If noisy vehicles using bright lights drive away wildlife on land, wouldn’t the same be true for a submersible or ROV operating underwater? This realization caused the Australian Research Council to contract with Harbor Branch to design and build tools that would not scare away the oceans’ wariest creatures in order to make it possible to film them and their behavior.

The result is the Medusa lander, an ocean observing system used during a September expedition to the Peru-Chile Trench off the South American coast to study bioluminescence and the biological rhythms of sea creatures in the mesopelagic, or twilight zone. Harbor Branch was represented onboard the German research vessel Sonne by senior ocean engineer Lee Frey, who was funded by the Australian Research Council, as part of its Deep Ocean Australia Project. Lee and his team designed and built the Medusa landers as part of an ongoing collaboration between the University of Queensland (UQ) and Florida Atlantic University (FAU).

Medusa is designed to be an unobtrusive observer equipped with water and light sensors  and an ultra low-light video camera and far-red LED lighting that cannot be seen by many creatures. It can be deployed on the seafloor as deep as 2,000 meters (6,562 ft) or, after removing the legs and adding a length of line and a fin for stability, it can float in the water column, as it did during this expedition. Naturally, it can be difficult for an immobile camera to witness any sea life without some means of attraction, which in this instance, took the form of a tuna head lashed to a bait support bar in the camera’s foreground.

Deployments at 1,000 and 585 meters (approximately 3,281 and 1,919 feet, respectively) produced little action, but when recovery of the third opportunity (500 meters) revealed that the bait was missing and the bait support bar was badly bent, UQ’s Dr. Justin Marshall, along with his doctoral candidate Wen-Sung Chung, and Harbor Branch’s Lee Frey reviewed the tape. There they saw several Humboldt Squid, which grow to six feet and 100 pounds, relentlessly working to liberate the free snack. A fourth deployment at 700 meters yielded similar results.

These data help characterize marine habitats in and near the Peru-Chile Trench and to record Humboldt Squid behavior unaffected by the effects of bright lights and the din of motors and mechanical systems.

Cruise Report (PDF)