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MISSION DISPATCH 4 August 23, 2005 | Brian Cousin - @SEA Correspondent We are underway to our next site for scientific exploration: the deep waters of Desoto Canyon. This morning's JOHNSON-SEA-LINK I (JSL) submersible dive to recover Dr. Tammy Frank's benthic traps and Dr. Edie Widder's Eye-in-the-Sea (EITS) camera started with a picture perfect launch and finished with an unusual recovery. Erika Raymond, who rode in the aft compartment of the sub describes the dive as the best and worst she has been on. "At first we spent a lot of time looking for the pinger." A pinger emits an acoustic signal that can be received by the sub to guide it to its location, in this case, to the vicinity of Tammy's traps. "The sub stirred up sediment off the bottom, and since there's hardly any current it just hung suspended in the water. That made the pinger hard to spot". 
The best part came when Erika noticed a juvenile 6-gill shark 8 to 10-feet long on the video monitor. The docile 6-gill hung around the sub for about 15-minutes, slowly investigating the Eye-in-the-Sea, and paying particular attention to the bait containers. Erika suspects there will be some excellent video of the 6-gill on the EITS. What she didn't plan on was the challenge of getting it onto the submersible and safely back on the deck. The Eye-in-the-Sea has been refined since last year in a number of ways. Most conspicuous is the elegant tubular fold-down assembly that aligns the bait container at the optimal distance and orientation to the camera lens. On last year's Deep Scope cruise, the bait positioning problem had to be resolved with whatever could be found at hand. Most appropriate was an old aluminum step ladder and a few other bits and pieces. So was invented the CLAM (Cannibalized Ladder Alignment Mechanism) - a shining example of inspirational technology. 
The new assembly works in essentially the same way as the CLAM, but features a sleeker profile and an official looking bait container fashioned out of residential plumbing parts. The clasp that stows it upright against rest of the EITS has been reengineered for easier opening and closing from the confines of the sub, and has been joined by another catch that secures the EITS to the submersible during trips to and from the surface. Picking up the Eye-in-the-Sea from the bottom with the sub hovering in the water column requires a great deal of skill under the best conditions. On this occasion the pilot had to approach the alignment mechanism from the side, instead of from the front, due to its proximity to an outcropping of rocks. During the process, the Eye-in-the-Sea was knocked over onto its side. Once upright again, and with the alignment mechanism stowed, the pilot moved to line up the spikes that support the EITS on the front of the sub with the receptacles on the EITS, and grasp another fitting with the subs mechanical claw. The pilot receives no tactile response to the forces being exerted and in this case, part of the Eye-in-the-Sea's frame was bent slightly. 
The sub's ascent went without incident until it was near the surface, when the EITS alignment mechanism opened unexpectedly, probably as a result of the bending of the frame. The sub crew took care of the problem by putting an additional swimmer in the water after the sub had been secured on its tow line and was floating in the calm sea behind the ship. The two swimmers were able to raise the mechanism and tie it off for normal recovery of the sub to the deck of the ship. With all personnel and equipment safely onboard, Dr.Edie Widder and grad student Erika Raymond turned their attention to the heart of the Eye-in-the-Sea: its camera and data recording package. Fortunately, the vital electronic components of the EITS sustained no damage, and fresh data is happily downloading to a computer in the ship's dry lab. Tammy Frank showed proof of concept with her traps, retrieving a benthic crab and a deep-sea shrimp from their confines. Unfortunately they had company - disgusting hagfish company - whose slime caused respiratory failure and death in all but themselves. 
Tammy's experience and success working in the deep pelagic regions of the sea fuels her curiosity and determination to work with animals from the benthic environment. She maintains a sense of humor about the trials and tribulations that go along with making advancements in science - but just barely when it's hagfish. Tammy believes the galatheid crab she's been studying on the physiological prep has an ultraviolet visual pigment absorbing at about 390 in addition to the standard 500 nm pigment she was expecting to find. This was recently confirmed with a second dark adaptation and more tests. This came as a complete surprise, as she had been looking for structural adaptations in the crab's eye that would increase its visual sensitivity to the surrounding light that is generally blue, around 480 nanometers. As far as anyone knows, there is no UV light down at 1800 feet, so this discovery came as a complete surprise. To support two pigments, the crab must actually sacrifice some sensitivity to the dim blue light found at depth. Why would it do so unless there was another type of light to see? 
By evening, Erika has downloaded the images from the Eye-in-the-Sea.
While there were no images of the 6-gill shark, a large squid passing
through the top of the frame caused a commotion in the dry lab. Is it the
same species as was seen during last year's Deep Scope mission? Erika says
that it's possible, but hard to say for sure at this time. Certain
features like size, mantle, tentacles and the depth it was recorded
support the possibility, or at least don't discount the possibility
outright.
Our twenty-hour transit to Desoto Canyon will be used to make repairs the frame of the Eye-in-the-Sea, and ponder further modifications to the benthic traps. 
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