the ML of the Pholidoteuthis was ~0.5 m, and the ML of the Archtiteuthis was ~1.7 m. These encounters suggest that unobtrusive camera platforms with luminescent lures are effective tools for attracting and studying large deep-sea squids.