The Freefall Benthos Observation System (FBOS) was used only during DISCOL 1 and 3. It was originally designed by engineers of the Institute of Hydrobiology from the University of Hamburg and consisted of a 2 m high stainless steel tetrapod equipped with a 35 mm Benthos survey camera, strobe, battery pack, data chamber encoder, tandem-release transponders and glass vacuum spheres for buoyancy. The ballast weight (an old train wheel) was mounted below the tetrapod frame. The camera was equipped with 30 to 90 m of film for 300 to 2400 pictures and was deployed at different sampling stations outside the DEA.
After two deployments, the tetrapod was rigged with a pole and a fish was attached as bait within the still camera’s field of view. For later deployments, the fish was put into a clear plastic trap to catch additional fish and crabs to learn about the behavior of the organisms attracted to the bait.
Seven deployments were executed during DISCOL 1, resulting in about 6000 exposures of various invertebrate and vertebrate animals attracted by the bait. At the end of the cruise, the FBOS was combined with a current meter chain and deployed at the centre of the DEA to be recovered during DISCOL 2, which unfortunately failed and the resulted in the loss of the device.
During DISCOL 3, six additional FBOS deployments were executed. However, at the end of the cruise the transponder attached to the device failed to respond and the device was lost.